石化废水中常见有机酸的液相色谱分析

利用高效液相色谱(HPLC)法同时检测石化废水中丙烯酸、对甲基苯磺酸、甲基丙烯酸。 水样调节pH=1.6,经0.45 μm醋酸纤维滤膜过滤后直接进行色谱分析。 色谱条件：流动相为体积比93∶7的磷酸盐缓冲溶液(pH=3)和乙腈,流速1.0 mL/min,ZORBAX-SB-C18色谱柱,柱温30 ℃,MWD检测器,检测波长195 nm,进样量10 μL。 丙烯酸、对甲基苯磺酸、甲基丙烯酸的最低检出限分别为0.030、0.028和0.050 mg/L;样品测定的相对标准偏差分别为1.83%、0.69%和0.84%;样品加标回收率96%~112%。     

pH-Responsive Self-assembled Nanoparticles of Simulated P(AA-co-SA)-g-PEG for Drug Release

Simulated graft copolymer of poly(acrylic acid-co-stearyl acylate) [P(AA-co-SA)] and poly(ethylene glycol) (PEG) was synthesized, where acrylic acid, stearyl acylate and PEG was employed as the pH-sensitive, hydrophobic and hydrophilic segment, respectively. Polymeric nanoparticles prepared by the dialysis of simulated graft copolymer solution in dimethylformamide against citrate buffer solution with different pH values were characterized by transmission electron microscopy (TEM), fluorescence technique and laser light scattering (LLS). TEM image revealed the spherical shape of the self-aggregates, which was further confirmed by LLS measurements. The critical aggregation concentration increased markedly (10 to 150 mg/L) with increasing pH (4.6 to 7.0), consistent with the de-protonation of carboxylic groups at higher pH. The hydrodynamic radius of polymeric nanoparticles decreased from 118 nm at pH 3.4 to 90 nm at pH 7.0. The controlled release of indomethacin from those nanoparticles was investigated, and the self-assembled nanoparticles exhibited improved performance in controlled drug release.     

Colorimetric sensing of trace UO2(2+) by using nanogold-seeded nucleation amplification and label-free DNAzyme cleavage reaction

In pH 4.4 HAC-NaAC buffer solution at 80 °C, nanogold particles (NG) strongly enhanced the slow, colored reaction of Ag(i)-gallic acid to form nanosilver particles, which exhibited a strong surface plasmon resonance (SPR) absorption peak at 460 nm, but the aggregated nanogold particles (ANG) exhibited a weak enhancement. The increased absorption value at 460 nm was linear to the NG concentration in the range of 3.6-72.5 ng mL(-1) Au. In pH 5.5 MES buffer solution at 80 °C, single-stranded substrate DNA and DNAzyme hybridize to form double-stranded DNA (dsDNA). The presence of uranyl (UO(2)(2+)) resulted in cleavage of the substrate DNA of dsDNA, releasing a short, single-stranded DNA that can be adsorbed onto the NG and protect them from aggregation; those un-adsorbed NG were aggregated to ANG. As the UO(2)(2+) concentration increased, more short, single-stranded DNA were released, and more NG were protected by the cleavage of substrate single-strand DNA, so the colored particle reaction and the absorption value at 460 nm enhanced linearly. On those grounds, 0.083-0.67 nmol L(-1) UO(2)(2+) can be detected rapidly by this colorimetric sensing assay, with a detection limit of 0.04 nmol L(-1).     

流动注射在线氧化荧光法结合透析采样研究盐酸硫利达嗪与牛血清白蛋白的结合作用

利用流动注射在线氧化结合在线透析采样技术建立了荧光法测定血浆中游离盐酸硫利达嗪的新方法, 并将其应用于盐酸硫利达嗪与牛血清白蛋白作用机制的研究. 将盐酸硫利达嗪与牛血清白蛋白以不同比例混合并在37 ℃下培养, 以流动注射透析采样技术从混合液中分离出游离盐酸硫利达嗪, 在线氧化为强荧光化合物后测定其浓度; 应用Scrathard方程分析所测数据, 求得盐酸硫利达嗪和牛血清白蛋白的结合常数为1.2×104 L/mol, 结合位点数为0.98; 根据热力学参数推断, 盐酸硫利达嗪与牛血清白蛋白之间以疏水作用力为主; 进一步基于荧光猝灭现象和Fster非辐射能量转移理论, 得到盐酸硫利达嗪小分子与牛血清白蛋白之间的能量转移效率(E=0.497)和结合距离(r0=3.27 nm).     

