Buff Mathias, Drab Ewa, Sugihara Kaori
Department of Physical Chemistry, University of Geneva, Quai Ernest Ansermet 30, 1211 Geneva 4, Switzerland.
Biointerphases. 2019 Feb 11;14(1):011004. doi: 10.1116/1.5082717.
The detection limits of impedance biosensors are dictated by the presence of background nonspecific binding, yet almost all the detection limits reported in the literature are determined using a clean buffer solution without confronting this real challenge. In this work, the authors employed the simplest "differential" impedance biosensor, composed of poly-l-lysine-polyethylene glycol-biotin-coated gold electrodes for the detection of streptavidin in the presence of 0.1% fetal calf serum, and studied the effect of the nonspecific binding on the performance of the differential impedance biosensing. The lowest streptavidin concentration detected by the system (5 μg/ml) was 1 order of magnitude higher (worse) than that from a previously demonstrated impedance biosensor where avidin was detected in the absence of background proteins. Interestingly, the origin of the differential signal was not due to the electrochemical properties of streptavidin itself but was that of the serum, where the coverage of the electrode by streptavidin indirectly modulated the electrical signal by suppressing the accessibility of the serum to the electrode.
阻抗生物传感器的检测限受背景非特异性结合的影响，但文献中报道的几乎所有检测限都是在不面对这一实际挑战的情况下，使用干净的缓冲溶液测定的。在这项工作中，作者采用了最简单的“差分”阻抗生物传感器，该传感器由聚-L-赖氨酸-聚乙二醇-生物素包被的金电极组成，用于在含有0.1%胎牛血清的情况下检测链霉亲和素，并研究了非特异性结合对差分阻抗生物传感性能的影响。该系统检测到的最低链霉亲和素浓度（5μg/ml）比之前展示的在无背景蛋白情况下检测抗生物素蛋白的阻抗生物传感器高1个数量级（更差）。有趣的是，差分信号的来源并非链霉亲和素本身的电化学性质，而是血清的电化学性质，链霉亲和素在电极上的覆盖通过抑制血清与电极的接触间接调节了电信号。
