Fluorescent N-doped Carbon Dot-Copper and Silver Nanocomposite - An effective uric acid sensor

Abstract

Green fluorescent Nitrogen doped Carbon Dots ( N-CDs) was synthesized by solvent free pyrolysis technique . Using the synthesized N-CDs, for first time we report the synthesis of Blue fluorescent Nitrogen doped silver and copper carbon dot nano composite using a Simple, Solvent free Green method. The N-CDs function as reducing agent to reduce Ag+ and Cu2+ ions to Ag0 and Cu0 which leads to the formation of composite. The synthesized N-CDs and nano composites were applied as Uric Acid(UA) sensor. N-CDs and the composites function as a flurophore in the recognition of Uric acid.Both the N-CDs and the composites were characterized using UV-Vis, FTIR, SEM-EDX, TEM and PL spectroscopic techniques. The UV-Vis and FTIR response of N-CDs in comparison with N-doped silver and N-doped copper carbon dot composites confirms that the surface functional groups on N-CDs have been used in the formation of silver and copper carbon dot composite Thesurface morphology and elemental composition of synthesized carbon dots and its nanocomposites were identified using SEM-EDAX analysis. High resolution transmission electron microscopy (HR-TEM) analysis shows that N-Cdot are spherical in shape with an average size of 15.23 nm, Cu/N-Cdot composite is found to be spherical and the size to be in the range of 18.02 nm and Ag/N-Cdot composite is found to be spherical and the size of the composite is found to be 16.40 nm. The PL spectra was also observed for Cu/N-Cdots, Ag/N-Cdots. With addition of Uric acid there was a quench in fluorescence which is immediately visible by our naked eye The quench in fluorescence is due to the synergistic effect between the fluorescence Inner Filter Effect (IFE) and the static quenching effect, with a Lower detection limit (LDL) of 4µM thus functioning as a highly rapid UA biosensor.Simple naked eye observation and the absence of catalytic effect by the metal ion in the detection of UA are the merits of the present study.