Responsive photonic alginate hydrogel particles for the quantitative detection of alkaline phosphatase

Alkaline phosphatase (ALP) is an important marker for many diseases, yet an efficient and reliable detection method is still lacking. Here, we present a novel photonic alginate hydrogel particle as an ALP sensor based on the competitive combination of an intermediary agent, the pyrophosphate ion (PPi), with a hydrogel crosslinker, which can trigger a phase-transition response from the hydrogel. This response can be converted into dual optical readouts, a fluorescence signal and a structural color signal. Quantitative determination of ALP was established based on this dual-indicator system with high accuracy and reliability. These features suggest potential ideal applications of responsive photonic hydrogel particles to detect ALP and other macromolecules.