Stimuli-responsive 1D photonic crystal hydrogel for rapid screening of clinical disinfectant o-phthalaldehyde

O-Phthalaldehyde (OPA) is a novel chemical disinfectant that has seen widespread use in healthcare environments. To ensure the efficacy of OPA-based disinfection in clinical practice, precise and reliable determination of its operational concentration is essential. Current methods, such as indicator strips, offer only semi-quantitative results, with their accuracy being influenced by multiple factors. Thus, there is an urgent need for the development of novel, efficient, and straightforward quantitative detection methods for OPA. DVD-R discs can be regarded as one-dimensional photonic crystals, which inspired the design of one-dimensional photonic crystal hydrogel (1DPCH) using DVD-R discs as templates. A sensor responsive to OPA was constructed by functionalizing the 1DPCH with ethylenediamine, thereby introducing amino groups into the hydrogel. These amino groups interact with OPA, and as the OPA concentration increases, the hydrogel undergoes enhanced crosslinking, leading to volume shrinkage. This shrinkage results in a reduction in the groove spacing of the embedded photonic crystal, which in increase the first-order diffraction spacing. By measuring the variation of the first-order diffraction spacing, the change in groove spacing can be quantified through a mathematical relationship. The experimental results exhibited a strong linear correlation with the change in groove spacing over the concentration logarithm range of 10¹–10⁶ nmol/L, the limit of detection was 1.26 nmol/L, additionally, the sensor exhibited high recovery rates (96.09–103.35 %) and low relative standard deviation (1.68–3.95 %) when detecting OPA in diluted disinfectant solutions.