Laboratory of Analytical Chemistry, Department of Chemistry, University of Athens , Athens, 157 71, Greece.
Immunoassays/Immunosensors Lab, INRaSTES, NCSR "Demokritos", Aghia Paraskevi, 15310, Greece.
Anal Chem. 2016 Jul 5;88(13):6897-904. doi: 10.1021/acs.analchem.6b01625. Epub 2016 Jun 14.
This work describes a new type of integrated lab-on-a-membrane foldable device suitable for on-site duplex electrochemical biosensing using drop-size sample volumes. The devices are fabricated entirely by screen-printing on a nylon membrane and feature two assay zones which are located symmetrically on either side of a three-electrode voltammetric cell with a bismuth citrate-loaded graphite working electrode. After the completion of two spatially separated drop-volume competitive immunoassays on the assay zones using biotinylated antibodies labeled with streptavidin-conjugated Pb- and Cd-based quantum dots (QDs), respectively, the QD labels are dissolved releasing Pb(II) and Cd(II) in the assay zones. Then, the two assay zones are folded over, and they are brought in contact with the voltammetric cell for simultaneous anodic stripping voltammetric (ASV) determination of Pb(II) and Cd(II) at the bismuth nanostructured layer formed on the working electrode by reduction of the bismuth citrate during the preconcentration step. The fabrication of the devices is discussed in detail, and their operational characteristics are exhaustively studied. In order to demonstrate their applicability to the analysis in complex matrices, duplex ASV-QDs-based determination of bovine casein and bovine immunoglobulin G is carried out in milk samples yielding limits of detection of 0.04 μg mL(-1) and 0.02 μg mL(-1), respectively. The potential of the devices to detect milk adulteration is further demonstrated. These new membrane devices enable duplex biosensing with distinct advantages over existing approaches in terms of cost, fabrication, and operational simplicity and rapidity, portability, sample size, disposability, sensitivity, and suitability for field analysis.
这项工作描述了一种新型的集成膜上折叠式设备，适用于使用小滴样品体积进行现场双电化学生物传感。该设备完全通过在尼龙膜上进行丝网印刷制造，其特点是在具有负载柠檬酸铋的石墨工作电极的三电极伏安电池的两侧对称地设有两个检测区。在使用分别用链霉亲和素偶联的 Pb 和 Cd 基量子点（QD）标记的生物素化抗体在检测区上完成两个空间分离的小滴体积竞争性免疫测定之后，QD 标记物被溶解，从而在检测区中释放出 Pb(II)和 Cd(II)。然后，将两个检测区折叠起来，并将它们与伏安电池接触，以便在通过还原柠檬酸铋在工作电极上形成的铋纳米结构层同时进行阳极溶出伏安法（ASV）测定 Pb(II)和 Cd(II)。详细讨论了器件的制造过程，并对其操作特性进行了详尽的研究。为了证明其在复杂基质分析中的适用性，在牛奶样品中进行了双 ASV-QD 基于牛血清白蛋白和牛免疫球蛋白 G 的测定，得到的检测限分别为 0.04μg mL(-1)和 0.02μg mL(-1)。该设备检测牛奶掺假的潜力也得到了进一步证明。这些新型膜器件在成本、制造、操作简便快速、便携性、样品量、一次性、灵敏度以及适合现场分析等方面具有明显优势，可用于双电化学生物传感。
