An emphatic orthogonal signal correction-support vector machine method for the classification of tissue sections of endometrial carcinoma by near infrared spectroscopy

A sequential injection analysis (SIA) spectrophotometric method for determining tetracycline (TC), chlortetracycline (CTC) and oxytetracycline (OTC) in different sample matrices were described. The method was based on the reaction between tetracyclines and yttrium (III) in weak basic micellar medium, yielding the light yellow complexes, which were monitored at 390, 392 and 395 nm, respectively. A cationic surfactant, cetyltrimethylammonium bromide (CTAB) was used to obtain the micellar system. The linear ranges of calibration graphs were between 1.0 × 10⁻⁵ and 4 × 10⁻⁴ mol L⁻¹, respectively. The molar absorptivities were 5.24 × 10⁵, 4.98 × 10⁴ and 4.78 × 10⁴ L mol⁻¹ cm⁻¹. The detection limits (3σ) were between 4.9 × 10⁻⁶ and 7.8 × 10⁻⁶ mol L⁻¹ whereas the limit of quantitations (10σ) were between 1.63 × 10⁻⁵ and 2.60 × 10⁻⁵ mol L⁻¹ the interday and intraday precisions within a weak revealed as the relative standard deviations (R.S.D., n = 11) were less than 4%. The method was rapid with a sampling rate of over 60 samples h⁻¹ for the three drugs. The proposed method has been satisfactorily applied for the determination of tetracycline and its derivatives in pharmaceutical preparations together with their residues in milk and honey samples collected in Chiang Mai Province. The accuracy was found to be high as the Student's t-values were found to be less than the theoretical ones. The results were compared favorably with those obtained by the conventional spectrophotometric method.     

多孔双金属氧化物/碳复合光催化剂对四环素的高效光催化降解

本工作以金属有机框架材料UiO-67为载体,通过原位水解负载TiO_2,经焙烧后得到系列ZrxTi/C光催化剂。我们以四环素为典型抗生素在300 W氙灯光源下进行光降解研究,Zr_(0.3)Ti/C复合催化剂表现出优异的光催化效率,对于10 mg×L~(-1)四环素溶液,30 min可以降解98%。光降解速率常数分别是TiO_2、纯Ui O-67焙烧产物Zr-O-C的16倍和3.7倍。这得益于Zr_(0.3)Ti/C较大的比表面积,对四环素具有优异的吸附性能;同时具有能级匹配的Zr-O-C/TiO_2异质结构和高导电性碳材料共掺,有效提高了电子-空穴对的分离与迁移;机理研究表明光照下产生的超氧自由基(O_2·-)、羟基自由基(·OH)以及少量的空穴(h~+),共同促进了光催化降解四环素。本研究基于吸附和光催化协同作用原理,所提出的高比表面积、双金属活性的复合光催化材料的制备方法,对抗生素等环境污染物光降解治理方面有一定的指导作用。     

Inner filter effect (IFE) as a simple and selective sensing platform for detection of tetracycline using milk-based nitrogen-doped carbon nanodots as fluorescence probe

A simple, selective, and sensitive turn-off fluorescent assay for detecting of tetracycline in pharmaceutical dosage form based on inner filter effect (IFE) sensing platform has been described. In this IFE sensing strategy, N-doped carbon dots (CDs) were prepared by one-pot solvothermal synthesis using milk as a precursor and were directly used as a fluorophore in IFE. The prepared CDs were characterized by common spectroscopic and microscopic techniques. The CDs exhibited excitation-wavelength dependent emission with 10% as the fluorescence quantum yield. The fluorescence of CDs was decreased in correlation to the addition of absorber (tetracycline), as the excitation spectrum of the fluorophore (CDs) matches the absorption spectrum of the absorber. The present IFE-based sensing platform showed a good linear relationship from 2.0 µM to 200 µM (R² = 0.9960) and provided a detection limit of 0.6 µM (signal-to-noise ratio of 3). Additionally, the cytotoxic effects of CDs were determined using normal healthy male Balb/C mice model treated with various doses of CDs and at the end of the study, no mortality or even no sign of toxicity was observed at oral doses of 100 and 200 mg/kg CDs in all treated animals. The proposed nanoprobe assay is a free from interferences, low-cost, biocompatible, and accurate for the detection of tetracycline in pharmaceutical formulation.     

Detection of tetracycline and oxytetracycline residues in pig and calf hair by ultra-high-performance liquid chromatography tandem mass spectrometry

An ultra-high-performance liquid chromatography tandem mass spectrometry method to detect residues of tetracycline (TC), epi-tetracycline (eTC) and oxytetracycline (OTC) in animal hair was developed. Hair samples were washed with water, extracted with NH₄OH 0.1 M, purified by SPE-C₁₈ cartridge and analyzed by tandem mass spectrometry (ESI⁺, MRM mode) with satisfactory results. For the first time, accumulation of TC, eTC and OTC was confirmed in livestock hairs after a therapeutic treatment with TC and OTC, respectively. Administered drug residues were detectable in hair samples up to 2 months after the last treatment, providing a retrospective evidence of TC and OTC administration. Hair analysis seems to offer a wider window of detection than edible tissues.     

