ZOOM MEETING ID: 967 5849 5307

Quantum information technologies enable great advances in security, communications, and computation but are fundamentally different than their classical counterparts. The common platforms that are used are susceptible to minor disturbances and require highly controlled environments (e.g. cryogenic refrigeration). Optical platforms use individual photons to generate quantum bits, or qubits, which are the basis of quantum technologies. Defect-based single-photon emitters (SPEs) exist in deep-level electronic states of wide-bandgap semiconductor materials and are shielded by environmental perturbations (e.g. thermal phonons, electromagnetic noise), making them a promising candidate for quantum devices that require robust operation. These emitters can be found in a wide range of materials (e.g. diamond, silicon carbide, hexagonal boron nitride etc.), but existing characterization techniques are limited in their ability to identify new SPEs. Taking advantage of the contrast in vibrational properties between the defect and the bulk material, we are able to identify the presence of defects in a material using infrared (IR) spectroscopies. Advanced IR nano-optic probe technologies—scattering-type scanning near-field optical microscopy (s-SNOM) and nanoscale Fourier Transform IR (nano-FTIR)—provide spectroscopic information and spatial resolution of defects on the scale of λ/100, well below the diffraction limit. Combining this novel technique with PL spectroscopic mapping, we will prove correlations between IR spectroscopic features and SPE behaviors, thereby enabling more efficient identification and qualification of new SPEs.

ZOOM MEETING ID: 915 9548 9690

Breast cancer is the most common cancer among women in the United States, with 1 in 8 women diagnosed with breast cancer in her lifetime. While many effective therapeutics exist to target and treat breast cancer, little progress has been made in preventing its formation through preventative, or prophylactic, vaccines. We sought to develop a preventative vaccine for triple-negative breast cancer (TNBC), a breast cancer that is often difficult to treat since it is lacking three of the major receptors necessary for targeted breast cancer therapies. Our “tumor nano-lysate” (TNL) vaccine is fabricated by sonicating 4T1 cancer cells, which are derived from a highly metastatic TNBC murine model. We characterized this vaccine by size, charge, morphology, and composition. A toxicity analysis was also conducted, and an in vivo mouse study was performed with mice pre-treated with the TNL vaccine showing delayed 4T1 tumor growth and metastasis compared to unvaccinated mice. Further immune studies were performed to analyze the mechanism behind this vaccine.

ZOOM MEETING ID: 922 8546 9530

Photonic crystal (PhC) cavities are useful for many emerging photonic technologies and fundamental investigations, ranging from on-chip light-emitting diodes and modulators to quantum information processing. A key advantage of PhCs is their ability to support both ultra-high Q factors (Q) and low mode volumes (V), leading to enhanced light-matter interaction and improved performance metrics of devices based on PhCs. Recently, a 1D PhC with a bowtie-shaped unit cell was reported for record low V in a dielectric material.1 In this abstract, we report the design of a 2D bowtie PhC comprising a two-dimensional triangular lattice of circular air holes in silicon with a bowtie-shaped air hole located inside a line defect. We report a simulated Q near 106 and a calculated mode volume near 10-3 (l/n)3.  The feasibility of fabrication has been demonstrated and optical trapping simulations suggest that the 2D bowtie PhC will be a highly advantageous platform for low-power optical trapping of nanoscale objects.

To demonstrate the feasibility of our approach, our initial 2D bowtie photonic crystal design simply added a bowtie unit cell in the center of a previously reported design for a PhC with an L9 defect (i.e., line defect with 9 missing air holes).2 This unoptimized 2D bowtie PhC has a simulated Q ≈ 103 near 1550 nm, V ≈ 4×10-3 (λ/n)3, and a more than 200-fold enhancement of the electric field at the center of the bowtie. Optical trapping simulations carried out in COMSOL suggest that the peak optical force on a 8 nm polystyrene bead positioned in this unoptimized bowtie PhC cavity with a coupled power of 0.27 mW is approximately 0.115 pN, which is sufficient to indefinitely trap the particle. A scanning electron microscopy image of the unoptimized 2D bowtie PhC fabricated in the CNMS.

To further increase the achievable light-matter interaction and optical trapping force, we carried out a particle swarm optimization (PSO) in Lumerical FDTD Solutions. Following prior work,3 we selected a 2D PhC with a L3 defect for the design optimization and allowed the 35 air holes nearest the defect to move by 0.2a where the lattice constant a = 410 nm, hole radius = 102.5 nm, and silicon slab thickness = 220 nm. The key differences from prior work are the incorporation of a bowtie unit cell in the L3 defect and the use of PSO as the inverse design algorithm. Employing 32 particles and 250 generations, the PSO simulations enabled the design of a 2D bowtie PhC with a simulated Q = 1.9×106 at 1551 nm and V = 4×10-3 (λ/n)3. These record-high metrics for a 2D PhC open the door to significantly improved performance metrics for applications relying on strong light-matter interaction, including low-power optical trapping.

1. Hu, S. & Weiss, S. M. Design of Photonic Crystal Cavities for Extreme Light Concentration. ACS Photonics 3, 1647–1653 (2016).
2. Akahane, Y., Asano, T., Song, B.-S. & Noda, S. High-Q photonic nanocavity in a two-dimensional photonic crystal. Nature 425, 944–947 (2003).
3. Asano, T. & Noda, S. Iterative optimization of photonic crystal nanocavity designs by using deep neural networks. Nanophotonics 8, 2243–2256 (2019).

This work was supported in part by the National Science Foundation (EECS1933109).

ZOOM MEETING ID: 986 0799 1832

Arrays of plasmonic nanoparticles with resonances in the visible spectrum can produce brilliant colors, enabling color pictures or displays with sub-micron resolution.  Incorporating an active material is a promising way to add switchable or tunable behavior to such devices.  We demonstrate multi-state plasmonic displays based on the phase-change material vanadium dioxide (VO2).  In addition to the thermally-induced metal-insulator transition in the pristine VO2, hydrogen doping creates two additional, reconfigurable VO2 phases to enable a quadri-state dynamic color display.  Moreover, we show that electron-doping from a thin metal film can locally tune the phase-transition temperature.  By leveraging thermal and electronic excitations (temperature, hydrogen doping, electron doping) we produce an encrypted display with two layers of information, each accessed by a different decryption key.  This ability to design multi-state optical systems, sensitive to multiple stimuli, significantly broadens the field of potential devices and applications for this phase-change material.