A design of nanosized PEGylated-latex mixed polymer solution for microchip electrophoresis

We report here advanced microchip electrophoresis using a nanoparticle doped polymer solution that enables greater separation of DNA. The proposed system is simple and effective without any new apparatus or complicated procedures. Various amounts and sizes (80 nm, 110 nm, and 193 nm) of polymer nanoparticle solutions (PEGylated-latex) were mixed with a conventional polymer solution for microchip electrophoresis. When a 0.49 wt% hydroxyl propyl methyl cellulose (HPMC) buffer solution was mixed with a 2.25 wt% 80 nm-PEGylated-latex a higher separation efficiency and a higher mobility of a wider molecular range of dsDNA (10 bp to 2 kbp) was achieved under low viscosity conditions (<5.5 cP) than in conventional 0.7% HPMC. The separation performance was dependent on the particle size and concentration. Furthermore, the effectiveness of the larger PEGylated-latex (193 nm) was not as high as the smaller one (80 to 110 nm). The observed separation improvement by polymer solution with latex-nanoparticles seems to derive from the balance between wider polymer mesh size and the structural obstacles of particles in the buffer.     

Hydrothermal Synthesis of Platinum‐Group‐Metal Nanoparticles by Using HEPES as a Reductant and Stabilizer

Platinum‐group‐metal (Ru, Os, Rh, Ir, Pd and Pt) nanoparticles are synthesized in an aqueous buffer solution of 4‐(2‐hydroxyethyl)‐1‐piperazineethanesulfonic acid (HEPES) (200 mM , pH 7.4) under hydrothermal conditions (180 °C). Monodispersed (monodispersity: 11–15 %) metal nanoparticles were obtained with an average particle size of less than 5 nm (Ru: 1.8±0.2, Os: 1.6±0.2, Rh: 4.5±0.5, Ir: 2.0±0.3, Pd: 3.8±0.4, Pt: 1.9±0.2 nm). The size, monodispersity, and stability of the as‐obtained metal nanoparticles were affected by the HEPES concentration, pH of the HEPES buffer solution, and reaction temperature. HEPES with two tertiary amines (piperazine groups) and terminal hydroxyl groups can act as a reductant and stabilizer. The HEPES molecules can bind to the surface of metal nanoparticles to prevent metal nanoparticles from aggregation. These platinum‐group‐metal nanoparticles could be deposited onto the surface of graphite, which catalyzed the aerobic oxidation of alcohols to aldehydes.     

High-performance capillary electrophoresis of gangliosides

Gangliosides are sialic acid-containing glycosphingolipids. In aqueous media, these glycolipids have been shown to exist as stable micelles. Ganglioside micelles could be analyzed by high-performance zonal capillary electrophoresis in uncoated fused-silica capillaries within 10 min. The mass sensitivity determined by monitoring the absorption of ultraviolet light at 195 nm was in the order of 10(-11) mol. Increasing the pH of the running buffer from 3.0 to 7.4 or the voltage from 10 to 30 kV increased the relative mobilities of gangliosides. By contrast, increasing the ionic strength of the buffer decreased the migration and broadened the elution peak widths of gangliosides. Ganglioside* micelles including GM1, GD1b, and GT1b were resolved into separate peaks by capillary electrophoresis at physiological pH shortly after mixing. Upon prolonged incubation, the ganglioside peaks merged to form a single species. The fusion process was temperature-dependent. At 50 degrees C, formation of mixed micelles between polysialogangliosides GD1b and GT1b was complete within 30 min. In contrast, no fusion of the ganglioside peaks was observed at 0 degrees C even after 75 h. Formation of mixed micelles between GD1b and other polysialogangliosides including GD1a, GT1b, and GQ1b at 37 degrees C required 1.5, 3.0, and 2.0 h, respectively. Formation of mixed micelles between monosialoganglioside GM1 and polysialogangliosides were 6- to 36-fold slower. No fusion was observed between monosialogangliosides GM1 and GM2 after 2 days of incubation. These findings indicate that polysialogangliosides may have higher propensities than monosialoganglioside to form mixed micelles.     

