The rGO/BiOBr/Bi4O5Br2 Composites with Stacked Nanosheets for Ciprofloxacin Photodegradation under Visible Light Irradiation

The rGO/BiOBr/Bi₄O₅Br₂ nanocomposite powders with stacked nanosheets were fabricated by one‐step solvothermal method. The components, morphologies, optical properties and the separate of photo‐induced carriers were explored by XRD, FT‐IR, SEM, TEM, UV/Vis DRS and PL experiments. The results manifest that the reduced graphene oxide (rGO) plays a vital part in transmitting and evacuating electrons, which promotes the separate efficiency of photo‐induced carriers and enhances the photodegradation efficiency of ciprofloxacin. The influences of synthesis conditions were also explored, which cover rGO content, solvent thermal reaction pH, temperature and time. In addition, a feasible photocatalytic mechanism over ciprofloxacin photodegradation under visible light irradiation was proposed.     

Mg-Al LDH的制备及Mg-Al LDH/H2O2体系降解水中环丙沙星的研究

分别以MgO和Al(OH)3为镁源及铝源,采用水热法制备Mg-Al LDH,研究了水热温度和氢氧化钠浓度对水热产物纯度的影响。结果显示在NaOH/MgO/Al(OH)3/(Na₂CO₃)摩尔比为2∶1∶0.5∶0.25,水热反应温度在120~150℃,反应12 h,可以得到纯相Mg-Al LDH。进一步以所制备的Mg-Al LDH为吸附剂,H₂O₂为氧化剂。系统研究了Mg-Al LDH/H₂O₂体系溶液pH、H₂O₂用量、污染物浓度、反应温度、反应时间等因素对Mg-Al LDH/H₂O₂体系降解水体中环丙沙星效果的影响。当Mg-Al LDH用量为0.05 g,H₂O₂用量为2 mL,系统pH为6.98,反应温度为35℃,环丙沙星浓度为30 mg·L^-1时,反应13 min环丙沙星的降解率可达97%。随着反应温度的升高,反应速率及平衡时降解率均有所提高,该过程可以用拟一级动力学方程描述,反应的表观活化能E a为19.29 kJ·mol^-1,指前因子A为0.38×10³ min^-1。Mg-Al LDHs/H₂O₂体系降解环丙沙星过程受反应速率控制,而非受传质控制。     

Disposable Pencil Graphite Electrode for Ciprofloxacin Determination in Pharmaceutical Formulations by Square Wave Voltammetry

In this work, a new electrochemical sensor based on pencil graphite with interesting features, such as low cost (US$ 0.01 per electrode), ease manufacture, and portability was developed. The sensor showed an adequate manufacturing reproducibility with RSD <5.3 %. Under this electrochemical platform, ciprofloxacin underwent an irreversible oxidation process at 1.03 V, characterized by the diffusion of electroactive species. A simple method by square wave voltammetry (SWV) has been optimized for the determination of ciprofloxacin in pharmaceutical formulations using a pencil graphite electrode (PGE). The method showed satisfactory analytical performance, with a wide linear range (12 to 55 μmol L⁻¹), low detection limit (5.6 μmol L⁻¹), adequate precision (RSD <3.2 %), and accuracy with an average recovery of (102±15)%. Samples of pharmaceutical formulations were evaluated, obtaining levels of ciprofloxacin close to those established by the manufacturers. In addition, the samples were analyzed by liquid chromatography and there was no significant difference between the methods at the 95 % confidence level. In this sense, the method developed proved to be reliable and promising for the quality control of pharmaceutical formulations.     

Synthesis and investigation of binding interactions of 1,4-benzoxazine derivatives on topoisomerase IV in Acinetobacter baumannii$

Abstract

Acinetobacter baumannii has emerged as an important pathogen for nosocomial infections having high morbidity and mortality. This pathogen is notorious for antimicrobial resistance to many common antimicrobial agents including fluoroquinolones, which have both intrinsic and acquired resistance mechanisms. Fluoroquinolones targeting the bacterial topoisomerase II (DNA gyrase and Topo IV) show potent broad-spectrum antibacterial activity by the stabilization of the covalent enzyme–DNA complex. However, their efficacy is now being threatened by an increasing prevalence of resistance. Fluoroquinolones cause stepwise mutations in DNA gyrase and Topo IV, having alterations of their binding sites. Furthermore, the water–Mg⁺² bridge, which provides enzyme–fluoroquinolone interactions, has a significant role in resistance. In this study, 13 compounds were synthesized as 1,4-benzoxazine derivatives which act as bacterial topoisomerase II inhibitors and their antibacterial activities were determined against multi-drug resistant Acinetobacter strains which have ciprofloxacin (CIP) resistant and GyrA mutation. Afterwards we performed docking studies with Topo IV (pdb:2XKK) of these compounds to comprehend their binding properties in Discovery Studio 3.5. The results of this study show significant conclusions to elucidate the resistance mechanism and lead to the design of new antibacterial agents as bacterial topoisomerase II inhibitors.     

