Preparation Of Carbon Quantum Dots And Their Application In Photoelectric Response And Fe³⁺ Recognition And Cell Imaging

Carbon quantum dots（CQDs）have received tremendous attention at the beginning of the study,because of the advantage of the unique fluorescence property,biocompatibility and low cost.In recent years,the preparation methods of CQDs and their application in metal ions recognition and cell imaging have become an advanced research hotspot.Herein,we used sulfuric acid oxidation and hydrothermal method to prepare the CQDs,and studied the characterization and functional test of them.The main content of the paper is as follows:（1）CQDs with the uniform size were prepared from glucose and sucrose by sulfuric acid oxidation with the diameter of 2nm.The neutralizer（Ba（OH）2）was introduced in purification process,which contribute to fewer dialytic times and less time consuming.The as-synesthesied CQDs were characterized by TEM,X-ray diffraction,Fourier transform infrared spectroscopy,UV-Vis absorption,fluorescent spectroscopy,and these particles also possess well water solubility and dispersibility.Comparing the quantum yields obtained from two kinds of CQDs,the CQDs using glucose as precursor is much higher.（2）Different metal ions recognition was investigated using the carbon dots with glucose as carbon material.The results reveal that the CQDs exhibit good selectivity toward Fe³⁺ ions,and the concentration of iron ions range from 0-950μM is link to fluorescence of CQDs with good liner correlation coefficient（R2=0.987）.We further investigate the mechanism of the fluorescence quenching,with adding the PO43-into the quenching system,which lead to the fluorescence resuming.Based on this result,we infer that the chelation of Fe³⁺ and surface groups of CQDs is a key factor of this phenomenon.After modifying the ITO electrode with CQDs,photocurrent and photovoltage response were also performed by electrochemical method.Compared with black group,the photocurrent and phtovoltage of modified electrode have increased 3.3 times and 5.3 times,respectively.These results indicate that the quantum effects of carbon quantum dots contribute to the increasement of excitons in the system.（3）Blue fluorescent CQDs were synthesized via one-step hydrothermal treatment with D-sorbitol as carbon material and ethylenediamine as nitrogen source.The as-synesthesied CQDs were characterized by transmission electron microscopy,X-ray diffraction,Fourier transform infrared spectroscopy,UV-Vis absorption,fluorescent spectroscopy.Spherical CQDs（QY=8.85%）with a particle size about 5 nm were observed and exhibit good water solubility and dispersibility.The recognition of Fe³⁺ was also investigated using the as-synthesized CQDs as the fluorescent label in this paper.The concentration of iron ions range from 0-400μM is link to F/F0 of CQDs with good liner correlation coefficient（R2=0.994）,and the detection limit is 1.16×10-8 mol/L.MTT assay were measured to investigated the cytotoxicity of CQDs.The results show that the viability of MCF-7 cells was over 85%even the concentration of CQDs up to lmg/mL.We further carried out the bioimaging of MCF-7 cells using Delta-Vision Personal microscopy after co-cultivation with CQDs solution.The results show that the CQDs can be applied to cell imaging as a fluorescent probe.