Black Phosphorous Quantum Dots And Their Applications In Photodynamic Therapy

As a new type of two-dimensional layered semiconductor material,black phosphorus has excellent properties that other two-dimensional materials such as graphene do not have,such as high electron mobility,switching ratio,direct band gap,and good biological safety etc,which makes it have a wide range of application potential in the fields of biology,medicine,photocatalysis and so on.This article first explored the process of preparing black phosphorous quantum dots.Black phosphorus quantum dots(BPQDs)are obtained by means of ultrasound and centrifuge,and products are characterized by means such as AFM,TEM,Raman,Zeta Potentialmeter,XPS.The surface modification of the prepared quantum dots was carried out,PEG cladding was used to obtain products with good dispersion and stability in water.Subsequently,its photocatalytic performance was explored,and its phototoxicity was finally verified in vitro cytotoxicity experiment.For the preparation and characterization part,The supernatant was extracted by ultrasonic centrifugation of cube black phosphorus in the ice bath of NMP solution by liquid phase stripping.The supernatant was collected by centrifugation and precipitated.TEM and AFM tests showed that the QDs with particle size of 2.5±0.9 nm were obtained.BPQDs obtained by centrifugation were dispersed in water,and PEG-4000 was added for ultrasonic stirring.After washing and collecting,PEG-coated BPQDs were obtained.Zeta potential test showed that the Zeta potential of the coated quantum dots changed from-22.3 m V to-28.2m V,indicating that the stability of the BPQDs in water was significantly enhanced.For the photocatalytic experiment part,EPR experiment showed that the products in the photocatalytic process of black phosphorus quantum dots are singlet oxygen and hydroxyl radicals.Then DPBF degradation experiment is conducted on the BPQDs,results showed that the singlet oxygen quantum yield of BPQDs is 0.43.Finally,the coated BPQDs were used to degrade Rhodamine B,and the degradation was more than 50% within two hours,but it has relatively low efficiency and poor cycling performance.For vitro cytotoxicity experiments part,a series of human normal cells and cancer cells in different conditions(BPQDs concentration,light)were studied in vitro cytotoxicity,the results showed that after surface modification of BPQDs for each cell all showed obvious light toxicity.The IC50 of human gastric cancer cells(mgc803)is less than 6 ppm.