Carbon Quantum Dots Co‐catalyzed with ZnO Nanoflowers and Poly (CTAB) Nanosensor for Simultaneous Sensitive Detection of Paracetamol and Ciprofloxacin in Biological Samples

A novel platform based incorporation of carbon quantum dots (CQDs) and zinc oxide nanoflowers (ZnO‐NFs) decorated with poly cetyltrimethylammonium bromide (CTAB) was developed as electrochemical sensor for the sensitive and selective simultaneous detection of Paracetamol (PAR) and Ciprofloxacin (CIP) in biological samples. For this, CQDs and ZnO‐NFs were first deposited on a glassy carbon electrode (GCE) and subsequently a Poly (CTAB) layer was grown onto their surfaces through electro‐polymerization. The synthesized nanostructures and the corresponding fabricated sensor were characterized by the techniques of TEM, XRD, FE‐SEM, and EDX analysis. Moreover electrochemical characterization by CV and DPV were performed to elucidate the construction process and electron transfer abilities of the CQDs/ZnO‐NFs/Poly(CTAB)/GCE. Increased sensitivity and efficiency of this sensing system was obtained due to the synergistic effects of CQDs, ZnO‐NFs and Poly (CTAB) with multi‐signal amplification. Under the optimum conditions, the DPV response of proposed sensor to PAR and CIP was linear at 0.05–30.0 μM and 0.01–30.0 μM, with the detection limit of 2.47 nM and 1.97 nM respectively. The sensor possessed high stability, reproducibility, sensitivity, and selectivity toward PAR and CIP detection, over potential interferents and presented high recovery percentage in the real sample matrices.     

Solid-phase UV spectrophotometric method for determination of ciprofloxacin

A simple and inexpensive method for the determination of ciprofloxacin has been developed using solid-phase spectrophotometry. The intrinsic absorbance of ciprofloxacin fixed on a dextran-type cation-exchange resin, Sephadex SP C-25, was measured directly at 277 and 380 nm after packing the gel beads in a 1-mm cell. Using a sample volume of 10 ml, the calibration graph was linear over the range 0.05-0.3 μg ml⁻¹ with a R.S.D. of 1.11% (n=8). The sensitivity obtained is 40 times higher than that of the corresponding solution method. The method was applied to the determination of ciprofloxacin in pharmaceutical preparations and was validated by standard addition.     

Encapsulation of ciprofloxacin,sparfloxacin, and ofloxacin drugs with α- and β-cyclodextrins: spectral and molecular modelling studies

Inclusion complexation of ciprofloxacin (CIP), sparfloxacin (SPA), and ofloxacin (OFL) drugs with α-CD and β-CD was studied by UV-visible, fluorescence, time-resolved fluorescence, Fourier transform infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance (¹HNMR), scanning electron microscopy (SEM), and molecular modelling techniques. Changes in the absorbance and fluorescence intensities and fluorescence lifetime of the drugs in the cyclodextrin (CD) solutions suggest the formation of inclusion complexes. Carbonyl stretching frequency moved to higher wave numbers and broadening of the N–H stretching band indicated the formation of inclusion complex. Cyclohexane ring protons of the drugs show remarkable upfield or downfield shift in the ¹HNMR spectrum, indicating that the cyclohexane part of the guest molecule is entrapped inside CD cavities. SEM images of CIP/CD, SPA/CD, and OFL/CD complexes have a crystal structure with different morphology from the isolated CIP, SPA, OFL, and CDs. Investigations of the energetic, thermodynamic, and electronic properties of parametric model number 3 computational calculations confirmed the stability of the inclusion complex.     

Nanoemulsion drug delivery by ketene based polyester synthesized using electron rich carbon/silica composite surface

A new carrier matrix for nanoemulsion drug delivery was synthesized from glycine as the raw material, using mesoporous/microporous electron rich carbon-silica composite surface (MAC(800)). MAC(800) was prepared from rice husk in two-stage carbonization. The surface area, pore volume, and pore size distribution of MAC(800) were measured, using nitrogen adsorption isotherms at 77K. The unpaired electron density of MAC(800) was measured in electron spin resonance spectroscopy (ESR), using TEMPOL (4-hydroxy-2,2,6,6-tetramethyl piperidine-1-oxyl) as the reference spin probe. Glycine was converted into ketene at the surface of MAC(800), which further underwent radical polymerization to form a low molecular weight ketene polymer (LMKP) of ester structure. The structure and the properties of LMKP were confirmed through (13)C, (1)H and DEPT nuclear magnetic resonance (NMR) spectroscopy, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and size exclusion chromatography (SEC). The two hydrophilic drugs namely ciprofloxacin hydrochloride (CPH) and gentamicin sulphate (GS) were chosen for the nanoemulsion preparation and characterization. They were characterized for morphology, interaction of drugs with the polymer and their crystallinity, using HR-TEM, DSC and XRD, respectively. The encapsulation efficiency of the LMKP towards the drugs ciprofloxacin hydrochloride and gentamicin sulphate were 26% and 12%, respectively. The dissolution studies of the nanoemulsion were carried out for the pH 6.5, 7.4 and 8.0. The cytocompatibility studies were done for LMKP as well as nanoemulsion using Hep2 epithelial cells.     

