Preparation Of N/B-Doped Carbon Dots And Their Application In Biological Small Molecule Detection

Biomolecules in the human body participate in a variety of important life activities,especially some biological small molecules,which have an important role in maintaining human health and protecting against diseases.Therefore,it is of great importance to develop methods for rapid and accurate detection of biological small molecules.In recent years,small molecule detection methods such as electrochemistry,fluorescence,colorimetry,and mass spectrometry are gradually emerging.Among them,fluorescence methods have attracted much attention because of their high sensitivity,selectivity,easy operation,and rapid response.As a new type of carbon nanomaterials,carbon dots have excellent fluorescence property and are often used as fluorescent probes in analysis and detection to achieve quantitative determination of target substances in complex systems.Research has shown that doping with heteroatoms and metal ions can improve the optical properties of carbon dots and endow them with special functions.For example,transition metal doped carbon dots,due to their variable valence states,have potential catalytic properties that enable them to serve as colorimetric probes for quantitative determination of small biological molecules.Based on these,three kinds of carbon dots with excellent fluorescence performance were prepared by a simple one pot hydrothermal/solvothermal method in this paper,and the detection of specific biological small molecules was achieved with the aid of fluorescence signal or colorimetric fluorescent dual channel signal.The details are as follows:（1）Using arginine and urea as raw materials,blue fluorescent carbon dots（Arg-CDs）were prepared by one-pot hydrothermal method.Based on F?rster resonance energy transfer（FRET）mechanism,a fluorescence sensor was constructed to realize the rapid and sensitive detection of dopamine（DA）.Arg-CDs in the DA concentration range of 10-100μM had a good linear relationship（R²=0.9964）and the limit of detection was as low as 0.28μM（S/N=3）.In addition,the sensor also exhibited strong anti-interference ability and excellent reproducibility（RSD<3.1%）,and good recoveries（98.28%-102.52%）were obtained in the spiking experiments in real human serum samples.Therefore,the constructed Arg-CDs sensor has potential application value in the detection of DA in human serum samples.（2）Blue fluorescent carbon dots（Fe-CDs）were successfully prepared by solvothermal method using 5,10,15,20-tetra（4-borate phenyl）-21H,23H iron porphyrin（Fe-TBPP）as precursor.It was found that Fe-CDs showed excellent peroxidase-like activity and leading to its fluorescence quenching after acting with H₂O₂.Based on the above catalytic activity and fluorescence properties of Fe-CDs,we have established a colorimetric and fluorometric dual-channel detection method for glucose,which achieved highly selective and sensitive detection of glucose.The detection limit of colorimetric and fluorometric methods were 3.86μM and 7.27μM,respectively.The Fe-CDs was used for the determination of glucose in human serum samples,and the detection results show good consistency with the results obtained from commercial blood glucose meters.Therefore,the glucose colorimetric and fluorometric dual-channel detection method based on Fe-CDs has potential application prospects in the analysis and detection of actual samples.（3）Boron-nitrogen doped carbon dots（B,N-CDs）were prepared by a simple one pot hydrothermal method using 6-aminopyridine boronic acid,citric acid and ferric chloride as materials.It was found that B,N-CDs showed excellent peroxidase like activity and could enhance their own fluorescence after acting with H₂O₂.Based on the catalytic activity and fluorescence properties of B,N-CDs described above,we established a colorimetric and fluorometric dual-channel detection method for cholesterol.The proposed method showed high sensitivity and selectivity for cholesterol,and the detection limit were 0.023μM and2.31μM,respectively.This CDs was applied to detect cholesterol in human serum samples with satisfactory results of spiked recovery（95.36%-100.20%）.Therefore,B,N-CDs have potential applications in analytical detection of real samples.