Xingping Zhou

Studies on Preparation of Photosensitizer Loaded Magnetic Silica Nanoparticles and Their Anti-Tumor Effects for Targeting Photodynamic Therapy

As a fast developing alternative of traditional therapeutics, photodynamic therapy (PDT) is an effective, noninvasive, nontoxic therapeutics for cancer, senile macular degeneration, and so on. But the efficacy of PDT was compromised by insufficient selectivity and low solubility. In this study, novel multifunctional silica-based magnetic nanoparticles (SMNPs) were strategically designed and prepared as targeting drug delivery system to achieve higher specificity and better solubility. 2,7,12,18-Tetramethyl-3,8-di-(1-propoxyethyl)-13,17-bis-(3-hydroxypropyl) porphyrin, shorted as PHPP, was used as photosensitizer, which was first synthesized by our lab with good PDT effects. Magnetite nanoparticles (Fe3O4) and PHPP were incorporated into silica nanoparticles by microemulsion and sol–gel methods. The prepared nanoparticles were characterized by transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and fluorescence spectroscopy. The nanoparticles were approximately spherical with 20–30 nm diameter. Intense fluorescence of PHPP was monitored in the cytoplasm of SW480 cells. The nanoparticles possessed good biocompatibility and could generate singlet oxygen to cause remarkable photodynamic anti-tumor effects. These suggested that PHPP-SMNPs had great potential as effective drug delivery system in targeting photodynamic therapy, diagnostic magnetic resonance imaging and magnetic hyperthermia therapy.

Formation and properties of hydrophobic CeO2 nanoparticles

Uniform hydrophobic cerium oxide (CeO2) nanoparticles in a cubic structure with an average size of 4.6 nm were obtained by a novel oil-water interface method in the presence of 0.40 M NaOH. Effects of reactants concentration, oxidation reaction temperature, and the type of surfactants on the final products were investigated. The products were characterized by X-ray diffraction, transmission electron microscopy, UV-visible spectroscopy, room-temperature photoluminescence spectroscopy and contact angle measurements. The products exhibited high luminescence and strong hydrophobicity. The data suggest that Ce(OH)x4−x (x < 4) is a precursor complex for the formation of CeO2 nanoparticles in liquid phase and its concentration controls the size of CeO2 particles. The adsorption of the surfactant influences the formation of the hydrophobic particles of CeO2 by the oil-water interface method.

One-pot synthesis of strongly luminesencing CdTe quantum dots and their conjugation with mouse antibody to alpha-fetoprotein

In this paper, strongly luminescent CdTe quantum dots (QDs) were synthesized in aqueous solution by a facile one-pot method. The CdTe QDs were synthesized in a weakly acidic or neutral buffer solution composed of sodium borate (Na2B4O7) and sodium citrate (C6H5Na3O7). The pH of buffer solution and the ratio of the precursors were systematically optimized; the high-quality CdTe QDs with progressively increasing fluorescence during 60 days storage were obtained. As-prepared QDs can be conjugated with a mouse antibody alpha-fetoprotein via the reaction mediated by N-hydroxysuccinimide and 1-ethyl-3(3-dimethylaminopropyl) carbodiimide hydrochloride. The conjugate showed a red shift of 9 nm for the emission position.

Preparation and stability of strongly luminescent CdSe/Cd(OH)2/SiO2 nanocomposite particles in aqueous solution

Cadmium hydroxide-deposited cadmium selenide nanoparticles were prepared by the addition of cadmium sulfate solution to cadmium selenide nanoparticles in a weak alkaline solution at room temperature. The photoluminescence measurements displayed that the luminescence intensity was greatly increased by the addition of cadmium ions due to the formation of cadmium hydroxide on the surfaces of the cadmium selenide nanoparticles. Then, CdSe/Cd(OH)2/SiO2 nanocomposite particles were synthesized using 3-mercatopropyl trimethoxysilane by Stöber method. After the formation of CdSe/Cd(OH)2/SiO2 nanocomposite particles, the emission ability was mostly stabilized. Additionally, the stabilization of the composite particles against dilution with the physiological saline was checked. The results showed that the photoluminescence stability was promoted after the deposition of silica on the surfaces of the CdSe/Cd(OH)2 nanoparticles. Comparison of the stability of CdSe/SiO2 nanoparticles with that of CdSe/Cd(OH)2/SiO2 ones showed that Cd(OH)2 shell could enhance the photoluminescence effectively.

Effect of trimethylamine on the formation of anatase titania nanoparticles by gel-sol method

The anatase titania particles with controlled size and shape were prepared in large amount in the presence of trimethylamine (TMA) from the hydrolysis of a Ti-triethanolamine (TEOA) complex by gel-sol method. In the absence of TMA, ellipsoidal particles were obtained due to the anisotropic growth caused by the specific adsorption of TEOA onto the crystal planes parallel to the c-axis of a titania particle. TMA acted as a complexing agent of Ti(IV) ion to promote the growth of ellipsoidal particles and then inhibited the anisotropic crystal growth to produce ellipsoids of a low aspect ratio, rather than a shape controller to produce ellipsoids with a high aspect ratio. This may be explained in terms of the weak complexing between TMA (a tertiary amine) and Ti(IV) ion. The particle size was also controlled by seeding of anatase titania. Moreover, the seeding suggested that the rate-determining step of the gel-sol process was not the dissolution of the hydroxide gel, but the deposition of the monomeric precursor from the solution phase. Some cationic surfactants also promoted the particle grown to produce particles with a high symmetry in a similar way to TMA.