Studies on electrostatic adsorption of proteins on modified surface by real-time surface plasmon resonance technique

The elucidation of key influence factors for electrostatic adsorption is ve ry important to control protein nonspecific adsorption on modified surfaces . In this study, real-time surface plasmon resonance technique is used to c haracterize the electrostatic adsorption of two proteins (mouse IgG and pro tein A) on carboxymethyldextran-modified surface. The results show that pro tein solution pH and ionic strength are key influence factors for efficient electrostatic adsorption. The influence of protein, solution pH on the amo unt of electrostatic adsorption depends on the type of the charge and the c harge density of both protein and modified matrix on the surface. The elect rostatic adsorption process involves a competition between the positively c harged protein and other positively charged species in the buffer solution. A decrease of ionic strength leads to an increasing electrostatic adsorpti on. The kinetic adsorption constants of protein A at different pH values we re also calculated and compared.