鉴别直肠组织癌变的环丙沙星铽络合物荧光染色新方法

用具有较强荧光性能的环丙沙星铽配合物对多例直肠正常和直肠癌组织切片进行了染色研究,并与传统的HE染色结果进行了对比。结果表明用环丙沙星铽配合物染色后的效果与HE染色具有相同的图像和光学反差。并同时通过测定直肠正常和直肠癌组织的荧光光谱和红外光谱得到的组织病变判据,其结论与染色结果相一致。     

环丙沙星铽荧光配合物与DNA的相互作用及染色新方法

合成了环丙沙星铽荧光配合物,并研究其与DNA分子的相互作用.对比DNA分子吸附配合物分子前后的显微红外及荧光光谱发现,以环丙沙星分子为配体的稀土配合物同DNA间存在相互作用,这种作用诱导了DNA二级结构的构象变化.基于这种相互作用,研究了环丙沙星铽配合物对口腔粘膜组织切片的荧光染色,得到了同经典的苏木精-伊红染色法类似的反差效果.     

环丙沙星与氨茶碱作用的拉曼光谱研究

利用密度泛函理论(density function theory,DFT)的B3LYP/6-31G(d,p)基组计算环丙沙星(ciprofloxacin,CIP)的拉曼峰,与实验拉曼峰相比,吻合度较高。并对其拉曼峰进行了全面的归属。环丙沙星溶液的表面增强拉曼光谱(surface enhanced Raman spectroscopy,SERS)与常规拉曼实验结果显示,以金纳米粒子为基底,对环丙沙星的拉曼峰有较好的增强效果。探究了结合时间对氨茶碱与环丙沙星混合物的影响,结果表明随着时间的延迟,两者之间的作用力加强,环丙沙星的部分拉曼峰消失。氨茶碱的加入,影响了环丙沙星的分子结构,使得环丙沙星拉曼信号减弱,多处拉曼峰发生改变,主要是1184 cm-1处的吡嗪环、1252 cm-1的C—F、1627 cm-1处的C C以及1458 cm-1处O—C—O的振动频率发生了变化;氨茶碱含量的增加,对环丙沙星结构的影响更为严重,其中800~1200 cm-1处的拉曼峰消失,当氨茶碱的量超过22.5 mg·L-1时,除1384 cm-1处有微弱信号出现外,几乎无其他峰出现。表面增强拉曼光谱作为一种常用的分析工具,具有分析时间短,灵敏度高等优点。实验利用SERS技术,考察氨茶碱与环丙沙星之间的相互作用,为其药理研究提供了参考。     

超高效液相色谱法测定水产品中3种喹诺酮类药物残留量

提出了应用超高效液相色谱法测定水产品中诺氟沙星、环丙沙星和恩诺沙星等3种喹诺酮类药物残留量的方法。样品采用酸化乙腈提取,减压蒸干后用流动相溶解,经正己烷脱脂。以ACQUITY UPLCTMBEH C18色谱柱为分离柱,以乙腈与甲酸(0.1+99.9)溶液按体积比10比90混合作为流动相,在激发波长280nm、发射波长450nm的条件下进行荧光光度检测。3种药物的线性范围均为1.25～500μg.L-1,检出限(3S/N)均为0.1μg.kg-1,测定下限(10S/N)均为0.3μg.kg-1。以鲳鱼、对虾、河蟹等空白样品为基体做加标回收试验,测得回收率均大于80%。     

Enzymatic rotating biosensor for ciprofloxacin determination

The high sensitivity that can be attained using an enzymatic system and mediated by catechol has been verified by on-line interfacing of a rotating biosensor and continuous flow/stopped-flow/continuous-flow processing. Horseradish peroxidase, HRP [EC 1.11.1.7], immobilized on a rotating disk, in the presence of hydrogen peroxide, catalyzed the oxidation of catechol, whose back electrochemical reduction was detected on a glassy carbon electrode surface at −200 mV. Thus, when ciprofloxacin (CF) was added to the solution, this piperazine-containing compound participate in Michael addition reactions with catechol to form the corresponding piperazine-quinone derivatives, decreasing the peak current obtained, in proportion with the increase of its concentration. The highest response for CF was obtained around pH 7. This method could be used to determine CF concentration in the range of 0.02-65 μM (r = 0.999). The determination of CF concentration was possible with a detection limit of 0.4 nM, in the processing of as many as 25 samples per hour. Application of this analysis to different pharmaceutical samples containing CF supports the utility of the HRP-rotating biosensor.     

HPLC determination of ciprofloxacin, cloxacillin, and ibuprofen drugs in human urine samples

This paper reports, for the first time, a liquid chromatographic method for the simultaneous determination of three frequently co-administered active principles, two antibiotics, ciprofloxacin (CIPRO) and cloxacillin (CLOXA) belonging to the fluoroquinolones and beta-lactam families, respectively, and ibuprofen (IBU), a non-steroidal anti-inflammatory drug. The chromatographic separation was performed on a C-18 analytical column, using isocratic elution with methanol-acetonitrile-pH 3 formate buffer (CT = 0.1 M) (15:12:73, v/v/v) for 3 min and, after that, a linear gradient with methanol-acetonitrile (88:12, v/v) for 8 min. Several absorption spectra were obtained for each peak using a DAD detector. Chromatograms at the maximum absorption wavelength for each analyte, 220 nm for both IBU and CLOXA, and 280 nm for CIPRO were selected as the most suitable. The proposed chromatographic method requires about 15 min per sample. The presence of a urine background was tested and no interference was found. The method was satisfactorily applied to the determination of CIPRO, CLOXA, and IBU, in fortified urine, and in urine samples from a patient undergoing treatment with these three active principles, among others. Limits of quantification in urine were 1.00, 1.70, and 2.87 microg/mL for CIPRO, CLOXA, and IBU, respectively.