Some Studies Of Functional Bioimaging Based On Fluorescent Nanoprticle

In recent years, fluorescent nanoparticles based bioimaging forms a major thrust of bio-photonics. Much focus has been given to the development of efficient optical agents and fluorescence imaging systems. In this thesis, we focuse on the applications of some novel fluorescent nanoparticles, including in vitro cell bioimaging, in vivo fluorescence bioimaging, and in vivo two-photon excited microscopic functional bioimaging. The detail content of our research work is as follows.For in vitro cell imaging:We systemically study the multi-photon excited fluorescence of graphene oxide nanoparticles. Grafted with PEG molecules, GO nanoparticles exhibited high chemical stability under various pH values. GO-PEG nanoparticles were also shown to have negligible cytotoxicity by a cell proliferation assay and histological analysis, which could facilitate their in vitro applications. In in vitro cell imaging, fluorescence bioimaging clearly illustrated the distribution of GO-PEG nanoparticles in cellular/subcellular components.Mesoporous silica nanoparticles are used to encapsulate PpIX (a kind of photodynamic therapy drugs), and the as-synthesized nanoparticles (PpIX@SiO2) are water soluble, with good chemical stability and biocompatibility. The one-photon and two-photon optical properties of PpIX@SiO2nanoparticles have been systematically investigated, and their applications in in vitro two-photon fluorescence imaging and photodynamic therapy of tumor cells have been demonstrated.For macroscopical in vivo bioimaging:Organically modified silica (ORMOSIL) nanoparticles are used to encapsulate a kind near infra-red (NIR) organic fluorescent agents (IR-820). Our study indicates that IR-820doped ORMOSIL nanoparticles, which located beneath1.5cm-depth in phantom, could be easily discriminated by utilizing NIR fluorescence imaging. We also demonstrate that intravenously injected NIR nanoparticles can target the subcutaneously xenografted tumor of a mouse through blood circulation and the "enhanced permeability and retention"(EPR) effect. ORMOSIL nanoparticles have bright prospects in future biomedical applications, such as disease diagnosis and clinical therapies.We report polymeric nanomicelles doped with organic fluorophores (StCN.(Z)-2.3-bis [4-(N-4-(diphenylamino)styryl)phenyl]-acrylonitrile), which have the property of aggregation-enhanced fluorescence. These fluorescent nanomicelles are utilized as efficient optical probes for in vivo SLN mapping of mice. The StCN@PEG nanomicelles, as well as their bioconjugates with arginine-glycine-aspartic acid (RGD) peptides, are used to target subcutaneously xenografted tumors in mice, and in vivo fluorescence images demonstrate the potential to use PEGylated phospholipid nanomicelles with aggregation-enhanced fluorescence as bright nanoprobes for in vivo diagnosis of tumors.PbS semiconductor quantum dots (QDs) with NIR photoluminescence were synthesized in oleic acid and paraffin liquid mixture by using aneasily handled and ’green’ approach. Surface functionalization of the QDs was accomplishedwith a silica and polyethylene glycol (PEG) phospholipid dual-layer coating and the excellentchemical stability of the nanoparticles is demonstrated. We then successfully applied the ultrastable PbS QDs to in vivo sentinel lymph node (SLN) mapping of mice. Histological analyses were also carried out to ensure that the intravenously injected nanoparticles did not produce any toxicity to the organism of mice. These experimental results suggested that our ultrastable NIR PbS QDs can serve as biocompatible and efficient probes for in vivo optical bioimaging and has great potentials for disease diagnosis and clinical therapies in the future.For microcosmic in vivo bioimaging:A new kind of organic fluorescent compounds (TPE-TPA-FN) with aggregation induced emission (AIE) property is studied. TPE-TPA-FN encapsulated DSPE-mPEG nanomicelles are prepared. We intravenously inject TPE-TPA-FN@PEG nanomicelles into mice body from the tail vein, and observed their flow, distributions in blood vessels, by utilizing a deep-penetrating in vivo two-photon imaging technique.