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Monday November 7th, 2005 Seminar 4:00 - 5:00 pm, Clark 110
Applications of Smart Polymers as Bioconjugates
Allan S. Hoffman Department of Bioengineering University of Washington
Over the past twenty years, we have been combining "smart" polymer molecules with different biomolecules for many unique applications in medicine and biotechnology. Our early work on these interesting hybrid materials was mostly focused on the random conjugation of a smart polymer to a protein, usually effected through reaction of an activated group on the polymer with a protein lysine amine group. The bioconjugate may be precipitated from solution by stimulating the smart polymer to phase separate. We have used this phenomenon for physical and affinity separations, and immunoassays. For the past ten years, we have extended these initial studies to the selective conjugation of the smart polymer to a specific site on the protein. The specific site has usually been a cysteine –SH group, which is selectively cloned into the protein at a specific site. By conjugating the polymer near the binding site of the protein, we have been able to control the ligand binding activity of the protein, and we have also effected the release of a bound ligand when the smart polymer is cycled through its phase separation transition. We have extended these studies to thermally-induced, size-controlled binding of biotinylated proteins to streptavidin. Single-stranded oligonucleotides (ODNs) have been conjugated to a smart polymer and also to streptavidin, allowing hybridization of the ODNs to control the distance of the polymer from the active site and also to effect the phase separation of the complex conjugate. We recently cloned a streptavidin mutant having the peptide cell receptor –GRGDS- inserted into its sequence, and complexed a biotinylated temperature-sensitive polymer to the streptavidin to provide for temperature-controlled cell attachment to a polymer surface. We also recently synthesized photo-sensitive polymers and conjugated them to an enzyme for photo-induced "on-off" control of the enzyme-substrate reactions. Most recently we have applied smart polymers and their conjugates in microfluidic devices. This talk will review these smart polymer systems. Everyone is welcome!
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