ZOOM MEETING ID: 960 7051 3783

Background. Osteoarthritis (OA) is a debilitating and prevalent chronic disease, but there are no approved disease modifying OA drugs (DMOADs), only pharmaceuticals for pain management. OA progression, particularly for post-traumatic osteoarthritis (PTOA), is associated with inflammation and enzymatic degradation of the extracellular matrix. In particular, matrix metalloproteinase 13 (MMP13) breaks down collagen type 2 (CII), a key structural component of cartilage extracellular matrix, and consequently, matrix degradation fragments perpetuate inflammation and a degenerative cycle that leads to progressive joint pathology. The rapid clearance rate of molecules from the joint space is a challenge of intra-articular treatments; small molecules clear through synovial vasculature, and macromolecules drain through the lymphatics This causes drugs to be rapidly cleared, with half-lives ranging from less than one hour for small molecules, 1-4 hours for NSAIDs/steroids, and ~1 day for large molecular weight Hyaluronic Acid. Here, we tested nano and macro-engineering approaches to make more efficient therapeutics with lower dosing and side effects. Specifically, extracellular matrix-binding MMP13 RNA interference (RNAi) nanoparticles (NPs) were synthesized as a DMOAD. The new retention approach pursued deviates from the convention of targeting specific cell types (e.g., through cell surface receptors) and instead leverages a monoclonal antibody (mAbCII) that targets extracellular CII that becomes uniquely accessible in OA-damaged cartilage. CII monoclonal antibody-functionalized nanoparticles carrying small interfering ribonucleic acid (siRNA) (mAbCII-siNPs) create an in situ NP depot for retention and potent activity within OA joints. Furthermore, we sought to engineer a nano-in-micro carrier system that has both the benefits of nano-biomaterials, i.e. ability to be internalized and escape endosomes within chondrocytes/synoviocytes for intracellular cargo delivery, and micro-biomaterials, i.e. ability to be retained within the joint space and escape rapid clearance mechanisms (due to lymphatics/venules). The rational thought design of our nano-in-micro engineered technology consisted of poly [DMAEMA67-b-(DMAEMA29-co-BMA75-co-PAA40)] (DDPB) endosome-escaping nanoparticles (siNP) embedded in poly(lactic-co-glycolic acid) (PLGA) microplates (μPLs) to create siRNA-delivering nano-in-microplates (siNP-μPLs).

Methods. The mAbCII-siNPs were synthesized comprising an endosome-escaping, RNA-condensing core and a passivating, colloidally-stabilizing poly (ethylene glycol) (PEG) surface amenable to antibody conjugation. The collagen II targeting monoclonal antibody (mAbCII) was conjugated to COOH-PEG-ECT by N-hydroxysulfosuccinimide; 1-Ethyl-3-(3-(dimethylamino)propyl) carbodiimide (sNHS/EDC) chemistry. Successful conjugation of PEG-bl-DB to mAbCII was validated by size exclusion chromatography. For the nano-in-micro system, a top-down approach was employed for synthetizing shape defined poly (D,L-lactide-co-glycolide) (PLGA) microPlates (μPLs) for local and sustained release of matrix metalloproteinase 13 (MMP-13) RNA interference nanoparticles (siMMP13-NPs). Both formulations (mAbCII-siNPs and siMMP13-NPs/μPLs) were physico-chemical and pharmacological characterized. Their therapeutic efficacy was assessed in a mechanically-induced OA mouse model (PTOA).

Results. The mAbCII-siNPs loaded with MMP13 siRNA (mAbCII-siNP/siMMP13) potently suppressed MMP13 expression (95% silencing) in TNFα-stimulated chondrocytes in vitro and had higher binding to trypsin-damaged porcine cartilage than control NPs. In an acute mechanical injury mouse model of PTOA, mAbCII-siNP/siMMP13 achieved 80% reduction in MMP13 expression (p = 0.00231), whereas control siNP/siMMP13 achieved only 55% silencing. In a more severe, longer-term PTOA model, weekly mAbCII-siNP/siMMP13 treatment provided significant protection of cartilage integrity (0.45+/-.3 vs 1.6+/-.5 on the OARSI scale; p=0.0013) and overall joint structure (1.3+/-.6 vs 2.8+/-.2 on the Degenerative Joint Disease scale; p=0.0418), including reduction of osteophyte formation (siMMP13 vs siNEG: 0.088+/-0.074 vs 0.47+/-0.107 mm femoral osteophyte outgrowth; p<0.0001). Multiplexed gene expression analysis of 254 inflammation-related genes showed that MMP13 inhibition suppressed clusters of genes associated with tissue restructuring, angiogenesis, innate immune response, and proteolysis. Finally, in benchmarking studies, intra-articular mAbCII-siNPs better reduced OA disease progression relative to either one time or weekly treatment with the clinical gold standard steroid methylprednisolone. For the nano-in-micro system, μPLs (square prims of 20 × 10 µm size), made out of 15 mg of PLGA, exhibited an apparent Young’s modulus of ~ 3 MPa value of about of 3.1 ± 0.9 Pa, similar to that of cartilage. Also, they showed a high damping capability. siNPs were able to withstand the PLGA embedding process to make siNP-μPLs with no change in chemicophysical properties. In an in-vitro release assay, siNP-μPLs were able to release siNPs for up to 5 weeks; released siNPs maintained chemicophysical properties, endosome-escaping ability, and gene silencing activity for the duration of the study (5 weeks), achieving over 50% silencing after 4 weeks (using siRNA against both a model gene, Luciferase, and against our pathologic gene of interest, MMP13). Nano-in-microplates complexed with siRNA against MMP13 (siMMP13-NPs μPLs) were tested for efficacy in a mechanical load-induced mouse model of PTOA and compared to mAbCII-siNPs. Longitudinal in-vivo studies demonstrated that unformulated DDPB siMMP13-NPs show no significant gene knockdown at 7 days and that mAbCII-siNPs lose knockdown at 10 days post-injection, but siMMP13-NPs μPLs achieved over 65% inhibition at 28 days in combined synovial and cartilage tissue, meanwhile medial synovial tissue by itself had over 75% MMP13 knockdown at 7, 14, and 28 days. MMP13 inhibition revealed marked reduction in the expression of global markers of inflammation (C1s, C2, IL-1b, IL-6, and TNFα). siMMP13-NPs μPL treatment decreased histological OARSI scoring (less meniscal deterioration/ mineralization, synovial hyperplasia, and hyaline cartilage degradation/fibrillation) and μCT analyses showed global decreases in osteoarthritic pathological changes i.e. osteophytes, subchondral bone loss, etc.

Conclusions. Overall, mAbCII-siNP/siMMP13 and siMMP13-NPs/μPLs were able to provide prolonged, localized, knockdown of MMP13 leading to a significant improvement in PTOA/OA phenotype; these results demonstrate the unique ability of targeted nano and nano-in-micro formulations for sustained delivery of intracellular-acting biologics, such as siRNA.

ZOOM MEETING ID: 973 9766 5981

Separating molecules or ions with sub-Angstrom scale precision is important but technically challenging. Achieving such a precise separation using membranes requires Angstrom scale pores with a high level of pore size uniformity. Herein, we demonstrate that precise solute-solute separation can be achieved using polyamide membranes formed via surfactant-assembly regulated interfacial polymerization (SARIP). The dynamic, self-assembled network of surfactants facilitates faster and more homogeneous diffusion of amine monomers across the water/hexane interface during interfacial polymerization, thereby forming a polyamide active layer with more uniform sub-nanometre pores compared to those formed via conventional interfacial polymerization. The polyamide membrane formed by SARIP exhibits highly size-dependent sieving of solutes, yielding a step-wise transition from low rejection to near-perfect rejection over a solute size range smaller than half Angstrom. SARIP represents an approach for the scalable fabrication of ultra-selective membranes with uniform nanopores for precise separation of ions and small solutes.

ZOOM MEETING ID: 960 0172 6429

Short interfering RNA (siRNA) is a powerful and specific gene silencing platform that can be used to target cancer-driving genes. However, translation to the clinic has been hindered by naked siRNA’s rapid clearance by the kidneys, susceptibility to nuclease degradation, and lack of innate targeting or penetration in to target tissues. Traditional lipid- or polymer-based nanocarriers have been explored in an attempt to overcome these obstacles but are often limited by complex synthesis, lack of specificity, and toxicity. Herein, we describe a platform that allows siRNA to bind endogenous albumin, the most abundant protein in human serum, to deliver the siRNA-albumin nanocomplex to tumors. Albumin’s natural tumor tropism, exceptional circulation time, and role as a carrier protein make it an appealing carrier for tumor delivery. We have optimized the structure of this albumin-siRNA nanocomplex to confer superior circulation time, tumor targeting, and ultimate tumor gene silencing.