Synthesis,characterization, and evaluation of enzymatically degradable poly(N‐isopropylacrylamide‐co‐acrylic acid) hydrogels for colon‐specific drug delivery

The enzymatically degradable poly(N‐isopropylacrylamide‐co‐acrylic acid) hydrogels were prepared using 4,4^′‐bis(methacryloylamino)azobenzene (BMAAB) as the crosslinker. It was found that the incorporated N‐isopropylacrylamide (NIPAAm) monomer did not change the enzymatic degradation of hydrogel, but remarkably enhanced the loading of protein drug. The hydrogels exhibited a phase transition temperature between 4°C (refrigerator temperature) and 37°C (human body temperature). Bovine serum albumin (BSA) as a model drug was loaded into the hydrogels by soaking the gels in a pH 7.4 buffer solution at 4°C, where the hydrogel was in a swollen status. The high swelling of hydrogels at 4°C enhanced the loading of BSA (loading capability, ca. 144.5 mg BSA/g gel). The drug was released gradually in the pH 7.4 buffer solution at 37°C, where the hydrogel was in a shrunken state. In contrast, the enzymatic degradation of hydrogels resulted in complete release of BSA in pH 7.4 buffer solution containing the cecal suspension at 37°C (cumulative release: ca. 100 mg BSA/g gel after 4 days). Copyright © 2008 John Wiley & Sons, Ltd.     

Electron-beam graft-modified membranes with externally controlled flux

Pre-irradiation grafting as a means to modify commerical poly(vinylidene fluoride) (PVDF) membranes has been studied. The membranes prepared were weak cation-exchange membranes (acrylic acid functionality), anion-exchange membranes (trimethyl ammonium functionality) and temperature-sensitive membranes (N-isopropyl amide functionality). Different graft loads were obtained by varying reaction time, radiation dose and in the case of acrylic acid the graft solution composition. The trimethyl ammonium chloride functionality was obtained by grafting vinyl benzyl chloride onto a PVDF membrane and aminating the benzyl chloride groups in a 45% trimethyl amine–water solution. For a membrane grafted with 9 wt% acrylic acid the flux increased approximately 70 times when the pH was decreased from 6 to 2. For a membrane with 5 wt% trimethyl ammonium functionality the flux increased both when pH was decreased below 3 and increased above 11. For a membrane grafted with 18 wt% N-isopropyl acrylamide a sharp increase of flux was observed when the temperature was raised above 32°C.     

Bioactive composites fabricated by freezing‐thawing method for bone regeneration applications

Hydrogels are widely used for controlled delivery of therapeutic agents. However, hydrogels lack bioactivity to encourage bone formation and mechanical integrity. Moreover, chemically crosslinked hydrogels exhibit cytotoxic effect. To overcome these limitations poly‐vinyl alcohol (PVA) and poly‐acrylic acid (PAA) blends were combined with ceramic materials based on β tricalcium phosphate, wollastonite, and magnesium silicate with different pore size distributions. The final 3D matrix was physically crosslinked using various freeze thawing (F/T) cycles. FTIR and SEM analysis showed that ceramics were dispersed within the polymer matrix and formed hydrogen bonds. Swelling studies in buffer solution pH 7.4 showed an increase in polymer swelling when ceramic was added. Furthermore, rheological testing demonstrated that incorporation of ceramics caused an increase in mechanical properties which varies with different pore size distributions of ceramics grains added. DSC thermograms showed increased T_g values for samples containing ceramics. Antimicrobial activity containing ciprofloxacin was tested against a pathogen associated with osteomyelitis and presented positive results with ciprofloxacin. The combination of increased strength and ability to encapsulate a clinically relevant antimicrobial agent indicates that the composite tested in this study has potential for the treatment of osteomyelitis. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 761–773     

