Rapid, High Affinity Binding by a Fluorescein Templated Copolymer Combining Covalent, Hydrophobic, and Acid⁻Base Noncovalent Crosslinks.
A new type of biomimetic templated copolymer has been prepared by reverse addition fragmentation chain transfer polymerization (RAFT) in dioxane. The initial formulation includes the template fluorescein, N-isopropylacrylamide (NIPAM, 84 mol %), methacrylic acid (MAA, 5-mol %), 4-vinylpyridine (4-VP, 9 mmol %), and N,N&prime;-methylenebis(acrylamide) (MBA, 2 mol %). PolyNIPAM is a thermosensitive polymer that comes out of aqueous solution above its lower critical solution temperature forming hydrophobic &lsquo;crosslinks&rsquo;. MAA and 4-VP interact in dioxane forming acid⁻base crosslinks. The excess 4-VP serves as a recognition monomer organizing around the template fluorescein to form a binding site that is held in place by the noncovalent and covalent crosslinks. The MBA is a covalent crosslinker. The RAFT agent in the resulting copolylmer was reduced to a thiol and attached to gold nanoparticles. The gold nanoparticle bound copolymer binds fluorescein completely in less than two seconds with an affinity constant greater than 10⁸ M&minus;1. A reference copolymer prepared with the same monomers by the same procedure binds fluorescein much more weakly.
['Grenier|Casey J|CJ|0000-0002-5370-8286', 'Timberman|Anthony|A|', 'Yang|Rongfang|R|', 'Csoros|John|J|0000-0002-1222-7320', 'Papantones|Alex|A|', 'Deravi|Leila F|LF|0000-0003-3226-2470', 'Seitz|W Rudolf|WR|']
fluorescein templates noncovalent crosslinks binding affinity binding kinetics moleculary imprinted polymers poly(N-isopropylacrylamide)