ZOOM MEETING ID: 922 8923 9017

Metal nanoparticles have captured the attention of the larger scientific community for the past few decades. Although there is a wide understanding on its applications and how it can be used to improve current technologies, the ability to understand its own synthetic intricacy is still unavailable. While many organic chemists can design synthetic pathways to obtain their final product, many nanoparticle chemists are unable to replicate the same vigor. Here, I use a wide range of thioureas to understand how the decomposition speed of a precursor to a monomer affects the synthetic pathway of a nanoparticle. 

ZOOM MEETING ID: 934 9809 2859

ZOOM MEETING ID: 982 6527 8548

Currently, cancer is the second-leading cause of death in the United States1 with colorectal cancer (CRC) being the third deadliest2. It is estimated that about half of CRC patients develop secondary metastatic tumors, at which point a cure is unlikely3-4. Metastatic cancer cells can migrate either by creating microtracks through stromal tissue, or through pre-existing pathways generated from the anatomical structure of the tissue5. It is well accepted that metastasis is influenced by intratumor heterogeneity, which is caused by genetic and epigenetic differences between cells in the primary tumor. As tumors progress, the cells accumulate mutations that cause differences within the population, forming different phenotypes associated with metastasis, such as: cell invasion, survival in circulation, intravasation/extravasation, and the ability to reattach to new organs6. How these heterogeneous phenotypes alter a cancer cell’s invasive and migratory abilities is still not fully understood. Here we show that primary tumor CRC cells (SW480) display greater migratory abilities in collagen than their metastatic counterparts (SW620). We found that the SW480 cells displayed a significantly higher migration speed than the SW620 cells when placed in collagen-based three-dimensional microtracks. The primary tumor cells’ migratory speed also had a much wider spread than the metastatic population and displayed a higher invasive fraction through collagen coated transwells. Our results contradict the prevailing hypothesis that the most migratory cancer cells cause the most metastasis in the body7. We hypothesize that the spread in migratory speed within the primary tumor cells may be attributed to heterogeneity within the cell line, correlating with intratumor heterogeneity observed in vivo. In order to continue studying the role of heterogeneity in CRC cell migration, we are conducting consecutive transwell assays with the SW480 cells to compare the motility of the highly and poorly migratory SW480 subpopulations to the metastatic SW620s in three-dimensional collagen microtracks.

1. Siegel, R. L., Miller, K. D. & Jemal, A. Cancer statistics, 2019. CA: A Cancer Journal for Clinicians 69, 7–34 (2019).
2. Marley, A. R. & Nan, H. Epidemiology of colorectal cancer. Int J Mol Epidemiol Genet 7, 105–114 (2016).
3. Global cancer statistics, 2012 - Torre - 2015 - CA: A Cancer Journal for Clinicians - Wiley Online Library. https://acsjournals.onlinelibrary.wiley.com/doi/abs/10.3322/caac.21262.
4. Molecular Basis of Colorectal Cancer. New England Journal of Medicine 362, 1245–1247 (2010).
5. Friedl, P. & Alexander, S. Cancer Invasion and the Microenvironment: Plasticity and Reciprocity. Cell 147, 992–1009 (2011).
6. Zeeshan, R. & Mutahir, Z. Cancer metastasis - tricks of the trade. Bosn J of Basic Med Sci 17, 172–182 (2017).
7. Luo, F. et al. Comparative profiling between primary colorectal carcinomas and metastases identifies heterogeneity on drug resistance. Oncotarget 7, 63937–63949 (2016).

ZOOM MEETING ID: 938 1334 4428

Silicon waveguides have enabled large-scale manipulation and processing of near-infrared optical signals on chip. Yet, expanding the bandwidth of guided waves to other frequencies would further increase the functionality of silicon as a photonics platform. Frequency multiplexing by integrating additional architectures is one approach to the problem, yet it is challenging to design and integrate within the existing form factor due to scaling with the free-space wavelength. Here, we demonstrate that a hexagonal boron nitride (hBN)/silicon hybrid waveguide enables dual-band operation simultaneously at both mid-infrared (6.5-7.0 µm) and telecom (1.55 µm) frequencies, respectively. Our device is realized via lithography-free transfer of hBN onto a silicon waveguide, maintaining near-infrared operation, while mid-infrared waveguiding of the hyperbolic phonon polaritons (HPhPs) supported in hBN is induced by the index contrast between the silicon waveguide and the surrounding air underneath the hBN, thereby eliminating the need for deleterious etching of the hyperbolic medium. We verify the behavior of HPhP waveguiding in both straight and curved trajectories, and validate their propagation characteristics within an analytical waveguide theoretical framework.  This approach exemplifies a generalizable approach based on the integration of hyperbolic media with silicon photonics for realizing frequency multiplexing in on-chip photonic systems.

ZOOM MEETING ID: 960 4535 7556

Nearly 70-90% of patients who succumb to metastatic breast and prostate cancer have tumors in their bones. Tumor establishment in bone causes bone destruction, which is associated with debilitating pain and fracture risk. Bone breakdown also releases bone matrix-associated growth factors (e.g., TGF-β) that catalyze further tumor growth, creating a “vicious cycle” known as tumor-induced bone disease (TIBD). Gli2 is a Hedgehog transcription factor which has been identified as a promising therapeutic target for TIBD. Gli2 is over-expressed in bone-associated tumor cells in which it drives expression of genes such as parathyroid hormone-related protein (PTHrP), a factor that leads to osteoclast activation. My central hypothesis is that selective silencing of Gli2 in metastatic tumor cells in bone can block osteoclast activation and the resultant bone destructive effects of TIBD. However, Gli family transcription factor inhibitors are not available that are highly selective to Gli2, and those Gli inhibitors that are available suffer from poor pharmacokinetics. These combined factors motivate my overall goal to develop a more selective, more potent, and bone tumor targeted Gli2 siRNA system to treat TIBD.

Short interfering RNA (siRNA) can be targeted with specificity to in theory any target gene. The first siRNA lipid nanoparticle (patisiran) was FDA approved in 2018. However, the next approved siRNA medicine (givosiran) was in the form of a conjugate structure based that utilizes multivalent GalNAc for targeting liver hepatocytes; in fact, most all late stage clinical trials on siRNA medicines now utilize conjugate approaches (focusing on hepatic targets). I am interested in opening a new realm of siRNA polymer-conjugates that will enable greater variation in composition for targeting other tissues sites, greater variation in targeting ligand valency and density, and tunable integration of additional components.

I present developments towards a highly controlled, high throughput, and application adaptable approach to engineer new polymer-siRNA conjugates. Most previous polymer conjugate strategies have focused on “grafting to” approaches that involve conjugation of pre-made polymer and siRNA molecules, an approach that is challenged by low conjugation efficiency and time intensive conjugate purification. I will develop a new “grafting from” strategy that involves the conjugation of a polymerization initiator to the siRNA and subsequent polymerization of monomers that grow off of the initiating site on the siRNA. I will adopt and extend open air (oxygen tolerant), aqueous, blue light activated reversible addition-fragmentation chain transfer (RAFT) polymerization methods that are highly amenable to structure and compositional tuning in small quantities through parallel polymerization reactions in a 96-well plate format. My proposed aims toward creating a bone-targeted, Gli2-inhibitiory TIBD therapy are outlined below.

