Study On The Preparation And Toxicity Of Black Phosphorus Quantum Dots

Two-dimensional(2D)nanomaterials(such as graphene,tungsten sulfide,and molybdenum sulfide)have emerged as a research focus of interest in many fields due to their unique physicochemical properties.As a new type of 2D nanomaterials,black phosphorus quantum dots(BP QDs)has received extensive attention for its superior electrical and optical properties.To date,BP QDs have been extensively studied in field effect transistor and solar cells.Besides,there have been numerous reports on the use of BP QDs in biomedicine,such as on the development of BP-based high sensitive medical biosensors,cancer imaging and photothermal therapy agents.Despite BP QDs' advantages in cancer diagnosis and therapy applications,their biosafety issues are still unclear.Herein,in this work,we report a systematic study on the in vitro and in vivo toxicity of black phosphorus quantum dots(BP QDs).Our findings provide insights into the rational design of BP QDs and guide their applications in biomedical and other fields.This work was conducted as follows:1.Preparation and characterization of BP QDsBP QDs were prepared by liquid etching of BP nanosheets combined ultrasonic.The surface morphology,diameter and thickness of the material were characterized using transmission electron microscope and atomic force microscope.Moreover,the stability of BP QDs were evaluated by nanosizer and microplate reader.The results show that BP QDs with good stability were prepared successfully.2.Study on the toxicity and mechanism of BP QDs to HUVECs and Beas-2B cellsThe toxicity of BP QDs to two kinds of normal human cells,human umbilical vein endothelial cells(HUVECs)and human bronchial lung epithelial cells(Beas-2B),were evaluated by CCK assay and ATP assay.In vitro experiments showed that BP QDs decrease the viability of both HUVECs and Beas-2B cells in a time-and dose-dependent manner.Apoptosis and cell cycle in HUVECs and Beas-2B cells were analyzed by flow cytometry.It showed that the cell cycle progression was blocked and cell apoptosis was induced obviously.The mechanism study showed that BP QDs interfered with mitochondrial membrane potential,leading to an increase in intracellular ROS.In vitro experiments showed BP QDs could accelerate the production of Hydroxyl radicals by H2O2 and induce the conformational change of Cytochrome c.Thus,it is speculated that the cytotoxicity of BP QDs related to the damage of mitochondrial.3.In vivo experiment of BP QDsIn vivo experiment of BP QDs on mice was carried out by gavage method.The weight of each mouse was measured,the hematological indexes were tested and organ tissue sections were observated.There was no obvious change detected,revealing that BP QDs doed not cause toxicity to mice.