Levonorgestrel-Protected Fluorescence Gold Nanoclusters For Cell Imaging And Detection Of Reactive Oxygen Species

In recent years,due to the unique physicochemical properties,good biocompatibility,ultra-small size and large Stokes shift,gold nanoclusters have became one of most promising nanoluminescent materials.To date,many gold nanoclusters based on ligands such as protein,oligopeptide etc.have been reported and attracted widespread attention in biological imaging,biological analysis and therapeutic applications among scientists.Nevertheless,most of gold nanoclusters rarely have precise structural composition.Atomically precise gold nanoclusters still have drawbacks such as short-wavelength emission and low quantum yield.Based on the above problems,in this paper,atom-precise levonorgestrel-protected gold nanoclusters were synthesized and optimized for cell imaging and highly reactive oxygen species(hROS)detection.The detailed research works are summarized as follows:Firstly,a structure-determined gold-levonorgestrel nanocluster Au10(C21H27O2)10(Au10NC)has been obtained via solvent induced crystal transformation from Au8(C21H27O2)8(Au8NC),accompanied by fluorescence color changed from green to yellow.Cationic polymer poly(allylamine hydrochloride)(PAH)was chosen to assemble with Au10NC to prepare monodisperse and stable particles(Au10NC-PAH),with a quantum yield increased to be 49.8%.The as-fabricated Au10NC-PAH has realized effective antibody-mediated actin imaging and sustained retinoic acid release induced differentiation of NG108-15 cells.Secondly,Au8NC and Au10NC protected by the same ligand levonorgestrel have different responsive properties upon reactive oxygen species(ROS)due to their different kernels.Au10NC is highly selective to highly reactive oxygen species(hROS)and the fluorescence could be quenched.The probe realized sensitive and rapid detection of hROS in living cells,and it could also realize hROS imaging in zebrafish.