Dual functional highly luminescence B, N Co-doped carbon nanodots as nanothermometer and Fe(3+)/Fe(2+) 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(−1), 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(2+) and Fe(3+) 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(2+) and Fe(3+) (R(2) = 0.9908 for Fe(2+) and R(2) = 0.9892 for Fe(3+)) with a detection limit of of 80.0 ± 0.5 nM for Fe(2+) and 110.0 ± 0.5 nM for Fe(3+). 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(2+) in iron capsules and total iron in serum samples successfully.