Biology subjects

Tanwar, S.

Publications and source records attributed to Tanwar, S..

3 recordsLinked to original sources

bioRxiv2025

Affordable plasmonic biosensing: democratizing SERS with scalable, field-compatible substrate fabrication

Efficient and accurate plasmonic biosensing in the field remains a significant challenge. Despite its potential to revolutionize point-of-care (PoC) diagnostics through its unparalleled sensitivity and precise molecular fingerprinting capabilities, adoption of traditional surface-enhanced Raman spectroscopy (SERS) in the field has not proven feasible yet. High production and material costs, complex fabrication methods, reliance on specialized equipment, and persistent issues with sensor stability and reproducibility continue to impede development for PoC use. Addressing these challenges, this study innovates a democratized and cost-effective fabrication kit that enables the production of SERS substrates using commonly available materials and straightforward electrochemistry techniques without compromising on sensitivity and reproducibility. Importantly, this method leverages commercially available bottled water and simple battery-powered fabrication, thereby eliminating reliance on a power grid and enabling the local production of biosensors in resource-restricted and conflict-affected areas. The cost of producing the fabrication kit is $39.54 with raw materials purchased at bulk retail prices, while the cost of consumables for fabricating each test is just 1.33{cents}. To ensure real-world feasibility, we conducted a comprehensive reproducibility analysis, where consistent plasmonic enhancement was observed across multiple production batches. Furthermore, we demonstrated their efficacy in two critical applications: the rapid detection of bacteria and pesticides. We detect trace levels of pesticides such as Thiram and Thiabendazole down to 0.1 ppm using a digital SERS approach. We also demonstrated the identification of bacteria isolated from culture, namely Escherichia coli and Bacillus subtilis. We envision that this label-free, high-sensitivity substrate, when paired with portable Raman spectrometers, could open doors for a new era of field-deployable biosensing, paving the way for its adoption for a plethora of applications, from public health to food testing.

bioengineering↗

bioRxiv2024

Disordered glass nanowire substrates produce in vivo-like astrocyte morphology revealed by optical diffraction tomography

Astrocytes, integral components of the central nervous system (CNS), fulfill crucial roles such as maintaining ion homeostasis, providing neuroprotection, and contributing to the blood-brain barrier. Their distinctive, star-like morphology is essential to these functions, and abnormalities in astrocyte structure are linked to numerous neurological disorders. However, our understanding of astrocyte morphology, particularly in vivo, remains limited. Traditional imaging methods, such as fluorescence microscopy, introduce challenges like restricting continuous observation and comprehensive morphological analysis. In this study, we present a novel approach utilizing optical diffraction tomography (ODT), an advanced imaging technique that generates 3D refractive index profiles, to image and quantify detailed astrocyte morphology. We demonstrate, for the first time, the application of ODT to image samples through and on disordered glass nanowire (NW) substrates, overcoming the typical challenges posed by nanostructures, which can disrupt phase reconstruction. Crucially, we show that disordered glass nanowire (NW) substrates can induce in vivo-like astrocyte morphology in cultured rat cortical astrocytes. Compared to traditional glass substrates, astrocytes grown on disordered glass NWs substrates exhibited enhanced process branching and greater total arbor length--features typically observed in their natural, in vivo state, a state of advanced maturation. This finding underscores the significant influence of substrate topography on astrocyte structure and highlights the unique potential of nanostructured environments to mimic physiological conditions. By leveraging ODT, we were able to monitor astrocyte behavior on these substrates, providing unprecedented insights into their morphological dynamics. Our study pioneers the use of nanostructured substrates for reconstructing astrocyte morphology and sets the stage for further exploration of how microenvironmental cues shape astrocyte morphology and behavior.

cell biology↗

bioRxiv2023

Shining Light on Osteoarthritis: Spatially Offset Raman Spectroscopy as a Window into Cartilage Health

Articular cartilage is a complex tissue, and early detection of osteoarthritis (OA) is crucial for effective treatment. However, current imaging modalities lack molecular specificity and primarily detect late-stage changes. In this study, we propose the use of Spatially Offset Raman Spectroscopy (SORS) for non-invasive, depth-dependent, and molecular-specific diagnostics of articular cartilage. We demonstrate the potential of SORS to penetrate deep layers of cartilage, providing a comprehensive understanding of disease progression. Our SORS measurements were characterized and validated through mechanical and histological techniques, revealing strong correlations between spectroscopic measurements and both Youngs modulus and depth of cartilage damage. By longitudinally monitoring enzymatically degraded condyles, we further developed a depth-dependent damage-tracking method. Our analysis revealed distinct components related to sample depth and glycosaminoglycan (GAG) changes, offering a comprehensive picture of cartilage health. Collectively, these findings highlight the potential of SORS as a valuable tool for enhancing OA management and improving patient outcomes.

bioengineering↗