Mwilu Samuel K, Aluoch Austin O, Miller Seth, Wong Paula, Sadik Omowunmi A, Fatah Alim A, Arcilesi Richard D
Department of Chemistry, Center for Advanced Sensors & Environmental Monitoring, State University of New York-Binghamton, P.O. Box 6000, Binghamton, New York 13902, USA.
Anal Chem. 2009 Sep 15;81(18):7561-70. doi: 10.1021/ac900834e.
Presented herein are two detection strategies for the identification and quantification of Bacillus globigii, a spore forming nonpathogenic simulant of Bacillus anthracis. The first strategy involves a label-free, metal-enhanced electrochemical immunosensor for the quantitative detection of Bacillus globigii (atrophaeus). The immunosensor comprises of antibacillus globigii (BG) antibody self-assembled onto a gold quartz crystal electrode via cystamine bond. A solid-phase monolayer of silver underpotentially deposited onto the cystamine modified-Au-electrode surface is used as the redox probe. The monolayer was also generated by adsorbing silver nanoparticles on the gold electrode. When the antibody-modified electrode is exposed to BG spores, the antibody-antigen (Ab-Ag) complex formed insulated the electrode surface toward the silver redox probe. The variation of redox current was found to be proportional to the concentration of the BG spores between 1 x 10(2)-3.5 x 10(4) spores/mL. A detection limit of 602 spores/mL was obtained, which is well-below the infectious dose of anthrax spores at 2.5 x 10(5) spores/mL. The second approach involves the use of ultrasensitive portable capillary biosensor (UPAC) to detect the spores. The capillary is an enclosed system that acts as the flow cell, the waveguide, and the solid support for immobilized bimolecular probes. An evanescent excitation generates a signal from an antigen-antibody-fluorophore complex, which propagates along the capillary and is guided to the detector. A limit of detection of 112 spores/mL was reported using the UPAC sensor. Both methods showed lower detection limits compared to the conventional ELISA. The effect of potential interferants tested using Bacillus pumilus confirmed the selectivity for the analyte. This work should allow the first responders to rapidly detect and quantify Bacillus globigii spores at concentrations that are well-below the infectious dose.
本文介绍了两种用于鉴定和定量球形芽孢杆菌的检测策略，球形芽孢杆菌是一种形成芽孢的炭疽芽孢杆菌非致病性模拟物。第一种策略涉及一种无标记、金属增强的电化学免疫传感器，用于定量检测球形芽孢杆菌（萎缩芽孢杆菌）。该免疫传感器由通过胱胺键自组装在金石英晶体电极上的抗球形芽孢杆菌（BG）抗体组成。欠电位沉积在胱胺修饰的金电极表面上的银固相单层用作氧化还原探针。该单层也通过在金电极上吸附银纳米颗粒产生。当抗体修饰电极暴露于BG芽孢时，形成的抗体-抗原（Ab-Ag）复合物使电极表面对银氧化还原探针绝缘。发现氧化还原电流的变化与BG芽孢浓度在1×10²-3.5×10⁴个芽孢/mL之间成正比。获得了602个芽孢/mL的检测限，这远低于炭疽芽孢的感染剂量2.5×10⁵个芽孢/mL。第二种方法涉及使用超灵敏便携式毛细管生物传感器（UPAC）来检测芽孢。毛细管是一个封闭系统，用作流通池、波导和固定化双分子探针的固体支持物。倏逝激发从抗原-抗体-荧光团复合物产生信号，该信号沿毛细管传播并被引导至检测器。使用UPAC传感器报告的检测限为112个芽孢/mL。与传统酶联免疫吸附测定（ELISA）相比，这两种方法均显示出更低的检测限。使用短小芽孢杆菌测试潜在干扰物的影响证实了对分析物的选择性。这项工作应能使应急人员快速检测和定量浓度远低于感染剂量的球形芽孢杆菌芽孢。
