Enzymatic synthesis of a DNA-templated alloy nanocluster and its application in a fluorescence immunoassay

Abstract

An enzymatic synthesis strategy of a DNA-template alloy nanocluster is presented. In this strategy, alkaline phosphatase (ALP) catalysed pyrophosphate (PPi) hydrolysis broke the coordination between Cu²⁺ and PPi. The fluorescent DNA-template alloy nanoclusters were produced in situ through the reduction of the Cu²⁺ and Ag⁺ in the presence of single strand DNA (ss DNA). The fluorescence intensity of the alloy nanocluster was related to the concentration of ALP. This fluorescence turn-on strategy exhibited high sensitivity and selectivity for the ALP assay. Additionally, this strategy was also applied in an ALP-linked immuno-sorbent assay for a-fetoprotein (AFP) detection. Taking AFP as the model protein, it could be detected at a range from 10 ng mL⁻¹ to 150 ng mL⁻¹ and the detection limit was 4 ng mL⁻¹ (0.042 nM). Finally, the diagnostic capability and practical application of this method was demonstrated by detecting AFP in human blood serum.