Glucose sensing through diffraction grating of hydrogel bearing phenylboronic acid groups.

A new glucose sensing strategy has been developed by using diffraction-gratings of a stimuli-responsive hydrogel bearing phenylboronic acid groups. The sensing gratings were fabricated through soft-lithographic duplication of photoinduced surface-relief-gratings (SRGs) on azo polymer films to the hydrogel surfaces. For the preparation, elastomeric stamps were obtained by casting PDMS prepolymer against the azo polymer masters and curing properly. The hydrogel gratings containing phenylboronic acid groups were shaped by contact printing with the PDMS stamps and a specially prepared "ink", which was a precursor solution curable by UV light irradiation. The gratings showed a fast and highly sensitive response to glucose in buffer solutions as read out by the increase of the diffraction efficiency (DE/DE0). The saturated DE/DE0 value was linearly correlated to the glucose concentration of the solutions. The gratings showed ability for the continuous detection and were durable for repeated applications. The sensing ability of the gratings was stable when kept in the neutral buffer at room temperature for more than one month. Owing to the versatile nature, this approach can be further explored to prepare various grating sensors for the saccharide recognition and detection.