Affinity of Antifluorescein Antibodies Encapsulated within a Transparent Sol-Gel Glass

Low temperature processed, porous sol-gel glasses represent a new class of materials for immobilization of biomolecules. The ability to form these materials into films, monoliths, and fibers to produce high-purity, porous glasses and the fact that they are optically transparent and chemically inert make them an intriguing platform for the development of chemical biosensors. In this paper, we report on the first attempt to encapsulate an intact antibody in a sol-gel glass matrix. Specifically, we present results on the affinity of solgel-encapsulated polyclonal antifluorescein. The results demonstrate that the sol-gel-encapsulated antibody retains an affinity for fluorescein; the affinity constant (K_f) for antibody-hapten complex is on the order of 10⁷ M⁻¹. The encapsulation process decreases K_f by about 2 orders of magnitude compared to the native system in buffer solution. The effect of aging and drying on the K_f for sol-gel-encapsulated antifluorescein is reported. Finally, we demonstrate that the intact antibody affinity can be maintained using simple storage protocols.