Smart poly(2-hydroxyethyl methacrylate/itaconic acid) hydrogels for biomedical application

pH- and temperature-sensitive hydrogels, based on 2-hydroxyethyl methacrylate (HEMA) and itaconic acid (IA) copolymers, were prepared by γ-irradiation and characterized in order to examine their potential use in biomedical applications. The influence of comonomer ratio in these smart copolymers on their morphology, mechanical and thermal properties, biocompatibility and microbe penetration capability was investigated. The mechanical properties of copolymers were investigated using the dynamic mechanical analysis (DMA), while their thermal properties and morphology were examined by thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The morphology, mechanical and thermal properties of these hydrogels were found to be suitable for most requirements of biomedical applications. The in vitro study of P(HEMA/IA) biocompatibility showed no evidence of cell toxicity nor any considerable hemolytic activity. Furthermore, the microbe penetration test showed that neither Staphylococcus aureus nor Escherichia coli passed through the hydogel dressing; thus the P(HEMA/IA) dressing could be considered a good barrier against microbes. All results indicate that stimuli-responsive P(HEMA/IA) hydrogels have great potential for biomedical applications, especially for skin treatment and wound dressings.     

Microchip electrophoretic separation for the fast diagnosis of Anaplasma phagocytophilum infection in cattle

We report a diagnostic method for Anaplasma phagocytophilum (A. phagocytophilum) infection in cattle using a nested PCR and microchip electrophoresis (ME). A. phagocytophilum causes human granulocytic anaplasmosis and granulocytic ehrlichiosis, which are emerging tick‐borne zoonotic diseases. Nested PCR was used to amplify genomic DNA samples extracted from cattle blood. The amplified PCR products were analyzed under a sieving gel matrix of 0.7% poly(ethyleneoxide) (M_r=8 000 000) in a conventional glass microchip. In the ME assay, A. phagocytophilum was analyzed within 35 s with a relative standard deviation of 1.30% (n=5) using a programmed field strength gradient (PFSG) as follows: 615.3 V/cm for 0–24 s, 66.7 V/cm for 24–34 s, 615.3 V/cm for 34–100 s. The ME‐PFSG assay was clinically validated by comparing the 16S rRNA gene levels obtained by this method with those measured using conventional slab gel electrophoresis performed with ten cattle blood samples suspected of A. phagocytophilum infection. In contrast to slab gel electrophoresis, the proposed ME‐PFSG methodology had increased sensitivity (200–450 pg/μL), a faster analysis time (<35 s), and required a smaller sample volume (～162 fL).     

Selective inhibitory effect of epigallocatechin-3-gallate on migration of vascular smooth muscle cells

In order to prevent restenosis after angioplasty or stenting, one of the most popular targets is suppression of the abnormal growth and excess migration of vascular smooth muscle cells (VSMCs) with drugs. However, the drugs also adversely affect vascular endothelial cells (VECs), leading to the induction of late thrombosis. We have investigated the effect of epigallocatechin-3-gallate (EGCG) on the proliferation and migration of VECs and VSMCs. Both cells showed dose-dependent decrease of viability in response to EGCG while they have different IC(50) values of EGCG (VECs, 150 mM and VSMCs, 1050 mM). Incubating both cells with EGCG resulted in significant reduction in cell proliferation irrespective of cell type. The proliferation of VECs were greater affected than that of VSMCs at the same concentrations of EGCG. EGCG exerted differential migration-inhibitory activity in VECs vs. VSMCs. The migration of VECs was not attenuated by 200 mM EGCG, but that of VSMCs was significantly inhibited at the same concentration of EGCG. It is suggested that that EGCG can be effectively used as an efficient drug for vascular diseases or stents due to its selective activity, completely suppressing the proliferation and migration of VSMCs, but not adversely affecting VECs migration in blood vessels.     

Correlating DFT-Calculated Energy Barriers to Experiments in Nonheme Octahedral Fe(IV) O Species

The experimentally measured bimolecular reaction rate constant, k(2) , should in principle correlate with the theoretically calculated rate-limiting free energy barrier, ΔG(≠) , through the Eyring equation, but it fails quite often to do so due to the inability of current computational methods to account in a precise manner for all the factors contributing to ΔG(≠) . This is further aggravated by the exponential sensitivity of the Eyring equation to these factors. We have taken herein a pragmatic approach for C?H activation reactions of 1,4-cyclohexadiene with a variety of octahedral nonheme Fe(IV) O complexes. The approach consists of empirically determining two constants that would aid in predicting experimental k(2) values uniformly from theoretically calculated electronic energy (ΔE(≠) ) values. Shown in this study is the predictive power as well as insights into energy relationships in Fe(IV) O C?H activation reactions. We also find that the difference between ΔG(≠) and ΔE(≠) converges at slow reactions, in a manner suggestive of changes in the importance of the triplet spin state weight in the overall reaction.     

Pt‐Nanoparticle Incorporated Carbon Paste Electrode for the Determination of Cu(II) Ion by Anodic Stripping Voltammetry

Pt‐nanoparticles were synthesized and introduced into a carbon paste electrode (CPE), and the resulting modified electrode was applied to the anodic stripping voltammetry of copper(II) ions. The synthesized Pt‐nanoparticles were characterized by cyclic voltammetry, scanning electron microscopy and X‐ray photoelectron spectroscopy techniques to confirm the purity and the size of the prepared Pt‐nanoparticles (ca. 20 nm). This incorporated material seems to act as catalysts with preconcentration sites for copper(II) species that enhances the sensitivity of Cu(II) ions to Cu(I) species at a deposition potential of ?0.6 V in an aqueous solution. The experimental conditions, such as, the electrode composition, pH of the solution, pre‐concentration time, were optimized for the determination of Cu(II) ion using as‐prepared electrode. The sensitivity changes on the different binder materials and the presence of surfactants in the test solution. The interference effect of the coexisted metals were also investigated. In the presence of surfactants, especially TritonX‐100, the Cu(II) detection limit was lowered to 3.9×10^?9 M. However, the Pt‐nanoparticle modified CPE begins to degrade when the period of deposition exceeds to 10 min. Linear response for copper(II) was found in the concentration range between 3.9×10^?8 M and 1.6×10^?6 M, with an estimated detection limit of 1.6×10^?8 M (1.0 ppb) and relative standard deviation was 4.2% (n=5).     

