Publications by authors named "Sudip Nag"

This paper presents an innovative, minimally invasive, battery-free, wireless, peripheral nervous system (PNS) neural interface, which seamlessly integrates a millimeter-scale, fascicle-selective integrated circuit (IC) with extraneural recording and stimulating channels. The system also incorporates a wearable interrogator equipped with integrated machine-learning capabilities. This PNS interface is specifically tailored for adaptive neuromodulation therapy, targeting individuals with paralysis, amputation, or chronic medical conditions.

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We report a nucleic acid-based point of care testing technology for infectious disease detection at resource limited settings by integrating a low-cost portable device with machine learning-empowered quantitative colorimetric analytics that can be interfaced via a smartphone application. We substantiate our proposition by demonstrating the efficacy of this technology in detecting COVID-19 infection from human swab samples, using the RT-LAMP protocol. Comparison with gold standard results from real-time PCR evidences high sensitivity and specificity, ensuring simplicity, portability, and user-friendliness of the technology at the same time.

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Article Synopsis
  • Researchers cloned a thermostable cytochrome P450 enzyme, CYP175A1, from Thermus thermophilus, noting its high thermal stability (Tm of 88°C) which suggests it could be useful in industrial applications as a biocatalyst.
  • Site-saturation mutagenesis targeting the tyrosine 68 residue revealed mutants with enhanced thermostability and altered substrate specificity; for example, Y68K showed improved interaction with myristic acid, while Y68R effectively catalyzed reactions with cholesterol.
  • The study demonstrates that modifying a single amino acid in the enzyme’s substrate binding pocket can significantly impact its binding preferences and catalytic activity, emphasizing the potential for engineering enzymes with
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Selective detection of gases has been a major concern among metal-oxide based chemiresistive gas sensors due to their intrinsic cross-sensitivity. In this endeavor, we report integration of single metal-oxide based chemiresistive sensor with different soft computing tools to obtain perfect recognition of tested analyte molecules by means of signal processing, feature extraction and machine learning. The fabricated sensor device consists of SnO hollow-spheres as the sensing material, which was synthesized chemically.

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Semiconducting metal oxide-based gas sensors have inadequate selectivity as they are responsive toward a variety of gases. Here, we report the implementation of gas sensing kinetic analysis of the sensor to identify the tested volatile organic compounds (VOCs) (2-propanol, formaldehyde, methanol, and toluene) precisely. A single chemiresistive sensor was employed having tin oxide-based hollow spheres as the sensing material, which were obtained by chemical synthesis.

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An antibiotic-conjugated protein-stabilized nanoparticle hybrid system was developed to combat the challenges faced during the treatment of drug-resistant bacterial biofilm-associated infections. Biocompatible silver nanoparticles were synthesized using intracellular protein and gentamycin was attached. The resulting nanohybrid was characterized and its antibacterial efficiency was assessed against Gram-positive, Gram-negative and drug-resistant bacteria.

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Medicinal plants are a source of phytochemicals and they are used for the treatment of several oxidative stress-related or other diseases for their effectiveness, low toxicity and easy availability. Five traditionally used and less characterized herbaceous weeds of West Bengal, India, namely, , , , and , were investigated for the current research study. Aqueous and 70% ethanolic extracts of the leaves were analyzed for estimation of essential phytochemicals and to evaluate their antioxidant status, medicinal properties and cytotoxic effects.

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The efficiency of drug depends not only on its potency but also on its ability to reach the target sites in preference to non-target sites. In this regard, protein assembled nanocarrier is the most promising strategy for intracellular anti-cancer drug delivery. The key motive of this study is to fabricate biocompatible protein assembled nanocarrier conjugated photosensitizer system for stimuli-responsive treatment of lung carcinoma.

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Multidrug resistance (MDR) of bacteria is a major threat to public health globally and its unprecedented increase calls for immediate alternative medical strategies. Antimicrobial photodynamic therapy (aPDT) offers alternative modalities to combat the growing MDR typically by means of targeted cellular internalization of a photosensitizer (PS) capable of producing photoinduced reactive oxygen species (ROS). However, aPDT is severely limited by the self-aggregation behavior and hydrophobicity of PS molecules, which significantly curbs its viability for clinical application.

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Activity-dependent myelination modulates neuron conduction velocity and as such it is essential for a correct wiring of a whole nervous system. Increasing myelination through inducing neuron activity has been proposed as a treatment strategy for demyelination diseases. Yet, the mechanisms and the effects of activity-dependent myelination remain elusive-new tools are needed.

