Immunoassays in sol-gel matrices

Parasites have been encapsulated within sol-gel silica matrices. Thermoporometry measurements show that the pore size depends strongly on experimental conditions. Pores as large as 100 Angstrom in diameter can be obtained, allowing the diffusion of large biomolecules such as immunoglobulins. TEM observations, performed on procaryote (bacteria) and eucaryote (protozoa) specimen show that the cellular organization and the integrity of the plasma membrane of entrapped parasites are preserved. Moreover they retain their antigenic activity and can react specifically with the corresponding antibodies. Sol-gel matrices have then been used for the realization of enzyme-linked immunosorbent assays (ELISA) directly with the sera of infected patients. Two examples are described, one with parasitic protozoa, Leishmania, and the other one with the cystic hydatid stage of tapeworm parasites, Echinococcus granulosus.