ZOOM MEETING ID: 974 3897 6159

Optical tweezers have emerged as a powerful tool for the non-invasive trapping and manipulation of colloidal particles and biological cells. However, the diffraction limit precludes the low power trapping of nanometer-scale objects. Significantly increasing the laser power can provide enough trapping potential depth to trap nanoscale objects. Unfortunately, the significant optical intensity required causes photo-toxicity and thermal stress in the trapped specimens, which hampers the usage of optical tweezers in nano-manipulation. Here, we proposed our novel optically controlled nanotweezers called opto-thermo-electrohydrodynamic tweezers (OTET) that enables the trapping and dynamic manipulation of nanometer-scale objects in a safe and energy-saving manner.

ZOOM MEETING ID: 930 4496 0940

Tumor-associated macrophages (TAMs) are the most prevalent immune cell in most cancers and are drivers of the immunosuppressive microenvironment that promotes tumor development. However, macrophages display phenotypic plasticity and can be reprogrammed to a pro-inflammatory, anti-tumor phenotype by activating the canonical nuclear factor-κB (NF-κB) signaling pathway. Small interfering RNA (siRNA) sequences specific for the inhibitor of NF-κB alpha (IκBα) have been previously identified by our labs and promote classical macrophage activation. To deliver the siRNA, we have developed an azide-labelled PEGylated diblock copolymer (AzPEGDB) that forms polymeric complexes (polyplexes) with oligonucleotides and can induce endosomal escape. Specific targeting to TAMs is achieved by conjugating a mannose-alkyne to the AzPEGDB via copper-catalyzed “click” chemistry to target the overexpressed CD206 macrophage mannose receptor. In initial studies, residual copper from this reaction led to toxicity in cell culture treatments, so we optimized the copper catalyst concentration to minimize cell death while achieving efficient mannose conjugation. Uptake studies revealed the mannosylated nanoparticles (MnNPs) successfully targeted M2-polarized bone marrow-derived macrophages (BMDMs), which most resemble TAMs. Additionally, treatment with the IκBα siRNA repolarized M2 BMDMs to the M1 pro-inflammatory phenotype. Following these studies, the optimized MnNP formulation was used for treatment of ovarian tumor models in mice. Female FVB mice injected intraperitoneally (IP) with TBR5 ovarian tumor cells developed tumors for one week before beginning biweekly IP treatments with MnNPs. Biodistribution studies revealed specific targeting to TAMs in the ascites and solid tumors with minimal accumulation in the spleens. Treatment with the MnNPs themselves had some therapeutic benefit by reducing ascites accumulation commonly associated with ovarian tumor severity, but only the IκBα siRNA treatment significantly reduced solid tumor progression. Overall, these studies describe the optimized process for fabricating mannose-decorated nanoparticles and demonstrate the effective reduction in tumor burden associated with targeted IκBα siRNA delivery to TAMs.

ZOOM MEETING ID: 991 5469 3755

The concept of atomic level stress was introduced as a powerful tool to describe a number of materials phenomena in computational materials science.  A definition of the atomic level stress is important both for physical interpretation of continuum fields and for understanding of molecular scale simulations from a continuum perspective.  In order for the atomic level description to have completeness from an energetic viewpoint, it is also necessary to define the corresponding local strains at the atomic level.  The local strain at atomic level results from three contributions: deformation of the lattice, thermal vibration, and structural heterogeneity which manifests as atomic level residual strain.  Therefore, the local deformation gradient resulting from lattice mismatch between reference and current configurations does not capture the local strain completely.  We note that the residual strain due to structural heterogeneity is the energetic conjugate of the atomic level residual stress.  Currently, there is no existing definition for the residual strain which is purely kinematic in nature.  In this paper, we define a dimensionless vibrational strain based on second moments of vibration.  We justify the proposed definition through both qualitative and quantitative energy based arguments.  The zero stress condition of an atom in a perfect crystal at a finite temperature corresponds to its thermal vibration trajectory tracing out a perfect sphere whose radius is specified by the temperature.  Any change of the trajectory from this spherical shape indicates a local strain of that atom.  Using the example of fcc Aluminum, we show that the vibrational strain is linearly related to lattice deformation strain for a perfect crystal, and serves as a suitable kinematic measure of the residual strain around a vacancy for a defective crystal.   

ZOOM MEETING ID: 931 0928 1587

Gate-all-around (GAA) silicon nanowire (NW) CMOS transistors demonstrate outstanding total ionizing dose (TID) tolerance due to the ultra-scaled gate dielectric thickness, enhanced electrostatic gate control, and suppression of parasitic leakage current paths. nFETs and pFETs show similar TID responses, making the GAA NW technology an excellent candidate for CMOS IC applications in high-radiation environments. The slight degradation of the threshold voltage suggests a limited charge buildup in the gate dielectrics. However, low-frequency noise and random-telegraph noise measurements show the importance of change in traps configurations in both the nearinterfacial SiO2 and HfO2 dielectric layers to the radiation response and reliability of GAA NW devices. These traps are due most likely to oxygen vacancies and/or hydrogen complexes.

ZOOM MEETING ID: 924 2382 7391

Solid state batteries can suffer from catastrophic failure at high current densities due to solid electrolyte fracture, interface decomposition, or lithium filament growth. Failure has been linked to chemo-mechanical material transformations that can manifest during electrochemical cycling. Herein, we systematically investigate the role solid electrolyte microstructure and interfacial decomposition (e.g. interphase) impact failure mechanisms in Lithium thiophosphates (Li3PS4, LPS) solid electrolytes. Kinetically metastable interphases are engineered with iodine doping and microstructural control is achieved using milling and annealing processing techniques.  In situ transmission electron microscopy reveals how iodine diffuses to the interphase and upon electrochemical cycling pores are formed in the interphase region. Pores/voids formed in the interphase are chemo-mechanically driven via directed ion transport. In situ synchrotron tomography reveals that interphase pore formation drives edge fracture events which are the origin of through-plane fracture failure.  Active Li metal has a tendency to fill the fracture region. Cycling lithium in fracture sites leads to localized stress within the solid electrolyte which accumulates and ultimately leads to catastrophic failure. Fractures in thiophosphate electrolytes actively grow toward regions of higher porosity and are impacted by heterogeneity in solid electrolyte microstructure (e.g. porosity factor). Dense solid electrolytes with metastable interphases are imperative for high rate-capability operation of solid-state batteries. This work provides framework to develop high performance solid-state batteries with tailored interphase chemistry as well as minimizing microstructure anisotropy. These design principles are identified by insights generated by multi-modal in situ characterization of solid-state battery system. Multi-modal in situ characterization, as described in this work, of solid-state batteries will be crucial for enabling rational design of high-performance solid-state batteries.

