高原鼠兔血清中N-isopropyl oxamate的RP-HPLC检测方法的建立

目的：探索N-isopropyl oxamate和血清蛋白结合水平,建立高原鼠兔血液中精子型乳酸脱氢酶（LDH-C4）特异性抑制剂N-isopropyl oxamate的高效液相色谱（HPLC）检测方法。方法：取体重150-200 g高原鼠兔20只,随机分为对照组和抑制剂组（n=10）。通过外源性加入不同浓度的N-isopropyl oxamate,检测其与血清蛋白的结合水平。采用将血清先用胰蛋白酶酶解,再加入三氯乙酸的前处理法进行HPLC检测。结果：当空白高原鼠兔血清加入抑制剂标准品达到血清中浓度为0.05 mmol/L、0.1 mmol/L、1 mmol/L、10 mmol/L、16.7 mmol/L、33.3 mmol/L、100 mmol/L时,抑制剂与血清蛋白的结合率分别为100%、100%、100%、86.84%、54.11%、40.10%、20.18%。在本文建立的方法下,回收率、精密度、稳定性均良好。N-isopropyl oxamate在0.0125-0.25 mmol/L内浓度与峰面积线性关系好。空白血清加入标准品达到终浓度为0.15 mmol/L、0.3 mmol/L和1 mmol/L时,平均回收率分别为98.05%、98.98%、98.12%;精密度相对标准偏差（RSD）分别为1.17%、0.92%、0.83%;稳定性RSD分别为1.38%、1.40%、0.88%。方法的重复性RSD为1.76%,最低定量限为0.0125 mmol/L。结论：N-isopropyl oxamate与高原鼠兔血清具有很强的亲和力,直接用三氯乙酸沉淀蛋白的前处理方法无法准确检测其浓度,而先用胰蛋白酶消化血清,再用三氯乙酸沉淀蛋白的方法可实现血液中HPLC的精确检测。

A Temperature-sensitive Hydrogel Refolding System: Preparation of Poly(N-isopropyl acrylamide) and Its Application in Lysozyme Refolding

Temperature-sensitive hydrogel—poly(N-isopropyl acrylamide) (PNIPA) was prepared and applied to protein refolding. PNIPA gel disks and gel particles were synthesized by the solution polymerization and inverse suspension polymerization respectively. The swelling kinetics of the gels was also studied. With these prepared PNIPA gels, the model protein lysozyme was renatured. Within 24h, PNIPA gel disks improved the yield of lysozyme activity by 49.3% from 3375.2U·mg^-1 to 5038.8U·mg^-1. With the addition of faster response PNIPA gel beads, the total lysozyme activity recovery was about 68.98% in 3h, as compared with 42.03% by simple batch dilution. The novel refolding system with PNIPA enables efficient refolding especially at high protein concentrations. Discussion about the mechanism revealed that when PNIPA gels were added into the refolding buffer, the hydrophobic interactions between denatured proteins and polymer gels could prevent the aggregation of refolding intermediates, thus enhanced the protein renaturation.

Thermo- and pH-Responsive Hydrogels Based on N-Isopropylacrylamide and Allylamine Copolymers

The thermo- and pH-responsive hydrogels were synthesized via copolymerization of N-isopropylacrylamide and al-lylamine hydrochloride monomers. The equilibrium swelling of the hydrogels was studied as a function of temperature and pH in aqueous solutions. It was shown that controlled alteration of the hydrogel phase transition temperature can be achieved by changing their composition and pH of the environment. Increase in content of hydrophilic allylamine from 10 to 60 wt% in monomer mixture causes a shift of the phase transition temperature from 35oC to 47oC. Hydrogels with N-isopropylacrylamide/allylamine hydrochloride mass ratio of 3:2 show the highest pH-response. Values of average molecular weight between polymer cross-links, , and Flory parameter, χ, were calculated using temperature dependences of the equilibrium swelling of the synthesized hydrogel.

Phototactic Poly(N-isopropyl acrylamide)Microgels with Photoresponsive Property

Smart functional microgels hold great potential in a variety of applications,especially in drug transportation.However,current drug carriers based on physiological internal stimuli cannot efficiently orientate to designated locations.Therefore,it is necessary to introduce the self-propelled particles to the drug release of the microgels.In order to study self-propulsion of microgels induced by light,it is also a challenge to prepare micronsized microgels so that they can be observed directly under optical microscopes.In this work,phototactic microgels with photoresponsive properties are prepared.The microgel particles can be observed by confocal laser scanning microscopy.The photoresponsive properties of microgels are fully investigated by various instruments.Light can also regulate the state of the microgel solution,making it switch between turbidity and clarity.The phototaxis of particles irradiated by UV light was studied,which may be used for microgels enrichment and drug transportation and release.

