Electrochemical detection of methyl-paraoxon based on bifunctional cerium oxide nanozyme with catalytic activity and signal amplification effect

A new electrochemical sensor for organophosphate pesticide (methyl-paraoxon) detection based on bifunctional cerium oxide (CeO₂) nanozyme is here reported for the first time. Methyl-paraoxon was degraded into p-nitrophenol by using CeO₂ with phosphatase mimicking activity. The CeO₂ nanozyme-modified electrode was then synthesized to detect p-nitrophenol. Cyclic voltammetry was applied to investigate the electrochemical behavior of the modified electrode, which indicates that the signal enhancement effect may attribute to the coating of CeO₂ nanozyme. The current research also studied and discussed the main parameters affecting the analytical signal, including accumulation potential, accumulation time, and pH. Under the optimum conditions, the present method provided a wider linear range from 0.1 to 100 μmol/L for methyl-paraoxon with a detection limit of 0.06 μmol/L. To validate the proof of concept, the electrochemical sensor was then successfully applied for the determination of methyl-paraoxon in three herb samples, i.e., Coix lacryma-jobi, Adenophora stricta and Semen nelumbinis. Our findings may provide new insights into the application of bifunctional nanozyme in electrochemical detection of organophosphorus pesticide.     

采用石墨烯修饰的电化学免疫传感器检测猪肉中的己二烯雌酚含量

利用石墨烯及己二烯雌酚修饰电极,研制了一种用于检测己二烯雌酚的高灵敏新型电化学免疫传感器;通过竞争结合,以铁氰化钾为探针,实现了对己二烯雌酚的高灵敏快速检测。结果表明:研制的石墨烯/己二烯雌酚电化学免疫传感器具有很高的灵敏度,并且在己二烯雌酚质量浓度为500~5 000 ng/mL的范围内具有良好的线性关系,检测限可达到0.2 ng/mL。该传感器具有良好的稳定性和重复性,对猪肉实际样品进行了己二烯雌酚的含量分析,回收率在83.8%~97.7%之间,结果令人满意。     

Validation and application by HPLC for simultaneous determination of vitexin-2″-O-glucoside,vitexin-2″-O-rhamnoside,rutin, vitexin,and hyperoside

A simple, precise, and rapid high-performance liquid chromatographic method was developed and validated for the simultaneous determination of vitexin-2″-O-glucoside, vitexin-2″-O-rhamnoside, rutin, vitexin, and hyperoside. The HPLC separation was performed using a Shim-pack VP-ODS C₁₈ column (250 mm×4.6 mm i.d., 5 μm) with the isocratic mobile phase consisting of tetrahydrofuran/ acetonitrile/0.05% phosphoric acid solution (20:3:77, v/v/v), and the flow rate was set at 1.0 mL/min. UV detection was carried out at a wavelength of 360 nm and the whole analysis took 25 min. The method was linear in the range of 4.12–206.00 μg/mL for vitexin-2″-O-glucoside, 4.05–202.50 μg/mL for vitexin-2″-O-rhamnoside, 1.64–82.00 μg/mL for rutin, 1.74–87.00 μg/mL for vitexin, and 1.41–70.60 μg/mL for hyperoside with the correlation coefficient for each analyte more than 0.998. The limit of detection (LOD) and limit of quantitation (LOQ) were 0.6 and 2 ng for vitexin-2″-O-glucoside, 0.6 and 2 ng for vitexin-2″-O-rhamnoside, 0.3 and 1 ng for rutin, 1 and 3 ng for vitexin, and 0.5 and 2 ng for hyperoside, respectively. Intra- and inter-day precision and accuracy (RSD) were less than 3%. The developed HPLC method was successfully applied to the analysis of five flavonoids in hawthorn leaves, hawthorn fruits, and the preparations containing hawthorn leaves or fruits.     

电化学免疫传感器超灵敏检测髓过氧化物酶的研究

目的：本研究拟建立一种电化学免疫传感器用于超灵敏检测人血清中髓过氧化物酶（MPO）水平的方法。方法通过石墨化多孔碳-金复合纳米材料（AuNPs＠ GMCs）将 MPO 抗体固定到玻碳电极表面,研制出一种新型 MPO 电化学免疫传感器,探讨了实验条件对传感器性能的影响,并与酶联免疫吸附试验（ELISA）进行方法学比较。结果在最优条件下该传感器对MPO 反应灵敏,其线性范围为2．000～300．000 ng／mL ,相关系数为0．999,检出限为0．5 ng／mL ,与 ELISA 法检测结果的相关系数为0．983。结论该电化学免疫传感器可实现对 MPO 的超灵敏检测。     

