A Study On The Synthesis And Fluorescence Imaging Of Red Gold Nanoclusters With High Quantum Yield

Red-emitting gold nanoclusters have been widely considered for application in medical imaging field because of their long emission wavelength,large Stokes shift and high biocompatibility and low toxicity.However,the low quantum yield(QY)greatly limits their imaging quality,so it is very meaningful to explore a novel method to enhance the photoluminescence(PL)intensity of these Au NCs.Herein,we select the bovine serium album-encapsulated gold nanoclusters(BSA-Au NCs)as research object,deeply exploring their growth process,emission mechanism and aggregation-induced emission phenomenon,then apply as obtained BSA-Au NCs of high QY for cancer cells fluorescence imaging and intracellular glutathione concentration degree reflex via imaging.The main research contents are list as following:1.Growth and fluorescence mechanism of BSA-Au NCs:Based on TEM and in-situ fluorescence testing,a three-stage growth process I of the BSA-AuNCs was explored.By regulating the synthesis parameters to adjust the growth process,Au(0)@Au(I)core-shell structured BSA-AuNCs with QY of 23%are obtained.Importantly,such Au NCs are in a rigidified state with high Au(I)content in the shell,offering an explanation for their high luminescence character.2.Aggregation-induced emission of BSA-Au NCs:By further introducing the polyallylamine hydrochloride(PAH)into BSA-Au NCs solutions,the confinement of Au NCs into PAH(Au NCs@PAH)is achieved,increasing the QY to 29%.Aggregation of Au NCs induces the reconstruction of Au NCs' structure and decreases the energy exchange between solution molecules and Au NCs,boosting the PL intensity.3.Fluorescence imaging of Au NCs@PAH:The presence of GSH can result in the decrease of PL intensity of Au NCs@PAH.Moreover,Au NCs@PAH can not only achieve fluorescence imaging of cancer cells,but also can reflex intracellular glutathione concentration degree in cancer cells via fluorescence imagings.