Fluorescent Mesoporous Nanoparticles for β-Lactamase Screening Assays

We present a sensitive and rapid screening method for the determination of β-lactamase activity of antibiotic-resistant bacteria, by designing a pH-sensitive fluorescent dye-doped mesoporous silica nanoparticle encapsulated with penicillin G as a substrate. When penicillin G was hydrolysed by β-lactamase and converted into penicilloic acid, the acidic environment resulted in fluorescence quenching of the dye. The dye-doped mesoporous nanoparticles not only enhanced the β-lactamase-catalyzed reaction rate but also stablized the substrate, penicillin G, which degrades into penicilloic acid in a water solution without β-lactamase. Twentyfive clinical bacterial samples were tested and the antibiotic resistant and susceptible strains were identified. The proposed method may detect the presence of β -lactamases of clinically relevant samples in less than 1 hour. Moreover, the detection limit of β-lactamase activity was as low as 7.8×10⁻⁴ U/mL, which was determined within two hours.     

Synthesis of Molecularly Imprinted Polymer for Sensitive Penicillin Determination in Milk

Abstract

Penicillin G (PG) in milk is unsafe for human and is a big problem for the foods industry. Hence, the better analytical and eliminative techniques are demanded. We investigated a PG molecular imprinted polymer (MIP), which can sensitively detect and extract the PG from milk and other samples. The MIP synthesis involved a β-lactam antibiotics PG, methacrylic acid (MAA) and dimethyl formamide (DMF). Its properties were analyzed with Scatchard plot, which showed that there were two affinity sites of the PG polymer. The first equilibrium dissociation constant of the high-affinity binding sites Kd₁ was 1.14 × 10^?4 mol/L and the binding capacity Q_max1 was 46.01 µmol/g; the second equilibrium dissociation constant of the low-affinity binding sites Kd₂ was 1.35 × 10^?3 mol/L and the binding capacity Q_max2 was 72.55 µmol/g. Furthermore, two PG determination methods using the polymer were developed. The first was carried out quantitatively with a spectrophotometer and the detection limit was 1 ppm. The other one was the combination of the MIP particles with milk fermentation for PG analysis and the sensitivity was 10 ppb.     

青霉素亚砜催化扩环制备头孢G酸

保护性甲硅烷基化;青霉素亚砜催化扩环制备头孢G酸     

青霉素结构的探究

青霉素是人类抗菌历史上最伟大的产物。在极其简陋的实验条件下,正是由于科学家不懈地探索,青霉素神秘的结构才逐渐展现在人类面前。现在广泛用于临床上的β-内酰胺抗生素,大都是在青霉素原有结构基础上修饰改造而来。     

Efficient synthesis of cefadroxil in [Bmim][NTf2]‐phosphate cosolvent by magnetic immobilized penicillin G acylase

For the first time, cefadroxil was synthesized from 7‐Amino‐3‐desacetoxycephalosporanic acid and d ‐hydroxyphenylglycine methyl ester in [Bmim][NTf₂]‐phosphate cosolvent capable of dissolving the substrates using the penicillin G acylase (PGA) immobilized on the micrometer‐size magnetic polymer microspheres having high activity of 2,083 U/g. The high synthesis/hydrolysis (S/H) ratio of 1.12 was achieved with 79.0% yield, where only the S/H ratio of 0.19 and yield of 20.0% was obtained using free PGA under the identical optimum reaction conditions. Cefadroxil had been synthesized efficiently in [Bmim][NTf₂]‐phosphate cosolvent by the magnetic immobilized PGA, which illuminated that there are two very critical and essential designs, that is, effective support and suitable solvent system by PGA, in enzymatic synthesis of cefadroxil. Obviously, there is great potential for the magnetic immobilized PGA and ionic liquid solvent in application to biocatalysis.     

