Lab-on-a-Membrane Foldable Devices for Duplex Drop-Volume Electrochemical Biosensing Using Quantum Dot Tags

Abstract

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.

Recent Advances in the Fabrication and Application of Screen-Printed Electrochemical (Bio)Sensors Based on Carbon Materials for Biomedical, Agri-Food and Environmental Analyses

“…A screen-printed lab-on-a-membrane foldable device was developed for the duplex determination of biomolecules with metallic ions released from quantum dots [35]. This allowed for the simultaneous determination of both Pb 2+ and Cd 2+ .…”

Nano-Biosensing Platforms for Detection of Cow’s Milk Allergens: An Overview

“…Other strategies for sensitive voltammetric analysis of allergens involve the coupling of bioreceptors with novel features (i.e., coding and amplification) of inorganic nanocrystals in order to achieve a highly selective, sensitive, and simultaneous sensing of multiple protein targets. A competitive immunosensor was proposed by Kokkinos et al [72] for bovine immunoglobulin G (bIgG) and bovine casein (CN) detection. The electrochemical devices are realized by screen-printed cell (SPC) with nylon membranes, symmetrically located on each side of SPC.…”

Electrochemical Affinity Biosensors Based on Disposable Screen-Printed Electrodes for Detection of Food Allergens

“…Recently, a lab-on-a-membrane device was described for simultaneous biosensing of casein and gamma−globulin G in milk [91] using Quantum Dot (QD)-labelled antibodies immobilized on two membranes. The membranes were folded and brought on top of screen-printed graphite electrodes.…”

“…Other strategies for sensitive voltammetric analysis of allergens involve QDs-labelled bioreceptors [91,95]. These have the advantage that allow simultaneous detection of several protein targets, using specific bioreceptors labelled with different QDs.…”