POLY(N-ISOPROPYL ACRYLAMIDE) MICROGEL DOPED WITH LUMINESCENT PBS QUANTUM DOTS

Thiol-stabilized PbS quantum dots （QDs） with dimensions 3-5 nm capped with a mixture of 1-thioglycerol/dithioglycerol （TGL/DTG） were coUoidally prepared at room temperature. Room temperature photoluminescence quantum efficiency of freshly prepared PbS QDs （7%-11%） remained higher than 5% upon aging for three weeks when the nanocrystals （NCs） were stored in an ice-bath in the dark, and higher than 5%for at least five weeks when extra DTG ligands were introduced into the nanocrystal solution followed by stirring every two weeks. Poly（N-isopropyl acrylamide） （PNIPAM） microgels were produced via precipitation polymerization with dimensions of ca. 230 nm and polydispersity of 3-5%. Incorporation of PbS QDs into PNIPAM microgels indicated that PbS can be incorporated into the interior of microgel particles and not at the microgel interface. The combination of reasonable room temperature quantum efficiency and strong, efficient luminescence covering the 1.3-1.55 μm telecommunication window makes these nanoparticles promising materials in optical devices and telecommunications.

Molecular chain properties of poly(N-isopropyl acrylamide)

A series of poly(N-isopropyl acrylamide) (PNIPAM) samples with molecular weight ranging from 2.23 × 104 to 130 × 104 and molecular weight distributionMw/Mn ≤1. 28 were obtained by free radical polymerization and repeat precipitation fractionation. The molecular weightMw, second virial coefficientA2 as well as the mean-square-root radius of gyration < S2 > for PNIPAM samples in tetrahydrofuran (THF) were determined by light scattering, and the relations were estimated atA2 ∞ M w- 0.25 and S2 1/2 = 1.56 × 10-9 Mw 0.56. The intrinsic viscosity for THF solution and methanol solution of PNIPAM samples was measured and the Mark-Houwink equations were obtained as [η] =6.90x 10-5 M0. 73(THF solution) and [η] = 1.07 × 10-4 M0.71(methanol solution). The above results indicate that both THF and methanol are good solvents for PNIPAM. The limit characteristic ratioC ∞ for PNIPAM in the two solutions was determined to be 10.6 by using Kurata-Stockmayer equation, indicating that the flexibility of PNIPAM chain is close to that of polystyrene. The intrinsic viscosity for the aqueous solution of PNIPAM was measured at 25-30.5°C. The result demonstrates that PNIPAM chain begins to shrink at 25°C, and from about 30°C, onward the molecular chain shrinks much more sharply till the solution becomes macroscopically unstable at 32°C.

Thermal reversible gelation during phase separation of poly(N-isopropyl acrylamide)/water solution

By dynamic viscoelastic measurement for PNIPAM/water solution it has been found that below the phase separation temperature (about 32°C), the system is homogeneous fluid; while upon being heated to about 32°C, the solution undergoes phase separation and the storage modulus G’ increases sharply and exceeds the loss modulus G”, indicating the physical network formation during the phase separation. Based on the percolation model, the gel points Tgel were obtained by applying the dynamic scaling theory (DST) and Winter’s criterion. The critical exponent n was also obtained to be 0.79 through DST, which is different from 0.67, the critical point of chemically crosslinked network predicted through DST. The obtained n value reflects the special property of physical network being different from chemical network.

Poly(N-isopropylacrylamide)-grafted Dual Stimuli-responsive Filter Paper for Protein Separation

Thermal and salt dual stimuli-responsive filter-paper-based membranes were prepared by UV-induced grafting of NIPAM-based polymers on paper surface. The grafting ratio could be controlled by monomer concentration during grafting polymerization. The results from pressure drop measurement of the mobile phase flowed cross the membrane demonstrate that an appropriate grafting ratio would be 8%-10%. Protein adsorption on the membrane through hydrophobic interaction could be promoted by increasing temperature and lyotropic salt concentration. The effect of grafted polymer structure on protein binding performance was studied. Filter paper grafted with NIPAM-based branched copolymer consisting of hydrophobic monomer moieties shows ten times higher protein binding capacity than that of the original filter paper. The separation of plasma proteins using the dual stimuli-responsive membrane was examined to demonstrate feasible application for hydrophobic interaction chromatographic separation of proteins.

Perioperative Evaluation of Cerebral Blood Flow Using ^123I-labeled N-isopropyl-p-iodoamphetamine Single-Photon Emission Computed Tomography without Blood Sampling in Patients Who Underwent Carotid Artery Stenting

The evaluation of regional cerebral vascular reserve （rCVR） with single-photon emission computed tomography （SPECT） is useful for predicting cerebral hyperperfusion following carotid artery stenting （CAS） and carotidendarterectomy （CEA）.

