Nanoantenna-assisted surface-enhanced infrared absorption (SEIRA) is powerful for the detection of biochemical species with its capability to strongly enhance the IR signal and to analyze molecular structural information with high specificity. However, the detection is still limited by the local analyte concentration in the vicinity of the nanoantenna sensing region. Here we coated a polyacrylamide hydrogel with imbedded radial chemical gradient, which can locally concentrate analytes prior to the sensing, on the nanoantenna SEIRA sensor.  4-Methylumbelliferyl phosphate disodium (MUP), a model organophosphate, was used to demonstrate the gradient-driven transport in a positive charge gradient and was focused in the gradient region with a 15-fold of concentration enhancement. Combining the IR signal enhancement from both the electric field enhancement capability of the nanoantenna structure and the concentration enhancement capability of the chemical gradient, this integrated signal enhancement technique enables the IR to detect molecules with a smaller amount.

Hydrogel with embedded chemical gradient for analyte collection on surface enhanced infrared absorption spectroscopy

255th National Meeting (2018)

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