A Green-Synthesized Fluorescent Carbon Dot Probe Derived from Banana Peel for Cellular Imaging and Sensing of Tetracycline

The valorization of biomass waste represents an important direction in green chemistry. This study successfully prepared blue fluorescent carbon dots (BP-CDs) from waste banana peels via a one-step hydrothermal method, establishing a dual-functional platform for both pollutant detection and cellular imaging. The resulting material exhibited uniform particle size (~2.05 nm), good water dispersibility, and strong fluorescence emission at 445 nm under 360 nm excitation. It maintained over 93% of its initial fluorescence intensity after 20 days, demonstrating excellent stability. Based on the inner filter effect, the probe enabled a highly selective detection of tetracycline with a detection limit of 0.191 µM and two wide linear ranges (0–15 µM, R2 = 0.996; 15–95 µM, R2 = 0.991). Cellular experiments confirmed the good biocompatibility of BP-CDs (cell viability > 84%) and their successful application in cell imaging. More importantly, the probe achieved visual observation and semi-quantitative analysis of the distribution and content of tetracycline in living cells, providing a direct tool for studying the cellular behavior of antibiotics. This work not only offers a new strategy for banana peel valorization but also develops a green fluorescence imaging platform suitable for tracking intracellular pollutants.