Development of electrochemical reporter assay using HeLa cells transfected with vector plasmids encoding various responsive elements

Redox Electrochemistry to Interrogate and Control Biomolecular Communication

Cells often communicate by the secretion, transport, and perception of molecules. Information conveyed by molecules is encoded, transmitted, and decoded by cells within the context of the prevailing microenvironments. Conversely, in electronics, transmission reliability and message validation are predictable, robust, and less context dependent. In turn, many transformative advances have resulted by the formal consideration of information transfer. One way to explore this potential for biological systems is to create bio-device interfaces that facilitate bidirectional information transfer between biology and electronics. Redox reactions enable this linkage because reduction and oxidation mediate communication within biology and can be coupled with electronics. By manipulating redox reactions, one is able to combine the programmable features of electronics with the ability to interrogate and modulate biological function. In this review, we examine methods to electrochemically interrogate the various components of molecular communication using redox chemistry and to electronically control cell communication using redox electrogenetics.

Electrochemical Biosensing System for Single Cells, Cellular Aggregates and Microenvironments

Applications of electrochemical biosensing for surveying intact cells and tissues have been focus of attention. Two experimental approaches have been used when performing amperometric measurements on biological cells, the stylus-type microelectrode probes and the electrode-integrated microdevices based on lithographic technologies. For the probe scanning approach, various types of microsensors were developed to monitor localized physical or chemical natures at a variety of surfaces in situ under wet conditions. Scanning electrochemical microscopy (SECM) has been applied for monitoring local oxygen, enzyme activity, and collection of transcripts. For the non-scanning type of approach, electrode array devices allow very rapid response, parallel monitoring, and multi-analyte assay. Sveral topics of on-chip-culture system were introduced especially concerning on gene expression monitoring by reporter system and reconstruction of in vivo-like nature by controlling microenvironments. Electrochemical reporter assay has been demonstrated to monitor the gene expression process of the gene-modified cultured cells. Long-term monitoring of cellular function of spheroids and three dimensionally-cultured cells were carried out by controlling microenvironments on the cellular chip.

Bifunctional tri(ethylene glycol) alkanethiol monolayer modified gold electrode for on-chip electrochemical immunoassay of pg level leptin

An on-chip enzyme-linked immunosorbent assay combined with an electrochemical detection method (EC-ELISA) was employed to detect a leptin, one of the most important adipose derived hormones, using gold electrodes modified with a tri(ethylene glycol) terminated short alkanethiol (TEGCnSH, Cn = (CH(2))n, n = 2, 4, 6, and 8) monolayer. These TEGCnSH monolayers on gold electrodes can suppress non-specific protein adsorption without affecting the electrochemical activity required for detecting p-aminophenol (PAP), which is an alkaline phosphatase (ALP) product. We measured leptin with a highly sensitive detection range (100 pg mL(-1) to 10 ng mL(-1) level) and with the desired detection limit (13.6 pg mL(-1)) by using electrochemical detection. For detecting leptin, the EC-ELISA method using TEGC4SH modified gold electrode with a poly(dimethylsiloxane) based microchannel was superior to the conventional ELISA method. With the EC-ELISA method, we were able to measure leptin with a satisfactory detection range and a pg level detection limit within 30 min, which is a much lower detection level than that obtained with conventional plate based ELISA.

Current application of micro/nano-interfaces to stimulate and analyze cellular responses

Microfabrication technologies have a high potential for novel approaches to access living cells at a cellular or even at a molecular level. In the course of reviewing and discussing the current application of microinterface systems including nanointerfaces to stimulate and analyze cellular responses with subcellular resolution, this article focuses on interfaces based on microfluidics, nanoparticles, and scanning electrochemical microscopy (SECM). Micro/nanointerface systems provide a novel, attractive means for cell study because they are capable of regulating and monitoring cellular signals simultaneously and repeatedly, leading us to an enhanced understanding and interpretation of cellular responses. Therefore, it is hoped that the integrated micro/nanointerfaces presented in this review will contribute to future developments of cell biology and facilitate advanced biomedical applications.