Aerosol-generated sol-gel-derived thin films as biosensing platforms

We have incorporated an antibody into a sol-gel-derived thin film composite and demonstrated that it retains affinity for its hapten. An inexpensive apparatus to produce and deposit, aerosol-generated sol-gel-derived thin films was also developed. The antibody antifluorescein (AF) was entrapped between two sol-gel thin films (0.62 ± 0.05 μm) in a sandwich architecture. The fluorescent hapten 5-(-and 6-)-carboxy-4',5'-dimethylfluorescein (Me₂F) was used to determine the accessibility and viability of the entrapped AF. Results demonstrate that a population of the entrapped antibodies recognizes and binds Me₂F for up to 13 weeks when stored in pH 8 phosphate buffer at 4°C. An intriguing result is that the response times of these AF-doped thin films actually improve as a function of storage time. We explain this observation in terms of decreased viability of AF molecules sequestered between the upper and lower films of the sandwich. Partial regeneration (40-50%) of the biosensor was obtained using a mild chaotropic reagent (NaCl) and the AF-doped films could be reset/regenerated up to six times.