Showing papers by "Tuhin Subhra Santra published in 2014"

Impact of pulse duration on localized single-cell nano-electroporation.

Abstract: We introduce a localized single-cell membrane nano-electroporation with controllable sequential molecular delivery by millisecond to nanosecond electrical pulses. An intense electrical field was generated by a pair of transparent indium tin oxide (ITO)-based nano-electrodes, which was confined to a narrow region of the single-cell membrane surface near the nano-electrode edges (approximately 2 μm × 50 nm area), whereas the remaining area of the membrane was unaffected. Moreover, a 250 nm SiO2 passivation layer on top of the nano-electrode reduced not only the thermal effect on the cell membrane surface, but it also avoided the generation of ions during the experiment, resulting in the reduction of cell toxicity and a significant enhancement of cell viability. Our approach precisely delivers dyes, Quantum Dots (QDs) and plasmids, through a localized region of single HeLa cells by considerably enhanced electrophoresis and diffusion effects with different duration of the pulsing process. The smaller molecules took less time to deliver into a single cell with a single pulse, whereas larger biomolecules took longer time even for multiple numbers of long lasting pulses. The system not only generates sequential well-controlled nano-pores allowing for the rapid recovery of cell membranes, but it also provides spatial, temporal and qualitative dosage control to deliver biomolecules into localized single-cell levels, which can be potentially beneficial for single cell studies and therapeutic applications.

Micro/Nanofluidic Devices for Single Cell Analysis

Abstract: 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]. [...]

Nanolocalized Single-Cell-Membrane Nanoelectroporation: For higher efficiency with high cell viability.

Abstract: TODAY, SINGLE-CELL RESEARCH is of great interest to analyze cell-to-cell or cell-to-environment behavior with their intracellular compounds, where bulk measurements of millions of cells together can provide an average value. To deliver biomolecules in a precise and localized way into single living cells with a high transfection rate and high cell viability is a challenging and promisible task for biological and therapeutic research.

Nanoelectroporation and controllable intracellular delivery into localized single cell with high transfection and cell viability

Abstract: Physical introduction of foreign biomolecules such as genes, proteins, DNA and RNA into living cells with high efficiency is a challenging task for biological and therapeutic research. Bulk electroporation technique, where high electric field pulses were applied to millions of cells together in-between two large electrodes, though widely employed, however is nonspecific resulting in variable efficiency with low cell viability. Here we demonstrate controllable nano-electroporation platform for HeLa cell and human Caucasian Gastric Adenocarcinoma (AGS) cell to achieve high efficient bimolecular delivery with high cell viability. Our system consists of 40nm triangular Indium Tin Oxide (ITO) metal tip with 60nm electrode gap to provide high intense electric filed into the local region of the single cell membrane. Therefore biomolecules can be delivered by much enhance electrophoresis and diffusion effects during pulsing process through a small specific nano-region of the single cell, where remaining other area of the cell membrane unaffected. This microfluidic device has great ability to offer spatial, temporal and qualitative dosage control as well as very high transfection efficiency and high cell viability.

Nanolocalized single cell membrane nanoelectroporation

Abstract: © 2014 IEEE. Today single cell research is a great interest to analyze cell to cell or cell to environment behavior with their intracellular compounds, where bulk measurement can provide average value. To deliver biomolecules precise and localized way into single living cell with high transfection rate and high cell viability is a challenging and promisible task for biological and therapeutic research. In this report, we present a nano-localized single cell nano-electroporation technique, where electroporation take place in a very precise and localized area on a single cell membrane to achieve high efficient delivery with high cell viability. We fabricated 60nm gap with 40 nm triangular Indium Tin Oxide (ITO) based nano-eletcrode tip, which can intense electric field in a nano-localized area of a single cell to permeabilize cell membrane and deliver exogenous biomolecules from outside to inside of the cell. This device successfully deliver dyes, proteins into single cell with high cell viability (98%). The process not only control precise delivery mechanism into single cell with membrane reversibility, but also it can provide special, temporal and qualitative dosage control, which might be beneficial for therapeutic and biological cell studies.