Synthesis of carbon nanosheet from barley and its use as non-enzymatic glucose biosensor

In this work, carbon nanosheet (CNS) based electrode was designed for electrochemical biosensing of glucose. CNS has been obtained by the pyrolysis of barley at 600–750 °C in a muffle furnace; it was then purified and functionalized. The CNS has been characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Raman spectroscopic techniques. The electrochemical activity of CNS-based electrode was investigated by linear sweep voltammetry (LSV) and square wave voltammetry (SWV), for the oxidation of glucose in 0.001 M H₂SO₄ (pH 6.0). The linear range of the sensor was found to be 10⁻⁴–10⁻⁶ M (1–100 µM) within the response time of 4 s. Interestingly, its sensitivity reached as high as ~26.002±0.01 μA/μM cm². Electrochemical experiments revealed that the proposed electrode offered an excellent electrochemical activity towards the oxidation of glucose and could be applied for the construction of non-enzymatic glucose biosensors.     

荧光分析法测定元宝枫叶中总黄酮含量的研究

目的 采用荧光分析方法,对元宝枫叶总黄酮含量进行测定研究.方法 以芦丁为标准对照品,利用黄酮与Al3＋形成稳定荧光络合物的性质,选择激发波长λex=470 nm,发射波长λem=547 nm,研究乙醇的体积分数、5%Al（NO3）3的加入量、pH、放置时间以及绿原酸对荧光强度的影响.结果最佳测定条件是以60%乙醇溶液作为溶剂,在10 mL的容量瓶中加入1 mL 5% Al（NO3）3,并使测定溶液pH=5.该方法测定芦丁质量浓度在6.55×10-6mol/L～3.20×10-5mol/L与荧光强度具有良好的线性关系,且回归方程为y=1.147 7x ＋ 0.430 4,R2=0.999 1.结论 采用荧光分析法,通过改变激发光的波长,能够减小绿原酸对黄酮测定的干扰,可作为元宝枫叶总黄酮含量测定的参考方法.     

人血浆中阿戈美拉汀浓度的测定及其药代动力学

建立测定人血浆中阿戈美拉汀浓度的LC-MS/MS方法,测定单剂量口服25 mg阿戈美拉汀片后其在中国健康受试者体内的血药浓度,利用Phoenix WinNonlin 6.3.0软件计算药代动力学参数。该方法中阿戈美拉汀浓度的线性范围为0.051 3~10.38 ng/mL(r=0.999 4),最低检测浓度为0.051 3 ng/mL。日内、日间精密度测定RSD均小于15%。单次口服给药后,阿戈美拉汀的c_max为(13.25±15.78)ng/mL,t_max为(0.68±0.41)h,AUC_last为(14.00±19.26)ng/mL·h,AUC_inf为(14.14±19.35)ng/mL·h,t_1/2为(0.78±0.44)h。本方法简便、准确、重现性好,可用于阿戈美拉汀血药浓度的测定及其人体药代动力学研究。     

Highly sensitive simultaneous electrochemical determination of myricetin and rutin via solid phase extraction on a ternary Pt@r-GO@MWCNTs nanocomposite

The simultaneous electrochemical determination of myricetin and rutin remains a challenge due to their indistinguishable potentials. To solve this problem, we constructed a ternary platinum nanoparticle, reduced graphene oxide, multi-walled carbon nanotubes (Pt@r-GO@MWCNTs) nanocomposite via a facile one-pot synthetic method. Under the optimized conditions, the ternary Pt@r-GO@MWCNTs nanocomposite exhibited good electrocatalytic activity toward myricetin and rutin via solid phase extraction and excellent performance for the simultaneous determination of myricetin and rutin. The oxidation peak current of myricetin was proportional to its concentrations in the range of 0.05–50 μM with a detection limit of 0.01 μM (S/N = 3). The linear range for rutin was 0.05–50 μM with a detection limit of 0.005 μM (S/N = 3). The ternary nanocomposite sensor also exhibited good reproducibility and stability, and was successfully used for the simultaneous determination of myricetin and rutin in real orange juice samples with recoveries ranging between 100.57% and 108.46%.     

