A study of polyethylene glycol backfilling for enhancing target recognition using QCM-D and DPI

Polyethylene glycol (PEG) is a promising candidate for protein resistance and preserving protein function in biomedical applications. In this study, a PEG-based bifunctional platform with antifouling for plasma proteins and high sensitivity for biomolecules was designed. Long PEG chains (PEG₂₄) were used to install functional biomolecules, and short PEG chains (PEG₄) served as a protective layer to backfill the surface and suppress nonspecific protein adsorption. Quartz crystal microbalance with dissipation (QCM-D) and dual polarization interferometry (DPI) were combined to investigate the dynamic process of PEG₄ backfilling and the recognition capacity of biomolecules with different ratios of PEG₄ and PEG₂₄ in real time. The amount of PEG₄ chain backfilling affected the flexibility of PEG₂₄ and exposed sites. The recognition capacity was improved by increasing the ratios of PEG₄ to PEG₂₄. Therefore, when the feeding ratio of PEG₄ to PEG₂₄ was 9 : 1, a highly efficient and sensitive platform was constructed for immobilization of antibodies and recognition of antigens either in pure PBS or in a complex biological environment.