A self-assembled aminopropylsilane film is prepared on the surfaces of piezoelectric quartz crystal disc.Under weak acidic or neutral pH condition

the film is positively charged and can adsorb BSA with negative charge by electrostatic pull.The quality change douring the adsorption process is monitored in real time by the resonant frequency of the piezoelectric quartz disc sensor.The result shows that the adsorption is partly irreversible while the isotherm is in Langmuir type.The rate constants for adsorption is 0.011 7 L·g-1·s-1

equilibrium constant of adsorption is 2.87 L·g-1

and saturation adsorbed mass is 0.954 μg·cm-2.