吡诺克辛钠-层状双氢氧化物纳米片及插层纳米粒复合物滴眼液的研究

为考察新型药物载体层状双氢氧化物(LDH)纳米片在眼部给药系统的应用,采用LDH纳米片为载体,羧甲基纤维素钠(CMC)为稳定剂,吡诺克辛钠(PRN)为模型药物,制备CMC-PRN-LDH纳米片复合物;采用共沉淀法制备PRN-LDHs插层纳米粒复合物。通过X射线衍射、原子力显微镜、透射电镜、激光粒度仪等对LDH纳米片、CMC-LDH纳米片复合物及两种载药-LDH纳米复合物理化性质进行研究。通过体外稳定性、体外释放、家兔泪液滞留实验比较了两种载药-LDH纳米复合物的差异。结果显示,CMC-PRN-LDH纳米片复合物相对稳定,而PRN-LDHs插层纳米粒稳定性较差,二者12 h体外累积释放百分率分别为70.44%和44.21%。CMC-PRN-LDH纳米片复合物滴眼液的AUC0-6 h和MRT分别为市售滴眼液的4.18和1.79倍,而PRN-LDHs插层纳米粒复合物滴眼液眼部滞留结果差异较大。CMC-PRN-LDH纳米片复合物滴眼液对眼部无刺激性。上述结果表明,LDH纳米片可作为眼部给药载体,能显著提高药物在角膜前的滞留时间。     

基于AgI模拟酶纳米材料构建阻抗型免疫传感器用于检测癌胚抗原

目的 设计一种基于AgI模拟酶纳米材料的阻抗型免疫传感器,对血清样品中的癌胚抗原(CEA)进行高灵敏检测.方法 合成一种壳聚糖修饰的碘化银(CS-AgI)纳米材料,利用透射电镜(TEM)和傅里叶红外光谱(FTIR)法对合成的CS-AgI进行表征,以CS-AgI为信号标记物修饰CEA抗体,采用夹心式免疫分析法在金电极表面制备一种高效、灵敏的电化学免疫传感器,采用电化学工作站定量分析检测所构建免疫传感器的电化学性能.结果 成功合成CS-AgI纳米颗粒,颗粒呈球形,粒径约为100 nm.以CS-AgI纳米颗粒为信号标记物构建的免疫传感器在pH7.0的磷酸盐缓冲液中检测CEA时表现出良好的电化学性能,其交流阻抗响应值与样品中的CEA浓度的对数呈线性增加趋势,并在CEA浓度为0.1～80 ng/mL范围内展现出良好的线性关系(r=0.996),检测限达到0.05 ng/mL.结论 基于AgI模拟酶纳米材料构建的阻抗型免疫传感器可以高灵敏检测CEA,同时具有较好的精确性、重现性和选择性,为癌症的早期诊断和早期治疗提供了实验依据.     

盐酸格拉司琼透皮贴剂在Beagle犬中多剂量给药的药代动力学研究

目的建立盐酸格拉司琼透皮贴剂在Beagle犬中的血药浓度测定方法,通过Beagle犬多剂量给药,揭示盐酸格拉司琼透皮贴剂在Beagle犬体内的药代动力学变化规律,阐明其在Beagle犬体内的药代动力学特征,提供重要的动力学参数。方法 Beagle犬给予盐酸格拉司琼透皮贴剂6次,每次贴片持续72 h,每次撤药和下次给药间隔24 h。用建立的HPLC-MS/MS法测定血浆中的格拉司琼的浓度,根据所得的血浆药物浓度-时间曲线,计算药动学参数。结果第1次给药和第6次给药后的谷浓度Cmin分别0.0459 ng/m L和0.2593 ng/m L,峰浓度Cmax分别为0.4637 ng/m L和1.3428 ng/m L,AUC0~96分别为18.92 h·ng/m L和40.21 h·ng/m L,第1次给药和第6次给药后的Tmax分别为48.3 h和45.3 h,MRT0-96分别为48.9 h和45.84 h。结论多次给药后格拉司琼在体内存在一定的蓄积效应,并在多次给药后第16天到达稳态。     

HPLC-MS/MS法测定依卡倍特钠原料药中潜在遗传毒性杂质

为了定量测定依卡倍特钠中潜在遗传毒性杂质依卡倍特磺酸乙酯(杂质Ⅰ),参考文献方法合成依卡倍特磺酸乙酯。采用高分辨质谱、结合二级质谱与核磁共振确定其相对分子质量及化学结构。采用Thermo C₁₈色谱柱,以5 mmol/L乙酸铵溶液(甲酸调pH至3.0)为流动相A;乙腈为流动相B,按照梯度:0 min 50%B,4 min 50%B,12 min 80%B,16 min 80%B,16.1 min 50%B,20 min 50%B进行洗脱,柱温40 ℃;采用电喷雾负离子化-MS/MS选择反应监测。杂质Ⅰ的线性质量浓度范围为4~150 ng/mL,且线性关系良好(r=0.999);最低定量限为4 ng/mL;杂质Ⅰ的进样精密度、重复性和加标回收率良好,耐用性良好。方法操作简便,灵敏度高,可用于依卡倍特钠原料药中潜在遗传毒性杂质依卡倍特磺酸乙酯的含量测定。     

