Electrochemically-Grafted Biotinylated Carbazoles
Worlikar, Deepali 1985-
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Biotin-Streptavidin is known to be one of the strongest non-covalent interactions with dissociation constant, Kd ~ 10-15. Non-specific adsorption of proteins is one of the major concerns in the design of a biosensor device which causes bio-fouling and ultimately reduces the life span of a bio-device. The main challenge in the surface functionalization for affinity-based methods is to immobilize one of the interacting compounds on the surface in such a way that nonspecific interactions of the protein with the surface are minimized. Taking into consideration the possibility of both, specific and nonspecific adsorption of streptavidin on surfaces, this study is designed to incorporate poly(ethyleneglycol) as a protein resistant functional moiety, and biotin for the formation of biotin-streptavidin bridge for protein immobilization. PEGylated carbazole compounds were first synthesized via a series of organic reactions. These compounds were further biotinylated through EDC-DMAP coupling chemistry. The biotinylated compounds were characterized by 1H NMR, 13C NMR, and ultraviolet-visible spectroscopy. Thin films of the biotinylated carbazole compounds were then fabricated on a quartz crystal of QCM by electrochemical deposition method. The electrodeposited films were further tested for the selective binding of streptavidin. In brief, the study aims to provide a new platform for the immobilization of streptavidin via electrochemical grafting. The ability to fine-tune the formation of a polymer film with electrochemically-controlled thickness will potentially enable the engineering of new molecular templates for biosensor applications.