离子键交联的聚两性电解质凝胶在不同pH和不同电解质溶液中溶胀行为研究

以丙烯酸(AA)和甲基丙烯酸二乙氨基乙酯(DEAM)形成的离子复合物与丙烯酰胺(AAm)共聚,合成了一种新型的离子键交联的聚两性电解质凝胶(PADA).由于分子之间的氢键作用,PADA凝胶并不是在A/C(负正离子单体摩尔比)为1,而是在A/C为1.55处有最大消溶胀.与共价键交联的聚两性电解质凝胶相比,PADA凝胶的溶胀行为具有更强的pH敏感性.PADA凝胶在不同pH缓冲溶液中的溶胀行为表明,在pH 3~4之间消溶胀程度最大.在偏离该pH区域时凝胶均发生溶胀.但凝胶的溶胀程度在pH<3的酸性溶液中随A/C的增加而降低;而在pH>4的偏碱性溶液中随其增加而增加.在不同价数的离子溶液中,离子浓度对于PADA凝胶的平衡溶胀有着不同的影响.对于一价的NaCl溶液,PADA凝胶有典型的反聚电解质效应.但对于高价的CaCl2和柠檬酸三钠溶液,只在较低的浓度下,才表现出反聚电解质效应.而在较高盐浓度时,随盐浓度的增加其溶胀比反而降低.这可能与高价离子形成的离子键交联有关.与pH对PADA凝胶溶胀程度的影响相似,在CaCl2溶液中,PADA凝胶的溶胀程度随A/C的增加而降低;而在柠檬酸三钠溶液中则刚好相反.这种独特的溶胀行为似乎与高价离子电荷的正负性有关.     

壳聚糖-聚丙烯酸复合水凝胶的药物控制释放行为

以壳聚糖(Cs)和丙烯酸(AA)为原料,利用自由基聚合法制备了具有孔洞结构的复合水凝胶Cs-PAA,并研究了AA的量、交联剂的量、聚合温度和AA的中和度对水凝胶溶胀度的影响以及复合水凝胶对烟酸的控制释放。 结果表明,Cs-PAA复合水凝胶具有良好的pH值、离子强度敏感性,且溶胀度最高达1228 g/g,其在pH=686的缓冲溶液中的烟酸累积释放率明显大于其在pH=1.80的缓冲溶液,因此Cs-PAA水凝胶可作为肠口服药物的载体。     

2,5-di-[2-(3,5-bis(2-pyridylmethyl)amine -4-hydroxy-phenyl) ethylene] pyrazine zinc complex as fluorescent probe for labeling proteins

The binding characteristics between 2,5-di-[2-(3,5-bis(2-pyridylmethyl)amine -4-hydroxy-phenyl) ethylene] pyrazine (1) or its complex (1-Zn) and serum albumins were studied by fluorescence spectroscopy in pH 7.4 aqueous solution. 1-Zn emitted weak fluorescence at 580 nm in a pH 7.4 Tris-HCl buffer solution when excited at 435 nm, however, the fluorescence intensity increased upon addition of serum albumins with the blue shift of emission peak to 524 nm. The binding constants were estimated as 8.40 x 10(7) and 3.03 x 10(6)mol(-1)L for bovine serum albumin (BSA) and human serum albumin (HSA) respectively, and the number of binding sites was 1 for each. The quenching mechanism of fluorescence of serum albumins by 1-Zn was considered as a static quenching process. The binding distance between 1-Zn and serum albumins and the energy transfer efficiency were obtained based on the theory of F?rester spectroscopy energy transfer. The effect of 1-Zn on the conformation of serum albumins was further analyzed using synchronous fluorescence spectrometry. The experiment results clearly showed that 1-Zn is a highly sensitive protein sensor.     

