Development Of Medical Nanoprobes And Their Applications In Fluorescent, Magnetic Labeling And Photothermal Therapy

With the rapid development of science and technology, miniaturization is the goal of equipment and instrument. Thus nanomaterials are gained much attention, duo to their special structural characteristics and optical characteristics. Quantum dots with excellent emission property, nanometal with surface plasmons resonance (SPR) properties, magnetic nanoparticles with superparamagnetism are three important nanomaterials. Compared to traditional fluorescent dyes, quantum dots have many advantages, such as continuously adjustable emission spectrum, good resistance to bleach, good stability and so on. Due to the localized surface plasmons, metal nanoparticles can enhance the fluorescence intensity of luminescent materials, which distribute around the metal particles. Metal nanoparticle with special structure can work as light absorbers and produce localized high temperatures to kill tumor cells. Photothermal therapy is a non-interventive, non-complaints care method. Magnetic nanoparticles with superparamagnetism have many applications such as drug delivery magnetic separation and hyperthermia. Recently, increasing attention has been diverted to the fabrication of bifunctional nanostructures consisting two kinds of materials with different properties, such as the nanoparticles possessing magnetic and luminescent property.In chapter1, we carry out a brief overview on the quantum dots, metal nanoparticles and magnetic nanoparticles. The overview includes the concept, property, the preparation method and relative application.In chapter2, we study the relative properties about quantum dots at first. Due to the quantum size effect, quantum dots (CdTeS) with various emission wavelengths were parpared through liquid phase method. In order to improve the fluorescence intensity, we coated a shell (CdS) on the surface of the CdTeS quantum dots. We studied the biomedical application of CdTeS@CdS core-shell quantum dots. We prepared Mn-doped ZnS quantum dots in order to avoid the toxicity of Cd ion. The influence factors on the optical property of Mn-doped ZnS quantum dots were discussed, which contain manganese ion concentration, ratio between Zn and S, reaction atmosphere. Through coated a shell (ZnS) onto the surface of Mn-doped ZnS quantum dots, the fluorescence intensity of quantum dots was also imporved.In chapter3, we carried out a study on the fluorescent enhancing effect using the metal nanoparticles, dut to its local surface plasmons. The fluorescence enhancement principle was firstly discussed. Two methods (seed crystal growth method and non-seed crystal growth method) were used to prepare gold nanorod with different size. We talked about the morphologies and optical properties of these gold nanorods. Silver nanocube and nanosphere were produced by reduction of aqueous silver nitrate with ethylene glycol in the presence of PVP as stabilizer. Finite-difference time-domain (FDTD) method was used to model the electrodynamics around the metal nanoparticles with certain incident light. Composite Ag@dye-SiO2particles were synthesized through a liquid phase method with good homogeneity and dispersity. The optical properties of Ag@dye-SiO2nanoparitcle with different thickness of dye-SiO2layer were investigated. The fluorescence signal of Ag@dye-SiO2nanoparticle was enhanced compared to the sample without silver core.In chapter4, we prepared several photothermal materials include metal nanoparticle and semiconductor nanoparticle. The photothermal materials are based on the strong absorption ability, through which the light energy is converted into heat energy effectively. Through liquid phase method, various gold nanoparticles (Au nanocage, Au nanostar, Au nanoshell) were prepared. The morphology and the optical property of these gold nanoparticles were discussed. FDTD solution also used to model the electrodynamics around the gold nanoparticles. We prepare gold nanostar/quantum dots-doped SiO2structured nanocomposite, which is composed of gold nanostar as the core with excellent photothermal property and quantum dots-doped SiO2as the shell layer with good fluorescence signal. We prepared a kind of non-toxicity copper material (CuSe and CuS). We studied the influence factors on the the optical property of copper material. We also studied the material’s photothermal effect on the cancer cell.In chapter5, we studied the superparamagnetism of magnetic nanoparticles. Three methods (coprecipitation method, hydrothermal method, high temperature pyrolysis) were used to prepare Fe3O4nanoparticles. The structure and properties of the nanoparticles were studied. A novel nontoxic, magnetic and luminescent nanoprobe was prepared by complex nanoparticles, which is composed of Fe3O4nanoparticle and Mn-doped ZnS quantum dots (QDs). The nanocomposite probe can provide both visible optical and magnetic resonance imaging simultaneously.In chapter6, we carry out a general summary about this thesis and analysis the potential work, which can be carried out in the future.