Biosensor/biosensing electrochemical

Toxic aromatic amines which constitute a very important class of environmental pollutants can be easily detected by electrochemical DNA biosensors. The electrochemical biosensing strategy was developed by Wang s group based on the intercalative behavior of aromatic amines onto an immobilized dsDNA layer... 

In Vivo Biosensing. In vivo biosensing involves the use of a sensitive probe to make chemical and physical measurements in living, functioning systems (60—62). Thus it is no longer necessary to decapitate an animal in order to study its brain. Rather, an electrochemical biosensor is employed to monitor interceUular or intraceUular events. These probes must be small, fast, sensitive, selective, stable, mgged, and have a linear response. 

Mainly, two principles are used in electrochemical pesticide biosensor design, either enzyme inhibition or hydrolysis of pesticide. Among these two approaches inhibition-based biosensors have been widely employed in analysis due to the simplicity and wide availability of the enzymes. The direct enzymatic hydrolysis of pesticide is also extremely attractive for biosensing, because the catalytic reaction is superior and faster than the inhibition [27],... 

Hu, Y., et al., Green-synthesized gold nanoparticles decorated graphene sheets for label-free electrochemical impedance DNA hybridization biosensing. Biosensors and Bioelectronics,... 

However, electrochemically based transduction devices are more robust, easy to use, portable, and inexpensive analytical systems [45]. Furthermore, electrochemical biosensors can operate in turbid media and offer comparable instrumental sensitivity. Many electrochemical sensing and biosensing devices were reported [46-48]. 

Electrochemical devices have proven very useful for sequence-specific biosensing of DNA. Electrochemical detection of DNA hybridization usually involves monitoring a current response under controlled potential conditions. The hybridization event is commonly detected via the increased current signal of a redox indicator (that recognizes the DNA duplex) or from other hybridization-induced changes in electrochemical parameters (e.g., conductivity or capacitance). Modern electrical DNA hybridization biosensors and bioassays offer remarkable sensitivity, compatibility with modern microfabrication technologies, inherent miniaturization, low cost (disposability), minimal power requirements, and independence of sample turbidity or optical pathway. Such devices are thus extremely attractive for obtaining the sequence-specific information in a simpler, faster, and cheaper manner, compared to traditional hybridization assays. 

The electrochemical based biosensors are the most widely used format in biosensing. Typically the reaction under investigation would either generate a measurable current (amperometric), a measurable potential or charge accumulation (potentiometric) or measurably alter the conductive properties of a medium (conductometric) between electrodes [55]. 

The preparation of dendrimer biocomposite-modified electrode is the primary step in the development of biosensors. Appropriate strategies have been formulated to prepare stable and highly reproducible dendrimer-modified surfaces. Immobilization of biomolecules like enzymes, proteins and other suitable ligands on the dendrimer-modified electrode with extended lifetime is very important. Some general procedures adopted for the preparation of dendrimer biocomposite-modified surfaces for electrochemical biosensing are described below. Some of the unique procedures developed by various authors are elaborated later during the discussion of the performance of biosensors. 

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