Development And Applications Of Black Phosphorus Quantum Dots Fluorescent Probes In Biosensing And Imaging

Black phosphorus as a metal-free layered semiconductor has received widespread attention.It has excellent electronic and optical properties such as adjustable bandgap,high carrier mobility and remarkable inplane anisotropic properties.These properties make it widely used in solar cells,photocatalysis and field effect transistors.In addition,black phosphorus can be degraded into non-biotoxic phosphate under certain conditions,it exhibits low cytotoxicity and excellent biocompatibility,which makes it potentially valuable in nanomedi cine.However,their application in the biomedical field are mostly concentrated on cancer treatment,such as photodynamic therapy,photodynamic therapy or other combination therapy,and there are few reports on the biosensing or bioimaging of black phosphorus.Black phosphorus has thickness-related photoluminescence properties,and small-sized black phosphorus has fluorescence properties.Therefore,it is very necessary to further explore the optical properties of black phosphorus in biosensing and bioimaging.Small size black phosphorus quantum dots?BPQDs?can be exfoliated from layered black phosphorus,and the BPQDs exhibits fluorescence properties depending on the excitation,making it has broad application prospects in the field of nanomedicine,such as biosensing and bioimaging.Herein,we prepared BPQDs and explored their fluorescent properties,and then developed fluorescent probes based on BPQDs for biosensing and imaging.The main contents are as follows:?1?Fluorescent BPQDs with a size of 2.9 nm was prepared by exfoliated method,and the stability of excitation-dependent emission fluorescence of BPQDs under different conditions was also investigated.Finally,the cell imaging of ovarian cancer was achieved by using the blue-green fluorescence of the BPQDs.?2?We developed a facile,direct and single-step detection platform for primary ovarian cancers related glycosidase activity based on the inner filter effect?IFE?between glycosidase catalytic product and BPQDs.Absorption spectrum of PNP has a good overlap with the excitation and emission spectra of BPQDs,leading t o efficient fluorescence quenching of BPQDs through the IFE.The activity of?-galactosidase was measured by quantifying the degree of fluorescence quenching of BPQDs.It was confirmed that the sensor has the advantage of simple preparation,higher selectivity,and sensitivity than other?-galactosidase detection platforms.?3?We proposed an IFE-based BPQDs-MnO₂ sensor for the detection of glutathione?GSH?in solution systems.The absorption of MnO₂ has a great overlap with the fluorescence excitation of BPQDs.Therefore,the fluorescence of BPQDs can be effectively quenched by MnO₂ through the IEF.MnO₂ is reduced to Mn²⁺in the presence of GSH,resulting in fluorescence recovery of the qu enched BPQDs.This work provides a fluorescence detection method based on BPQDs to achieve effective detection of GSH in solution.