Tuhin Subhra Santra

Bio: Tuhin Subhra Santra is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Electroporation & Materials science. The author has an hindex of 16, co-authored 69 publications receiving 676 citations. Previous affiliations of Tuhin Subhra Santra include Indian Institutes of Technology & Tsinghua University.

Microfluidic platforms for single neuron analysis

Abstract: Single-neuron actions are the basis of brain function, as clinical sequelae, neuronal dysfunction or failure for most of the central nervous system (CNS) diseases and injuries can be identified via tracing single-neurons. The bulk analysis methods tend to miscue critical information by assessing the population-averaged outcomes. However, its primary requisite in neuroscience to analyze single-neurons and to understand dynamic interplay of neurons and their environment. Microfluidic systems enable precise control over nano-to femto-liter volumes via adjusting device geometry, surface characteristics, and flow-dynamics, thus facilitating a well-defined micro-environment with spatio-temporal control for single-neuron analysis. The microfluidic platform not only offers a comprehensive landscape to study brain cell diversity at the level of transcriptome, genome, and/or epigenome of individual cells but also has a substantial role in deciphering complex dynamics of brain development and brain-related disorders. In this review, we highlight recent advances of microfluidic devices for single-neuron analysis, i.e., single-neuron trapping, single-neuron dynamics, single-neuron proteomics, single-neuron transcriptomics, drug delivery at the single-neuron level, single axon guidance, and single-neuron differentiation. Moreover, we also emphasize limitations and future challenges of single-neuron analysis by focusing on key performances of throughput and multiparametric activity analysis on microfluidic platforms.

Scalable Parallel Manipulation of Single Cells Using Micronozzle Array Integrated with Bidirectional Electrokinetic Pumps.

Abstract: High throughput reconstruction of in vivo cellular environments allows for efficient investigation of cellular functions. If one-side-open multi-channel microdevices are integrated with micropumps, the devices will achieve higher throughput in the manipulation of single cells while maintaining flexibility and open accessibility. This paper reports on the integration of a polydimethylsiloxane (PDMS) micronozzle array and bidirectional electrokinetic pumps driven by DC-biased AC voltages. Pt/Ti and indium tin oxide (ITO) electrodes were used to study the effect of DC bias and peak-to-peak voltage and electrodes in a low conductivity isotonic solution. The flow was bidirectionally controlled by changing the DC bias. A pump integrated with a micronozzle array was used to transport single HeLa cells into nozzle holes. The application of DC-biased AC voltage (100 kHz, 10 Vpp, and VDC: -4 V) provided a sufficient electroosmotic flow outside the nozzle array. This integration method of nozzle and pumps is anticipated to be a standard integration method. The operating conditions of DC-biased AC electrokinetic pumps in a biological buffer was clarified and found useful for cell manipulation.

Microfluidic Technologies for Cell Manipulation, Therapeutics, and Analysis

Abstract: This chapter discusses in detail some of the prominent microfluidic strategies employed for cellular manipulation, analysis, and treatment and their feasibility in clinical applications. The major advantage of microfluidic techniques over other conventional methods is that they provide high-throughput devices for the manipulation and analysis of cells. Many high-throughput microfluidic devices have been used for single-cell trapping using electro-osmotic flow manipulation, microvortex manipulation, etc. The chapter discusses microfluidic-based physical techniques, such as electroporation and mechanoporation, for single-cell therapeutic and diagnostic purposes. Droplet microfluidics is frequently employed for single-cell analysis due to its high specificity and potentiality to isolate single cells. Additionally, microfluidic technologies are widely used to analyze single-cell intracellular components, such as DNA, RNA, proteins, and amino acids. Analysis of these components on a single-cell level is important due to the extreme variation in the composition of proteins within a population of cells.

Nanofocused electric field for localized single cell nanoelectroporation with membrane reversibility

Abstract: Despite the significant research in electroporation, high electric field was applied to the whole cells resulted in permeabilizing the membrane of millions of cells without reversibility [1]. To deliver biomolecules through the specific region of the cell membrane with high cell viability and high transfection rate is important for various biological and therapeutic applications.This report presents a new type localized single cell membrane electroporation (LSCMEP), at specific region of the single cell with the application of 800 μs electric pulse. The ITO nano-electrodes with 100nm thickness and 500 nm gap between two electrodes can generate an intense electric field to track biomolecules inside HeLa cell in our studies. This small gap between two nano-electrodes can neglect thermal effect on cell membrane and permit reversible electroporation with high cell viability (90%) and minimum effected electroporation region (0.48 μm). Our approach successfully delivers biomolecules through a specific region of single cell with high transfection rate (82%) and high cell viability. This process, not only generates well-controlled nano-pores allowing rapid recovery of cell membrane, but also it provides a clear optical path potentially tracking of drugs to deliver inside single cell.

Self-Supported Interconnected Pt Nanoassemblies as Highly Stable Electrocatalysts for Low-Temperatur

Abstract: In it for the long haul: Clusters of Pt nanowires (3D Pt nanoassemblies, Pt NA) serve as an electrocatalyst for low-temperature fuel cells. These Pt nanoassemblies exhibit remarkably high stability following thousands of voltage cycles and good catalytic activity, when compared with a commercial Pt catalyst and 20 % wt Pt catalyst supported on carbon black (20 % Pt/CB).

One Bacterial Cell, One Complete Genome

Abstract: While the bulk of the finished microbial genomes sequenced to date are derived from cultured bacterial and archaeal representatives, the vast majority of microorganisms elude current culturing attempts, severely limiting the ability to recover complete or even partial genomes from these environmental species. Single cell genomics is a novel culture-independent approach, which enables access to the genetic material of an individual cell. No single cell genome has to our knowledge been closed and finished to date. Here we report the completed genome from an uncultured single cell of Candidatus Sulcia muelleri DMIN. Digital PCR on single symbiont cells isolated from the bacteriome of the green sharpshooter Draeculacephala minerva bacteriome allowed us to assess that this bacteria is polyploid with genome copies ranging from approximately 200-900 per cell, making it a most suitable target for single cell finishing efforts. For single cell shotgun sequencing, an individual Sulcia cell was isolated and whole genome amplified by multiple displacement amplification (MDA). Sanger-based finishing methods allowed us to close the genome. To verify the correctness of our single cell genome and exclude MDA-derived artifacts, we independently shotgun sequenced and assembled the Sulcia genome from pooled bacteriomes using a metagenomic approach, yielding a nearly identical genome. Four variations we detected appear to be genuine biological differences between the two samples. Comparison of the single cell genome with bacteriome metagenomic sequence data detected two single nucleotide polymorphisms (SNPs), indicating extremely low genetic diversity within a Sulcia population. This study demonstrates the power of single cell genomics to generate a complete, high quality, non-composite reference genome within an environmental sample, which can be used for population genetic analyzes.