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Surface Coatings That Permit Covalent Protein Immobilization but Also Prevent Nonspecific Protein Adsorption

Xinyan Bi and Kun-Lin Yang. Department of Chemical and Biomolecular Engineering, National University of Singapore, 4 Engineering Dr 4, Singapore, 117576, Singapore

In this presentation, we report a surface coating derived from homo-bifunctional tri(ethylene glycol) (EG3) and hexa(ethylene glycol) (EG6) molecules which have two terminal aldehyde groups. These homo-bifunctional molecules can be used to functionalize an amine-terminated surface through crosslinking one aldehyde group to surface amine groups, while leaving the other aldehyde group available for covalent immobilization of proteins on the surface. Best of all, after reducing remaining aldehyde groups on the surface with a reducing agent, such as sodium borohydride, the surface becomes oligo(ethylene glycol) (OEG)-terminated. The OEG-terminated surface can resist nonspecific protein adsorption, a feature that is often required for biosensors and for many other biomedical devices. Although surface coatings that permit covalent protein immobilization but also resist nonspecific protein adsorption can be achieved by using mixed self-assembled monolayers (SAMs) formed from two different organothiols, the procedure reported herein requires only one homo-bifunctional linker and is much more convenient to be used. These surface coatings also permit the immobilization of small molecules, such as oligopeptides and oligonucleotides. Hence, it may find potential applications to investigate peptide-protein interaction or DNA hybridization. Compared to previous work, this system may effectively resist the non-specific adsorption of target protein or DNA.