Autor(es):
Alves, Catarina M.
; Reis, R. L.
; Hunt, J. A.
Data: 2010
Identificador Persistente: http://hdl.handle.net/1822/20643
Origem: RepositóriUM - Universidade do Minho
Descrição
Dynamic contact angle (DCA) analysis was used to investigate the kinetics and dynamics of protein
interactions in a time-dependent manner for a group of organic natural-based surfaces during their
initial contact with aqueous and protein solutions. Starch-based biomaterials were used to analyze the
influence different materials with different surfaces had on the adsorption, desorption and
configuration of proteins. Polymeric blends of starch and cellulose acetate (SCA), polycaprolactone
(SPCL) and ethylene vinyl alcohol (SEVA-C) were used. The model protein systems included single
protein solutions of human serum albumin, fibronectin, vitronectin and fibrinogen, and also complex
solutions of human blood plasma. In the adsorption studies, very small and nearly equal advancing and
receding contact angles were measured for all the materials. Highly wetting and low contact angle
hysteresis, therefore, are exhibited by these surfaces. This effect was more noticeable for SCA surfaces.
Moreover, the effect of protein concentration was also assessed and demonstrated to substantially
affect the DCA wetting forces of SEVA-C and SPCL surfaces. In the desorption studies, during the
rinsing phase with saline solution, the DCA loops became larger than that observed for the adsorption
phase, which indicated increases in the contact angle hysteresis. The hysteresis of SCA and SPCL
surfaces reversibly changed through the desorption phase, at the end of which, hysteresis was
comparable to that of surfaces immersed in saline solution. The results indicated that adsorbed proteins
could desorb more readily on SCA and SPCL than on SEVA-C. In the later case, stronger interactions
such as hydrophobic forces were established and it is likely the rearrangement of protein conformation
had occurred. Monitored by DCA, the evolution of hysteresis demonstrated the progressive bond
strengthening between protein molecules and solid substratum, further elucidating the behaviour of
proteins that regulate cellular interactions with implanted devices.