We report the formation of optically responsive hydrogel sensors capable of rapid quantification of metal ions in aqueous solutions. The robust and reversible chemosensor gels are prepared in one step. Treatment of a nucleophilic chemosensor dye with chloromethyl styrene, polar monomer, cross-linker, and free radical initiator in the presence of a reactive silanized glass surface leads to an optically transparent gel film covalently bound to the glass surface. The resulting glass-bound gel is optically transparent and retains dye after thorough washes indicating the dye is covalently attached to the polymer backbone. Aqueous acid removes metal from sensors; sensing ability is retained after hundreds of cycles of binding and removal of the metal ion. In order to further enhance the sensing capabilities of our polymers, a polyethylene glycol based monomer was synthesized that when polymerized contains high concentrations of amine terminuses allowing for attachment of the dye via acylation. Using this design, polymers have been made that can accurately predict the concentration of metals in the single digit ppb range. These and other closely-related chemosensor gels are somewhat selective for various metal ions, and somewhat different in their spectral response to different metal ions. They are appropriate as sensor arrays for simultaneous evaluation of mixtures of metal ion analytes. Analysis by UV/Vis absorbance spectroscopy allows real-time quantitation of metal ions, with some discrimination of identity. Arrays of dye sensors allow for highly specific simultaneous quantitation of multiple analytes, demonstrated in separate work.

Hydrogel polymers as sensors for the quantitation of metal ions in aqueous solutions

2019 Spring National Meeting

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