Dual functional highly luminescence B, N Co-doped carbon nanodots as nanothermometer and Fe/Fe sensor.

Dual functional fluorescence nanosensors have many potential applications in biology and medicine. Monitoring temperature with higher precision at localized small length scales or in a nanocavity is a necessity in various applications. As well as the detection of biologically interesting metal ions using low-cost and sensitive approach is of great importance in bioanalysis. In this paper, we describe the preparation of dual-function highly fluorescent B, N-co-doped carbon nanodots (CDs) that work as chemical and thermal sensors. The CDs emit blue fluorescence peaked at 450 nm and exhibit up to 70% photoluminescence quantum yield with showing excitation-independent fluorescence. We also show that water-soluble CDs display temperature-dependent fluorescence and can serve as highly sensitive and reliable nanothermometers with a thermo-sensitivity 1.8% °C, and wide range thermo-sensing between 0-90 °C with excellent recovery. Moreover, the fluorescence emission of CDs are selectively quenched after the addition of Fe and Fe ions while show no quenching with adding other common metal cations and anions. The fluorescence emission shows a good linear correlation with concentration of Fe and Fe (R = 0.9908 for Fe and R = 0.9892 for Fe) with a detection limit of of 80.0 ± 0.5 nM for Fe and 110.0 ± 0.5 nM for Fe. Considering the high quantum yield and selectivity, CDs are exploited to design a nanoprobe towards iron detection in a biological sample. The fluorimetric assay is used to detect Fe in iron capsules and total iron in serum samples successfully.