Engineering a turn-on ratiometric fluorescence platform based on porphyrin COFs Coupled with Au nanoclusters and carbon dots

A dual-emission COFs@AuNCs@CDs probe for Al 3 ⁺ detection was developed. • Ratiometric fluorescence improves accuracy and anti-interference ability. • Strong coordination-induced enhancement enables sensitive Al 3 ⁺ sensing. • Low detection limit of 0.47 μM achieved with high selectivity. • Smartphone platform enables rapid visual and on-site Al 3 ⁺ monitoring. Aluminum is a prevalent environmental contaminant with known toxicity to humans. However, despite the existence of various detection methods, a facile and rapid sensor for Al 3+ in aqueous environments has yet to be developed. In this work, a two-dimensional porphyrin COF was employed as a host for the encapsulation of carbon dots (CDs) and the uniform assembly of gold nanoclusters (AuNCs) within its pores. AuNCs were covalently linked to amino-functionalized COF nanospheres, while the incorporated CDs enhanced both the visible absorption and charge-transfer efficiency of the COF matrix. The as-prepared COFs@AuNCs@CDs showed blue emission of CDs at 468 nm and red emission of COFs at 687 nm at excitation of 410 nm. Consequently, a novel ratiometric fluorescence sensor was constructed to detect Al 3+ , owing to the strong complexation-induced fluorescence enhancement to achieve highly selective and accurate analysis with a limit of detection (LOD) of 0.47 µM. Furthermore, a smartphone visual sensing platform integrated with COFs@AuNCs@CDs was developed based on the color transformation and successfully applied to visual smart real-time monitoring of Al 3+ . This study is expected to offer valuable insights into the formation mechanism of fluorescent nanostructures, thereby facilitating their applications in the development of high-performance biosensors for precise monitoring. Here, we successfully constructed a novel ratiometric fluorescent sensor, COFs@AuNCs@CDs, for the sensitive and accurate detection of Al 3 ⁺. A portable smartphone-assisted visual analysis platform was designed for on-site determination of Al 3 ⁺. This work provides new ideas for the future design of intelligent and integrated smartphone-based fluorescent sensing platforms for environmental monitoring and point-of-care testing, and expands the application of COFs composites in fluorescent sensing. Download: Download high-res image (194KB) Download: Download full-size image