Alkaline phosphatase-responsive Zn2+ double-triggered nucleotide capped gold nanoclusters/ alginate hydrogel with recyclable nanozyme capability

Abstract

A novel hydrogel loaded with adenosine 5′-monophosphate capped Au nanoclusters (AuAMP NCs) is fabricated in a gentle route by double-triggering of Zn2+. This built-in fluorescent hydrogel material not only has good optical properties of Au NCs, but also possesses excellent mechanical structure of hydrogel materials. Free phosphate ions may trigger the devastation of the “egg-box” structure of the as-prepared ZnSA-AuAMP hydrogel, thus releasing the immobilized fluorescent AuAMP NCs, with a release efficiency up to 93.62% within 3 h. On this basis, a fast, sensitive fluorescent detection method for alkaline phosphatase (ALP) is achieved, with a linear detection of ALP in the range of 0.47–10.03 U/L and a limit of detection of 0.09 U/L. This allows the accurate detection of ALP in diluted human serum samples. Last but not least, the ZnSA-AuAMP hydrogel also exhibits peroxidase-like activity with good recyclability, because it is facile to be separated and extracted from catalytic reaction buffer. This work suggests that hydrogels may act as an inexpensive container for controllable regulation of nanozyme activity.