Labib Mahmoud, Hedström Martin, Amin Magdy, Mattiasson Bo
Department of Biotechnology, Lund University, Box 124, 221 00 Lund, Sweden.
Anal Chim Acta. 2009 Feb 23;634(2):255-61. doi: 10.1016/j.aca.2008.12.035. Epub 2008 Dec 25.
Contamination of food with biological toxins as well as their potential use as weapons of mass destruction has created an urge for rapid and cost effective analytical techniques capable of detecting trace amounts of these toxins. This paper describes the development of a sensitive method for detection of cholera toxin (CT) using a flow-injection capacitive immunosensor based on self-assembled monolayers. The sensing surface consists of monoclonal antibodies against the B subunit of CT (anti-CT), immobilized on a gold transducer. Experimental results show that the immunosensor responded linearly to CT concentrations in the range from 1.0x10(-13) to 1.0x10(-10) M under optimized conditions. The limit of detection (LOD) was 1.0x10(-14) M. Two more analytical methods were employed for detection of CT using the same antibody namely, sandwich ELISA and surface plasmon resonance (SPR)-based immunosensor. The former had an LOD of 1.2x10(-12) M and a working range from 3.7x10(-11) to 2.9x10(-10) M whereas, the later had an LOD of 1.0x10(-11) M and a linearity ranging from 1.0x10(-9) to 1.0x10(-6) M. These results demonstrate that the developed capacitive immunosensor system has a higher sensitivity than the other two techniques. The binding affinity of CT to the immobilized anti-CT was determined using the SPR-based immunosensor and an association constant (K(A)) of 1.4x10(9) M(-1) was estimated.
食品被生物毒素污染以及生物毒素被用作大规模杀伤性武器的可能性，促使人们迫切需要能够检测痕量这些毒素的快速且经济高效的分析技术。本文描述了一种基于自组装单分子层的流动注射电容免疫传感器检测霍乱毒素（CT）的灵敏方法的开发。传感表面由固定在金换能器上的抗CT B亚基单克隆抗体（抗CT）组成。实验结果表明，在优化条件下，免疫传感器对CT浓度在1.0×10⁻¹³至1.0×10⁻¹⁰ M范围内呈线性响应。检测限（LOD）为1.0×10⁻¹⁴ M。还采用了另外两种分析方法，即夹心ELISA和基于表面等离子体共振（SPR）的免疫传感器，使用相同抗体检测CT。前者的LOD为1.2×10⁻¹² M，工作范围为3.7×10⁻¹¹至2.9×10⁻¹⁰ M，而后者的LOD为1.0×10⁻¹¹ M，线性范围为1.0×10⁻⁹至1.0×10⁻⁶ M。这些结果表明，所开发的电容免疫传感器系统比其他两种技术具有更高的灵敏度。使用基于SPR的免疫传感器测定了CT与固定化抗CT的结合亲和力，估计缔合常数（K(A)）为1.4×10⁹ M⁻¹。