The correlation between molecular structure parameters of O-ethyl N-isopropyl phosphoro(thioureido)thioates and their retention data in RP-HPLC

A retention prediction system(RPS)of seven O-ethyl N-isopropyl phosphoro(thioureido)- thioates in reversed phase HPLC was investigated.The system is based on the solvent selectivity triangle concept.Three molecular structure parameters(hydrophobicity Ⅱ,substituent length L, and substituent maximum width B_5)were used to describe the quantitative structure-retention relation- ships.With these quantitative relationships,the retention behaviours of other eight homologs for different mobile phase composition were predicted.The predicted values were consistent with the measured values within relative error of 10%,which means that it is possible to apply the reported method to predict retention values for qualitative purposes for different mobile phase compositions.

Computer-assisted retention prediction system in reversed-phase HPLC for O-ethyl O-aryl N-isopropyl phosphoramidothioates

A computer-assisted retention prediction system (RPS) of fifteen O-ethyl O-aryl N-iso- propyl phosphoramidothioates (1) in reversed-phase HPLC was investigated. The system is based on the use of four physicochemical parameters (hydrophobicity , electric effect σ, field effect F and steric effect ) which is closely related to the retention mechanism in reversed-phase HPLC. The system was evaluated by comparing the measured retention data with the predicted ones. The predicted values were consistent with the measured values within a relative error of 11.5%.

蛋氨酸羟基类似物异丙酯和N-氨甲酰谷氨酸对奶牛初乳免疫指标、犊牛生长和血浆指标的影响

试验旨在研究围产期添加蛋氨酸羟基类似物异丙酯(HMBi)和N-氨甲酰谷氨酸(NCG)对奶牛初乳免疫指标、新生犊牛生长性能和血浆指标的影响。选择年龄、胎次、体况、上一胎次日产奶量及预产期相接近的围产期母牛100头,随机分为2组,每组50个重复,每个重复1头牛。对照组饲喂基础饲粮,试验组饲喂基础饲粮+30 g/(头·d)HMBi+20 g/(头·d)NCG。试验期为42 d,其中围产前期21 d,围产后期21 d。结果显示,与对照组相比,试验组母牛初乳中肿瘤坏死因子-α含量显著升高(P<0.05),犊牛初生重增加了1.12 kg(P>0.05),犊牛胸围和管围极显著提高(P<0.01),犊牛血浆中总蛋白含量显著增加(P<0.05)。研究表明,围产期奶牛补饲HMBi和NCG可以提高犊牛胸围和管围,有增加犊牛初生重的趋势。

高原鼠兔脑组织中精子特异性乳酸脱氢酶的作用

高原鼠兔对高原低氧环境有很强的适应性。研究发现,精子特异性乳酸脱氢酶(LDH-C4)基因在高原鼠兔脑组织中表达,为阐明LDH-C4在高原鼠兔脑组织中的作用,应用荧光定量PCR和Western blot方法,测定了Ldh-c基因在高原鼠兔脑组织中的表达水平;应用对精子特异性乳酸脱氢酶(LDH-C4)特异性的抑制剂(N-isopropyl oxamate),通过肌肉注射后,研究抑制剂对高原鼠兔脑组织中LDH比活力、乳酸和ATP含量的影响。结果表明,在mRNA和蛋白水平,Ldh-c基因在高原鼠兔脑组织中均有表达,相对表达水平分别为0.38±0.05和0.74±0.13;当肌肉注射1 m L 1 mol/L的抑制剂30 min后,血液中抑制剂浓度为0.08 mmol/L;与对照组相比,抑制剂组脑组织中LDH比活力、乳酸和ATP含量显著下降,抑制剂对LDH、乳酸和ATP的抑制率分别为30.78%、46.47%和21.04%。结果表明,精子特异性乳酸脱氢酶基因在高原鼠兔脑组织中表达。LDH-C4通过催化无氧糖酵解过程,为其脑组织生命活动提供至少20%的ATP,可能使高原鼠兔减小在低氧环境中对氧气的依赖,增强对低氧环境的适应能力。

阳离子型温敏水凝胶的合成与性质

阳离子型温敏水凝胶的合成与性质王昌华卢英先曹维孝（北京大学化学与分子工程学院北京１００８７１）关键词热缩温敏水凝胶，Ｎ异丙基丙烯酰胺，Ｎ乙烯基吡啶氟硼酸盐，Ｎ甲基４乙烯基吡啶硫酸甲酯盐水凝胶可看作是水溶或亲水高分子的一种亲水网络．多数...

