Development Of Fluorescence Probes Based On Carbon Dots And Gold Nanoclusters And Their Application To Detection Of Drugs And Environmental Contaminants

Carbon dots and gold nanoclusters,as fluorescent probes of great interest at present,have demonstrated their excellent performance in the fields of heavy metal ion detection,drug analysis,cell imaging and biosensing.Among the synthesis of carbon dots and gold nanoclusters,multi-element doping of carbon dots and rapid synthesis of gold nanoclusters have been the hot spots of research.In this paper,nitrogen and sulfur doped carbon dots of bromelain and gold nanoclusters of ovalbumin fluorescent probes were synthesized and successfully used for the detection of drugs such as adriamycin hydrochloride,picric acid and glutathione and environmental pollutants.Chapter 1 of this paper describes the definition of fluorescent probes,the sources of carbon dots synthesis,the synthesis of gold nanoclusters and their application studies in several fields.In the second chapter of this paper,nitrogen and sulfur doped pineapple protease carbon dots（N,S-Bro@CDs）with green fluorescence emission were synthesized in one step by high-temperature hydrothermal method using pineapple protease as raw material.The prepared pineapple protease carbon dots were characterized by transmission electron microscopy（TEM）,and the results showed that the N,S-Bro@CDs were spherical in shape with good dispersion and obvious lattice structure,and the particle size was about 3.5 nm.The elements contained in the carbon dots and their valence states were characterized by X-ray photoelectron spectroscopy,and the results showed that the carbon dots mainly contained C,N,O and S,and the surface was rich in-COOH and-NH₂functional groups.The fluorescence properties of N,S-Bro@CDs were investigated,and it was found that the fluorescence emission spectra of the carbon dots overlapped to a large extent with the UV absorption spectra of adriamycin hydrochloride.Based on the fluorescence resonance energy transfer mechanism between adriamycin and N,S-Bro@CDs can burst the fluorescence of carbon dots,a new method was established for the rapid and sensitive detection of adriamycin hydrochloride.The concentration of adriamycin hydrochloride showed a good linear relationship with the degree of fluorescence burst of carbon dots in the range of 9.0～127μmol/L with the correlation coefficient r=0.997 and the detection limit of 2.6μmol/L.The relative standard deviations were 3.4%,2.5%and 3.2%,respectively.The spiked recoveries in real blood were 96.80%～109.2%.In the third chapter of this paper,ovalbumin gold nanoclusters（OVA-AuNCs）emitting red fluorescence were synthesised within 50 s using a microwave-assisted method using ovalbumin as a template.The prepared OVA-AuNCs were characterised by transmission electron microscopy（TEM）and the nanoclusters had good dispersion,a circular-like appearance,an average particle size of 2.1 nm and a distinct lattice structure.The analysis of the elements and valence states using XPS showed that the material contains C,N,O,S and Au elements and is rich in functional groups such as amino,hydroxyl and carboxyl groups.The fluorescence spectra of the material showed that the maximum excitation wavelength was 350 nm and the maximum emission wavelength was 680 nm.The internal filtration effect was found.The linear range of the method was 20～240μmol/L,and the detection limit was 6.4 mol/L with r=0.998.The relative standard deviations（RSD）were1.4%,2.6%and 1.7%,indicating that the method has good precision.The spiked recoveries of PA in actual water samples were 90.88%～108.2%.In Chapter 4,an OVA-AuNCs/Cu²⁺sensing system was constructed for the analysis of GSH based on the fluorescence"Off-ON"strategy.When GSH is added to the system,the fluorescence signal is"turned on"due to the higher affinity of GSH and Cu²⁺,and the fluorescence signal is"turned on"when Cu²⁺binds to GSH.The fluorescence signal of OVA-AuNCs was proportional to the concentration of GSH in a certain range（0.8-16μmol/L）.The detection limit of the method was 0.42 mol/L,r=0.998,with good linearity and relative standard deviations（RSD）of2.4%,1.3%and 1.4%,respectively.The spiked recoveries in the actual drugs ranged from 97.8%to 105.9%.