Yinfeng Liu

Self assembled magnetic PVP/PVA hydrogel microspheres; magnetic drug targeting of VX2 auricular tumours using pingyangmycin

Chemotherapy in cancer treatment is associated with serious side effects and as a result there is great interest in research aimed at bringing down the level of systemic cytotoxicity. With advances in material science, magnetic drug targeting has emerged as one of the viable ways of attaining this. In this study, we used self assembled PVP/PVA magnetic hydrogel microspheres to deliver pingyangmycin (Bleomycin A5) to rabbit auricular VX2 tumours in the presence of a 0.5 T permanent magnet both during and 24 h after perfusion. A total of 22 New Zealand white rabbits ranging from 13 to 16 weeks and weighing 2.5–3.0 kg (2.46 ± 0.2) successfully implanted with tumours 200–300 mm2 in size were used. In group D (1 mg pingyangmycin in 50 mg ferrofluid without a magnet) 2 weeks post treatment, there was statistically significant difference compared to the control (p = 0.05) in favor of group D. However, when compared to the group with 1 mg pingyangmycin(BLM) in 50 mg of ferrofluid and 0.5 mg (BLM) in 50 mg ferrofluid both with a permanent magnet in place for 24 h, the statistically significant difference was in favor of combined treatment, i.e. ferrofluid carrying drug in presence of a permanent magnet (p = 0.01). The microspheres in conjunction with the magnet did deliver pinyangmycin to the tumour and hence may be of use in future as far as magnetic drug targeting is concerned. However, more studies are still required to establish biodistribution and biostability not to forget drug release of ferrofluid of different chemotherapeutic agents available.

A nitric oxide biosensor based on the photovoltaic effect of nano titanium dioxide on hemoglobin

A nitric oxide biosensor based on the photovoltaic effect of nano titanium dioxide on hemoglobin was fabricated with high sensitivity, selectivity, as well as stability. The linear detection concentration range was 5.0 × 10−6–4.0 × 10−4 M. The detection limit was 1.0 × 10−6 M with a sensitivity of 8 nA/μM. The possible coexisting compounds would not interfere with the nitric oxide detection.

High thermal conductive composites based on flake graphite filled in a partial compatible polyamide 6/polypropylene

In this study, a series of thermally conductive materials was obtained based on flake graphite (FG) filled in a partially compatible system of polyamide 6 (PA6)/polypropylene (PP) blends at a loading of 30 wt % of FG. The thermal conductivity of PA6/PP/FG composites containing 1 wt % of the compatibilizer PP-graft-maleic anhydride (MAH) reached 2.703 W/(m K). The SEM images show that FG formed a long thermally conductive pathway in the partially compatible system. The result of Fourier transform infrared analysis indicates that the compatibilizer changes the compatibility between PA6 and PP and affects the distribution of FG. The crystallization behavior of the composites studied by X-ray diffraction and differential scanning calorimetry further proved that the filler in the composites distributed rationally. The impact strength and dynamic mechanical analysis confirmed that when the compatibilizer content was 1 wt %, the system was in a partially compatible state. The dynamic rheology of the composites was also studied to understand the effect of the distribution of FG on the conductivity of the composites.

Kinetics of the Coordination Transformation for Preparation of Nanosized ZnS in a PVA Film

Abstract This study was focused on the pervasion process of sulfion in a PVA–Zn2+ complex film. A diffusion equation for this process, based on the Fick first diffusion law, is suggested, which was in good agreement with the experimental results. The diffusion constant was 9.92 × 10−6 cm2/sec, calculated by combining the model and the experimental results.

Comparison of oxidation polymerization methods of thiophene in aqueous medium and its mechanism

Precipitation method of oxidation polymerization for preparing polythiophene was carried out as well as dispersion and emulsion methods in aqueous medium by using (NH4)2S2O8 and CuCl2 as the oxidant and catalyst, respectively. In precipitation method, ethanol was served as an auxiliary solvent to water. The effective conjugated length (ECL) of the obtained polythiophene was demonstrated to be evaluated by the UV absorption spectrum. The ECL of the polythiophene gradually increases with the rise of the content of ethanol in the mixed solvent in precipitation polymerization, and it was higher comparing to the ECL of the product prepared by aqueous dispersion or emulsion method. An electron transition mechanism of the oxidation polymerization of thiophene was suggested.

