High-bright fluorescent carbon dot as versatile sensing platform

The surface functionalization will introduce additional functional groups on carbon dots (CDs) surface and then enrich the properties of CDs. Here, we show the various surface functionalized CDs (-COOH, -OH, -SH, -NH₂, etc, named as NS-CDs) were synthesized with fascinating features, including high quantum efficiency (38.9%), long-term stability and good biocompatibility. Notably, it can serve as multifunction fluorescent probe in sensing system, including label-free detections in hydrogen peroxide (H₂O₂) with a wide linear range (1.20 × 10^-3 - 8.80 × 10^-12M) and a low limit of detection (LOD, 1.00 × 10^-12M); and glutathione, covering a concentration range of 2.00 × 10^-3 - 1.00 × 10^-7M and LOD of 1.00 × 10^-7M. In addition, the NS-CDs as fluorescent probe could selectively detect metal ions (such as, Hg²⁺, 1.00 × 10^-8 - 1.50 × 10^-3M, 1.00 × 10^-7M), antibiotics (tetracycline, 1.00 ×10^-10 - 2.50 × 10^-5M, 1.00 ×10^-10M) and toxic pollutant (nitrobenzene, 5.00 × 10^-7 to 1.00 × 10^-3gL^-1, 5.00 × 10^-7gL^-1) with wide linear range and satisfactory detection limits.