ZOOM MEETING ID: 987 0738 9323

Strong coupling between optical modes can be implemented into nanophotonic design to modify the energy-momentum dispersion relation, which plays an integral role in thermal emission and a broad array of other optical processes. In the context of thermal emitters, such an approach offers potential avenues for tuning the emission frequency, linewidth, polarization, and spatial coherence. Here, we induce three-mode strong coupling between propagating phonon polaritons, localized surface phonon polaritons, and zone-folded longitudinal optic phonons within the Reststrahlen region of 4H-SiC using nanopillars. Energy exchange, mode evolution, and coupling strength between the three polariton branches are explored experimentally and theoretically through electromagnetic simulations and Hopfield models. The influence of the strong coupling upon the angle-dependence of thermal emission spectra was directly measured, providing excellent agreement with theory. We demonstrate five-fold improvement in the spatial coherence and three-fold enhancement of the quality factor of the polaritonic modes within the strong coupling regime in comparison to the uncoupled modes, with these hybrid modes also exhibiting a mixed character that could enable opportunities to realize electronically driven emission. Our results show that by leveraging polariton strong coupling that thermal emitters can be engineered to meet the requirements for a host of IR applications extending from spectroscopy, sensing, and communications in a simple, lightweight and yet bright emitter.

ZOOM MEETING ID: 976 8683 4345

ZOOM MEETING ID: 915 1596 4243

Saphenous vein grafts used to bypass complex arterial disease have a high rate of failure associated with intimal hyperplasia (IH). In IH, vascular smooth muscle cells (VSMCs) in the graft undergo a contractile-to-synthetic phenotype switch, leading to increased proliferation, migration, and neointima formation. We test the hypothesis that brief intra-operative graft treatment with MAPKAP kinase 2 inhibitory peptide nano-polyplexes (MK2i-NPs) reduces IH through a mechanism of action that involves blocking the VSMC phenotype switch. MK2i-NPs produced higher cellular delivery and more potent pharmacodynamic effects compared to free MK2i peptide using phosphorylated CREB as a biomarker of MK2 inhibition in VSMCs. MK2i-NP treatment also reduced proliferation and lowered vimentin levels (synthetic phenotype marker), while maintaining higher levels of alpha smooth muscle actin (a-SMA, contractile phenotype marker), in primary rat VSMCs cultured in serum-containing media for 7 passages. MK2i-NPs also decreased vimentin, increased a-SMA, and reduced IH, along with allowing effective graft endothelialization, in an in vivo rabbit vein graft model. MK2i-NP inhibition of VSMC phenotype switch was also validated in an ex vivo human saphenous vein model. Looking forward, this delivery system is being tested in an in vivo delivery system to prevent intimal hyperplasia and phenotype switching in arteries after angioplasty.

ZOOM MEETING ID: 971 4876 1718
*this poster is part of the IMS first year student 10-week research rotation side competition

Two aluminum alloys, AA-5052 and AA-6061, were welded to form a butt joint using friction stir extrusion.  A dovetail groove was formed in a sheet of steel atop which the aluminum thin sheets were welded.  The groove was offset from the join by several increments of up to one pin diameter, and the effect on material flow was recorded using etched transverse cross-sections.

ZOOM MEETING ID: 972 0595 4699
*this poster is part of the IMS first year student 10-week research rotation side competition

Microfluidics technology is extensively used in biological applications. The advantages of using microfluidics for biological applications include, but are not limited to, high biological compatibility, transparency in visible range, and high throughput screening of biological species. However, high-quality optical analysis or imaging of organism in microfluidics often relies on expensive and bulky microscopes. On the other hand, metasurface is a flat optics which forms miniature interfaces for accurate wavefront manipulation. In recent ten years, versatile compact and high-performance optical components based on the metasurfaces have been demonstrated, including lenses, axicons, holograms and gratings. This boom in the development of metasurfaces reveals a possibility of integrating microfluidics with metasurfaces to achieve a compact and high-performance optical platform for organism sensing. Based on my previous research work on a microfluidic device for C. elegans sorting and literature review, the disadvantage of conventional optical system for microfluidics, the motivation of integrating microfluidics with metasurfaces, and a potential experimental plan will be discussed in details.

ZOOM MEETING ID: 976 8175 9755

Wild-type erythropoietin (EPO) is promising for neuroprotection, but its therapeutic use is limited because it causes a systemic rise in hematocrit. We have developed an EPO-R76E derivative that maintains neuroprotective function without effects on hematocrit, but this protein has a short half-life in vivo. Here, we compare the efficacy and carrier-induced inflammatory response of two polymeric microparticle (MP) EPO-R76E sustained release formulations based on conventional hydrolytically degradable poly(lactic-co-glycolic acid) (PLGA) and reactive oxygen species (ROS)-degradable poly(propylene sulfide) (PPS). Both MP types effectively loaded EPO-R76E and achieved sustained release, providing detectable levels of EPO-R76E at the injection site in the eye in vivo for at least 28 days. Testing in an in vitro oxidative stress assay and a mouse model of blast-induced indirect traumatic optic neuropathy (bITON) showed that PPS and PLGA MP-mediated delivery of EPO-R76E provided therapeutic protection. While unloaded PLGA MPs inherently increase levels of pro-inflammatory cytokines in the bITON model, drug-free PPS MPs have innate antioxidant properties that provide therapeutic benefit both in vitro and in vivo. Both PLGA and PPS MPs enabled sustained release of EPO-R76E, providing therapeutic benefits including reduction in inflammation and axon degeneration, and preservation of visual function as measured by electroretinogram. The PPS-based MP platform is especially promising for further development, as the delivery system provides inherent antioxidant benefits that can be harnessed to work in complement with EPO-R76E or other drugs for neuroprotection in the setting of traumatic eye injury.

ZOOM MEETING ID: 913 1572 6549

Introduction. Tuberculosis (TB) is an infectious disease caused by the bacterium Mycobacterium tuberculosis. M. tuberculosis primarily infects the lungs with ~9 million cases of TB worldwide annually. TB is also a common opportunistic infection in HIV+ patients. In 2010, the World Health Organization recommended use of the nucleic acid amplification Xpert MTB/RIF assay for TB diagnosis. However, expensive devices are located in central facilities, leaving primary rural clinics to rely on sputum smear inspection for point-of-care diagnosis. While sputum inspection using microscopy is inexpensive and has high specificity, it suffers from low sensitivity (~50%), and requires a bacterial load 100x greater than Xpert. It also cannot differentiate between pathogenic and nonpathogenic mycobacterial species, which is important for treatment decisions in HIV+ patients. The inability to rapidly diagnose patients with a TB infection at the point-of-care is a confounder in disease transmission.

We hypothesized that we could use microvirin-N’s (MVN) carbohydrate-specific binding of terminal mannose-α-(1,2)-mannose linkages to develop a mycobacterial species-specific magnetic capture particle for volumetric concentration of TB from patient sputum. Specifically, MVN binds to the mycobacterial surface marker lipoarabinomannan (LAM), which is mannose-capped in pathogenic species, but phospho-inositol capped in nonpathogenic species. This should yield binding specificity for disease-causing mycobacterial species. In this report, we demonstrate the feasibility of this approach using flow cytometry.

Materials and Methods. Two-hundred nanometer (200 nm) streptavidin particles were loaded with the manufacturer’s recommended concentration of biotinylated MVN, and blocked in excess free D-biotin to saturate unbound streptavidin binding sites. These nanoparticles were added to a sample of AF405-tagged Mycobacterium bovis BCG (BCG), a TB analog, or mCherry expressing Mycobacterium smegmatis, a nonpathogenic mycobacterial species, in 1x PBS + 0.02% Tween-20, and allowed to incubate for 30 minutes on rotisserie to facilitate binding. The samples were then processed using a BD FACSAriaII and analysed using FlowJoV. Binding specificity of MVN for mannose-capped LAM (ManLAM) or phospho-inositol capped LAM (PI-LAM) was also studied using biolayer interferometry.

