Development Of Fluorescent Nanoprobes With Aromatic Compounds As Carbon Sources And Their Applications

Carbon dots（CDs）are a new class of carbon nanomaterials,which have the desired advantages of low toxicity,environmental friendliness,low cost and simple synthetic routes.Moreover,surface passivation and functionalization of CDs can effectively control the physicochemical properties.CDs have been applied to many applications in the fields of biosensing,bioimaging,nanomedicine,photocatalysis and electrocatalysis since they were discovered.Using phenolic compounds as carbon sources,the CDs were perpared by solvothermal synthesis and column chromatographym,which are applied to the quantitative determination of biothiol and ferri ions.The works are as follows:Chapter 1.The development background,physicochemical properties and application research of carbon nanoparticles were introduced,and the recent research progress of fluorescent carbon dots by hydrothermal solvothermal was summarised.Chapter 2.The carbon dots were synthesized by one step solvothermal treatment of3-diethylaminophenol,which showed green fluorescence under 365 nm irradiation.Then,CDs were covalently functionalized with 2,4-dinitrobenzenesulfonyl chloride（DNS-Cl）to afford a virtually non-fluorescent 2,4-dinitrobenzene functionalized CD（g-CD-DNS）.Upon addition of biothiols,the DNS group of the g-CD-NDS was removed through a SNAr reaction and returned back to the starting g-CDs,thus resulting in a dramatic increase in fluorescence intensity(λ_em=525 nm).Based on the above mechanism,a CD-based fluorescent probe for detecting biothiols was developed.The detection limits for cysteine and glutathione are 69 and 69 nM（S/N=3）.The proposed nanoprobe exhibits high selectivity toward biothiols over other amino acids and biological species and has been demonstrated to be able to detect biothiols in serum samples and fluorescence imaging of biothiols in living cells.Chapter 3.The polyhydroxyl carbon dots（P-CDs）were synthesized by one-step solvothermal treatment of 1,2,4 benzenetriol.FTIR and XPS spectroscopy of P-CDs indicate that its surface contains a large amount of hydroxyl groups.It was observed that the fluorescence intensity of P-CDs can be dramatically quenched with the addition of Fe ions.This is because the hydroxyl groups on the surface of P-CDs can form a non-fluorescent complex with Fe ions,which induces agglomeration of carbon dots,resulting in fluorescence quenching of the system.Based on the above mechanism,a fluorescent probe for detecting Fe ions was developed.The fluorescence intensity at 525nm decreased linearly with Fe ions concentration in the range of 0-2μM.The detection limit was calculated to be 0.45 nM（3σ）.The synthesized P-CDs can detect Fe ions in the presence of glutathione,and the results indicate that P-CDs showed high selectivity toward Fe ions over other common metal ions.The proposed probe has been applied for the detection of of Fe ions in real water samples.