Nonspecific-adsorption behavior of polyethylenglycol and bovine serum albumin studied by 55-MHz wireless-electrodeless quartz crystal microbalance

摘要

The nonspecific binding ability of polyethylenglycol (PEG) and bovine serum albumin (BSA) on modified and unmodified surfaces is quantitatively studied by a wireless-electrodeless quartz crystal microbalance (WE-QCM). PEG and BSA are important blocking materials in biosensors. but their affinities for proteins and uncoated substrates have not been known quantitatively. The WE-QCM allows quantitative analysis of the adsorption behavior of proteins on the electrodeless surfaces. Affinities of PEG, BSA, human immunoglobulin G (hlgG), and Staphylococcus protein A (SPA) for alpha-SiO2(quartz), Au thin film, PEG, and BSA are systematically studied by the homebuilt flow-injection system. PEG shows low affinities for the SiO2 surface (K-A = 4.2 x 10(4) M-1) and the Au surface (K-A = 6.6 x 10(4) M-1). but BSA shows higher affinity for the SiO2 surface (K-A = 1.4 x 10(6) M-1). Both PEG and BSA show low affinities for hIgG (K-A similar to 1.5 x 10(5) M-1). However, the number of binding sites of PEG to hIgG is significantly larger than that of BSA, indicating that blocking for hIgG is favorably achieved by BSA, rather than PEG.