Advanced Materials Research Vols. 194-196

Abstract: The aim of this study was to prepare and investigate the potential use of liposomes in the transdermal drug delivery of meloxicam (MX). The vesicles containing a constant amount of MX, phosphatidylcholine (PC), cholesterol (Chol) and cetylpyridinium chloride (CPC) (1:5:1:1 MX/PC/Chol/CPC molar ratio) to obtain liposomes. MX loaded liposomes were investigated for particle size, zeta potential, entrapment efficiency (%EE) and in vitro skin permeation. The results indicated that the liposomes were spherical in structure, 77 to 100 nm in size and charged. The %EE of MX in the vesicles ranged from 55 to 56%. The elastic liposomes consisting of MX/PC/Chol/CPC provided a significantly higher skin permeation of MX compared to the other formulations. Fourier Transform Infrared Spectroscopy (FT-IR) and Differential Scanning Calorimetry (DSC) analysis indicated that the application of liposomes may disrupt the stratum corneum lipid. Our research suggests that MX loaded elastic liposomes can be potentially used as a transdermal drug delivery system.

Abstract: Chitosan nanoparticles were prepared by crosslinking chitosan (CS) with tripolyphosphate (TPP) solution using electrohydrodynamic spraying technique. The effects of CS and TPP concentration as well as electrical potential on particle size and shape were investigated. Appropriated formulations for preparing nanoparticles were chosen to encapsulate DNA. In vitro evaluation of the obtained nanoparticles as gene carrier such as entrapment efficiency and DNA release was performed. The results showed that 2 mg/ml TPP was dropped at 10 kV into 1 mg/ml CS (MW 20 kDa (F1) and 200 kDa (F2)) yielded the spherical shape and small particles of 227.67 and 240.33 nm, respectively. In DNA entrapment study, all formulations were tested by altering DNA loading to 10, 25 and 50 mg/g of CS. The results revealed that F1 with initial DNA 10 mg/g of CS showed the highest entrapment efficiency of 95.31%. While F2 with initial DNA of 25 mg/g of CS showed the highest entrapment efficiency of 89.16%. The DNA release study from CS nanoparticles indicated that the increasing of DNA amount slowed down the release rate. F1 and F2 with the initial DNA of 10 mg/g of CS had faster release rate than those with 25 and 50 mg/g of CS. It can be concluded that F1 yielded the nanoparticles with the smallest size, high DNA entrapment efficiency and enabled DNA sustained release.

Abstract: Lead selenide (PbSe) is quite an important semiconductor material with several superior physical properties, e.g. optical and electrical ones. In this paper, PbSe nanocrystals (NCs) with different morphologies such as sphere, rod and hexagon were successfully prepared by an ultrasonic electrochemical method, using sodium citrate as the coordination agent, at room temperature. The crystal structure and the morphology of the as-prepared PbSe NCs were confirmed by means of the Transmission Electron Microscopy (TEM) and X-ray diffractometer (XRD). The ultraviolet-visible Spectrophotometer (UV) was performed to analyze the optical properties of the PbSe NCs. Results show that the nanospheres were about 60 nm in diameter, and the nanorods were 20 nm in diameter with a slenderness ratio of 25. The possible mechanism for the nanorods growth was discussed. The energy gap of the PbSe NCs deduced from the UV-visible spectra was much larger than their bulk counterparts, due to the quantum size effect.

Abstract: Delivery of drugs through skin is obstructed by the excellent barrier properties of the outermost skin layer, the stratum corneum (SC). A strategy employing microneedles have recently emerged as a minimally invasive device for disrupting the SC structure and creating holes for molecules to pass through. Hollow-typed microneedles permit drug delivery which can be modulated over time via active delivery controlled by hand or pump. In this study, the potential of hollow microneedle for overcoming the outermost skin barrier and facilitating drug delivery into skin was investigated. Fluorescein isothiocyanate (FITC)-dextrans (4.3 kDa), FD-4, was used as a model large molecular compound. The effects of injection volume and formulation on drug release behavior from skin were determined. FD-4 was favorably loaded into the lower epidermis as well as the superficial dermis of the skin by a hollow microneedle. The release profiles of FD-4 were analyzed by Higuchi model based on Fick’s law of diffusion. The higher the volume of FD-4 solution injected, the faster the FD-4 release rate from skin. Liposome formulation exhibited no difference on drug release profiles compared with the solution. The results provide information for designing an effective hollow microneedles system.

