Adsorption of monoclonal antibodies to glass microparticles

Microparticulate glass represents a potential contamination to protein formulations that may occur as a result of processing conditions or glass types. The effect of added microparticulate glass to formulations of three humanized antibodies was tested. Under the three formulation conditions tested, all three antibodies adsorbed irreversibly at near monolayer surface coverages to the glass microparticles. Analysis of the secondary structure of the adsorbed antibodies by infrared spectroscopy reveal only minor perturbations as a result of adsorption. Likewise, front-face fluorescence quenching measurements reflected minimal tertiary structural changes upon adsorption. In contrast to the minimal effects on protein structure, adsorption of protein to suspensions of glass microparticles induced significant colloidal destabilization and flocculation of the suspension.