The Applications Of Two-Photon SiO₂ Nanoparticles And Other Novel Nanomaterials In Bioimaging And Therapy

With the increasing development of life science, it’s extremely important to conveniently, intuitively monitor the complex physiological activities in vivo. Due to the unique advantages, nanomaterials have attracted more and more attention in bioimaging and cancer therapy field. The fluorescent nanomaterials with good biocompatibility can be applied in real-time monitoring of life activities and bioimaging, while the stimuli-response and targeting nanoparticles modified with small molecules have the ability to cure the tumor on demand, reducing the side effect of normal cells. In this paper, making use of the technology of bioimging and tumor therpy, we utilized the novel nanomaterials to construct a nanoplatform for the detection of ascorbic acid and a photosensitizer carrier vectors MnO2 nanosheet for an activated efficient photodynamic therapy based on special redox reaction. The main contents are shown as follows:1. In Chapter 2, on the basis of laboratory studies on the two-photon dyes, we synthesized two-photon molecular doped fluorescent silica nanomaterials via sol-gel process. The fluorescent nanomaterials have characteristics of high fluorescence intensity, low toxicity and good imaging effect in cells, which are suitable for further application platform in biological detection and bioimaging.2. In Chapter 3, based on the Chapter 2, we constructed a nanocomposite to detect ascorbic acid effectively. We used CoOOH nanoflake as a quencher and a recognition material which adsorbed on the surface of silica nanomaterials via electrostatic interaction to obtain fluorescent silica nanocomposite. In the presence of ascorbic acid, with gradually disintegrating of CoOOH, the fluorescence of the silica nanoparticles would recovery. In this way, we realized the low background of target detection. Experimental results showed that the nanocomposites are low toxicity, good biocompatibility, high fluorescence intensity, suitable for the detection of living cells and tissue imaging.3. In Chapter 4, we designed and synthesized a MnO2 nanosheet as photosensitizer carrier to enhance the therapeutic effect of photodynamic therapy. The MnO2 nanosheet could increase the cellular uptake of the photosensitizer and release into the tumor cells after entering the cells. In addition, MnO2 would react with the intracellular glutathione, the consumption of intracellular reducing substances, increasing the content of singlet oxygen, which improve the photodynamic therapeutic effect.