Preparation And Application Of Optical Nanoprobes For Bio-imaging And Bio-sensing

Fluorescent nanomaterials,with their unique structural and optical properties,have show tremendous potential in the field of bioimaging and biosensing platform.Till now,optical nanoprobe have been widely investigated for in vivo/vitro imaging,bioactive molecules sensing,environment monitoring,ect.In this thesis,we have constructed series of fluorescent nanoprobes and their applications ranging from the qualitative analysis of biological imaging to the quantitative sensing of intracellular analytes.The main research work and relative results are as follows:1.We demonstrate a versatile one-step synthesis strategy of aqueous fluorescent AIE composite fluorescence nanoprobe for targeted cell imaging.The surface modification of AIE molecules by the amphiphilic polysuccinimide effectively improved its solubility,biocompatibility and well maintained its fluorescence intensity.In addition,the size of the probe can be adjusted by changing the ratio of hydrophilic to hydrophobic moiety of the polymer.The ultra-small particle size of the probe,on the one hand is conducive to the effective close packing of AIE molecules,which greatly enhance the fluorescence intensity;On the other hand,it is favor for probes to get into cells by endocytosis effect,reducing the potential biological toxicity.Finally,we have modified cell targeting RGD peptide on the probe surface,allowing for specific cancer cell imaging,ideal results clearly demonstrated the bioimaging potential of this AIE fluorescent nanoprobe.2.We report a simple and versatile strategy to fabricate a multifunctional upconversion luminescent nanocapsule for effective gene delivery and real-time luminescence tracking.In virtue of the unique optical and biological properties of lanthanide-doped upconversion nanoparticles,by using positively charged amphiphilic polymer PSIoAm together with PEG-PLGA as capping agent,the luminescent nanocapsules were successfully fabricated.Further results demonstrated that our nanocapsule has ideal biocompatibility,satisfactory gene loading capacity and great bioimaging ability,which is promising for imaging guided cell therapy and gene engineering.In addition,the method is universal and can be used for drug/gene transport systems or multimodal imaging systems.3.We have successfully proposed a new strategy for the preparation of gold nanoclusters with good biocompatibility,high flurescence intensity and ideal stability under full pH range and high salinity.The sensitive and selective detection of hydrogen sulfide is of great importance due to its crucial role in pathological and physiological processes.Herein,by impregnating Au nanoclusters into a biocompatible cationic polymLer matrix,glycol-chitosan nanogel,the AuNCs@GC probe can be obtained.The confinement effect from GC significantly increased the emissive Au(I)units,resulting in a 6-fold enhancement of quantum yield.In addition,the prepared positively charged AuNCs@GC nanogel exhibits excellent selectivity and improved sensitivity to aqueous sulfides.Moreover,the AuNCs@GC showed very good biocompatibility and super fluorescence stability across the full pH range and good salt tolerance,which demonstrated excellent adapt ability toward intracellular sulfide imaging.This newly developed sensing system broadens the scope of application of fluorescent metal clusters and provides new ideas and guidance for the design of new fluorescent probes.