Issue 63, 2021

Hydrogel gratings with patterned analyte responsive dyes for spectroscopic sensing

Abstract

This is an unprecedented report of hydrogel gratings with an analyte responsive dye immobilised in alternating strips where the patterned dye is its own dispersive element to perform spectroscopy. At each wavelength, the diffraction efficiency of hydrogel gratings is a function of dye absorbance, which in turn is dependent on the concentration of analytes in samples. Thus, changes in intensity of diffracted light of hydrogel gratings were measured for sensing of analytes. Equally, the ratio of diffracted intensities at two wavelengths was used for quantification of analytes to reduce errors caused by variations in intensity of light sources and photobleaching of dyes. 15.27 μm pitch gratings were fabricated by exposing 175 μm thick films of photofunctionalisable poly(acrylamide) hydrogel in a laser interferometric lithography setup, generating an array of alternating lines with and without free functional groups. The freed functional groups were reacted with pH sensitive fluorescein isothiocyanate to create gratings for measurement of pH. The ratio of intensity of diffracted light of hydrogel gratings at 430 and 475 nm was shown to be linear over 4 pH units, which compares favourably with ∼2 pH units for conventional absorption spectroscopy. This increased dynamic range was a result of cancellation of the opposite non-linearities in the pH response of the analyte responsive dye and the diffraction efficiency as a function of dye absorbance.

Graphical abstract: Hydrogel gratings with patterned analyte responsive dyes for spectroscopic sensing

Supplementary files

Article information

Article type
Paper
Submitted
24 nov 2021
Accepted
09 dec 2021
First published
17 dec 2021
This article is Open Access
Creative Commons BY license

RSC Adv., 2021,11, 40197-40204

Hydrogel gratings with patterned analyte responsive dyes for spectroscopic sensing

R. Gupta, S. El Sayed and N. J. Goddard, RSC Adv., 2021, 11, 40197 DOI: 10.1039/D1RA08610C

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