Results and Discussion. Biolayer interferometry indicates that of MVN has a strong binding affinity for ManLAM, with a Kd measured at 5.95 × 10-10 M. MVN does not show any binding to PI-LAM. This demonstrates MVN’s specificity between individual proteins. Flow cytometry indicates that MVN-functionalized nanoparticles readily bind to BCG, as evidenced through co-localization of nanoparticles with AF405-tagged BCG and significant reduction in the number of unbound BCG. BCG does not significantly bind to blank nanoparticles, with minimal co-localization observed. Further, M. smegmatis does not significantly bind to MVN-functionalized nanoparticles or blank nanoparticles, with minimal co-localization observed between nanoparticles and mCherry M. smegmatis, and minimal change in the proportion of nanoparticles to bacteria, demonstrating specificity for the mannose cap on ManLAM over PI-LAM.

Conclusions. MVN provides a TB-specific method to magnetically concentrate TB pathogens from a liquid sample. This is the first instance demonstrating that MVN binds to and can isolate intact cells. Work is ongoing to optimize the capture system for use in sputum, which is viscous and biologically complex. We are also working on a system to rapidly magnetically isolate the nanoparticles from a sample, since magnetic nanoparticles routinely take hours to fully separate from an aqueous sample on a stationary magnet.

ZOOM MEETING ID: 943 8562 4892

Semiconductor superlattices provide a powerful tool for creating materials with tailored phonon properties. This has been thoroughly studied with acoustic phonons, which experience zone-folding in response to the superlattice periodicity. In optic phonons, new interface modes and phonon confinement have been observed in Raman scattering measurements. To fully understand these phenomena, it is ideal to measure the off-gamma phonon dispersion – however the size restrictions and spectral resolution of conventional techniques have been a significant limitation. Recently, we have employed high-resolution inelastic x-ray scattering measurements to probe superlattice optic phonons at momenta not accessible in conventional optical measurements. By experimentally observing the superlattice phonon dispersion and coupling with theoretical results and infrared (IR) optical characterization, we hope to create a framework by which we can leverage the superlattice modification of optic phonons to create designer IR optical materials.  

ZOOM MEETING ID: 926 2528 0393

This work establishes that Kupffer cell release of platelet activating factor (PAF), a lipidic molecule with pro-inflammatory and vasoactive signaling properties, dictates dose-limiting siRNA nanocarrier-associated toxicities. High-dose intravenous injection of siRNA-polymer nano-polyplexes (si-NPs) elicited acute, shock-like symptoms in mice, associated with increased plasma PAF and consequently reduced PAF acetylhydrolase (PAF-AH) activity. These symptoms were completely prevented by prophylactic PAF receptor inhibition or Kupffer cell depletion. Assessment of varied si-NP chemistries confirmed that toxicity level correlated to relative uptake of the carrier by liver Kupffer cells and that this toxicity mechanism is dependent on carrier endosome disruptive function. PAF-mediated toxicities were generalizable to commercial delivery reagent in vivo-jetPEI® and an MC3 lipid formulation matched to an FDA-approved nanomedicine. These collective results establish Kupffer cell release of PAF as a key mediator of siRNA nanocarrier toxicity and identify PAFR inhibition as an effective strategy to increase siRNA nanocarrier tolerated dose.

ZOOM MEETING ID: 987 5124 6522

Vanadium dioxide(VO2) films and crystals undergo a metal-to-insulator phase transition at near-room temperature(68°C).  This tunable switching behavior has applications ranging from oxide electronics to smart windows.  In VO2 nanoparticles, it is possible to reduce the phase-changing temperature as low as -20°C without degrading the sharpness of the transition.  Here, we describe a quick and highly reproducible method for VO2 nanoparticle formation based on the solid-state dewetting of VO2 thin films.  We show that the size distribution of nanoparticles can be predicted with a simple model.  Our results suggest that there is a repeatable method for obtaining nanoparticles of a desired size, shape and transition temperature from the solid state self-organization of nanoparticles.           

ZOOM MEETING ID: 951 8625 6843

ZOOM MEETING ID: 914 0049 2196

All solid-state batteries are considered as the most potential replacement to liquid electrolyte containing Li-ion batteries. The system contains a solid electrolyte which enables Li metal as anode, providing significantly higher energy density and electrochemical stability. However, a major hurdle is to overcome the poor solid-solid interfacial contact during battery assembly and general operation. By applying mechanical (stack) pressure, interfacial contact in the battery can be considerably improved. But further uncertainty remains on stable battery cycling at higher current densities when Li metal forms dendrites and interfacial voids. These cause gradual failure or catastrophic short-circuiting, thereby limiting the prospect of solid-state battery development. In this work, we investigate the kinetics and operational failure mechanism in a solid-state battery by regulating two important mechanical factors: pressure and temperature. The work provides a brief understanding of interfacial evolution in the battery from an electrochemical perspective. 

ZOOM MEETING ID: 922 3196 8440

The use of cobalt complexes as redox-mediators in dye-sensitized solar cells has increased efficacy and lowered cost compared to many other molecular and complex mediators. It has been posited that while properly aligned energetically for electron transfer, the limiting factor in increasing the efficacy of electron transfer is the internal reorganization energy of some cobalt complexes.  To further examine the role of the reorganization energy of these cobalt complexes in electron transfer, we examined three cobalt complexes, cobalt trisethylenediamine2+/3+, cobalt sepulchrate2+/3+, and cobalt sarcophagus2+/3+, by quenching the fluorescence of CdSe quantum dots. These complexes have drastically varying reorganization energies although their reduction potentials are similar. We found that while the rate of electron transfer is minimally changed with the variation in reorganization energy, the rate of resonant energy transfer (RET) is drastically changed directly with the reorganization energy. This analysis indicates that reorganization energy must be included for resonant energy transfer applications.

ZOOM MEETING ID: 965 6352 4066

Metabolism and migration are intrinsically linked in the context of cancer cell metastasis. Metastasis, which is heavily associated with cancer cell mortality1, is initiated when cells break through basement membrane to migrate through the primary tumor microenvironment (TME)2. The TME is comprised a complex network of collagen fibers and pores that require cells to alter their shape and behavior to efficiently navigate to the bloodstream. Cytoskeletal remodeling and migratory mechanisms are thought to depend heavily on metabolic efficiency3. Cell metabolism usually relies on one of two pathways: the less efficient glycolysis to produce energy, or the more efficient, but oxygen-dependent, mitochondrial respiration4 depending on environmental cues, cell heterogeneity, and secondary site locations during metastasis. Here, we use a collagen microtrack system that recapitulates pre-existing collagen tunnels in vitro to determine how cell behavior is altered in the short and long term during confined migration, and how metabolism contributes to these migratory changes depending on different mechanical cues. Silicon wafers were patterned using either a Bosch etch process or SU8 patterning to be cast in PDMs to create template stamps to mold liquid collagen. Patterns of confining, unconfining, and intermittently confined microtracks were used to determine cell behavior in response to external cues. We determined that not only does confinement result in altered cell morphology and increased speed in the short term but alters cell migration after cells have left confinement. Additionally, we find that metabolic pathways and energy consumption rates are significantly altered during confined migration, and that the link between migration and metabolism may rely heavily on migratory mode. Ultimately, we successfully reproduced confined migration in vitro to determine what mechanical and metabolic factors alter cell migration and memory to determine what therapeutic targets are viable for inhibiting and slowing metastasis.  

