Analysis of leaching and stability of microporated PEG spheres for fluorescent analyte detection

Poly(ethylene glycol) (PEG) microspheres have been used to sense a variety of analytes by encapsulating fluorescently labeled molecules into a PEG hydrogel matrix. This matrix is designed to retain the sensing molecules while simultaneously allowing nearly unhindered analyte diffusion. Some sensing assays, however, depend on the conformational rearrangement or binding of large macromolecular compounds which may be sterically prohibited in a dense polymer matrix. A new microporation process has been developed in order to create small cavities in the spheres containing aqueous solution and the assay components. This configuration insures a small mesh size for the supporting polymer, which limits leaching, while allowing the large assay components space to react within the aqueous cavities. Three hydrogel compositions (100% PEG, 50% PEG hydrogels, and microporated 100% PEG) were studied by embedding traditional pH (FITC) and oxygen sensitive fluorophores (Ru(Phen)). These hydrogels were analyzed for leaching and dynamic response to evaluate the functionality of the new microporated hydrogel.

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