An ultrasensitive micropillar-based quartz crystal microbalance device for real-time measurement of protein immobilization and protein-protein interaction.

A new sensing device was developed to achieve ultrahigh sensitivity, by coupling polymer micropillars with a quartz crystal microbalance (QCM) substrate to form a two-degree- of-freedom resonance system (QCM-P). The sensitivity of these QCM-P devices was evaluated by measuring mass changes for both deposited gold film and adsorption of bovine serum albumin (BSA), respectively, on poly(methyl methacrylate) (PMMA) micropillar surfaces, as well as assessing ligand-analyte binding interactions between anti-human immunoglobulin G (anti-hIgG) and human immunoglobulin G (hIgG). The anti-hIgG and hIgG binding results show QCM-P achieved an eightfold improvement in sensitivity relative to conventional QCM sensors. In addition, the binding affinity obtained from the QCM-P device for anti-hIgG and hIgG proteins was found in good agreement with that measured by surface plasmon resonance (SPR) for the same binding reaction.