[1] Christofori, G. Nature. 2006.
[2] Hapach, L.A. et al., Nature Precision Oncology, 2019.
[3] Shiraishi, T., et al., Oncotarget, 2015.
[4] Webster, K.A. et al., Journal of Experimental Biology, 2003.

ZOOM MEETING ID: 920 5171 4174

The energy distributions of electrons in gate-all-around (GAA) Si MOSFETs are analyzed using full-band 3D Monte Carlo (MC) simulations. Excellent agreement is obtained with experimental current-voltage characteristics. At typical operating voltages, there is a drifted Maxwellian distribution of electron energies together with a quasi-ballistic energy peak and an extended energy tail. This extension of the tail results primarily from Coulomb and carrier-carrier scattering within the channel. A significant fraction of electrons that enter the drain quasi-ballistically retain their energy, resulting in an out-of-equilibrium distribution in the entire drain. The simulated density and average energy of the hot electrons correlate well with experimentally observed device-degradation. We propose that the interaction of high-energy electrons with hydrogen-passivated phosphorus dopant complexes within the drain may provide an additional pathway for interface-trap formation in nanoscale devices.

ZOOM MEETING ID: 962 1053 6669

Hydrogels are a distinct class of polymeric materials defined by the formation of a physical/covalent threedimensional network that becomes hydrated and swollen but mechanically intact in the presence of aqueous solutions. They are of particular interest for biomedical applications because their intrinsic properties mimic those of native tissue1. Shear-thinning hydrogels, specifically, have emerged as a new generation of viscoelastic materials characterized by transition from elastic solid to viscous liquid in the presence of shear forces or high strain making them attractive for injectable delivery. The unique supramolecular structure of shear-thinning materials involves rapidly-forming, reversible, non-covalent interactions (charge, hydrophobic domain, guest-host interactions, etc.) between two components mixed in solution. These physical interactions are broken by mechanical disruption but rapidly reform (or “self-heal”) upon force relaxation2. Conjugating guest-host pendants to complementary polymer backbones has been previously shown to produce reliable and mechanically robust hydrogels3, and we sought to expand upon this technology by integrating drug-carrying nanoparticles previously developed in our lab. We recently synthesized a set of new polymers endowed with complementary guest-host pendants β-Cyclodextrin (Cd, host) or Adamantine (Ad, guest). These hydrogels were characterized by rheology where shear-thinning behavior was confirmed with a storage modulus at low-strain of approximately 1 kPa and at high-strain of 0.1 kPa. In parallel, we have also synthesized siRNAcondensing nanoparticles surface-modified with guest/host moieties for integration into a hybrid polymer/nanoparticle composite system. Modified nanoparticles loaded with luciferase (luc) siRNA were shown to silence luc in lucexpressing 3t3 cells with approximately 75% knockdown after 24 hours in comparison to scrambled siRNA controls.

1. Caló, E. & Khutoryanskiy, V. V. Biomedical applications of hydrogels: A review of patents and commercial products. Eur. Polym. J. 65, 252–267 (2015).
2. Guvendiren, M., Lu, H. D. & Burdick, J. A. Shear-thinning hydrogels for biomedical applications. Soft Matter 8, 260–272 (2011).
3. Rodell, C. B., Kaminski, A. L. & Burdick, J. A. Rational Design of Network Properties in Guest–Host Assembled and Shear-Thinning Hyaluronic Acid Hydrogels. Biomacromolecules 14, 4125–4134 (2013).

This poster has been withdrawn

With the recent progress in additive manufacturing, lattice structures are being intensively researched for applications such as shock absorption, biomaterial scaffolds, and aerospace structures. They can be considered as structures at the scale of the lattice features, but materials at scales which are orders of magnitude larger. The materials and geometry of lattice structures can be optimized to meet target mechanical properties at the larger scale.  In particular, homogenization-based optimization has been extensively studied since it saves computational resources as compared to full-resolution analysis.  In this work, we show that the granular micromechanics approach is especially suitable for homogenization-based optimization because of the possibility to obtain closed form relationships between the macro-scale properties and the microstructural features.  Elastic, plastic as well as viscoelastic behavior has been investigated.  Effects of inter-nodal stiffness and orientation distribution of the struts on the macro-scale properties are specifically determined.   It is demonstrated that the method may be extended in a straightforward manner to optimize chemically active lattice networks.  

ZOOM MEETING ID: 928 0308 0394

A bipolar membrane (BPM) is composed of laminated films of anion-exchange and cation-exchange polymers (AEP and CEP). These membranes have the unique capability of splitting water into H+ and OH- ions, at the interface where the AEP and CEP meet, at a potential as low as 0.8 V, while conventional electrolysis requires at least 1.2 V. Utilizing this unique property, BPMs are currently employed in plenty of important industrial processes. Traditional BPMs have been prepared with a 2D junction, in which the cation exchange and anion exchange layers are co-assembled. Intrinsic problems with 2D BPMs include delamination from the pressures at the start-up and shut-down during water splitting processes, and membrane dehydration because of the slow water permeability into the junction region. Recently, our group reported a novel method to fabricate 3D BPMs by employing electrospun nanofiber mats to provide an extended water splitting region. Since the electrospun dual nanofibers originate from the CEP and AEP used as outerlayers, we can include an interpenetration of these two polymers in the junction. This extended water splitting area cannot only increase adhesion between the anion and cation exchange polymers, but also create a mechanically robust interface, thereby reducing the possibility of delamination as well as dehydration during water splitting.

ZOOM MEETING ID: 924 7949 4164

The stable optical trapping of nanometer-scale objects is an indispensable tool in physics and life sciences. Plasmonic nanotweezers employing metallic nanoantennas provide a powerful tool for trapping nanoscale particles but the strong heating effect resulting from light absorption limits the applications. Here, we propose an all-dielectric nanotweezer harnessing quasi-bound states in the continuum (quasi-BICs) to enable the trapping of nanoscale objects with low laser power and negligible heating effect. The quasi-BIC system provides very high field intensity enhancement that is at least an order of magnitude higher than plasmonic systems as well as high quality-factor resonances comparable to photonic crystal (PhC) cavities. Furthermore, the quasi-BIC metasurface tweezer array provides many hotspots with high field confinement, thereby generating multiple trapping sites for high throughput trapping of nanometer-scale objects. By breaking the symmetry of the system, we also demonstrate for the first time that trapped particles can improve the resonance mode of the cavity, which in turn enhances the trapping process. Our study paves the way for applying quasi-BIC systems into particle trapping and sensing applications and provides a new way to achieve a self-induced back-action force to enhance the overall trapping stability.

ZOOM MEETING ID: 922 7573 2624

A novel, composite, non-PFSA-based fuel cell membrane has been fabricated using a pore filling technique. The membrane consists of a mechanically stabilizing skeleton from an electrospun poly(phenylene sulfone) (PPSU) fiber mat and a thermally crosslinkable poly(phenylene sulfonic acid) (cPPSA) proton conducting ionomer that fills the interfiber voids. cPPSA copolymer was synthesized using Ullmann coupling copolymerization of 4,4-dibromobiphenyl 3,3-disulfonic acid with 1,4-dibromobenzene-2,5- disulfonic, followed by grafting a certain fraction of backbone sulfonic acid groups with biphenyl linker. The PPSU fiber mat was electrospun from NMP/acetone solution. Pore-filling was carried out by pouring a solution of cPPSA in methanol over the mat, followed by heating at 70℃ to evaporate solvent. The cPPSA was crosslinked by an additional heating step, in a vacuum oven at 210℃ for 5 hours. The resultant membrane had excellent proton conductivity, 5 times greater than that of Nafion 211 in the 40-90% RH range at 80℃ .

