Multicolor Gold Clusterzyme-Enabled Construction of Ratiometric Fluorescent Sensor Array for Visual Biosensing

The simultaneous detection of multiple bioanalytes with similar structures has been a long-standing challenge for biological research and disease diagnosis. Bioreceptor-inspired sensor arrays provide an attractive and competitive solution for addressing this challenge, but applying this technique to biosensing in practical application scenarios is complicated by many factors such as the lack of robust probes, interference from the biological matrix, and difficulty for on-site analysis. In this work, by taking advantage of the intrinsic fluorescence and enzyme-mimic properties of gold nanoclusters (AuNCs), we report the design of an innovative ratiometric sensor array toward enhanced fluorescent visual biosensing. With biologically important phosphates as an example, we show that the present fluorescent clusterzyme-based ratiometric sensor array could effectively discriminate and detect eight types of phosphates. In particular, AuNCs with three different emission colors (blue, green, and red) and good peroxidase-mimic properties were employed as the sensing units, and the presence of phosphates affected both the intrinsic fluorescence and the enzymatic activity of these AuNCs, yielding distinct optical responses in a ratiometric manner. Moreover, a portable sensor array was established by further integrating these fluorescent clusterzymes into a hydrogel matrix, which could visually identify different phosphates based on their distinct fluorescence color changes. Consequently, the point-of-care diagnosis of urinary tract infections at different levels was achieved by analyzing urinary microbial ATP via the present strategy. This study illustrates the great potential of clusterzyme-based fluorescent sensor arrays as a promising biosensing platform for disease diagnosis.