高分子纳米粒

纳米粒作为一种新材料,已在许多领域呈现出了其特有的应用价值。高分子纳米粒是纳米粒的一个分支,本文结合对纳米粒的一般介绍,着重说明了高分子纳米粒在制备方法、本体和表面性能的改进,以及形貌结构可调控等方面的特点;最后,通过近年来高分子纳米粒在生物医学领域的应用研究实例,对高分子纳米粒在生物医学领域的重要意义和应用前景进行了探讨。

Study on preparation of In_2O_3 superfine powder via polymer-network process

Nanocrystalline,single-phase undoped In 2O 3 was prepared by a polymer-network synthesis technique with indium nitrate as the starting material;several methods such as X-ray diffractometry (XRD) and transmission electron microscopy (TEM) were employed to obtain detailed information on the crystallography and microstructual appearance of In 2O 3 superfine powders. The influence of the concentration of starting solution,calcination temperature and time on the particle size was also that investigated by means of the XRD patterns. Results indicate that the obtained powders are mostly crystalline single phase with uniform size and also that the size of the products can be controlled under proper condition.

Diffusion of Nanoparticles in Semidilute Polymer Solutions： A Multiparticle Collision Dynamics Study

The diffusion of nanoparticles immersed in semidilute polymer solutions is investigated by a hybrid mesoscopic multiparticle collision dynamics method. Effects of polymer concentration and hydrodynamic interactions among polymer monomers are focused. Extensive simulations show that the dependence of diffusion coefficient D on the polymer concentration c agrees with Phillies equation D-exp （-αc^δ） with a scaling exponent δ≈0.97 which coincides with the experimental one in literature. For increasing nanoparticle size, the scaling prefactor α increases monotonically while the scaling exponent always keeps fixed. Moreover, we also study the diffusion of nanoparticle without hydrodynamic interactions and find that mobility of the nanoparticle slows down, and the scaling exponent is obviously different from the one in experiments, implying that hydrodynamic interactions play a crucial role in the diffusion of a nanoparticle in semidilute polymer solutions.

Design of fast crystallization of nanosized zeolite omega crystals at higher temperatures

Fast crystallization of nanosized zeolite crystals is a very popular process used for practical zeolite catalyst applications. Herein, we report a designer crystallization process for nanosized zeolite omega crystals based on the relationship between the crystallization time and temperature in the Arrhenius equation. Compared to the conventional hydrothermal synthesis of zeolite omega(72 h at room temperature and 240 h at 100℃, MAZ-100), the crystallization of zeolite omega presented in this work only requires a very short time interval(5 h at 180℃, MAZ-180). Physicochemical characterizations, including XRD, SEM, N2 sorption isotherms, and 27 Al MAS NMR show that the product of zeolite omega(MAZ-180) has good crystallinity and uniform nanocrystals. More importantly, after the loading of Pt nanoparticles(0.5 wt%), the Pt/H-MAZ-180 catalyst exhibits higher isomer selectivity and lower cracking selectivity than those of the Pt/H-MAZ-100 catalyst in the hydroisomerization of n-dodecane. These results suggest the potential applications of these omega nanocrystals as supporting catalyst compounds in industrial processes.

Formation of Rutile Nanoparticles from the Condensed Disperse Phase at a Surface of High-Temperature Particles

The photos, which are done by electron microscope, of the condensed disperse phase, surrounding high-temperature metal particles are presented. The dependence of concentration of condensed dispersive phase which surrounds a high-temperature metal particle upon the temperature of the particle was obtained. The dependence of concentration of electrons in condensed dispersive phase upon the temperature of the particle was studied. The dependence of an equilibrium charge of a metal particle surrounded with condensed disperse phase on the temperature of a particle in a positive and negative region is presented. The dependence of a charge of a metal particle on time at the fixed temperature is obtained.

Optical super-resolution microscopy and its applications in nano-catalysis

The resolution of conventional optical microscopy is only -200 nm, which is becoming less and less sufficient for a variety of applications. In order to surpass the diffraction limited resolution, super-resolution microscopy （SRM） has been developed to achieve a high resolution of one to tens of nanometers. The techniques involved in SRM can be assigned into two broad categories, namely ＂true＂ super-resolution techniques and ＂functional＂ super-resolution techniques. In ＂functional＂ super-resolution techniques, stochastic super-resolution microscopy （SSRM） is widely used due to its low expense, simple operation, and high resolution. The principle process in SSRM is to accumulate the coordinates of many diffraction-limited emitters （e.g., single fluorescent molecules） on the object by localizing the centroids of the point spread functions （PSF）, and then reconstruct the image of the object using these coordinates. When the diffraction-limited emitters take part in a catalytic reaction, the activity distribution and kinetic information about the catalysis by nanoparticles can be obtained by SSRM. SSRM has been applied and exhibited outstanding advantages in several fields of catalysis, such as metal nanoparticle catalysis, molecular sieve catalysis, and photocatalysis. Since SSRM is able to resolve the catalytic activity within one nanoparticle, it promises to accelerate the development and discovery of new and better catalysts. This review will present a brief introduction to SRM, and a detailed description of SSRM and its applications in nano-catalysis.

Entrapment and Sustained Release of Hydrophobic Drugs with Different Molecular Weights from PHBHHx-PEG Nanoparticles

Biodegradable polymeric nanoparticles are more and more frequently used in drug delivery systems, which represent one of the most rapidly developing areas. In our previous study, a novel natural hybrid polyester, polyethylene glycol 200 （PEG200） end-capped poly （3-hydroxybutyrate-co-3-hydroxyhcxanoate） （PHBHHx-PEG） was directly produced by Aeromonas hydrophila fermentation. In this study, the performance of the novel biodegradable PHBHHx-PEG copolyester as a sustained release carrier for hydrophobic drugs with different molecular weights and the in vitro sustained release profile were investigated. 5-Fluorouracil （5-Fu, Mw=130.1）, TGX221 （Mw=364.4）, and Rapamycin （RAP, Mw=914.2） were used as the model drugs. PHBHHx-PEG nanoparticles entrapped with 5-Fu, TGX221 and RAP were fabricated by a modified emulsification/solvent evaporation method, respectively. The average diameter of 5-Fu, TGX221, and RAP loaded PHBHHx-PEG nanoparticles was between 198.2-217.4 nm, and the entrapment efficiency of the three drugs was 62.5%, 93.4% and 91.9%, respectively. The in vitro release profiles of 5-Fu, TGX221 and RAP from PHBHHx-PEG nanoparticles were different. 5-Fu showed faster release rate and an obvious initial burst release phase. TGX221 and RAP were demonstrated to be released more slowly and steadily. The release percentages of 5-Fu, TGX221 and RAP were 97.7%, 85.1% and 74.7% after releasing for 72 h. PHBHHx-PEG is a kind of promising material as a carrier for the entrapment and delivery of hydrophobic drugs especially for those drugs with high molecular weight.