有机相变材料的发展及在纺织领域的应用

相变材料因为其优良的热性能,被广泛应用于纺织品、航空航天、交通运输、农业、国防、建材、太阳能系统和医疗设备等领域。近年来,开发应用新型相变材料已经成为研究热点。本文首先概括介绍了相变材料发展进程,着重介绍了有机相变材料,包括它的分类、性能和应用。详细介绍了有机相变材料在纺织行业的应用,以及对调温纺织品测试手段的研究和建立的相关数学模型的建立。     

The banded spherulites of iPP induced by pressure vibration injection molding

Isotactic polypropylene(i PP) samples obtained by pressure vibration injection molding(PVIM) and conventional injection molding(CIM) were studied by polarized-light microscopy(PLM), respectively. It was found that the alternating bright and dark banded spherulites were generated in the transitional region of PVIM parts. It is the first time that the banded spherulites of isotactic polypropylene were observed in polymer processing. What's more, the banded spherulites were proved to be constituted of ?-form crystal by hot stage polarized-light microscopy(HT-PLM) and wide angle X-ray diffraction(WAXD). Morphology of the banded spherulites was also studied by scaning electronical microscopy(SEM).     

Reactivity of iron(II) 5,10,15,20-tetraaryl-21-oxaporphyrin with arylmagnesium bromide: formation of paramagnetic six-coordinate complexes with two axial aryl groups

Coordination of sigma-aryl carbanions by chloroiron(II) 5,20-ditolyl-10,15-diphenyl-21-oxaporphyrin (ODTDPP)Fe(II)Cl has been followed by (1)H NMR spectroscopy. Addition of pentafluorophenyl Grignard reagent (C(6)F(5))MgBr to the toluene solution of (ODTDPP)Fe(II)Cl in the absence of dioxygen at 205 K resulted in the formation of the high-spin (ODTDPP)Fe(II)(C(6)F(5)). The titration of (ODTDPP)Fe(II)Cl with a solution of (C(6)H(5))MgBr carried at 205 K yields a rare six-coordinate species which binds two sigma-aryl ligands [(ODTDPP)Fe(II)(C(6)H(5))(2)](-). Warming of the [(ODTDPP)Fe(II)(C(6)H(5))(2)](-) solution above 270 K results in the decomposition to mono-sigma-phenyliron species (ODTDPP)Fe(II)(C(6)H(5)). Controlled oxidation of [(ODTDPP)Fe(II)(C(6)H(5))(2)](-) with Br(2) affords (ODTDPP)Fe(III)(C(6)H(5))Br, which demonstrates a typical (1)H NMR pattern of low-spin sigma-aryl iron(III) porphyrin. The considered oxidation mechanism involves the (ODTDPP)Fe(III)(C(6)H(5))(2) species, which is readily reduced to the iron(I) 21-oxaporphyrin, followed by oxidation with Br(2) and replacement of one bromide anion by aryl substituent. The (1)H NMR spectra of paramagnetic iron complexes have been examined in detail. Functional group assignments have been made with the use of selective deuteration. The peculiar (1)H NMR spectral features of [(ODTDPP)Fe(II)(p-CH(3)C(6)H(4))(2)](-) (sigma-p-tolyl: ortho, 30.8; meta, 53.6; para-CH(3), 42.1; furan: -16.0; beta-H pyrrole: -27.5, -34.3, -41.8 ppm, at 205 K) are without a parallel to any iron(II) porphyrin or heteroporphyrin and indicate a profound alteration of the electronic structure of iron(II) porphyrin upon the coordination of two sigma-aryls.     

The structural phase transitions of aminoguanidinium(1+) dihydrogen phosphate—study of crystal structures, vibrational spectra and thermal behavior

Aminoguanidinium(1+) dihydrogen phosphate was prepared by crystallization from aqueous solution. On the basis of the results of DSC measurements, X-ray structural analysis was carried out at temperatures of 160, 215 and 293 K for three aminoguanidinium(1+) dihydrogen phosphate phases ( |Z=2|non-ferroic |melting point 408 K; II |201-222 K|(2) |Z=2|non-ferroic|-; III |<201 K|(2)|Z=4|non-ferroic|-). The triclinic unit cell dimensions (a=6.8220(2), b=7.1000(2), c=7.4500(2) Å, α=86.925(2)°, β=80.731(2)°, γ=79.630(2)°, V=350.21(2) Å³—phase I) are similar for all three structural phases with the exception of phase III, where doubling of the c-axis length leads to an increase in the volume to 692.34(3) Å³. The crystal structure of all three modifications consists of parallel layers of dihydrogen phosphate anions that are interconnected by aminoguanidinium(1+) cations through hydrogen bonds of the N-H…O type. The planar aminoguanidinium(1+) cations are oriented almost parallel to each other and are perpendicular to the anion layers. The primary differences amongst phases I, II and III lie in the location of the H atom in the short O-H…O bonds connecting the dihydrogen phosphate anions in layers. The FTIR and FT Raman spectra of natural and deuterated compounds were recorded and interpreted. The FTIR spectra were studied down to a temperature of 90 K.