Differentially Degradable Janus Particles for Controlled Release Applications

Janus particles with differentially degradable compartments were prepared by electrohydrodynamic (EHD) co‐jetting and subsequent controlled crosslinking. These bicompartmental particles are composed of an interpenetrating polymer network of poly(ethylene oxide) and poly(acrylamide‐co‐acrylic acid) in one hemisphere and a crosslinked copolymer of dextran and poly(acrylamide‐co‐acrylic acid) segments in the second compartment. The compositional anisotropy caused differential hydrolytic susceptibility: Although both compartments were stable at pH 3.0, selective degradation of the PEO‐containing compartment pH 7.4 was observed wtihin 5 days. Janus particles with differentially degradable polymer compartments may be of interest for a range of oral drug delivery applications because of their propensity for decoupled release profiles.     

用水溶性四苯基乙烯基荧光探针检测ctDNA

设计合成了一种水溶性的四苯基乙烯(TPE)衍生物TPEDPyMe,研究了该化合物的吸收和发射特性,发现TPEDPyMe具有聚集诱导发光(AIE)性能.在pH值为7.2的三羟甲基氨基甲烷-盐酸(tris-HCl)缓冲溶液中用TPEDPyMe检测小牛胸腺DNA(ctDNA)时观察到,随着ctDNA的浓度从0μg/mL增大到...     

环丙沙星在BTR缓冲液中的紫外光谱性质研究与应用

研究了不同缓冲溶液 ,不同pH介质中环丙沙星的紫外光谱性质 ,提出在BrittonRobinson(BTR)缓冲溶液中为紫外分光光度法测定环丙沙星的最佳条件 .在吸收波长 2 77nm处 ,测得其表观摩尔吸收系数为 2 .6 3× 10 4L/mol.cm ,浓度在 3.0～ 2 3.0mg/L范围内 ,吸收度与浓度符合比尔定律 ,该法成功用于药物制剂中环丙沙星含量的测定 ,结果满意     

聚苯乙烯-丙烯酸嵌段共聚物在不同pH值和Ca2+浓度下的胶束行为

近年来, 对具有纳米尺寸的聚合物自组装结构的研究日益增多. 其中, 嵌段共聚物在选择性溶剂中的胶束行为研究得最为广泛和深入[1~5]. 纳米胶束表现出诸多常规尺寸材料所不具备的特殊性能, 在材料化学、生物医学以及环境科学等领域有广阔的应用前景. Webber等[6]对聚丙烯酸和聚苯乙烯接枝共聚物的研究发现, 聚合物的接枝率和聚合物浓度以及溶液离子强度对胶束结构有影响; Eisenberg等[1,7]对不同嵌段比例的苯乙烯-丙烯酸嵌段共聚物的自组装行为进行研究发现, 不同嵌段比例所对应的胶束结构不同. 胶束形成的环境对胶束的形成与稳定性的影响是人们研究的重点. 本文报道了聚苯乙烯-丙烯酸嵌段共聚物在水中的胶束行为, 着重讨论了溶液pH值和钙离子浓度对聚丙烯酸链段相互作用的影响.     

In vitro swelling studies in simulated physiological solutions and biocompatibility of NIPAM-based hydrogels with some biochemical parameters of human sera

In modern medicine, commonly used biomaterials originating from metals, ceramics and polymers have shown biocompatibility with blood, tissues, cells, etc., in the human body. Polymeric biomaterials are usually understood as polymeric materials and articles made from them which are used in medicine, biotechnology biomedicine, bioengineering, pharmaceutical, veterinary, food industry, agriculture and related fields. In this in vitro study, swellings and the biocompatibility of environmentally sensitive N-isopropyl acrylamide-based (ES) hydrogels such as N-isopropyl acrylamide/acrylamide (ES/0), and N-isopropyl acrylamide/acrylamide/ carboxylic acids (ES/XAc) prepared by free radical polymerization in aqueous solutions has been investigated. Selected carboxylic acids for this study were acrylic, methacrylic, crotonic, itaconic, maleic, mesaconic and aconitic acid. The equilibrium swelling of the hydrogels are investigated in simulated physiological fluids or crystalloid solutions such as HCl-KCl buffer (pH = 1.1), universal buffer (pH = 5.5), phosphate buffer (pH = 7.4), urea, isotonic NaCl, isotonic KCl, 5% dextrose, 5% dextrose+isotonic NaCl, Ringer's lactate, human blood serum and human serum albumin solution at 37°C. For the analysis of biocompatibility, ES hydrogels are incubated in 5 different human sera and their biocompatibilities with some biochemical parameters have been investigated for 24 h at 37°C. No significant differences in values before and after the test procedures have been found. It is therefore concluded that environmentally sensitive N-isopropyl acrylamide-based hydrogels are biocompatible for biochemical parameters of human sera.     

