Novel electroactive sol-gels for the design of electrochromic materials and biosensors

Critical design criteria for developing novel bioelectronic and electrochromic devices from redox active (bio)molecules rely on the electronic and optical response that can be controlled and modulated, as well as the mild environment for stabilizing (bio)molecules.; The sol-gel process provides extraordinary opportunities for integrating solution chemistry into a solid state framework. There were three foci of this research. First, sol-gel based synthesis methods were developed to prepare electroactive silica-based glasses. Second, biomolecules such as redox proteins, co-factors, and enzyme were immobilized in these glasses to fabricate novel bioelectronic systems. Third, the unique optical-electronic properties of redox dyes were exploited for designing novel electrochromic devices (ECDs).; The transparent electroactive matrix was prepared by doping Sn and In into silica sol-gels. The resulting gels are amorphous semiconductors, which possess both ionic and electronic conductivities. During the process of drying, the electronic conductivity increases and the ionic conductivity decreases. The evolution of the structural, morphological, and optical properties are also studied. These matrices were used for design of electronic to optical, and chemical to electronic signal transduction devices.; For bioelectronic applications, flavin mononucleotide, cytochrome c, and horseradish peroxidase were encapsulated in the electroactive matrices. Reversible electronic signal transfer between the external electrodes and the protein containing gels was observed. On the other hand, the feasibility of direct ET was achieved from electrodes modified by HRP containing films for design of a H₂O₂ biosensor. It is found that the sol-gel matrix can increase enzyme loading dramatically, and therefore, enable a high linear detection range.; Finally, redox dye MB and/or PS were immobilized to design novel ECDs. Since this electroactive matrix can transfer electrons, as well as serve as an electrolyte, these dye immobilized glasses exhibit good performance with a simplified ECD configuration.