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Microbial synthesis of gold nanoparticles (GNPs) has attracted considerable attention in recent times due to their exceptional capability for the bioremediation of industrial wastes and also for the treatment of wastewater. A bacterial strain Staphylococcus warneri, isolated from the estuarine mangroves of Sundarbans region produced highly stable GNPs by reducing hydrogen auric chloride (HAucl) salt using intracellular protein extract. The nanoparticles were characterized utilizing ultraviolet-visible spectrophotometry, transmission electron microscopy, scanning electron microscopy, atomic force microscopy, X-ray diffraction, and surface enhanced Raman scattering.

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Myelination is governed by neuron-glia communication, which in turn is modulated by neural activity. The exact mechanisms remain elusive. We developed a novel in vitro optogenetic stimulation platform that facilitates subcellular activity induction in hundreds of neurons simultaneously.

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The global knowledge of microbial diversity and function in Sundarbans ecosystem is still scarce, despite global advancement in understanding the microbial diversity. In the present study, we have analyzed the diversity and distribution of bacteria in the tropical mangrove sediments of Sundarbans using 16S rRNA gene amplicon sequencing. Metagenome is comprised of 1,53,926 sequences with 108.

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Neural stimulation using injected electrical charge is widely used both in functional therapies and as an experimental tool for neuroscience applications. Electrical pulses can induce excitation of targeted neural pathways that aid in the treatment of neural disorders or dysfunction of the central and peripheral nervous system. In this review, we summarize the recent trends in the field of electrical stimulation for therapeutic interventions of nervous system disorders, such as for the restoration of brain, eye, ear, spinal cord, nerve and muscle function.

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Introduction: A long-term peripheral neural interface is an area of intense research. The use of electrode interfaces is limited by the biological response to the electrode material.

Methods: We created an electrode construct to harbor the rat sciatic nerve with interposition of autogenous adipose tissue between the nerve and the electrode.

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Mangroves are among the most diverse and productive coastal ecosystems in the tropical and subtropical regions. Environmental conditions particular to this biome make mangroves hotspots for microbial diversity, and the resident microbial communities play essential roles in maintenance of the ecosystem. Recently, there has been increasing interest to understand the composition and contribution of microorganisms in mangroves.

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Wireless power delivery and telemetry have enabled completely implantable neural devices. Current day implants are controlled, monitored, and powered wirelessly, eliminating the need for batteries and prolonging the lifetime. A brief overview of wireless platforms for such implantable devices is presented in this paper alongside an in-depth discussion of wireless platform for peripheral nerve implants covering design requirements, link design, and safety.

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Mangrove microbial communities and their associated activities have profound impact on biogeochemical cycles. Although microbial composition and structure are known to be influenced by biotic and abiotic factors in the mangrove sediments, finding direct correlations between them remains a challenge. In this study we have explored sediment bacterial diversity of the Sundarbans, a world heritage site using a culture-independent molecular approach.

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Neuroprosthetic devices that interface with the nervous system to restore functional motor activity offer a viable alternative to nerve regeneration, especially in proximal nerve injuries like brachial plexus injuries where muscle atrophy may set in before nerve re-innervation occurs. Prior studies have used control signals from muscle or cortical activity. However, nerve signals are preferred in many cases since they permit more natural and precise control when compared to muscle activity, and can be accessed with much lower risk than cortical activity.

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The influence of temporal and spatial variations on the microbial community composition was assessed in the unique coastal mangrove of Sundarbans using parallel 16S rRNA gene pyrosequencing. The total sediment DNA was extracted and subjected to the 16S rRNA gene pyrosequencing, which resulted in 117 Mbp of data from three experimental stations. The taxonomic analysis of the pyrosequencing data was grouped into 24 different phyla.

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Stimulation of biological neurons using electrical charges has gained popularity in neuro-engineering studies. Wireless power delivery to electrical stimulators is an essential requirement for long term and maintenance-free implantable applications. Voltage compliance is often a limiting factor in these systems.

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Electrical stimulations of neuronal structures must ensure net injected charges to be zero for biological safety and voltage compliance reasons. We present a novel architecture of general purpose biphasic constant current stimulator that exhibits less than 5.6 fC error while injecting 140 nC charges using 1.

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Functional Electrical Stimulation (FES) is widely adopted in neuro-engineering to partially alleviate diseased functions in the brain, retina and cochlea. We present a 32-channel wirelessly powered constant current stimulator and low power recording amplifier for FES based applications. The biphasic stimulator utilizes innovative techniques for matched positive/ negative currents and thus improves charge balance.

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Piezoresistive micro-cantilevers are interesting bio-sensing tool whose base resistance value (R) changes by a few parts per million (DeltaR) in deflected conditions. Measuring such a small deviation is always being a challenge due to noise. An advanced and reliable DeltaR/R measurement scheme is presented in this paper which can sense resistance changes down to 6 parts per million.

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