Browsing by Author "Kale, Sohan"
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- Biomanufacturing of Bacteria-Mediated Drug Delivery Systems and Investigation of Their Interaction with the Tumor MicroenvironmentZhan, Ying (Virginia Tech, 2024-05-14)The limited transport of conventional chemotherapy within the tumor microenvironment (TME) is due to irregular vascularization, increased tumor interstitial pressure, and a dense extracellular matrix (ECM). The lack of selectivity of anticancer drugs often leads to systemic toxicity and damage to healthy tissues. Bacteria-based cancer therapy (BBCT) is a promising alternative, as tumor-targeting bacteria have been shown to preferentially colonize primary and metastatic tumors and induce anti-tumor effects. In this dissertation, we focus on several aspects of bacteria-nanoparticle conjugates, wherein BBCT is synergistically combined with nanomedicine to augment the efficacy of both treatment modalities. We explore biofabrication of our bacteria-nanoparticle conjugates called NanoBEADS (Nanoscale Bacteria Enabled Autonomous Drug Delivery Systems) and their interaction with the TME. Specifically, (1) we investigate the effects of two bacteria-NP conjugation chemistry and assembly process parameters of mixing method, volume, and duration, on NP attachment density and repeatability. We evaluate the influence of linkage chemistry and NP size on NP attachment density, viability, growth rate, and motility of NanoBEADS. (2) We investigate the effect of dense stroma and ECM production on the intratumoral penetration of bacteria with a mathematical model of bacterial intratumoral transport and growth. (3) We develop a microfluidic device with multicellular tumor spheroids to study the transport of tumor-targeting bacteria and support real-time imaging and long-term experiments. (4) We develop a new type of bacteria-based bio-hybrid drug delivery system using engineered cell surface display for enhancing the attachment of nanoparticles.
- Closure Modeling for Accelerated Multiscale Evolution of a 1-Dimensional Turbulence ModelDhingra, Mrigank (Virginia Tech, 2023-07-10)Accelerating the simulation of turbulence to stationarity is a critical challenge in various engineering applications. This study presents an innovative equation-free multiscale approach combined with a machine learning technique to address this challenge in the context of the one-dimensional stochastic Burgers' equation, a widely used toy model for turbulence. We employ an encoder-decoder recurrent neural network to perform super-resolution reconstruction of the velocity field from lower-dimensional energy spectrum data, enabling seamless transitions between fine and coarse levels of description. The proposed multiscale-machine learning framework significantly accelerates the computation of the statistically stationary turbulent Burgers' velocity field, achieving up to 442 times faster wall clock time compared to direct numerical simulation, while maintaining three-digit accuracy in the velocity field. Our findings demonstrate the potential of integrating equation-free multiscale methods with machine learning methods to efficiently simulate stochastic partial differential equations and highlight the possibility of using this approach to simulate stochastic systems in other engineering domains.
- Electric fields for the detection, characterization and treatment of subcellular contributors to cancer progressionDuncan, Josie Lee (Virginia Tech, 2023-12-21)
- Interactions of Fibroblast with Cytotoxic and Invasive Strains of Pseudomonas aeruginosa on ECM Mimicking FibersBerman, Lauren Kathryn (Virginia Tech, 2021-09-22)It is estimated that approximately 2 million fires which occur in United States each year result in 1.2 million burn victims. Fibroblasts are responsible for responding to this tissue damage by breaking down the damaged extracellular matrix (ECM) and secreting a new ECM which aids in wound repair and supports the migration of immune cells. Pseudomonas aeruginosa is an opportunistic pathogen commonly associated with health-care infections (HCAIs) due to its ability to take advantage of immunocompromised hosts. However, little research has investigated how wound invading P. aeruginosa interacts with wound repairing fibroblasts. To address this lack of understanding, this thesis focuses on quantifying changes in fibroblast morphology, migratory behavior, and force exertion to investigate this host cell's response to representative cytotoxic (PAO1) and invasive (PA14) strains of P. aeruginosa. These assays study host cell-pathogen interactions on highly aligned nanofibers of varied spacing and diameter, which mimic the fibroblast deposited ECM and dictate fibroblast morphology. We discovered that the cytotoxic strain of P. aeruginosa induced significantly shorter fibroblast death times. Furthermore, two modes of death, sharp and gradual, were identified and found to be dependent on both fiber configuration and strain of P. aeruginosa. In addition, fibroblasts exposed to PAO1 migrating on the parallel formation were found to be significantly slower and less persistent than those exposed to PA14, however, fibroblasts exposed to both strains of bacteria were shown to exert similar forces. Lastly, exposure to PA14 led to the greatest change in actin, evident by increased actin punctae and less prominent actin stress fiber formation.
