DILATATIONAL PROPERTIES OF ADSORBED POLY(D,L-LACTIDE) AND BOVINE SERUM-ALBUMIN MONOLAYERS AT THE DICHLOROMETHANE WATER INTERFACE/

The use of the dynamic pendant drop method has permitted the accumulat ion of information in real time on the kinetic and theological process es that accompany the adsorption of bovine serum albumin (BSA) at the dichloromethane (DCM)/water interface in the presence and in the absen ce of poly(D,L-lactide) (PLA50). These results have been compared with those obtained at the air/water interface. The study of the adsorptio n kinetics of BSA at the DCM/water and air/water interfaces has shown that the adsorption process was diffusion controlled in both cases for relatively low concentrations of protein (0.005 g/L) In the presence of PLA50, the adsorption of BSA at the DCM/water interface led to a mi xed interfacial layer. The mechanism of the formation of this mixed in terface involves the penetration of BSA into the saturated layer of PL A50 with the displacement and condensation of the PLA50 segments. In a ll cases, theological results indicated a pure elastic behavior for th e mixed BSA/PLA50 interfacial layers. The absence of relaxation upon t he application of dilatational stress was attributed to the instantane ous displacement of the PLA50 segments and the nonexpulsion of the BSA segments. These results are interpreted with respect to the preparati on of biodegradable PLA50 microparticles related to an emulsion-based process.