ZOOM MEETING ID: 968 8053 3680

For many industrial and manufacturing applications detecting and identifying low concentrations of harmful gases and byproducts are performed using non-dispersive infrared (NDIR) sensors. These simple devices utilize a broadband IR emitter, thermopile detector and a spectrally narrow bandpass filter tuned to a vibrational resonance of the analyte of interest. However, such filters are expensive to fabricate and limit the NDIR to operation at only a single frequency, unless filter wheels are employed, which expand the size and complexity of the device considerably. Here, we create a nanophotonic infrared emitting metamaterial (NIREM) fabricated from thin films of doped CdO grown on patterned sapphire substrates (PSS) that exhibit narrowband thermal emission. By coupling this emitter with a simple broadband detector such as a thermopile, the functionality of the NDIR sensor can be replicated without the need for the narrow bandpass filter. Unlike many metamaterial-based emitters our device emits both p- and s-polarized light with near-unity emissivity at angles ranging from 0 to 40° off the surface normal without complicated and expensive lithography steps. As a proof of concept, we implement this NIREM for CO2 gas detection within an FTIR spectrometer, demonstrating performance comparable with a conventional black-body/filter combination. This demonstrates that the NIREM concept can provide a suitable plug-and-play replacement for NDIR devices as they can be implemented in a form-factor commensurate or significantly reduced in comparison to the current state of the art. In principle, by incorporating multiple NIREM dies tuned to emit at different frequencies, multiple vibrational modes could be sequentially detected, making the approach amenable to identification and quantification of complicated molecules within a single NDIR configuration.

ZOOM MEETING ID: 925 1453 1933

High refractive index dielectric nanostructure is emerging as a significant tool for controlling light in nanoscale. Among numerous designs, the non-radiating “anapole” mode shows its intriguing performance in generating localized field enhancement by a single slotted silicon disk. As the nature of the dielectric structure, high electric field enhancement and low-temperature variation merits can be well applied in the optical trapping area. Here we introduce a hybrid structure, combining the gold reflection layer with the slotted dielectric silicon disk. At the resonance wavelength, the anapole mode is excited with its special field distribution, and stably optical trapping can be achieved. Numerical calculation shows that different sizes of particles can be trapped inside or on the top of the silicon nanodisk slot. The design is based on the real experiment environment, with the normal silicon refractive index and loss parameter. The ultra-low temperature raising with the same illumination condition is also proved in the numerical calculation, which denotes ignorable heat generated by the device. 

ZOOM MEETING ID: 996 5277 3455

Chronic wounds are those that are unable to heal properly on their own and often are associated with a pathologic state of inflammation. This not only poses risk for infection, but also causes pain and distress to the patient. One of the most common types of chronic wounds is the diabetic foot ulcer, which is caused in part by the disruption of oxygen homeostasis, leading to a cascade effect impairing growth factor production, angiogenesis, and granulation tissue formation. The purpose of this project is to characterize a library of stimuli-responsive poly(thio ketal) urethane (PTK-UR) polymeric scaffolds for the tunable, carrier-free release of a biological therapeutic to promote natural wound healing. The PTK-UR library shows an increased hydrophilicity with an increase in the PEG constituent in the polymer, as well as an accelerated degradation rate when exposed to hydroxyl radicals over time compared to non-ROS degradable polyester-urethane (PEUR) controls. Additionally, the increased availability of ROS-responsive thioketal bonds within the scaffold allow for greater radical scavenging and antioxidant capacity. PTK-UR scaffolds also show comparable Young’s moduli and glass transition temperatures to PEUR controls. Scaffolds are able to support cell viability in vitro as well as provide cytoprotection from oxidative environments in vitro.

ZOOM MEETING ID: 970 5891 3523

The cyclic GMP-AMP synthase (cGAS)/Stimulator of Interferon Genes (STING) pathway is an innate immune pathway that senses double stranded DNA in the cytosol of cells.  This is important as cytosolic DNA can be of sign of viral infection (adenoviruses, DNA viruses) as well as a sign of dysfunction within the cell (anti-tumor immunity).  However, aberrant overactivation of STING contributes to the development and progression of a variety of inflammatory diseases and type-I interferonopathies, including nonalcoholic steatohepatitis, colitis, sepsis, macular degeneration, Aicardi–Goutières syndrome (AGS), and some forms of lupus.  We hypothesize that nanoparticle-mediated delivery of RU.521 and H-151 (small molecule cGAS and STING inhibitors respectively) to the desired cells/tissues can improve outcomes in many of the inflammatory diseases listed above.  To address this, we have encapsulated RU.521 and H-151, cGAS and STING inhibitors respectively, in hydrolytic poly(lactic-co-glycolic acid) (PLGA) and ROS-degrading poly(propylene sulfide) (PPS) nanoparticles.  We have investigated the size, loading, and in vitro drug release kinetics of both PLGA and PPS nanoparticles.  Importantly, we found that nanoparticle formulations were more effective in blocking cGAS/STING-driven inflammatory responses than dose-matched free drug in both human and murine macrophages. This motivates future experiments to determine the in vivo distribution and therapeutic potential of these formulations in murine models of STING-associated inflammatory diseases.

ZOOM MEETING ID: 939 5173 7744
*this poster is part of the IMS first year student 10-week research rotation side competition

An active research objective in photonic device design and fabrication is silicon-based photonic crystals (PCs). For many applications, such as optical communications and optical sensors, silicon is a favorable material due to high index contrast with air and dielectric modes and compatibility with current silicon integrated circuit fabrication. Loss budgets must be considered both for photonic crystal device integration in a chip-based device and for experimental test setups in novel, proof-of-concept devices. This work seeks to develop and qualify a relatively well-understood sub-wavelength grating coupler design (X. Xu, et. al. Applied Physics Letters 101, 031109 (2012)) for future modulation and resonance experiments with novel PCs. Current Weiss group methods utilize an end-coupled fiber setup with up to 10 dB built-in system loss. It is expected that an improved grating coupler setup will achieve built-in loss of 5 dB or less. Additional advantages of fully-etched grating couplers include easily adapted lithography and etch for quick fabrication turnaround when added to design layouts with photonic crystal nanobeams (PCN) and other devices.

ZOOM MEETING ID: 984 5233 3013
*this poster is part of the IMS first year student 10-week research rotation side competition

Atomically thin sheets of graphene with size-controlled and doped defects yield a tunable diffusive barrier. Literature shows that the diffusion properties of defected graphene lend potential for the material to act as an anode in lithium-ion batteries (Deya, et. al., 2013), a molecular sieve to desalinate water (Cheng, et. al., 2020), a membrane for gas separation (Levdansky, et. al., 2020), etc. Density functional theory (DFT) is utilized to optimize the diffusive energy barrier for various ions by manipulating the size of the defect and dopant species surrounding the defect. Applying DFT to generate electron density maps allow visualization of the impact on the graphene sheet resulting from defecting and doping the material.