A smartphone-integrated optical sensing platform based on Lycium ruthenicum derived carbon dots for real-time detection of Ag+

Growing global environmental pollution problems challenge the need for converting biomass into an advantageous product. In this paper, Lycium ruthenicum is successfully turned into beneficial green emissive (527 nm) fluorescent nitrogen doping carbon dots (N-CDs) via the hydrothermal treatment for the first time. The horizontal and vertical dimensions of N-CDs are demonstrated to be about 4.5 and 0.73 nm, respectively. The N-CDs possess an extremely stable green fluorescence and quantum yield up to 21.8%. Meaningfully, N-CDs exhibit a good linear relationship with Ag+ in the range of 0.7-36 μM, and its detection limit is determined to be 59 nM. The practicability of the fluorescent probe is further validated in lake water and the satisfactory spiked recoveries of Ag+ ranges from 98.99% to 104.19%. Besides, based on the sensitive and selective photoluminescence quenching properties, a smartphone-based laboratory device and RGB analysis software are used to directly capture and analyze fluorescence images with a sensitive detection limit of 83 nM for Ag+. This novel sensor based on N-CDs and smartphone provides a reliable way for on-site monitoring of Ag+ and expands application prospect in the field of environmental pollution detection.