Determination of free clindamycin,flucloxacillin or tedizolid in plasma: Pay attention to physiological conditions when using ultrafiltration

Pharmacokinetic/pharmacodynamic indices of anti-infective drugs should be referenced to free drug concentrations. In the present study, clindamycin, flucloxacillin and tedizolid have been determined in human plasma by HPLC–UV. The drugs were separated isocratically within 3–6 min on a C₁₈ column using mixtures of phosphate buffer–acetonitrile of pH 7.1–7.2. Sample treatment for the determination of total drug concentrations in plasma included extraction/back-extraction (clindamycin) or protein precipitation (flucloxacillin, tedizolid). The free drug concentrations were determined after ultrafiltration. An ultrafiltration device with a membrane consisting of regenerated cellulose proved to be suitable for all drugs. Maintaining a physiological pH was crucial for clindamycin, whereas maintaining body temperature was essential for tedizolid. The methods were applied to the analysis of total and free drug concentrations in clinical samples and were sufficiently sensitive for pharmacokinetic studies and therapeutic drug monitoring.     

药物化学课程思政教学模式的探索与实践*——青霉素抗生素专题

药物化学是药学专业核心课程,拥有丰富的思政资源。以药物化学课程为研究对象,在明确课程思政育人目标基础上,将药物化学课程思政教学主线设置为“定目标、拆内容、寻热点、挖元素、隐融入、明效果、做评价”等7个环节。进一步以青霉素专题为例,展示思政内容有机融入课程教学的全过程,为其他理工类专业课程思政教学提供一种参考模式。     

Dissipation and residue determination of penicillin G and its two metabolites in citrus under field conditions by DSPE/UPLC–MS/MS

A rapid determination method of residual penicillin G and its two metabolites in citrus was developed and validated by dispersive solid-phase extraction and ultra-high performance liquid chromatography–tandem mass spectrometry (DSPE/UPLC–MS/MS). The samples were extracted with 80% acetonitrile and purified with octadecylsilane. High linearity was obtained with correlation coefficients (r²) >0.9981. The limits of quantification were 0.005–0.01 mg/kg. The recoveries of penicillin G and its metabolites spiked in blank citrus were within 76.7–107%, with relative standard deviations of 1.3–9.6%. The dissipation dynamics and distribution of penicillin G in citrus followed first-order kinetics, with half-life of 1.7–2.7 days. Penicillin G degraded easily in citrus and the metabolite was mainly penilloic acid, which can exist stably for long time. The terminal residues of penicillin G in pulp, whole citrus and peels were 0.015–0.701, 0.047–7.653 and 0.162–13.376 mg/kg, respectively. The hazard indexes for risk assessment of citrus were significantly <1, suggesting that the health risks to humans after consumption of citrus were insignificant and negligible. These results could provide necessary data for evaluating the safe and proper use of penicillin G in citrus.     

超高效液相色谱-串联质谱法同时测定全血中青霉素G及其主要代谢产物

建立了同时检测全血中青霉素G及其2种主要代谢产物青霉噻唑酸和脱羧青霉噻唑酸的超高效液相色谱-电喷雾串联质谱分析方法。血样经简单的蛋白沉淀提取后,目标化合物经BEH C18色谱柱(50 mm×2.1 mm, 1.7 μm),以含0.1%甲酸溶液-乙腈为流动相,梯度洗脱分离后,选用正离子电喷雾多反应监测(MRM)模式检测。方法检出限(信噪比(S/N)为3计)为0.1～2.0 ng/mL,定量限(S/N=10)为0.5～5.0 ng/mL。各被测物的线性相关系数均大于0.9974,准确度为92.3%～105.5%,日内精密度小于10%。考察了不同储存温度(18、4、-18、-80 ℃)下全血中青霉素G及其代谢物的稳定性,结果表明随着储存温度升高和时间的延长,青霉素G的质量浓度下降明显。应用建立的方法检测了给予20 mg/kg青霉素G后的大鼠血液样本,血液中青霉素G原形药物在给药后0.5 h即消除完全(低于检出限),而其代谢物的体内消除时限可延长至36 h。所建方法对司法鉴定的适用性得到了进一步扩大,同时对食品残留检测也具有一定的参考价值。