LAUSR

Abstract Carbon dots (CDs) doped with heteroatom not only permits enhancement in fluorescence efficiency, but offers favourable sites in CDs to expand their utility in sensing of various chemical species. Silicon is essential biological element enables an auspicious path for doping of CDs. Highly blue fluorescent and water soluble Si doped CDs were synthesized via a simple and facile one-step hydrothermal route using (3-aminopropyl) triethoxysilane (APTES) and chitosan as reagent. Doping of Si atoms into CDs plays key role to enhance quantum yield (QY) to 18.1% for Si-doped CDs as compared to QY of bare CDs (7.8%). More amazingly, the Si doped CDs acted as an excellent nanoprobe for fluorescence assay of Fe3+ ion through “turn-off mechanism” with a limit of detection (LOD) of 0.002 μM. With Fe3+ ion, fluorescence of Si-doped was remarkably quenched due to the formation of Si-doped CDs-Fe3+ ion aggregates. This method was free from several interfering chemical species, which confirms the selectivity of the probe towards Fe3+ ion. The Si-doped CDs-based fluorescence “turn-off” mechanism was used to quantify Fe3+ ion in biofluids (plasma and urine). This method exhibited good accuracy and precision for the analysis of Fe3+ ion in biofluids. Furthermore, Si-doped CDs act as an effective patterning agent for fluorescent labelling.