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The present study explores genetic engineering of the respiratory chain and the application of two different flexible osmium redox polymers to achieve efficient electric communication between the gram-positive organism Bacillus subtilis and an electrode. Poly(1-vinylimidazole)(12)-[Os-(4,4'-dimethyl-2,2'-bipyridyl)(2)Cl(2)](+/2+) (osmium redox polymer I) and poly(vinylpyridine)-[Os-(N,N'-methylated-2,2'-biimidazole)(3)](2+/3+) (osmium redox polymer II) were investigated for efficient electrical "wiring" of viable gram-positive bacterial cells to electrodes. Using a B. subtilis strain that overproduces succinate/quinone oxidoreductase (respiratory complex II), we were able to improve the current response several fold using succinate as substrate, in both batch and flow analysis modes, and using gold and graphite electrodes. The efficiency of the osmium redox polymer, working as electron transfer mediator between the cells and the electrode, was compared with that of a soluble mediator (hexacyanoferrate). The results demonstrated that mediators did not have to pass the cytosolic membrane to bring about an efficient electronic communication between bacterial cells with a thick cell wall and electrodes.

This article examines the usefulness of a conducting polymer, polypyrrole, in the design of molecularly imprinted polymer-based sensors. Basic electrochemical techniques previously described in this Journal are applied in the preparation of the molecularly imprinted conducting polymer polypyrrole (mPpy). Pulsed amperometric detection (PAD) method is applied for the estimation of success in the preparation of mPpy and for the detection of analyte interaction with the complementary cavities imprinted within the polymeric backbone. Caffeine was selected as a template molecule for molecular imprinting of polypyrrole. Estimation of caffeine concentration has an analytical impact owing to its high biological activity. Moreover, caffeine is well known to the students. Application of electrochemical polymerization techniques enables preparation of molecularly imprinted conducting polymer-based analytical systems. Such systems exhibit an artificially created affinity and can act as synthetic receptors.

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