Preparation of magnetic molecularly imprinted polymer for the separation of tetracycline antibiotics from egg and tissue samples

Magnetic molecularly imprinted polymers were prepared using hydrophobic Fe₃O₄ magnetite as the magnetically susceptible component, oxytetracycline as template molecule, methacrylic acid as functional monomer, and styrene and divinylbenzene as polymeric matrix components. The polymers were applied to the separation of tetracycline antibiotics from egg and tissue samples. The extraction and clean-up procedures were carried out in a single step by blending and stirring the sample, extraction solvent and polymers. The analytes can be transferred from the sample matrix to the polymers directly or through the extraction solvent as medium. When the extraction was complete, the polymers adsorbing the analytes were easily separated from the sample matrix by an adscititious magnet. The analytes eluted from the polymers were determined by liquid chromatography–tandem mass spectrometry. The recoveries ranging from 72.8% to 96.5% were obtained with relative standard deviations in the range of 2.9–12.3%. The limit of detection was less than 0.2 ng g⁻¹. The feasibility of this method was validated by analysis of incurred egg and tissue samples, and the results were compared with those obtained by the classical method in which solvent extraction, centrifugation, and subsequent clean-up and concentration by solid-phase extraction were applied. The proposed method reduced the complicacy of classical method and improved the reliability of method.     

组织中的四环素族药物残留的HPLC检测方法的改进

通过前处理方法和色谱分析条件的选择优化,改进了组织中四环素族药物残留的检测方法.与国标方法相比,方法不仅无腐蚀性溶剂,而且具有灵敏度高、重复性好、准确等特点.     

Effect of Regulation of HSV-tk Gene Expression and Tumor Killed Activity with a Single Tetracycline-regulatable Plasmid Vector on HeLa Cells

To construct a single tetracycline-regulatable plasmid vector based on the double tetracycline-regulatable plasmid vector system for regulating HSV-tk gene expression so as to effectively kill HeLa cells. Two tetracycline operator(TetO2) was cloned into pcDNA3.1 and a cassette was made for a cytomegalovirus-type 2 tetracycline operator(CMV-TetO2) promoter, and the obtained vector was named pcDNA3.1-CMV-TetO2. Herpes simplex virus thymidine kinase(HSV-tk) gene and tetracycline repressor(TR) gene were cloned ...     

A Water‐Stable Uranyl Organic Framework as a Highly Selective and Sensitive Bifunctional Luminescent Probe for Fe3+ and Tetracycline Hydrochloride

A new coordination polymer (H₂bpy)_0.5?[(UO₂)_1.5(ipa)₂(H₂O)] ( 1 ) (H₂ipa=isophthalic acid, bpy=4,4′‐bipyridine) was synthesized by hydrothermal condition. It was characterized by IR spectroscopy, elemental analysis, TG‐DTA analysis, and powder X‐ray diffraction. Analysis of single‐crystal X‐ray diffraction results showed that the title compound exhibited a double chain bridged by the different uranyl ions and ipa^2? ligands. Through the hydrogen bond interactions and π???π stacking interactions, the double chains were assembled into the three‐dimensional supramolecular framework. Furthermore, the compound can be used as a promising bifunctional luminescence sensor for detecting and identifying Fe³⁺ and tetracycline hydrochloride antibiotic molecules with high selectivity and sensitivity in aqueous solutions. Moreover, the luminescent sensing mechanisms for different analytes were proposed. Moreover, the electronic properties of title compound were explored by density functional theory (DFT) calculations. The sensor system has been successfully applied for the detection of Fe³⁺ and tetracycline hydrochloride with high recovery percentages and low relative standard deviation in real river water samples.     

High-throughput analysis of tetracycline and penicillin antibiotics in animal tissues using electrospray tandem mass spectrometry with selected reaction monitoring transition

A simple, rapid, and simultaneous analysis method for oxytertracycline, tetracycline, chlortetracycline, penicillin G, ampicillin, and nafcillin in meat has been developed by using electrospray ionization tandem mass spectrometry. The sample preparation was performed by homogenizing with water followed by a centrifugal ultrafiltration, after addition of internal standards (demeclocycline, penicillin G-d5, ampicillin-d5 and nafcillin-d6). The MS/MS analysis involves the combined use of sample enrichment on the short column and a multiple reaction monitoring technique. The overall recoveries from animal (bovine and swine) muscle, kidney, and liver fortified at the levels of 0.05 and 0.1 ppm ranged from 70 to 115% with the coefficients of variation ranging from 0.7 to 14.8% (n = 5). Analysis time, including sample preparation and determination, is only 3h per eight sample and detection limits for all antibiotics are 0.002 ppm. The method is considered to be satisfactory for the rapid screening of the tetracycline and penicillin antibiotic residues in meat.     

Separation of tetracycline and its related substances by capillary zone electrophoresis

Tetracycline was separated from its main impurities 4-epitetracycline, anhydrotetracycline, 4-epianhydrotetracycline, chlortetracycline, and demethyltetracycline by capillary electrophoresis. Systematic method development was performed in which following parameters were consecutively optimized: type and pH of the buffer, buffer concentration, type and concentration of organic modifier, voltage and temperature. Qualitative and quantitative aspects of the method are compared with liquid chromatography.