Polymers as Surface-Based Tethers with Photolytic Triggers Enabling Laser-Induced Release/Desorption of Covalently Bound Molecules

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Abstract
A novel design for suface-based macromolecular docking and release is presented together with a strategy to improve and extend biopolymer structure determination capabilities. Polymeric surfaces with arrays of tethers for covalent molecular attachment were designed with photolytic triggers to enable spatially defined, laser-induced uncoupling/desorption of the tethered molecules. Upon photolytic cleavage, a defined portion of the tether (“tail”) remains attached to the biomolecule as a probe. Chemically defined memory, determined by the number of reporter tails, reflects the biomolecule interaction with tether−probe devices encountered (i.e., footprint) on the probe surface. To demonstrate function, a surface of poly(4-vinylpyridine) was extended through the pyridinium nitrogens with spacer arms (-N-ethylsuccinamyl-) producing photolytic pyridinium nitrogen bonds. The photolabile tether was terminated with leaving groups (N-hydroxysulfosuccinimide) for covalent attachment of biopolymers. An 18-residue peptide (N terminus of human β-casein) was covalently docked to these tether−probes, irradiated with coherent UV light, and released with two reporter tails of a mass predicted by tether formation at the two primary amine groups and subsequent photolytic cleavage at the intended site. This is the first demonstration of polymeric surface structure enabling the covalent docking and laser-induced uncoupling/desorption of intact macromolecules through the use of photolytic tethers. Surface-based tether−probe devices, operated by coherent light, should advance our ability to explore covalent modifications in biopolymer structure and alterations in conformation, generated either in advance of tethering or through chemical/enzymatic manipulations performed directly in situ.