Abstract: The corrosion resistance of Ultra-fine grain (UFG) chromium bronze, prepared by Equal-channel angular pressing (ECAP), was investigated at room temperature and atmospheric pressure by electrochemistry technique and immersion experiment. The electrochemistry experiment showed that ECAP processing don’t change the corrosion nature of chromiun bronze, the corrosion potential of UFG chromium bronze is a little more positive than that of CG chromium bronze, the differences are in the range of 10mV-20mV. Meantime, the immersion experiment showed that the UFG chromium bronze is more resistant to corrosion than its CG counterpart. The difference between UFG chromium bronze and its CG counterpart is also significant in terms of corrosion morphology. Though the structure is uniform corrosion, the microstructure is honeycomb-like morphology for CG chromium bronze and the corrosion pit is deeper. The shallower corrosion pits are displayed for UFG chromium bronze and grain drop off in local region.

Abstract: Uniformly sized microspheres of poly(d, l-lactic-co-glycolic) (PLGA) encapsulating tamoxifen(TAM) were successfully prepared by solvent evaporation. In this study three different polylactide-co-glycolides were used with differing lactide-glycolide ratios (50:50, 75:25, and 85:15, respectively). The sphere size distribution and morphology was analyzed using Laser Particle Size Analyzer and SEM. The drug loading and release in vitro of the microspheres were also investigated. The result showed that the microspheres have good spherical and better sustained release.

Abstract: High surface area porous silicon carbide was synthesized by employing polymethylhydrosiloxane (PMHS) as soft template in the sol-gel process. In the sol-gel method, furfuryl alcohol and tetraethoxysilane were used respectively as carbon and silicon precursors for preparing a carbonaceous silica xerogel. PMHS was employed as pore-adjusting agent in the sol-gel process. The purified SiC sample was characterized by XRD、FTIR、SEM、HRTEM and BET. The results show that the SiC products are found to have high specific surface area of 125 m² /g and an average pore diameter of about 17 nm. PMHS has important effect on the surface area of the SiC products.

Abstract: The PPO films with ordered structures have many potential applications in electronics, optics, separation, etc. Its self-supporting film with regular pores is prepared by evaporating the polyphenylene oxide (PPO) solution in carbon bisulfide under humid ambience. It is demonstrated that the nucleation, growth and ordered packing of water droplets condensed on the PPO solution layer as templates in the process are crutial for high-quality honeycomb films. The humidity, concentration, spreading volume of the PPO solution and the direction of airflow have great impact on the pore size, regularity of the film and so on, which are clarified by experiments.

Abstract: For the high cost, poor nano-size controlling and the complex technology in the existing Preparation of nano-materials, Gas-Powder Mixed Spark Discharge Reaction (GPMSGR) was used for the preparation of nano-powders. Nano-powders, average particle diameter of 100-150nm were obtained by using GPMSGR with improving the existing ordinary column type EDM machines.

Abstract: This paper presents an interesting sputtering phenomenon when high-energy beams irradiated ZnS nanoparticles with graphite sheaths in a transmission electron microscope (TEM). Sputtered nanoparticles were spherical and well dispersed on the copper grids. Results of high-resolution TEM and X-ray diffraction showed that sputtered particles were ZnS nanoparticles. The sizes of deposited ZnS nanoparticles appeared a good gradient distribution according to their distance away from the sputtering target. These nanoparticles had gradual changes in diameter from about 0.5 to 12 nm. We also discussed the mechanism of this sputtering phenomenon. This research may afford a simple and efficient method to prepare well-dispersed semiconductor nanocrystals in a small size range.