Ratiometric fluorescence sensing of copper ion and enzyme activity by nanoprobe-mediated autocatalytic reaction and catalytic cascade reaction

Abstract

Despite the tremendous potential of ratiometric method, its development has been limited by challenges such as the lack of signal amplification. Ratiometric sensing that is highly reliable, sensitive and selective would greatly facilitate optical analysis. Inspired by the natural biocatalysis and cascade catalysis, we demonstrate that the nanoprobe-mediated ratiometric detection coupled with autocatalytic reaction enables fluorescence sensing with ultrahigh sensitivity. Furthermore, the integration of the ratiometric analysis with catalytic cascade reactions allows amplified optical sensing of enzyme activity including alkaline phosphatase or acetylcholinesterase and their inhibitors. Our data show that ratiometric nanoplatforms combined with autocatalytic reaction or catalytic cascade reactions mediated by nanoprobes may represent a viable approach to improve performance of fluorescence sensing.