Tuhin Subhra Santra

Characterization of diamond-like nanocomposite thin films grown by plasma enhanced chemical vapor deposition

Diamond-like nanocomposite (DLN) thin films, comprising the networks of a-C:H and a-Si:O were deposited on pyrex glass or silicon substrate using gas precursors (e.g., hexamethyldisilane, hexamethyldisiloxane, hexamethyldisilazane, or their different combinations) mixed with argon gas, by plasma enhanced chemical vapor deposition technique. Surface morphology of DLN films was analyzed by atomic force microscopy. High-resolution transmission electron microscopic result shows that the films contain nanoparticles within the amorphous structure. Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, and x-ray photoelectron spectroscopy (XPS) were used to determine the structural change within the DLN films. The hardness and friction coefficient of the films were measured by nanoindentation and scratch test techniques, respectively. FTIR and XPS studies show the presence of CC, CH, SiC, and SiH bonds in the a-C:H and a-Si:O networks. Using Raman spectroscopy, we also found that the hardness of...

Recent Trends on Micro/Nanofluidic Single Cell Electroporation

The behaviors of cell to cell or cell to environment with their organelles and their intracellular physical or biochemical effects are still not fully understood. Analyzing millions of cells together cannot provide detailed information, such as cell proliferation, differentiation or different responses to external stimuli and intracellular reaction. Thus, single cell level research is becoming a pioneering research area that unveils the interaction details in high temporal and spatial resolution among cells. To analyze the cellular function, single cell electroporation can be conducted by employing a miniaturized device, whose dimension should be similar to that of a single cell. Micro/nanofluidic devices can fulfill this requirement for single cell electroporation. This device is not only useful for cell lysis, cell to cell fusion or separation, insertion of drug, DNA and antibodies inside single cell, but also it can control biochemical, electrical and mechanical parameters using electroporation technique. This device provides better performance such as high transfection efficiency, high cell viability, lower Joule heating effect, less sample contamination, lower toxicity during electroporation experiment when compared to bulk electroporation process. In addition, single organelles within a cell can be analyzed selectively by reducing the electrode size and gap at nanoscale level. This advanced technique can deliver (in/out) biomolecules precisely through a small membrane area (micro to nanoscale area) of the single cell, known as localized single cell membrane electroporation (LSCMEP). These articles emphasize the recent progress in micro/nanofluidic single cell electroporation, which is potentially beneficial for high-efficient therapeutic and delivery applications or understanding cell to cell interaction.

Tuning nano electric field to affect restrictive membrane area on localized single cell nano-electroporation

Interaction of electric field with biological cells is an important phenomenon for field induced drug delivery system. We demonstrate a selective and localized single cell nano-electroporation (LSCNEP) by applying an intense electric field on a submicron region of the single cell membrane, which can effectively allow high efficient molecular delivery but low cell damage. The delivery rate is controlled by adjusting transmembrane potential and manipulating membrane status. Thermal and ionic influences are deteriorated from the cell membrane by dielectric passivation. Either reversible or irreversible by LSCNEP can fully controlled with potential applications in medical diagnostics and biological studies.

Microfluidic Devices in Advanced Caenorhabditis elegans Research

The study of model organisms is very important in view of their potential for application to human therapeutic uses. One such model organism is the nematode worm, Caenorhabditis elegans. As a nematode, C. elegans have ~65% similarity with human disease genes and, therefore, studies on C. elegans can be translated to human, as well as, C. elegans can be used in the study of different types of parasitic worms that infect other living organisms. In the past decade, many efforts have been undertaken to establish interdisciplinary research collaborations between biologists, physicists and engineers in order to develop microfluidic devices to study the biology of C. elegans. Microfluidic devices with the power to manipulate and detect bio-samples, regents or biomolecules in micro-scale environments can well fulfill the requirement to handle worms under proper laboratory conditions, thereby significantly increasing research productivity and knowledge. The recent development of different kinds of microfluidic devices with ultra-high throughput platforms has enabled researchers to carry out worm population studies. Microfluidic devices primarily comprises of chambers, channels and valves, wherein worms can be cultured, immobilized, imaged, etc. Microfluidic devices have been adapted to study various worm behaviors, including that deepen our understanding of neuromuscular connectivity and functions. This review will provide a clear account of the vital involvement of microfluidic devices in worm biology.

Electroporation Based Drug Delivery and Its Applications

When a certain strong electrical pulse applied across a cell or tissue, the structures of the cell or tissue would be rearranged to cause the permeabilization of the cell membrane, named in early 1980’s “electroporation”[1]. The theoretical and experimental studies of electric field effects on living cells with their bilayer lipid membrane has been studies in 1960’s to 1970’s century [1-6]. During these years, the researches were primarily dealt with reversible and irreversible membrane breakdown in vitro. Based on these research, the first gene transfer by custom-built electroporation chamber on murine cells was performed by Neumann et al. in 1982 [7]. When electric field (E≈0.2V, Usually 0.5-1V) applied across the cell membrane, a significant amount of electrical conductivity can increase on the cell plasma membrane. As a result, this electric field can create primary membrane “nanopores” with minimum 1 nm radius, which can transport small amount of ions such as Na+ and Clthrough this mem‐ brane “nanopores”. The essential features of electroporation included (a) short electric pulse application (b) lipid bilayer charging (c) structural rearrangements within the cell mem‐ brane (d) water-filled membrane structures, which can perforate the membrane (“aqueous pathways” or pores) and (e) increment of molecular and ionic transportation [8]. In conven‐ tional electroporation (Bulk electroporation) technique, an external high electric field pulses were applied to millions of cells in suspension together in-between two large electrodes. When this electric field was above the critical breakdown potential of the cell, a strong polarization of the cell membrane occur due to the high external electric field. Applying a very high electric field could be resulted in the formation of millions of pores into the cell membrane simultaneously without reversibility [9]. Several methods other than electropora‐ tion can be used for gene transfer like microprecipitates, microinjection, sonoporation,