Separation of Basic Proteins in Bare Fused-Silica Capillaries with Diethylentriamine Phosphate Buffer as the Background Electrolyte Solution

The effectiveness of diethylentriamine (DIEN) phosphate buffer at separating basic proteins in bare fused-silica capillaries at various pH values was examined. Such a buffer consists of an aqueous solution of DIEN titrated to the desired pH value with phosphoric acid. The study was conducted by investigating the effect of DIEN phosphate buffer on the electrophoretic mobility and efficiency of four basic proteins at various pH values within the ranges over which the phosphate salts of DIEN are effective at controlling the protonic equilibrium on the basis of the acidic pKa values of either diethylentriamine or phosphoric acid. The ranges were taken as one pH unit below and above the acidic pKa values of either DIEN or phosphoric acid. Electrophoretic separations of the four basic proteins performed at the selected pH values, ranging from pH 3.0 to pH 8.0, showed well-resolved efficient and symmetric peaks, demonstrating the capability of DIEN phosphate buffer at inhibiting untoward interactions of basic proteins with the active sites on the inner wall of bare fused-silica capillaries. Such effect is ascribed to the absorption of DIEN ions at the interface between the capillary wall and the electrolyte solution resulting in drastic variations of the positive charge density in the compact region of the electric double layer that, however, are is not suppressing completely the negative charges due to the ionization of silanol groups. Consequently, the net charge within the immobilized region of the electric double layer is negative as evidenced by the cathodic electroosmotic flow measured at any pH value within the range 3.0–8.0, indicative of negative zeta potential.     

pH- and cinnamic acid-triggerable dioleoylphophatidylethanolamine liposome bearing polyethyleneimine/palmitic acid mixture

pH and cinnamic acid (CA)-triggerable liposome was prepared by stabilizing dioleoylphosphatidylethanolamine (DOPE) bilayer with polyethyleneimine (PEI)/palmitic acid (PA) mixture. PEI/PA mixture was air/water interface-active, possibly due to the formation of PEI/PA salt conjugate. When the weight ratio of DOPE to PEI/PA mixture was 200:1, 100:1, 50:1, and 20:1, the fluorescence quenching degree of calcein loaded in the DOPE/PEI/PA assembly prepared using PBS (10 mM, pH 7.4) was 70.7%, 68.7%, 35.3%, and 14%, respectively, indicating that DOPE could be assembled into liposome at the physiological pH value with the aid of the PEI/PA mixture. The hydrodynamic mean diameter of liposome increased from 289 nm to 702 nm on increasing the weight ratio of the DOPE to PEI/PA mixture, possibly because of the bulky PEI chains. The release degree in 120 seconds at pH 4.5, pH 6.0, pH 7.4, and pH 9.0 was about 85%, 24.1%, 10.1%, and 62.0%, respectively, when the suspension of liposome of which the DOPE to PEI/PA mixture weight ratio was 50:1 (pH 7.4) was injected into the release medium of different pH values. The triggered release upon the acidification (i.e., pH 7.4–4.5) and the alkalization (i.e., pH 7.4–9.0) was possibly because PA and PEI were deionized under acidic and alkali conditions, respectively; thus the salt bridge of PEI/PA conjugate could break down. The DOPE liposome also exhibited CA-triggered release. The release degree in 120 seconds at 25°C was 23.1% and it was higher than the release degree at 50°C, 10.9%, possibly because CA could render PEI chains condensed and assembled under upper the critical solution temperature.