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In this report, exploitation of the unique properties of single-walled carbon nanotubes (SWNT) leads to the achievement of direct electron transfer with the redox active centres of adsorbed oxidoreductase enzymes. Flavin adenine dinucleotide (FAD), the redox active prosthetic group of flavoenzymes that catalyses important biological redox reactions and the flavoenzyme glucose oxidase (GOx), were both found to spontaneously adsorb onto carbon nanotube bundles. Both FAD and GOx were found to spontaneously adsorb to unannealed carbon nanotubes that were cast onto glassy carbon electrodes and to display quasi-reversible one-electron transfer. Similarly, GOx was found to spontaneously adsorb to annealed, single-walled carbon nanotube paper and to display quasi-reversible one-electron transfer. In particular, GOx immobilized in this way was shown, in the presence of glucose, to maintain its substrate-specific enzyme activity. It is believed that the tubular fibrils become positioned within tunnelling distance of the cofactors with little consequence to denaturation. The combination of SWNT with redox active enzymes would appear to offer an excellent and convenient platform for a fundamental understanding of biological redox reactions as well as the development of reagentless biosensors and nanobiosensors.

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Fully (99+ %) hydrolyzed poly(vinyl alcohol) (PVA) was electrospun from water using Triton X-100 surfactant to lower the surface tension. The diameter of the electrospun PVA fibers ranged from 100 to 700 nm. Treatment of the PVA fiber mats with methanol for 8 h stabilized the fibers against disintegration in contact with water. In addition, the mats showed increased mechanical strength due to increased crystallinity following post-spinning treatment with methanol. We suggest that methanol treatment serves to increase the degree of crystallinity, and hence the number of physical cross-links in the electrospun PVA fibers. This may occur by removal of residual water within the fibers by the alcohol, allowing PVA-water hydrogen bonding to be replaced by intermolecular polymer hydrogen bonding resulting in additional crystallization. Potential applications of electrospun PVA include filters, precursors to graphitic fibers, and biomedical materials.

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In situ dielectric spectroscopy has been used to characterize vapor-deposited glasses of methyl-m-toluate (MMT), an organic glass former with low fragility (m = 60). Deposition near 0.84T(g) produces glasses of very high kinetic stability; these materials are comparable in stability to the most stable glasses produced from more fragile glass formers. Highly stable glasses of MMT, when annealed above T(g), transform into the supercooled liquid by a heterogeneous mechanism. A constant velocity propagating front is initiated at the free surface and controls the transformation of thin films. The transition to a bulk-dominated transformation process occurs at 5 μm, the largest length scale reported for any glass. Contrary to recent conclusions, we find that physical vapor deposition can form highly stable organic glasses across the entire range of liquid fragilities.

Silicon carbide (SiC) has been around for more than 100 years as an industrial material and has found wide and varied applications because of its unique electrical and thermal properties. In recent years there has been increased attention to SiC as a viable material for biomedical applications. Of particular interest in this review is its potential for application as a biotransducer in biosensors. Among these applications are those where SiC is used as a substrate material, taking advantage of its surface chemical, tribological and electrical properties. In addition, its potential for integration as system on a chip and those applications where SiC is used as an active material make it a suitable substrate for micro-device fabrication. This review highlights the critical properties of SiC for application as a biosensor and reviews recent work reported on using SiC as an active or passive material in biotransducers and biosensors.