Influence of flow rate on different properties of diamond-like nanocomposite thin films grown by PECVD

Diamond-like nanocomposite (DLN) thin films were deposited on pyrex glass substrate using different flow rate of haxamethyldisiloxane (HMDSO) based liquid precursor with nitrogen gas as a glow discharged decomposition by plasma enhanced chemical vapor deposition (PECVD) technique. The significant influence of different precursor flow rates on refractive index and thickness of the DLN films was measured by using spectroscopic filmatrics and DEKTAK profilometer. Optical transparency of the DLN thin films was analyzed by UV-VIS-NIR spectrometer. FTIR spectroscopy, provides the information about shifted bonds like SiC2, Si-C, Si-O, C-C, Si-H, C-H, N-H, and O-H with different precursor flow rate. We have estimated the hardness of the DLN films from Raman spectroscopy using Gaussian deconvolution method and tried to investigate the correlation between hardness, refractive index and thickness of the films with different precursor flow rates. The composition and surface morphology of the DLN films were investigat...

Diamond, Diamond-Like Carbon (DLC) and Diamond-Like Nanocomposite (DLN) Thin Films for MEMS Applications

T. S. Santra1, T. K. Bhattacharyya2, P. Patel3, F. G. Tseng1 and T. K. Barik4 1Institute of Nanoengineering and Microsystems (NEMS), National Tsing Hua University, Hsinchu, Taiwan 2Department of Electronics and Electrical Communication Engineering, Indian Institute of Technology, Kharagpur, West Bengal, 3Department of Electrical and Computer Engineering, University of Illinois at Urbana Champaign, 4School of Applied Sciences and Humanities, Haldia Institute of Technology, Haldia, Purba Medinipur, West Bengal, 1Republic of China 2,4India 3USA

Micro/Nanofluidic Devices for Single Cell Analysis

The Special Issue of Micromachines entitled “Micro/Nanofluidic Devices for Single Cell Analysis” covers recent advancements regarding the analysis of single cells by different microfluidic approaches. To understand cell to cell behavior with their organelles and their intracellular biochemical effect, single cell analysis (SCA) can provide much more detailed information from small groups of cells or even single cells, compared to conventional approaches, which only provide ensemble-average information of millions of cells together. Earlier reviews provided single cell analysis using different approaches [1–3]. The author demonstrates invasive and noninvasive with time and non-time resolved SCA [1]; whereas some other literature provided destructive (with dyes, DNA, RNA, proteins and amino acids) and nondestructive (electroporation, impedance measurement and fluorescence based methods) cellular content analysis using microfluidic devices [3]. Further literature also suggest that single cell analysis is possible with capillary electrophoresis (CE) combined with a detection method such as electrochemical detection (ED), laser induced fluorescence (LIF) detection and mass spectrometry (MS) [4,5]. [...]

Dielectric passivation layer as a substratum on localized single-cell electroporation

Single-cell electroporation is a powerful technique to understand cellular behavior with heterogeneity, which might be impossible based on bulk measurements of millions of cells together. In this study, a dielectric passivation layer was deposited on top of an indium-tin oxide micro-electrode-based transparent chip surface using a plasma enhanced chemical vapour deposition technique. We theoretically and experimentally investigated the key effects of the dielectric passivation layer on localized single-cell electroporation for different cancer cells, which were randomly distributed with a high density throughout the chip surface as a monolayer. The passivation layer not only prevented the conventional or bulk electroporation with bubble and ion generation, but also provide an intense electric field in-between electrode gap for localized single-cell electroporation with high cell viability. Thus, devices with dielectric passivation layers are potentially applicable for single-cell studies.

Microinjection for Single-Cell Analysis

The mere existence of life, from unicellular organisms to well-organized multicellular organisms, pathological conditions and death, has always fascinated human beings and demanded understanding of biological systems over several centuries. Further, an efficient treatment strategy for genetic disorders requires understanding of pathological conditions at the single-cell level. Numerous experimental methodologies have been developed over several decades to facilitate our understanding of cellular functions, by modulating the molecular pathways. Needle microinjection is one of them and it is widely used to modulate cellular functions by introducing foreign cargo into the cell. Microinjection is a method that can directly deliver a precise amount of foreign cargo either into the cytoplasm or the nucleus of a single cell using micropipettes. It is considered a gold standard method of direct cargo delivery. After introduction of this technique in the early 1900s, numerous modifications were made to improve its efficiency and it was applied to a wide variety of fields from scientific research to clinical therapy. This chapter is intended to provide a basic knowledge of the microinjection technique, its advantages and disadvantages, its development, the basic instrumentation required along with a basic protocol, and its uses collected extensively from numerous literatures up-to-date. Further, several modifications that have been carried out to improve the basic instrumentation setup, in order to increase the efficiency and rate of microinjection by the addition of semi-automated and automated computerized systems, are also discussed. Finally, this chapter provides a gateway to explore advanced understanding of microinjection for single-cell analysis.