Biosensing films

Sol-gel-derived silane-based materials have been proven as a suitable matrix for entrapment of bioactive species, due to biocompatibility of silica and the mild operating conditions. We recall that the solutions used for cathodic electrochemical deposition of silane-based sol-gel films are usually mild acidic (pH 3-6), and the deposition is achieved by electrochemically driving the inter- cial pH near the cathode to mild basic, about pH 8. This environment is favorable for maintaining the activity of biological species such as proteins, enzymes, and bacteria. Many researchers have reported the fabrication of biosensing films by co-electrodeposition of silane with different bioactive substances. The essence of the concept is to entrap bioactive substances within the sol-gel matrix during... 

Yogeswaran, U., S. Thiagarajan, and S. M. Chen. 2007. Nanocomposite of functional multiwall carbon nanotubes with nafion, nano platinum, and nano biosensing film for simultaneous determination of ascorbic acid, epinephrine, and uric acid. AnaZ. Biochem. 365 122-131. 

Chen H, Ye T, Qiu B, Chen G, Chen X (2008) A novel approach based on ferricyanide-mediatra immobilized in an ion-exchangeable biosensing film for the determination of bio-chcanical oxygen demand. Anal Chim Acta 612(l) 75-82. doi 10.1016/j.aca.2008.02.006... 

H. Wang, C.C. Wang, C.X. Lei, Z.Y. Wu, G.L. Shen, and R.Q. Yu, A novel biosensing interfacial design produced by assembling nano-Au particles on amine-terminated plasma-polymerized films. Anal. Bioanal. Chem. 377, 632-638 (2003). 

M.D. Gulcev, G.LG. Goring, M. Rakic, and J.D. Brennan, Reagentless pH-based biosensing using a fluorescently-labelled dextran co-entrapped with a hydrolytic enzyme in sol-gel derived nanocomposite films. Anal. Chim. Acta 457, 47-59 (2002). 

J.D. Jordan, R.A. Dunbar, and F.V. Bright, Aerosol-generated sol-gel-derived thin films as biosensing platforms. Anal. Chim. Acta 332, 83-91 (1996). 

For applications as electro- or photo-catalysts, or for other applications as sensors, solar cells, electrodes in biosensing and biofuel cells, etc. the problem of the amount of titania is less critical, but there is still the need to optimize the film thickness. One of the active directions of research in this area, in fact, is to maintain the nanostructure, but increase the film thickness. A new benchmark for Ti02 nanotube arrays was recently reached. 

Of particular interest is the ability to control and manipulate the permeability of size-exclusion films to meet specific biosensing needs. Electropolymerization processes are particularly suitable for creating controllable size-exclusion films (4). 

Yoon SJ, Kim D (2007) Thin-film-based field penetration engineering for surface plasmon resonance biosensing. J Opt Soc Am A 24 2543-2549... 

There may be instances where one wishes to detect die absorption of molecules from a liquid into a polymeric film on the plate surface. And in biosensing, one may wish to detect the adsorption or attachment of a layer of protein molecules, cells, bacteria or other organisms on a surface. Figure 3.48 (page 130) shows an exploded view of a three-chip FPW liquid flow cell made for such applications. 

Jia F, Shan CS, Niu L et til (2008) Ctubon ntmotube/gold nanoparticles/polyethylenimine-functionaUzed ionic liquid thin film composites for glucose biosensing. Biosens Bioelectron 24 945-950... 

Abdulhalim I, Karabchevsky A, Patzig C, Rauschenbach B, Fuhrmann B, Eltzov E, Marks RS, Xu J, Zhang F, Lakhtakia A (2009) Surface-enhanced fluorescence from metallic sculptured thin films with application to biosensing in water. Appl Phys Lett 94 063206... 

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