Smart nanozyme of silver hexacyanoferrate with versatile bio-regulated activities for probing different targets

Smart nanozymes that can be facile and rapidly produced, while with efficiently bio-regulated activity, are attractive for biosensing applications. Herein, a smart nanozyme, silver hexacyanoferrate (Ag₄[Fe(CN)₆]), was constructed in situ via the rapid, direct reaction between silver(I) and K₄[Fe(CN)₆]. And the activity of the nanozyme can be rationally modulated by different enzymatic reactions including the glucose oxidase (GOx, taken as a model oxidoreductase), alkaline phosphatase (ALP), and acetylcholinesterase (AChE). On the basis of which, a multiple function platform for the highly sensitive detection of glucose, ALP and AChE were developed through colorimetry. Corresponding detection limits for the above three targets were found to be as low as 0.32 μM, 3.3 U/L and 0.083 U/L (S/N = 3), respectively. The present study provides a novel nanozyme that can be produced in situ, which rules out the harsh, cumbersome, and time-consuming synthesis/purification procedures. In addition, it establishes a multiple function platform for the amplified detection of versatile targets by the aid of the developed nanozyme, whose detection has the advantages of low cost, ease-of-use, high sensitivity, and good selectivity.