Synthesis Of Fluorescent Gold Nanoparticles And Carbon Nanoparticles And Their Applications In Sensing And Bioimaging

Recently, novel fluorescent nanomaterials have inspired intensive research efforts due to their excellent optical/chemical properties, and been widely used in biological and environmental fields. In contrast to conventional organic dyes, fluorescent nanomaterials are superior in the aspects of strong and tunable fluorescence emission, good chemical stability, high resistance to photobleaching, and easy functionalization. To date, researchers have developed several kinds of fluorescent nanomaterials, including semiconductor quantum dots (QDs), up-converting lanthanide-doped nanoparticles, mental nanoparticles (e.g., Au nanoparticles (Au NPs)) and carbon nanoparticles (CPs). However, the sever synthetic conditions and their toxicity to tissues, potential environmental hazards associated with heavy metals such as Cd, Pb, and Hg have limited the potential applications of QDs. The materials used for preparation of up-converting lanthanide-doped nanoparticles are expensive. Thus, Au NPs and CPs with low toxicity and good biocompatibility have gained much more attention.In this thesis, we synthesized five novel fluorescent nanomaterials, carefully investigated their fluorescent and targeting properties, and discussed their targeting mechanism. Main works include:1. Captopril-stabilized fluorescent Au NPs and their use for Hg2+detectionA simple, facile, and green method was developed for the synthesis of water-soluble and well-dispersed fluorescent Au NPs within5min, using captopril as the capping agent and THPC as the reducing agent. Further studies found that the fluorescence of the Au NPs can be specifically quenched by Hg2+. Based on this, a fluorescent probe for the detection of Hg2+with high sensitivity and selectivity in environmental water samples was developed.2. Peptide-templated synthesis of wavelength-tunable fluorescent Au NPs and the study of its propertiesAu NPs with wavelength-tunable emissions were prepared using different short-peptides as templates and NaBH4as the reductant. Thus formed Au NPs have fascinating characteristics such as large Stokes shift, long fluorescence lifetime and good stability. The Au NPs were demonstrated as selective and sensitive probe for sensitive and selective detection of Hg2+. TEM, XPS, and fluorescence lifetime measurements were conducted to get an insight into the quenching mechanism.3. Synthesis of nitrogen-doped CPs (NCPs) from strawberry juice and its application as a fluorescent probe for mercury ionsA simple, green, and low-cost way was developed in the synthesis of fluorescent NCPs by one-pot hydrothermal treatment of strawberry juice. The as-prepared NCPs showed good water solubility and chemical stability, and can be used as a fluorescent sensor.4. Facile and green synthesis of fluorescent CPs from grape juice for cellular imagingA facile, green, and economic strategy was designed for preparation of fluorescent CPs by one-pot hydrothermal treatment of grape juice. The as-prepared CPs had good water-solubility and high quantum yield, low cytotoxicity, and excellent stability. Further studies showed that the CPs can be used as a fluorescent probe for cellular imaging.5. Solvent-free route to nitrogen-sulfur-codoped fluorescent CPs (NSCPs) for cellular imagingA simple, green, and solvent-free method for preparation of the NSCPs was developed by thermal treatment of gentamycin sulfate. The as-obtained NSCPs displayed good water solubility, robust chemical inertness, long fluorescence lifetime, excellent biocompatibility, and can be used as a fluorescent probe for cell imaging.