Biosensors composite-based

X. Chen and S. Dong, Sol-gel-derived titanium oxide/copolymer composite based glucose biosensor. 

An inherent advantage of the biosensor designs based on the use of rigid composite electrodes is the possibility of surface renewability. This regeneration treatment is performed by simple polishing of the electrode surface for approximately 5 s on a 150 grit SiC paper. 

Composite based electrodes have shown improved selectivity by inhibiting the interference reaction at the electrode. The large surface area, electrochemical properties, catalytic abilities and inherent biocompatibility make composites suitable for use in amperometric biosensors. Composites of gold nanopaiticles carbon based materials, Prussian blue nanopaiticles have been utilized for the fabrication of electrochemical... 

An immunosensor based on amine-functionalized CNT-SPE was described for detection of the cardiac troponin T, an important marker of acute myocardial infarction. The disposable sensor was fabricated by squeezing an adhesive carbon ink containing carbon nanotubes onto a polyethylene terephthalate substrate forming a thin film. The use of CNTs increased the reproducibility and stability of the sensor, and the amine groups permitted a nonrandom immobilization of antibodies against cardiac troponin T. Another example of the use of carboxylated CNTs is found by the work presented by Rafiee and Fakhari, who prepared a composite based on CNTs and Nafion for the development of a biosensor for the determination of insulin. Carboxylated CNTs plus Nafion were dispersed in water under ultrasonic conditions to get a homogeneous suspension and then a certain volume of that dispersive solution was dropped on the carbonaceous surface of the SPE. 

Lev O., Wu Z., Bharathi S., GlraaV., Modestov A.D., Gun J., Rabinovich L., Sampath S. Sol-gel materials in electrochemistry. Chan. Mater. 1997 9(11) 2354-23 Li J., Chia L.S., Goh N.K., Tan S.N. Renewable silica sol-gel derived carbon composite based glucose biosensor. J. Electroanal. Chem. 1999 460(1-2) 234-241 Lipatov Y.S. Polyma blends and interpenetrating polymer networks at interface with solids. Prog. Polym. 2002 27(9) 1721-1801... 

CNTs are also widely used in actuators [168-171], The addition of CNTs to PANI fibers increased the electromechanical actuation because the CNTs improved the mechanical, electronic and electrochemical properties of the PANI fibers [172-174], Composites based on CNTs are studied for a variety of sensor applications [175-177], For example, polypyrrole or PANI deposited on single-walled CNT networks that can be used as solid state pH sensors [178], A DNA sensor was created fi om a composite of polypyrrole and CNTs fimctionalized with carboxylic groups to covalently immobilize DNA onto CNTs [179], In general, the presence of CNTs tends to increase the overall and selectivity of biosensors, The thermal transport properties of polymer composites can be improved with the addition of CNTs due to the excellent thermal conductivity of CNTs, Such composite are quite attractive for usages as printed circuit boards, connectors, thermal interface materials, heat sinks, lids, housings, etc, [92,180],... 

Tan, X.C.,Tian, Y.X., Cai, P.X. andZou, X.Y. (2005) Glucose biosensor based on glucose oxidase immobilized in sol—gel chitosan/silica hybrid composite film on Prussian blue modified glass carbon electrode. Analytical and Bioanalytical Chemistry, 381, 500-507. 

A strain of yeast and a strain of bacterium were co-immobilized to fabricate a biochemical oxygen demand (BOD) sensor based on sol-gel derived composite materials97. This novel type of biosensor was developed for water monitoring and was used to determine the BOD values of OECD synthetic wastewater, domestic wastewater, and lake waters. The microorganisms Trichosporon cutaneum and Bacillus subtilis were coimmobilized in the sol-gel composite material, which was composed of silica and the grafting copolymer of poly (vinyl alcohol) and 4-vinylpyridine (PVA-g-P(4-VP)). 

Jia J., Tang M., Chen X., Qi L., Dong S., Co-immobilized microbial biosensor for BOD estimation based on sol-gel derived composite material, Biosens. Bioelectr. 2003 18 1023-1029. 

P.A. Fiorito and S.I.C. de Torresi, Hybrid nickel hexacyanoferrate/polypyrrole composite as mediator for hydrogen peroxide detection and its application in oxidase-based biosensors. J. Electroanal. Chem. 581, 31 (2005). 

In recent years, there are more applications based on the layer-by-layer fabrication techniques for CNT-modified electrodes. This technique clearly provides thinner and more isolated CNTs compared with other methods such as CNT-composite and CNT coated electrodes in which CNTs are in the form of big bundles. This method should help biomolecules such as enzymes and DNA to interact more effectively with CNTs than other methods, and sensors based on this technique are expected to be more sensitive. Important biosensors such as glucose sensors have been developed using this technique, and further development of other sensors based on the layer-by-layer technique is expected. 

P.P. Joshi, S.A. Merchant, Y. Wang, and D.W. Schmidtke, Amperometric biosensors based on redox polymer-carbon nanotube-enzyme composites. Anal. Chem. 77, 3183—3188 (2005). 

X.C. Tan, MJ. Li, RX. Cai, LJ. Luo, and X.Y. Zou, An amperometric cholesterol biosensor based on multiwalled carbon nanotubes and organically modified sol-gel/chitosan hybrid composite film. Anal. Biochem. 337, 111-120 (2005). 

V.S. Tripathi, V.B. Kandimalla, and H.X. Ju, Amperometric biosensor for hydrogen peroxide based on ferrocene-bovine serum albumin and multiwall carbon nanotube modified ormosil composite. Biosens. Bioelectron. 21,1529-1535 (2006). 

Constantinos G. Tsiafoulis et al. report the electrochemical behaviour of a composite film based on ferrocene intercalated V205.nH20 xerogel (FeCp2-VXG) with photocrosslinkable polyvinyl alcohol with styrylpyridinium residues (PVA-SbQ), in order to be used as an electrocatalyst and host protein platform to develop an amperometric biosensor. 

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