Kinetic Spectrophotometric Analysis and Spectrofluorimetric Analysis of Ciprofloxacin Hydrochloride and Norfloxacin in Pharmaceutical Preparations Using 4‐Chloro‐7‐Nitrobenzo‐2‐Oxa‐1,3‐Diazole (NBD‐Cl)

Simple, reliable, sensitive and accurate kinetic spectrophotometric and spectrofluorimetric methods were proposed for the determination of ciprofloxacin hydrochloride (CPX) and norfloxacin (NRX) in pure form and in pharmaceuticals. The methods are based on coupling the studied drugs with 4‐chloro‐7‐nitrobenzo‐2‐oxa‐1,3‐diazole (NBD‐Cl) in the presence of alkaline borate buffer. Spectrophotometric measurement was achieved by recording the absorbance at 477 nm after a fixed time of 20 and 15 min on a water bath adjusted at 70 ± 1 °C for CPX and NRX, respectively. The same product exhibited emission peaks at 540 nm. The different experimental parameters affecting the development and stability of the color were carefully studied and optimized. The absorbance concentration plots were linear over the ranges 3‐18 and 2.5‐15.0 μg/mL for CPX and NRX, respectively, while the fluorescence concentration plots were linear over the ranges 0.06‐0.36 and 0.05‐0.30 μg/mL for CPX and NRX, respectively. The limit of detection of the kinetic method was about 0.2 μg/mL for both drugs while the fluorescence measurement enabled their detection at a concentration of about 0.012 μg/mL. The proposed methods were successfully applied for the assay of the two drugs in their commercial products. The results obtained were statistically compared with those obtained by reference HPLC and spectrophotometric methods. The stoichiometry of the reaction was determined and the reaction pathway was postulated.     

盐酸环丙沙星分子印迹电化学传感器

本文将电化学合成与分子印迹技术相结合,采用循环伏安法在石墨电极表面,形成盐酸环丙沙星(CPX)分子印迹聚吡咯薄膜,制备了CPX分子印迹传感器。实验对传感器的制备条件进行了优化,用铁氰化钾作为活性电子探针,采用方波伏安法研究了传感器性能。结果表明,在1×10~(-8)~1×10~(-4)mol/L范围内,峰电流与CPX浓度负对数呈良好的线性关系,检出限(S/N=3)为3.5×10~(-9)mol/L。传感器对模板分子CPX选择性强,重现性和稳定性好,置于室温下15d峰电流强度无明显变化。     

Comparative study on ciprofloxacin removal in sulfur-mediated biological systems

The removal of ciprofloxacin(CIP) in sulfur-mediated bio processes,e.g.,sulfate-reducing bacteria(SRB)-mediated process and sulfur-oxidizing bacteria(SOB)-mediated process,was examined for the first time.The results showed that the SRB-mediated process had more efficient CIP removal than that in SOB-mediated process.Adsorption was the primary removal pathway of CIP in SRB-mediated process and SOB-mediated process with the specific adsorption removal rate of 131.4±1.1 μg/g-SS/d and30.1±1.4 μg/g-SS/d,respectively,at influent CIP concentration of 500 μg/L.In addition,extracellular polymeric substances(EPS) also played an important role on CIP migration and removal in both types of sludge.Further study was conducted to specify the different adsorption of CIP in these two sludge systems from the perspective of sludge properties.The results indicated that there are more potential adsorption sites exist on the SRB-mediated sludge for CIP adsorption than SOB-mediated sludge since the higher protein(PN) content and more kinds of aromatic amino acid substances in EPS,more negative zeta-potential and stronger and more numbers of functional groups in SRB-mediated sludge compared to SOB-mediated sludge.The findings of this study provide insights into the sludge properties affecting CIP removal in sulfur-mediated bioprocesses,and are of guiding significance to employ sulfur-mediated biological systems for treating CIP-containing wastewaters.     

光谱法研究环丙沙星与牛血清白蛋白的相互作用

用荧光光谱法、紫外光谱法研究了生理条件下环丙沙星(CPFX)与牛血清白蛋白(BSA)相互作用的光谱特性。测定了CPFX与BSA在18、28℃两个温度下的结合常数KA(18℃:5.75×105L.mol-1,28℃:1.54×105L.mol-1)和结合位点数n(18℃:0.99,28℃:0.93)。结果表明:CPFX对BSA有明显的猝灭作用,其方式为静态猝灭。由热力学参数分析其结合力主要是氢键和范德华力。同步荧光分析的结果表明CPFX的存在改变了牛血清白蛋白的分子构象。     

分子印迹-后化学发光法测定盐酸环丙沙星

以α-甲基丙烯酸为功能单体、乙二醇二甲基丙烯酸酯为交联剂合成了盐酸环丙沙星分子印迹聚合物, 并制备了在线富集发光流通柱. 建立了环丙沙星-Ce(Ⅳ)-亚硫酸体系的分子印迹-化学发光分析法. 盐酸环丙沙星浓度在5×10-7～5×10-5 mol/L 范围内与发光强度呈线性关系, 方法的检出限为5.2×10-8 mol/L. 方法已用于尿与鲅鱼样品中环丙沙星的检测.     

Formation of Oxygen Vacancies on the {010} Facets of BiOCl and Visible Light Activity for Degradation of Ciprofloxacin

BiOCl nanosheets with oxygen vacancies on the exposed {010} facets were assistant-synthesized by triethanolamine(TEOA) via hydrothermal method. We explored the surface properties, crystal structure, morphology and optical absorption ability of the prepared samples via various characterization technologies. The results indicate that the morphologies and microstructures of the obtained samples depend on the amount of TEOA in the synthesis. The addition of TEOA induces the production of oxygen vacancy on the surface of the samples. Therefore, the synthesized samples with TEOA-assistance hold higher photoactivity for the degradation of colorless antibiotic agent ciprofloxacin(CIP) under visible light(λ ≥ 420 nm). The obtained sample upon the addition of 20 mL of TEOA exhibits the highest photocatalytic performance, which is nearly 14 times as high as that of the sample prepared without TEOA and twice as high as that of the prepared samples with NaOH or NH₃·H₂O. The possible degradation mechanism was discussed on the basis of the experiment results.