Esterification of Luffa with Acetic Anhydride under Microwave Radiation determined by FTIR

Luffa, mainly made up of cellulose, hemicellulose, and lignin, is fruit of the sponge gourd. It has a special porous physical structure, which leads to a high adsorption property. In this study, luffa was pretreated in alkali/ethanol/water solution. XRD of luffa showed that after pretreatment, the cellulose structure in luffa changed from cellulose I to II, which implied that the crystal structure was destroyed to some extent and the accessibility to reaction was increased. The analysis by FT-IR indicated that the alkali treatment had little significant effect on luffas chemical structure but can remove the lignin. The pretreated luffa was then esterified with acetic anhydride under microwave radiation, and the relative esterification degree was quantified by FT-IR using an improved internal standard method. The results showed that microwave radiation could rapidly increase the esterification degree in the reaction process. The esterification degree of luffa esterified 20 min under microwave radiation was nearly 25 times that esterified 90 min under oil heat. The esterification degree initially increased quickly with radiation time and trended to become constant after 15 min radiation.

Synthesis and Optical Properties of CdS Nanocrystals in Polyacrylonitrile Film

A novel process using polyacrylonitrile (PAN) containing well-distributed ligands as a medium for forming CdS nanocrystals by an ion coordination method is presented in this paper. PAN consists of a large number of repeat units, and each unit has a ligand or group like CN and CO. A metal ion with a strong capability of complexing, such as Cd, Zn, Mn, etc., can complex with the group in PAN, and the complexed metal ion will react with negative ionlike S2− to be transformed into semiconductor nanocrystals. This growth mechanism has been identified by the results of Infrared Spectroscopic Analysis. The typical morphologies observed by TEM show that the CdS nanocrystals are rather evenly distributed throughout the PAN film and the size is estimated to be about 1–10 nm in diameter, depending on the growth parameters. The results of x-ray diffraction show that the crystallites of CdS nanocrystals in PAN film might be a mixture of crystals including both α-hexagonal CdS and β-cubic CdS. Quantum-size effects at room temperature have been demonstrated using ultraviolet–visible absorption spectra, excitation, and emission spectra, respectively. A rather sharp and strong emission band peaked at about 610 nm was observed and its mechanism is also briefly discussed.

Dielectric Properties in Ferroelectric Optically Active Polyamides

A relationship between dielectric constant ε or dielectric loss tan δ and structure was studied for optically active polyamides. The samples of these polyamides exhibited a chiral smectic phase due to their asymmetric structures and strong hydrogen bonds. The dielectric parameters were significantly influenced by temperature, but were hardly affected by frequency in the high-frequency region. The hindered rotations of the mesogens, which affect the polarization, depended on the structures and the phase transitions.

Thermal phase transition of poly(N-propionylethyleneimine) hydrogel

This article presents the preparation of the hydrogel of poly(N-propionylethyleneimine) and its interpenetrating polymer network (IPN) hydrogel containing polyacrylamide by means of γ-ray radiation and a study of the phase transition temperature of these hydrogels. As a result, the hydrogel of the crosslinked poly(N-propionylethyleneimine) exhibited swelling below and shrinking above the phase transition temperature (about 61°C), as well as the lower critical solution temperature (LCST) of the liner polymer–water system. The experiment also showed that the LCST of the IPN hydrogel could be adjusted by the incorporation of the second component polyacrylamide.

Preparation Principle of Super-Hydrophobic Surfaces by Phase Separation

The Flory–Huggins theory of polymer solutions combined with an evaporation process was employed to interpret the preparation mechanism of a super-hydrophobic surface by phase separation. The ternary phase diagram of a polymer/solvent/nonsolvent was calculated by using the solubility parameters of the components in the system. It indicated that with the increase of the nonsolvent fraction, the initial volume fraction of the polymer or the evaporation rate of the solvent, the evaporation time for phase separation would shorten and the phase separation rate would speed up. The polymer volume fraction in the dense phase would increase and the precipitating particles tended to collide and aggregate, resulting in a rough, super-hydrophobic surface. Experimental results were in agreement with this principle of phase separation for preparing super-hydrophobic surfaces. Membranes of acrylic resin and fluorinated acrylic resin with rough surfaces were successfully obtained by the phase separation method. Especially, the water contact angle of the fluorine-containing acrylic resin with the rough surface was greater than 150°, which satisfied the requirement of super-hydrophobicity.