Research On Synthesis Of Perovskite Quantum Dots And Application For STED Imaging

Fluorescence microscopy with high molecular specificity and multicolor imaging capability can directly show the interactions between specific molecular species,and its low invasiveness also allows the study of living systems under physiological conditions,which make it play a central role in studying the molecular tissues and interactions of biological systems.However,the resolution of a far-field optical microscope is limited by diffraction,which is unable to observe smaller information and hinders the development of optical microscopy in the field of subcellular bioscience.In recent years,researchers have conducted a series of researches on the improvement of the resolution of optical microscopy,and proposed different super-resolution fluorescence microscopy technologies which have broken the diffraction resolution barrier,and STED microscopy has been widely used due to its advantages of fast imaging speed and relatively high imaging resolution.There is no doubt that the development of STED microscopy is inseparable from the development of various staining methods and fluorescent probes.At present,it has been reported that the fluorescent probes used in STED microscopy mainly include:organic fluorescent molecules,nano-fluorescent materials,etc.However,they all have some limitations in practical application,such as poor bleaching resistance,high STED laser power and slow scanning speed.In recent years,the new halid perovskite quantum dots have been widely studied due to their great optoelectric properties,such as tunable emission wavelength,good monochromaticity and Photoluminescence quantum yield.Therefore,CsPbX₃ nanoparticles?NCs?were prepared by a new method,the regulation of emission bands and morphology was studied too.And CsPbX₃ nanoparticles were used as fluorescent probes in STED microscopy.The main innovations and research contents of this paper are as follows:?1?CsPbX₃ nanoparticles were successfully prepared in the air at low temperature by a simple and easy-to-operate solvent thermal method without the protection of inert gas by improving the traditional preparation methods.The microstructure,morphology and optical properties of CsPbX₃ nanoparticles were studied by different Optical instruments.The results show that the prepared CsPbX₃ nanoparticles are cube phase with average particle size of 14nm,uniform distribution,great monochromaticity,the highest quantum efficiency up to 92%,and the emission wavelength covering the whole visible region.?2?An in-situ anion exchange method was developed to tune CsPbX₃ NCs photoluminescence emission using PbX₂ dissolved in octane as the halide source.The CsPbClxBr₃-x and CsPbIxBr_3-x-x NCs obtained by the developed in-situ anion exchange method from CsPbBr₃ NCs showed similar morphologies with CsPbBr₃ NCs,indicating that the anion exchange reaction process only substituted Br^-sites in the CsPbBr₃ matrix with Cl^-or I^-ions.The emission bands and their width increased gradually with increasing halide ratio?Br/Cl or I/Br?and linear to it,and the halide ion exchange was reversible.Therefore,the emission bands of CsPb?Br/X?₃ NCs can be precisely regulated in the visible region?410–700nm?.In addition,nanocrystal shape was controlled by dissolving specific metal organic salts into the precursor solution prior to nucleation,and nanocubes,nanodots,nanosheets,nanoplatelets,nanorods,and nanowires were obtained following a general method.?3?CsPbBr₃ NPs are used as probes for STED nanoscopy imaging and an ultrahigh lateral resolution of 24.6 nm is obtained for a single nanoparticle.Perovskite CsPbBr₃ NPs possess higher photoluminescence quantum yield of 92%,larger absorption cross-section which is 2.0×10^-1414 cm²,and suitable fluorescence lifetime,so the saturation intensity of the CsPbBr₃ NPs is extremely low and estimated to be only 0.4 mW,making them a more effective probe for STED nanoscopy.And good resolution can be achieved at very low intensity of excitation light and STED light.The fluorescence intensity of the CsPbBr₃ sample is hardly weakened at all after 200 min irradiation with a 39.8 mW depletion laser,indicating excellent photobleaching resistance of the CsPbBr₃ NPs.In addition,CsPbX₃ nanoparticles were successfully applied to observing the morphology of AAO?anodized aluminum oxidation?and super-solution imaging of epidermal cells of onion.