Abstract

Terpenoids of medicinal plants are one of the most important sources of therapeutic drugs. Among them, Vincristine (VCR) is prescribed for a wide variety of cancer types. Therefore, development of sensitive methods for VCR determination is urgently required. Here, a label-free and highly sensitive impedimetric biosensor was fabricated for electrochemical detection of VCR. First, multi-wall carbon nano tubes (MWCNTs) were dropped on the surface of a glassy carbon electrode. Then, the VCR monoclonal antibody (Ab) was covalently immobilized on the MWCNTs via carbodiimide coupling reaction using N-(3-dimethylaminopropyl)-N'-ethyl carbodiimide and N-hydroxy succinimide. The step-by-step modification process was characterized by electrochemical impedance spectroscopy and cyclic voltammetry in presence of a redox probe [Fe(CN)₆]^3–/4–. The VCR concentration was measured through increasing impedance values in the corresponding specific binding of VCR to the Ab. The increased electron-transfer resistance (R_et) values were proportional to the concentration of VCR and the biosensor detected concentrations varied in the range of 0.2–50 nM with a detection limit of 8 × 10^–2 nM (S/N = 3). Practical analytical utility of the proposed method was demonstrated by VCR determination in medicinal plant extracts and human serum samples with satisfactory recoveries. The proposed biosensor may be a promising alternative for screening of medicinal plants to produce VCR and for the determination of drug concentration in cancerous potions.

中文翻译：

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用于生物样品中长春新碱的筛选和测定的阻抗式免疫传感器的制备

摘要

药用植物的萜类化合物是治疗药物的最重要来源之一。其中，长春新碱（VCR）被指定用于多种癌症类型。因此，迫切需要开发用于VCR确定的敏感方法。在这里，无标记和高灵敏度的阻抗生物传感器被制造用于VCR的电化学检测。首先，将多壁碳纳米管（MWCNT）滴在玻璃碳电极的表面上。然后，VCR单克隆抗体（Ab通过使用N-（3-二甲基氨基丙基）-N'-乙基碳二亚胺和N-羟基琥珀酰亚胺的碳二亚胺偶联反应将）共价固定在MWCNT上。在氧化还原探针[Fe（CN）₆ ] ^{3– / 4–}存在的情况下，通过电化学阻抗谱和循环伏安法对逐步修饰过程进行了表征。通过在VCR与Ab的相应特异性结合中增加阻抗值来测量VCR浓度。电子转移电阻（R _et）的增加值与VCR的浓度成正比，生物传感器检测到的浓度在0.2-50 nM的范围内变化，检测极限为8×10 ^-2nM（S / N = 3）。通过VCR测定在药用植物提取物和人血清样品中具有满意的回收率，证明了该方法的实际分析实用性。所提出的生物传感器可能是筛选药用植物以产生VCR并确定癌性部位药物浓度的有前途的替代方法。