羧基功能化石墨烯修饰电极伏安法对芦丁的检测研究

目的：制备羧基功能化石墨烯修饰玻碳电极,研究芦丁在该电极上的电化学行为,建立芦丁测定的新方法。方法：分别采用循环伏安法和差示脉冲伏安法研究了芦丁在修饰电极上的电化学行为,优化了包括支持电解质、缓冲液pH、修饰剂用量等测定条件。结果：在10mmol／LpH=7．5的Tris-Hcl缓冲溶液中,还原峰电流与芦丁的浓度对数在4．0×10-7-8．0×10-5mol／L范围内呈良好的线性关系,检出限为1．0×10-7mol／L（S／N=3）,加样回收率在97．60％-106．30％。结论：该方法灵敏度高、检测范围宽,已用于复方芦丁片中芦丁的测定,结果令人满意。     

Quantitative determination of D4-cystine in mice using LC-MS/MS and its application to the assessment of pharmacokinetics and bioavailability

Cystine is the primary source material for the synthesis of glutathione. However, the pharmacokinetics and tissue distribution of cystine are largely unknown. A surrogate analyte D₄-cystine was employed to generate calibration curves for the determination of levels of D₄-cystine and endogenous cystine in mice by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Validation assessments proved the sensitivity, specificity and reproducibility of the method with a lower limit of quantification (LLOQ) of 5 ng/mL over 5–5000 ng/mL in plasma. The pharmacokinetics of D₄-cystine were evaluated after administering injections and oral solutions, both of which minimally impacted endogenous cystine levels. The absolute bioavailability of cystine was 18.6%, 15.1% and 25.6% at doses of 25, 50 and 100 mg/kg, respectively. Intravenously injected D₄-cystine resulted in dramatically high plasma levels with reduced levels in the brain and liver. Intragastrically administered D₄-cystine resulted in high levels in the plasma and stomach with relatively low levels in the lung, kidney, heart and brain.     

An ionic liquid supported CeO2 nanoparticles–carbon nanotubes composite-enhanced electrochemical DNA-based sensor for the detection of Pb2+

An electrochemical sensor incorporating a signal enhancement for the determination of lead (II) ions (Pb²⁺) was designed on the basis of the thrombin-binding aptamer (TBA) as a molecular recognition element and ionic liquid supported cerium oxide (CeO₂) nanoparticles–carbon nanotubes composite modification. The composite comprises nanoparticles CeO₂, multi-wall carbon nanotubes (MWNTs) and hydrophobic room temperature ionic liquid (RTIL) 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF₄). The electrochemical sensors were fabricated by immersing the CeO₂–MWNTs–EMIMBF₄ modified glassy carbon electrode (GCE) into the solution of TBA probe. In the presence of Pb²⁺, the TBA probe could form stable G-quartet structure by the specific binding interactions between Pb²⁺ and TBA. The TBA-bound Pb²⁺ can be electrochemically reduced, which provides a readout signal for quantitative detection of Pb²⁺. The reduction peak current is linearly related to the concentration of Pb²⁺ from 1.0×10^–8 M to 1.0×10^–5 M with a detection limit of 5×10^–9 M. This work demonstrates that the CeO₂–MWNTs–EMIMBF₄ nanocomposite modified GCE provides a promising platform for immobilizing the TBA probe and enhancing the sensitivity of the DNA-based sensors.     

