Molecularly imprinted 2D photonic crystal hydrogel sensor for sodium dichloroisocyanurate

Sodium dichloroisocyanurate (SDIC) is an efficient, safe and convenient halogen disinfectant that is widely used for hospital, tableware and swimming pool disinfection. In order to ensure its effective use and safety, especially in clinical settings, effective identification methods are necessary. The effective chlorine content is one of the quality standards for chlorine-containing disinfectants, but its complex experimental operation as well as poor specificity and portability limit its application. In contrast, testing based on molecularly imprinted photonic crystal sensors provides excellent performance. Therefore, it is of great significance to establish a new and simple SDIC recognition method. We prepared a novel molecularly imprinted two-dimensional (2D) photonic crystal hydrogel (MIPH) for sensitive and label-free recognition of SDIC. The response performance of the resultant MIPH sensor was determined by monitoring particle spacing changes in the polystyrene (PS) 2D photonic crystals embedded in the hydrogel. Particle spacing changes were recorded by measuring changes in the diameter of the Debye diffraction ring of the MIPH sensor. As the concentration of SDIC in solution increased from 1 × 10⁻² to 1.0 mmol L⁻¹, the diameter of the Debye diffraction ring increased by 6 mm, and the corresponding photonic crystal particle spacing decreased by 56 nm. The particle spacing changes in the MIPH sensor showed a linear relationship with the SDIC concentration in the range of 1 × 10⁻²–1.0 mmol L⁻¹, and the limit of detection (S/N = 3) was found to be 3 × 10⁻³ mmol L⁻¹. The constructed hydrogel sensor was successfully used to detect SDIC in sodium dichloroisocyanurate disinfectant powder, demonstrating recoveries of 96–100% and RSD of 7.2–7.6%. Our molecularly imprinted SDIC photonic crystal hydrogel provides a universal strategy for designing sensors for other clinical disinfectants.