- Investigating Cell Viscoelastic Properties with Nanonet Force MicroscopyZhang, Haonan (Virginia Tech, 2022-08-04)Determining the mechanical properties of living cells accurately and repeatably is critical to understanding developmental, disease, and repair biology. The cellular environment is composed of fibrous proteins of a mix of diameters organized in random and aligned configurations. In the past two decades, several methods, including modified atomic force microscopy (AFM) and micro-pipette aspiration have been developed to measure cellular viscoelastic properties at single-cell resolution. We inquired if the fibrous environment affected cellular mechanobiology. Using our non-electrospinning Spinneret based Tunable Engineered Parameters (STEP) fiber manufacturing platform, we developed fused nanonets to measure single-cell forces and viscoelasticity. Using computer-controlled probes, we stretched single cells attached to two-fiber and three-fiber systems precisely and recorded the relaxation response of cells. The viscoelastic properties were determined by fitting the data to the standard linear viscoelastic solid model (SLS), which includes a spring (k0) in parallel with a spring (km)-damper (cm) series. In cases in which cells are seeded on two fibers, we tested hMSCs and BJ-5TA cells, and the viscoelastic components measurements k0, km, and cm are 26.16 ± 3.38 nN/µm, 5.81 ± 0.81 nN/µm, and 41.15 ± 5.97 nN-s/µm, respectively for hMSCs, while the k0, km, and cm, measurements of BJ-5TA cells are 20.02 ± 2.89 nN/µm, 4.62 ± 0.75 nN/µm, and 45.46 ± 6.00 nN-s/µm respectively. Transitioning to the three-fiber system resulted in an overall increase in native contractility of the cells while allowing us to understand how the viscoelastic response was distributed with an increasing number of fibers. Viscoelastic experiments were done twice. First, we pulled on the outermost fiber similar to the two-fiber case. The cell was then allowed to rest for two hours, sufficient time to regain its pre-stretching contractility. The cell was then excited by pulling on the middle fiber. The experimental results of cell seeding on three fibers proved that the viscoelastic property measurements depend on the excitation position. Overall, we present new knowledge on the cellular viscoelasticity of cells attached to ECM-mimicking fibers.
- Mapping mechanical stress in curved epithelia of designed size and shapeMarin-Llaurado, Ariadna; Kale, Sohan; Ouzeri, Adam; Sunyer, R.; Torres-Sanchez, A.; Latorre, E.; Gomez-Gonzales, M.; Roca-Cusach, P.; Arroyo, M.; Treapat, X. (2023-07-07)The function of organs such as lungs, kidneys and mammary glands relies on the three-dimensional geometry of their epithelium. To adopt shapes such as spheres, tubes and ellipsoids, epithelia generate mechanical stresses that are generally unknown. Here we engineer curved epithelial monolayers of controlled size and shape andmap their state of stress. We design pressurized epithelia with circular, rectangular and ellipsoidal footprints. We develop a computational method, called curved monolayer stress microscopy, to map the stress tensor in these epithelia. This method establishes a correspondence between epithelial shape and mechanical stress without assumptions of material properties. In epithelia with spherical geometry we show that stress weakly increases with areal strain in a size-independent manner. In epithelia with rectangular and ellipsoidal cross-section we find pronounced stress anisotropies that impact cell alignment. Our approach enables a systematic study of how geometry and stress influence epithelial fate and function in three dimensions.