基于双重信号放大的电化学免疫法对前列腺特异性抗原的检测

以谷胱甘肽修饰的CdTe量子点(GSH-CdTe QDs)与金纳米粒(AuNPs)形成复合材料(AuNPs@GSH-CdTe)为信号标记物,并在还原氧化石墨烯(rGO)和AuNPs双重信号放大的作用下,建立了一种高灵敏检测前列腺特异性抗原(PSA)的三明治免疫夹心式电化学方法。在rGO/AuNPs表面固定二抗蛋白(Ab₂),捕获目标物PSA和标记有一抗蛋白(Ab₁)的AuNPs@GSH-CdTe信号物,形成“三明治”免疫夹心结构。经HNO₃溶解后,采用方波溶出伏安法(SWSV)测定酸解的Cd²⁺的峰电流用于定量分析PSA。其中AuNPs较大的比表面积以及较好的生物相容能力,达到了成功装载抗体以及放大信号的效果,同时具有较大表面积的rGO起到了协同放大的作用。所构建的免疫分析方法实现了对肿瘤标志物PSA的检测,其线性范围为0.5~200 ng/mL,检测限为5.0 pg/mL,并且该方法专属性、重复性以及稳定性好。此外,在实际样品的检测中,加标样回收率为98.20%~106.2%,结果准确度良好,为检测PSA提供了准确可靠且灵敏度高的新方法。     

一种新型锰金属有机框架纳米载体用于克服肿瘤缺氧增效光动力治疗

使用简单的溶剂法制备了一种新型的锰簇卟啉金属有机框架纳米载体(nMn-MOF),并对其体外增效光动力治疗的能力进行了考察。通过动态光散射仪、透射电镜、X射线光电子能谱对该纳米载体进行表征,采用氧探针、ICG荧光染料考察其催化过氧化氢产生氧气和光照下产生单线态氧(¹O₂)的能力。在细胞水平上,采用CCK-8法检测纳米载体的暗毒性和光毒性,通过荧光染色观察纳米载体改善肿瘤细胞乏氧和产生活性氧的能力。结果表明,制备的纳米级的锰簇卟啉金属有机框架纳米载体具有过氧化氢特异性产氧和产生高水平单线态氧的能力,改善肿瘤乏氧,从而增效光动力治疗。     

分离测定鱼腥草和山楂果实中槲皮素、芸香苷和绿原酸反向迁移胶束毛细管电泳新方法

建立了反向迁移胶束毛细管电泳法同时分离测定鱼腥草和山楂果实中槲皮素、芸香苷和绿原酸的新方法。运行缓冲溶液为70mmol／L十二烷基硫酸钠和30mmol／L NaH2PO4,pH2．1,分离电压-15kV,检测波长214nm。在此最佳条件下,分析物可在15min内实现基线分离。槲皮素、芸香苷和绿原酸的线性范围分别为25-400、25-400、12．5-200μg／mL,相关系数分别为0．9992、0．9992、0．9999,3种分析物的检测限（S／N=3）分别为2．52、3．10、3．64μg／mL。槲皮素、芸香苷、绿原酸的回收率分别为98．5％-103．7％、95．8％～97．6％、99．1％-103．8％。     

溶出伏安法测定血清中维生素K3

目的:建立一种快速、准确、灵敏的测定血清中维生素K(3VK3)的电化学方法。方法:镀汞膜修饰玻碳电极为工作电极,Ag/AgCl电极为参比电极,铂片电极为辅助电极,组成三电极体系,在pH=9.4、浓度为1.0 mol.L-1氨水-氯化铵缓冲液的底液中,用差分脉冲溶出伏安法对血清中VK3进行测定。结果:峰电流(ip)与VK3的浓度(C)在0.23～1.6 ng.mL-1范围内呈现良好的线性关系,检出限为0.23 ng.mL-1,并具有很好的平行性,对于0.92 ng.mL-1的VK3,6次平行测定结果的标准偏差RSD为1.64%。应用此方法对血清中VK3含量进行了测定,方法的平均回收率为99.91%,RSD为1.03%。结论:该方法与高效液相色谱法相比简单、快速、灵敏度高,可作为血清中VK3的高敏检测方法。     

Chemiluminescence determination of melamine with Luminol-K3Fe(CN)6 system

A sensitive chemiluminescence (CL) method was developed for determining melamine in urine and plasma samples based on the fact that melamine can remarkably enhance the chemiluminescence of Luminol-K₃ Fe(CN)₆ system in alkaline medium. The determination conditions were optimized. Under optimum conditions, the chemiluminescence intensity had a good linear relationship with melamine in the range of 9.0 × 10^?9 – 7.0 × 10^?6 g/mL with a correlation coefficient of 0.9992. The detection limits (3σ) were 3.54 ng/mL for urine sample and 6.58 ng/mL for plasma sample. The average recoveries of melamine were 102.6% for urine sample and 95.1% for plasma sample. Melamine in samples was extracted with liquid-liquid extraction procedures and the assay results coincided very well with that determined with flow injection chemiluminescence method. The method provides a reproducible and stable approach for sensitive detection and quantification of melamine in urine and plasma samples.