title: Enhanced detection of quantum dots labeled protein by simultaneous bismuth electrodeposition into microfluidic channel.
abstract: In this study, we propose an electrochemical immunoassay into a disposable microfluidic platform, using quantum dots (QDs) as labels and their enhanced detection using bismuth as an alternative to mercury electrodes. CdSe@ZnS QDs were used to tag human IgG as a model protein and detected through highly sensitive stripping voltammetry of the dissolved metallic component (cadmium in our case). The modification of the screen printed carbon electrodes (SPCEs) was done by a simple electrodeposition of bismuth that was previously mixed with the sample containing QDs. A magneto-immunosandwich assay was performed using a micromixer. A magnet placed at its outlet in order to capture the magnetic beads used as solid support for the immunoassay. SPCEs were integrated at the end of the channel as detector. Different parameters such as bismuth concentration, flow rate, and incubation times, were optimized. The LOD for HIgG in presence of bismuth was 3.5 ng/mL with a RSD of 13.2%. This LOD was about 3.3-fold lower than the one obtained without bismuth. Furthermore, the sensitivity of the system was increased 100-fold respect to experiments carried out with classical screen-printed electrodes, both in presence of bismuth.
authors.affiliation: Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, Barcelona, Spain.
authors.forename: Mariana
authors.initials: M
authors.lastname: Medina-Sánchez
authors.affiliation: Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, Barcelona, Spain.
authors.forename: Sandrine
authors.initials: S
authors.lastname: Miserere
authors.affiliation: Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, Barcelona, Spain.
authors.forename: Miquell
authors.initials: M
authors.lastname: Cadevall
authors.affiliation: Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, Barcelona, Spain.|Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
authors.forename: Arben
authors.initials: A
authors.lastname: Merkoçi
mesh_terms: D001729:Bismuth / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000379:methods*; D004867:Equipment Design; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods*; D007074:Immunoglobulin G / Q000097:blood; D057230:Limit of Detection; D046210:Microfluidic Analytical Techniques / Q000295:instrumentation / Q000379:methods*; D045663:Quantum Dots / Q000737:chemistry*; D015203:Reproducibility of Results
chemical_list: D007074:Immunoglobulin G; D001729:Bismuth
keywords: Bismuth; Microfluidics; Quantum dots