NIPA/DMAA共聚物及其水溶液相转变温度的研究

合成了不同配比的Ｎ－异丙基丙烯酰胺（ＮＩＰＡ）／Ｎ，Ｎ－二甲基丙烯酰胺（ＤＭＡＡ）共聚物并用红外光谱对它们进行了验证。ＤＳＣ分析表明，共聚物的Ｔｇ随ＮＩＰＡ含量逐渐增大先是显著升高，当ＮＩＰＡ含量为４６．５ｍｏｌ％时，Ｔｇ达１３２℃，随后共聚物的Ｔｇ仅有微小的升高。共聚物水溶液的相转变温度比ＰＮＩＰＡ均聚物高，当ＮＩＰＡ的含量为４６．５ｍｏｌ％时，共聚物的雾点温度高达５１．６℃，我们认为这是因为共聚物分子链的疏水性较ＰＮＩＰＡ均聚物分子链的低所致。

快速响应型P(NIPA-co-SA)水凝胶制备及温敏性能

研究具有较高LCST且响应速率快的温敏性水凝胶。以NaCl水溶液为反应介质,采用相分离法合成了多孔水凝胶P(NIPA-co-SA)。利用傅立叶变换红外光谱仪(FT-IR)表征产物结构,并借助扫描电子显微镜、差示扫描量热法(DSC)、浊度法等手段研究了反应介质浓度对产物微观形貌、相变温度和相变响应速率的影响规律。结果表明,P(NIPA-co-SA)水凝胶具有对温度敏感的响应特性,其低临界溶解温度(LCST)可达到75℃。NaCl水溶液浓度不影响产物的LCST,且随着反应中NaCl水溶液浓度的提高,水凝胶表面逐渐出现不连续的浅而封闭的小孔到互相贯穿的开孔,水凝胶相变响应速率在一定范围内逐渐提高,具有快速响应特性。

N-异丙基丙烯酰胺与N-异丙基甲基丙烯酰胺的酸催化合成改进

用Ｎ异丙基丙烯酰胺（ＮＩＰＡＭ）与Ｎ异丙基甲基丙烯酰胺（ＮＩＰＭＡＭ）单体可合成温度敏感型高分子材料。作为单体的合成方法，首先把浓硫酸与异丙醇混合，而后加入丙烯腈（或甲基丙烯腈），经催化反应后，反应液用乙醚萃取、正己烷重结晶，可得相应的氮取代丙烯酰胺。报告了在常温、常压下，在浓硫酸催化下，丙烯腈与异丙醇的摩尔比为１∶１时，Ｎ异丙基丙烯酰胺与Ｎ异丙基甲基丙烯酰胺的产率为６０％～７０％。分别测定了它们的红外光谱与核磁共振谱，发现与对应样品的标准图谱基本一致。通过改变萃取剂，用乙醚替代一般方法使用的二甲苯，可使萃取物易于从萃取剂中分离出来。乙醚可重复使用，每个操作周期乙醚损失约１０％。

温度敏感型材料聚(N-异丙基丙烯酰胺)壳聚糖的制备与表征

以天然聚合物壳聚糖为原料,在其2-NH2上引入具有温度敏感的基团聚(N-异丙基丙烯酰胺),制得了新型的N-取代聚(N-异丙基丙烯酰胺)壳聚糖。通过FT-IR1、3C-NM R1、H-NM R对其结构进行表征;用粉末X射线衍射、差示扫描量热法对其物理性质进行了分析。

羟丙基壳聚糖的制备与表征

本文用环氧丙烷对壳聚糖进行了化学改性。结果表明:在壳聚糖、氢氧化钠和异丙醇重量比为1:1:16,反应温度30℃,反应时间4 h时,其产物有良好的水溶性,并用IR对产物进行了结构表征,其反应主要发生在-NH_2基团上。

水中硝酸盐氮的麝香草酚分光光度测定法

目的建立水中硝酸盐氮(NO3-)的快速测定方法。方法在浓硫酸存在下,麝香草酚与水中硝酸盐反应生成硝基化合物,加入氨基磺酸铵和硫酸银消除干扰后,滴加氨水使溶液呈碱性,硝基化合物在此碱性溶液中发生分子重排,产生黄色化合物,在波长415nm比色定量。结果NO3-浓度在0～15.0mg/L范围内与吸光度呈良好的直线关系,r=0.9998,最低检测质量浓度为0.25mg/L,回收率为96%～108%,RSD为1.6%～4.0%。该法与紫外分光光度法测定结果差异无统计学意义(P>0.05)。结论该方法操作简捷、灵敏、快速、准确。适用于水中NO3-的测定。