2018 Volume 67 Issue 2 Pages 73-79
In the present study, electrodes covered with biopolymer film were constructed as a scaffold for the sensing of biological molecules. First, chitin powder was dissolved with lithium chloride and organic solvents, and chitin film was prepared. The protonated film could immobilize glucose oxidase due to an electrostatic interaction. When a platinum electrode was covered with the film, a glucose sensing system was easily fabricated. Next, biological molecules were detected by using an electrode covered with protein/chitin film. To electrochemically measure a biological molecule, the molecule was labeled with an electroactive compound. The measurement principle was that the electrode response changed due to a competitive reaction to the binding sites of the protein between the target molecule and the labeled molecule. In addition, a carbohydrate molecular recognition protein was modified on the chitin film because the protein combined with the chitin surface through N-acetylglucosamine moieties. As a result, a chitin film with a new function was fabricated. To examine whether the film was suitable for a scaffold, a carbohydrate probe with an electroactive compound was synthesized through Schiff base reaction. When the amount of the probe was constant, the peak current increased as the amount of the native carbohydrate increased. Therefore, immobilization of the protein on the film was simply achieved based on molecular recognition. On the other hand, the electrochemical detection of protein was carried out using an electrode coated with collagen including a metal complex. The proteins in foods were determined using the electrode with the complexes. Furthermore, carbon/biopolymer film with conductivity was fabricated to improve the sensitivity of the target biomolecule. The sensitivities of several biomolecules were three-fold compared with that using the electrode with collagen alone. Consequently, these systems with a high biocompatibility can be applied to the sensing of biological molecule.