No abstract

This review focuses on recent advances in the use of hydrogels for chemical and biochemical analysis. Specifically, we discuss recognition elements encapsulated within synthetic hydrogels, synthetic polymers grafted with biological molecules that form freestanding gels, and gels made of naturally occurring polymers, such as proteins or polysaccharides. Gels considered here serve as a platform for the analysis or separation of chemical systems with a high degree of selectivity. Analysis or separation was achieved primarily by incorporating biologically active molecules into a gel matrix. Future developments in biologically integrated gel research for chemical analysis are promising due to the diversity of chemical systems yet to be investigated by these versatile analytical platforms.

Cyclic voltammetry and controlled‐potential (bulk) electrolysis have been used to study the direct electrochemical reduction of cyclohexyl bromide (1) and cyclohexyl iodide (2) at glassy carbon cathodes in dimethylformamide (DMF) containing 0.10 M tetramethylammonium tetrafluoroborate (TMABF4). Direct reduction of 1 is a one‐step process that affords a carbanion intermediate, whereas 2 undergoes stepwise reduction to a radical and then a carbanion intermediate. Mixtures of cyclohexane, cyclohexene, and bicyclohexyl arise from bulk electrolyses of both 1 and 2. Catalytic reduction of 1 and 2 by nickel(I) salen and cobalt(I) salen electrogenerated at glassy carbon cathodes in DMF‐TMABF4 has been investigated with the aid of both cyclic voltammetry and bulk electrolysis. Products arising from these catalytic reductions are cyclohexane, cyclohexene, and bicyclohexyl, although significant amounts of unreduced 1 are found when cobalt(I) salen is utilized as the catalyst. Mechanistic aspects of the direct and catalyzed reductions of 1 and 2 are discussed.

We describe an abiotic hydrogel that mimics selectivity of the nuclear pore complex. Copolymerization of peptide tetramers (phenylalanine-serine-phenylalanine-glycine, FSFG) with acrylamide results in hydrophobic interactions significant enough to allow the formation of freestanding hydrogel structures. Incorporation of FSFG motifs also renders the hydrogels selective. Selective binding of importins and nuclear transport receptor-cargo complexes is qualitatively demonstrated and compared with polyacrylamide, hydrogels prepared from a control peptide, and hydrogels prepared from the nuclear pore complex protein Nsp1. These abiotic hydrogels will enable further studies of the unique transport mechanisms of the nuclear pore complex and provide an interesting paradigm for the future development of synthetic platforms for separations and selective interfaces.