Immobilization of biotin tagged protein molecules on the zero background PEG surface

MicroSurfaces, Inc. enables the proteomics & biosensor industries

micro surface

Advanced Surface Coatings for Protein Microarrays, Microfluidics & Biomedical Research

		Application note:
		The zero-background biotin surface for protein, peptide, & antibody immobilization
			Figure 1. Left: biotin groups tethered to the high-density PEG coating. Right: the immobilization of a biotinylated protein molecule to the biotin/PEG surface via the intermediate streptavidin.
		Biotin-streptavidin interaction is one of the most widely used in bioconjugation chemistry, owing to the strong affinity and high specificity of the interaction. The binding strength (Kd ~ 1x10^15 M^-1) between biotin and streptavidin is about four orders of magnitude stronger than that of typical antigen-antibody interaction and is the strongest among all noncovalent interactions. The presence of four binding sites on each streptavidin molecule makes it possible to link a biotin-tagged molecule to a biotinylated surface. The exceptionaly strong interaction ensures the integrity of the linker under a wide range of experimental conditions. When this interaection is used for the immobilization of a biotin tagged protein molecule to a solid surface, the interaction is through the tag, thus minimizing disturbance to protein structure.

		Figure 2. Left: the specific adsorption of Cy3-labeled streptavidin to the biotin-PEG surface. Note that the biotin surface remains resistant to the non-specific adsorption of fibrinogen (middle). Right: an array of Cy3-labeled streptavidin spotted on the biotin/PEG surface.
		To take advantage of the biotin-streptavidin interaction for protein immobilization, we have developed a surface of high density biotin groups on an otherwise zero background poly-ethyleneglycol (PEG) brush, Figure 1 (left). As a demonstration of the specificity and exceptional low background of this surface, we show in Figure 2 the adsorption of Cy3-labeled streptavidin on the biotin/PEG suface. The surface remains resistant to the adsorption of fibrinogen. With the adsorption of streptavidin on the biotin/PEG surface, the unoccupied binding sites on the tetravalent streptavidin molecule can be used for the immobilization of biotin-tagged proteins, such as biotinylated BSA (see Technology). The streptavidin surface can be freshly prepared on the biotin/PEG surface to ensure optimal interaction. The biotin/streptavdin surface is available on standard microscope slides, cover slips, and silicon wafers. We also provide customer coating service for specific samples and devices. Our customers have successfully applied the biotin/PEG surfaces for a range of applications, including protein sensors, protein microarrays, single molecule spectroscopy, biological atomic force microscopy and other biophysical experiments. READ Publications using our biotin surface: Anal. Biochem. 08
		3913 Todd Lane, Suite 102, Austin, TX 78744 Phone: (512) 916-0802; Fax: (512) 916-0855; E-mail: