钙钛矿型A位掺杂复合氧化物La1-xSrxCoO3-6的光催化活性研究

用柠檬酸溶胶-凝胶法制备了钙钛矿型La1-xSrxCoO3-6复合氧化物，用XRD、XPS、EDS、红外、紫外等技术进行了表征，测定了其对活性艳红等水溶性染料光催化脱色的活性．结果表明：在A位掺Sr^2＋，由于产生较多氧空位，表面非晶格活性氧量增加，使LaCoO3的光催化活性明显提高，其中La1-xSrxCoO3-6效果最佳．     

荧光/MRI双模态靶向成像诊疗试剂的制备

在聚乙二醇二胺(NH_2-PEG-NH_2)修饰的石墨烯量子点(GODs)表面以酰胺键偶联二乙基三胺五乙酸(DTPA)分子,之后将Gd~(3+)离子与其进行配合,得到了GODs-Gd(DTPA)复合纳米粒子,然后再通过酰胺键在GODs-Gd(DTPA)的表面修饰叶酸(FA)靶分子,最后进一步将阿霉素(DOX)通过π-π堆垛吸附在造影剂的表面,制备了FA/GODs-Gd(DTPA)/DOX荧光/MRI双模态靶向肺癌细胞成像诊疗试剂,通过透射电子显微镜、紫外可见吸收光谱、荧光光谱和激光共聚焦扫描显微镜等手段表征了其形貌、发光性能和靶向成像性能。MRI、激光共聚焦扫描显微镜和MTT等结果表明,相对于正常的HLF细胞,所制备的FA/GODs-Gd(DTPA)/DOX纳米粒子能够靶向检测FA受体高表达的肺癌H460细胞,并具有明显的抗肿瘤活性。     

镧系金属-有机框架免修饰荧光各向异性探针检测磷酸根离子

荧光各向异性(FA)分析法具有免分离、高通量和实时检测等优势,广泛应用于诸多领域。然而,当分析物的体积或质量较小时,与荧光探针结合后不能产生明显的信号变化,导致灵敏度较低。为解决此问题,研究者通常采用纳米材料增强发光体的质量或体积的方式放大FA来提升检测灵敏度。然而,这些方法也存在纳米材料易猝灭荧光而降低准确度以及荧光探针修饰步骤复杂等弊端,因此,有必要开发不需要放大体积和质量且免修饰的新型FA探针。发光金属-有机框架作为一种新兴的发光纳米材料,由于其自身具有较大的体积和质量以及较高的FA值(r),无需额外的信号放大,是作为FA探针的理想材料。本研究通过微波辅助法成功合成了以铈离子(Ce³⁺)为中心离子、5,10,15,20-四(4-羧基苯基)卟啉(H2TCPP)为配体的镧系金属-有机框架(Ce-TCPP MOF),并将其作为一种新型的免修饰FA探针用于检测磷酸根离子(Pi)。未加入Pi时,Ce-TCPP MOF具有较大的r;加入Pi后,MOF中的Ce³⁺与Pi发生反应,破坏了MOF的结构,产生质量或体积更小的碎片,使r降低。随着Pi浓度增加...     

老翘中三种苯乙醇苷类化合物生物活性比较

比较老翘中三种苯乙醇苷类化合物:连翘酯苷A(FA)、R,S-株木苷(SS)和株木苷甲基醚(SSM)的体外生物活性,为研究老翘中的活性成分提供依据.通过检测1,1-二苯基-2-苦肼基(DPPH·)清除率,考察三种成分的抗氧化活性;利用二倍稀释法测定三种成分对金黄色葡萄球菌以及大肠杆菌的最小抑菌浓度(MIC),比较抑菌活性...     

TiO2纳米粒子包覆聚苯乙烯球的结晶性能与表面光电压特性

TiO2具有很高的光催化活性，同时TiO2纳米粒子具有耐酸碱和耐光化学腐蚀、低成本、无毒等性质，在许多领域引起广泛关注．据报道，TiO2的锐钛矿晶型比金红石晶型具有更好的光催化活性．由于金红石是TiO2的热力学稳定相，而锐钛矿是亚稳相，通常锐钛矿相在550-800℃温度范围内形成金红石相，从而降低其催化活性，限制了其应用．     

钙钛矿型A位掺杂复合氧化物La1-xSrxCoO3-δ的光催化活性研究

用柠檬酸溶胶-凝胶法制备了钙钛矿型La1-xSrxCoO3-δ复合氧化物,用XRD、XPS、EDS、红外、紫外等技术进行了表征,测定了其对活性艳红等水溶性染料光催化脱色的活性.结果表明:在A位掺Sr2+,由于产生较多氧空位,表面非晶格活性氧量增加,使LaCoO3的光催化活性明显提高,其中Ia0.9Sr0.1CoO3-δ效果最佳.     

一种荧光增强型甲醛荧光探针的合成及其性能研究

甲醛(FA)对环境和人们的身体健康息息相关,例如曝露在环境中的FA被人体吸收后,轻则会引起头痛、喉咙发炎等不适,重则会损害人体重要器官进而引发诸如白血病、阿尔兹海默症等疾病.针对环境中FA的快速检测,开发了一个荧光增强性的FA探针HSU-FA.该探针选用萘酰亚胺染料作为荧光平台,以肼基基团作为识别FA的位点,通过肼基基团与羰基缩合成腙的反应达到识别FA的效果.通过测试条件优化得出,在乙酸含量为30%测试条件下探针HSU-FA对FA的识别效果最佳.通过紫外-可见吸收光谱可知,在FA的作用下探针的吸收光谱发生显著增强现象.通过荧光光谱测试得出,该探针对FA具有突出的识别能力和响应速度.此外,该探针具有较强的抗光漂白能力,能够在溶液状态下稳定存在.在溶液中该探针与FA相互作用可以展示出不同的荧光强度,显示出了较强的浓度依赖性.更重要的是,利用无纺布制备的FA检测卡实现了环境中FA的快速检测.     

多光谱法和分子对接模拟法研究黄腐酸与胃蛋白酶的相互作用

利用荧光光谱、 同步荧光光谱、 三维荧光光谱、 紫外-可见吸收光谱、 傅里叶变换红外光谱和圆二色光谱以及分子对接模拟方法研究了黄腐酸(FA)与胃蛋白酶(PEP)之间的相互作用. 荧光光谱分析表明, FA-PEP荧光猝灭的类型为静态猝灭. 根据Stern-Volmer方程和静态猝灭双对数公式计算得到猝灭常数K_sv和结合位点数n. 根据Vant’t Hoff方程计算得到热力学常数ΔH=-59.86 kJ/mol, ΔS=-98.13 J·mol ^-1·K ^-1, ΔG=-30.62 kJ/mol(298 K). 热力学分析表明, 氢键和范德华力是PEP与FA之间的主要结合力, 其反应为自发过程. 根据F?rster非辐射能量转移理论, 计算得到PEP和FA之间的结合距离为2.436 nm, 表明在FA与PEP之间发生了非辐射能量转移. 三维荧光光谱分析表明, 在FA存在下PEP的肽链骨架结构发生了改变. 此外, 紫外-可见吸收光谱、 同步荧光光谱和红外光谱结果表明, FA使PEP的二级构象发生变化. 分子对接模拟结果表明, FA引起PEP荧光猝灭的结合作用力不仅有氢键和范德华力, 还有疏水作用力.     

离子液体萃取阿魏酸和咖啡酸的性能研究

以1-甲基-3-丁基咪唑六氟磷酸盐([C4mim][PF6])和1-甲基-3-己基咪唑六氟磷酸盐([C6mim][PF6])离子液体为萃取剂,采用紫外分光光度法研究了溶液pH值、温度、相比率及盐的种类和浓度对其萃取阿魏酸和咖啡酸效率的影响,考察了被萃取物的回收及离子液体的循环使用,探讨了两种离子液体替代传统有机溶剂阿魏酸和咖啡酸的可能性。实验结果表明:萃取温度和无机盐的种类及浓度对FA和CA萃取效率的影响较小;水相pH值对萃取效率有较大的影响,萃取FA适宜pH应小于3.67,萃取CA适宜pH应小于3.71;被萃取物浓度增大,萃取效率降低,而相体积比增大其萃取效率升高;两种离子液体对FA和CA的萃取效率[C4mim][PF6]大于[C6mim][PF6],同种离子液体对FA的萃取效率大于CA;在萃取相中的FA和CA可定量回收,且被萃取物中离子液体的残留[C6mim][PF6]小于[C4mim][PF6],离子液体可循环使用。     

青海翠雀化学成分的研究

用柱层析、制备薄层层析等对青海翠雀的化学成份进行了分离，并用IR，FA， MS，1HNMR，13C NMR及DEPT等光谱确定了化合物的结构，共分得5种二萜生物碱， 其中一种为新化合物，还分得一种非生物碱β-谷甾醇．     

Surface functionalization of two-photon dye-doped mesoporous silica nanoparticles with folic acid: cytotoxicity studies with HeLa and MCF-7 cancer cells

Two-photon dye-doped mesoporous silica nanoparticles (NPs) have been conjugated with folic acid (FA) in order to obtain efficient nanotools for bioimaging of cancer cells. The surface of the NPs was first functionalized with 3-aminopropyltriethoxysilane. The amine-covered NPs were subsequently reacted with an activated ester derivative of FA. Cytotoxicity studies performed with MCF7 and HeLa cancer cells demonstrate that these functionalized NPs are much less cytotoxic than the non-functionalized NPs against both cell lines. Unfortunately, the grafting of FA enables the formation of charge transfer complexes between the two-photon dye and FA which leads to quenching of the fluorescence of the NPs. Hence although these NPs cannot be used for biomaging purposes, they offer interesting potentialities if the two-photon dye used can be replaced by a two-photon fluorophore which do not interact with FA or if the interaction between the encapsulated dye and FA can be prevented by using a suitable spacer between the surface and the FA moiety.     

Synthesis and Characterization of Amino Acid Modified Chitooligosaccharides

Amino acid modified chitooligosaccharides were synthesized by the new synthetic route. The chloroacetyl-chitooliogosaccharide intermediates were prepared under a mild condition via a reaction between chitooligosaccharide (COS) and chloroacetic anhydride. The intermediates were subsequently reacted with a variety of amino acids, e.g., glycine, aspartic acid, alanine, arginine, and serine, under a basic condition, yielding amino acid modified COS products. The degree of chloroacetylation was calculated based on new ¹H NMR absorption peaks at 3.80 and 3.94 ppm, corresponding to  NH CO CH₂ Cl and  O CO CH₂ Cl, respectively. The degrees of chloroacetylation determined were 0.40, 0.44, 0.62, and 0.93 when the mole ratios of chloroacetic anhydride to COS were 0.5, 1, 2, and 4, respectively. The chemical structures of the COS derivatives were also determined using ¹H NMR spectroscopy. The biological properties of the derivatives were evaluated. Cytotoxicity of the derivatives was assessed by a direct contact, using L929 cells. An MTT assay was a method of choice to evaluate the efficacy of the derivatives to enhance the proliferation of L929 cells.     

Direct characterization of iodine covalently bound to fulvic acids by electrospray mass spectrometry.

Numerous studies have demonstrated that humic substances (HS) react with iodine to form iodo derivatives and thereby can control the bioavailability of radioisotopes. Unfortunately, none of these studies have provided detailed insights into product compounds and so far, to our knowledge, the direct analysis of these species by electrospray ionization (ESI) mass spectrometry has not been explored. The reactivity of iodine with fulvic acids (FA) present in HS was investigated by means of ESI coupled with a quadrupole time-of-flight (Q-TOF) mass spectrometer. ESI spectra of solutions, that were indicated by MS/MS analysis to have formed iodinated species, apparently displayed singly charged ions corresponding in m/z to hypothesized species, viz., [RI - H](-), R = (substituted FA compound). MS/MS analysis based on the diagnostic fragment ions for FA compounds and their iodo derivatives suggests that FA undergo aromatic substitutions. Furthermore, significant differences in mass profiles are observed that presumably result from extended redox reactions. The ESI-MS technique opens up new opportunities to understand the scavenging properties of HS towards radionuclides and heavy metals for environmental studies.     

In vitro cytotoxic evaluation of a novel phosphinyl derivative of boldine

2,9-Dimethoxymethylboldine (2), 2,9-dimethoxymethyl-3-bromoboldine (3) and 2,9-dimethoxymethyl-3-diphenylphosphinylboldine (4) have been synthesized in an effort to find compounds with potential pharmacological applications. The cytotoxic activities of the natural precursor 1 and these three derivatives have been measured as IC?? inhibitory growth. The diphenylphosphinyl derivative 4 showed a significant cytotoxic activity on two breast cancer cell lines, namely MCF-7 and MDA-MB-231, with IC?? values of 55.5 and 62.7 [μM], respectively. These results suggest that the kind of structural modifications introduced to synthesize compound 4 represent a promising way to enhance the cytotoxic activity of boldine derivatives.     

Folate-equipped pegylated archaeal lipid derivatives: synthesis and transfection properties

We have previously shown that synthetic archaeal lipid analogues are useful vectors for drug/gene delivery. We report herein the synthesis and gene transfer properties of a series of novel di- and tetraether-type archaeal derivatives with a poly(ethylene glycol) (PEG) chain and further equipped with a folic acid (FA) group. The synthetic strategy and the purification by dialysis ensured complete removal of free FA. The lipids were mixed with a conventional glycine betaine-based cationic lipid and the resulting formulations were tested in transfection assays after complexation with plasmid DNA. All four novel co-lipids afforded efficient in vitro gene transfection. Moreover, the FA-equipped derivatives permitted ligand/receptor-based targeted transfection; their activity was inhibited when free FA was added to the transfection medium. These novel archaeal derivatives equipped with FA-PEG moieties may thus be of great interest for targeted in vivo transfection.     

Detection of oxidative stress. Interest of GC-MS for malondialdehyde and formaldehyde monitoring

Ischemia-reperfusion syndrome is a condition where the role of oxygen free radicals is important. Malondialdehyde (MDA) and formaldehyde (FA), products of lipid peroxidation, are the presumptive markers for the development of oxidative stress in tissues and plasmas. A GC-MS method for the determination of MDA and FA in rat brain extract is described. Rat brains were homogenized with deionized water. The homogenates were derivatized with 2,4-dinitrophenylhydrazone (DNPH) to obtain hydrazines derivatives of MDA and FA. The hydrazine derivatives were analyzed by GC-MS and quantitation was by single ion monitoring (SIM). The retention times of FA and MDA were, respectively, 13.75 and 14.20 min, and for SIM quantitation, ion at m/z 210 for FA, and m/z 158 for MDA were used. The results showed that it is possible to estimate the products of lipid peroxidation in brain and to monitor the oxidative stress developed during the ischemia-reperfusion syndrome compared to the normal values.     

Synthesis and cytotoxicity of phenyl-vinyl derivatives of 4,6,6-trimethyl-2-oxo-1,2,5,6-tetrahydropyridine-3-carbonitrile

A series of phenylvinyl derivatives of 4,6,6-trimethyl-2-oxo-1,2,5,6-tetrahydropyridine-3-carbonitriles has been synthesized and their cytotoxic activity towards HT-1080 (human fibrosarcoma) and MG 22A (mouse hepatoma) tumor cells studied. It was found that the 2-nitro-, 2- and 3-chloro, 2-fluoro, and 2-bromophenyl derivatives showed high cytotoxic activity towards both cell lines. The toxicity towards NIH 3T3 normal mouse embryonic fibroblasts depends on the nature and position of the substituent in the phenyl ring. The greatest selectivity of cytotoxic effect was seen in the 2-bromophenyl derivative.     

Development of a Novel Covalent Folate‐Albumin‐Photosensitizer Conjugate

There is considerable interest in the development of novel and more efficient delivery systems for improving the efficacy of photodynamic therapy (PDT). The authors in this highlighted issue describe the synthesis and the photobiological characterizations of two photosensitizer (PS) conjugates based on β‐carboline derivatives covalently conjugated to folic acid (FA) coupled to bovine serum albumin (BSA) as a carrier system specifically targeting cancer cells overexpressing FA receptor alpha (FRα). Accordingly, only the FA–BSA–β‐carboline conjugates are internalized specifically in FRα‐positive cells and are proved to be phototoxic. On the other hand, albumin–β‐carboline conjugates without FA or β‐carboline derivatives alone are not internalized and nontoxic. This conjugate is among the first to produce a conjugate composed of a PS and FA molecules that are directly conjugated to BSA. In addition, the in vitro studies are the first evidence that directly conjugated FA‐BSA can be used as carriers to selectively enhance cytotoxicity by PDT relative to unmodified PS or nontargeted BSA‐PS. This strategy is a positive step forward for the covalent design and construction of a photodynamic nanomedicine for FR‐positive tumors.     

Biotransformation of Rice Bran to Ferulic Acid by Pediococcal Isolates

Ferulic acid (FA) is widely used in foods, in beverages, and in various pharmaceutical industries as a precursor of vanillin. FA biotransformation can occur during the growth of lactic acid bacteria (LAB), and its conversion to other phenolic derivatives is observed by many scientists, where ferulic acid esterase (FAE) and ferulic acid decarboxylase (FDC) play significant roles. The present study aimed at screening a panel of LAB for their ability to release FA from rice bran, an agro waste material. FAE and FDC activities were analyzed for the preliminary screening of various dairy isolates. Two Pediococcus acidilactici isolates were selected for studying further the hydrolysis of FA from rice bran and its bioconversion into phenolic derivatives like 4-ethylphenol, vanillin, vanillic acid, and vanillyl alcohol. P. acidilactici M16, a probiotic isolate, has great potential for the production of FA from rice bran and could be exploited as starter culture in the food industry for the production of biovanillin.     

The capture of carbonyl sulfide by N-methyldiethanolamine: A systematic density functional theory investigation

In this contribution, the mechanism of carbonyl sulfide (COS) absorption by N-methyldiethanolamine (MDEA) aqueous solution was explored via theoretical computations. Detailed reaction mechanisms were analyzed using density functional theory (DFT) calculations at the B3LYP-D3 level of theory. In total, four different pathways for COS absorption by MDEA have been considered. The most favorable pathway for the removal of COS is a three-step mechanism including the hydrolysis, proton transfer, and dissociation of CO₂, and hydrolysis is the rate-determining step. The mechanisms of the COS absorption by different amines were investigated, and the calculated results suggest that the total energy barrier for the COS absorption by MDEA is comparable to that by monoethanolamine (MEA), diethanolamine (DEA), and diisopropylamine (DIPA), indicating the COS absorption by all the four amines are feasible, while MDEA gives a better performance in terms of thermodynamics.