title: A microfluidic device for the automated electrical readout of low-density glass-slide microarrays.
abstract: Microarrays are a powerful platform for rapid and multiplexed analysis in a wide range of research fields. Electrical readout systems have emerged as an alternative to conventional optical methods for microarray analysis thanks to its potential advantages like low-cost, low-power and easy miniaturization of the required instrumentation. In this work an automated electrical readout system for low-cost glass-slide microarrays is described. The system enables the simultaneous conductimetric detection of up to 36 biorecognition events by incorporating an array of interdigitated electrode transducers. A polydimethylsiloxane microfluidic structure has been designed that creates microwells over the transducers and incorporates the microfluidic channels required for filling and draining them with readout and cleaning solutions, thus making the readout process fully automated. Since the capture biomolecules are not immobilized on the transducer surface this readout system is reusable, in contrast to previously reported electrochemical microarrays. A low-density microarray based on a competitive enzymatic immunoassay for atrazine detection was used to test the performance of the readout system. The electrical assay shows a detection limit of 0.22±0.03 μg L(-1) similar to that obtained with fluorescent detection and allows the direct determination of the pesticide in polluted water samples. These results proved that an electrical readout system such as the one presented in this work is a reliable and cost-effective alternative to fluorescence scanners for the analysis of low-density microarrays.
authors.affiliation: Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), Campus UAB, 08193 Bellaterra, Barcelona, Spain. Electronic address: maria.diaz@imb-cnm.csic.es.
authors.forename: María
authors.initials: M
authors.lastname: Díaz-González
authors.affiliation: Nanobiotechnology for Diagnostics (Nb4D) Group, IQAC-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain.
authors.forename: J Pablo
authors.initials: JP
authors.lastname: Salvador
authors.affiliation: Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), Campus UAB, 08193 Bellaterra, Barcelona, Spain.
authors.forename: Diana
authors.initials: D
authors.lastname: Bonilla
authors.affiliation: Nanobiotechnology for Diagnostics (Nb4D) Group, IQAC-CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain.
authors.forename: M Pilar
authors.initials: MP
authors.lastname: Marco
authors.affiliation: Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), Campus UAB, 08193 Bellaterra, Barcelona, Spain.
authors.forename: César
authors.initials: C
authors.lastname: Fernández-Sánchez
authors.affiliation: Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), Campus UAB, 08193 Bellaterra, Barcelona, Spain.
authors.forename: Antoni
authors.initials: A
authors.lastname: Baldi
mesh_terms: D001681:Biological Assay / Q000295:instrumentation*; D015374:Biosensing Techniques / Q000295:instrumentation*; D003217:Conductometry / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D005898:Glass / Q000737:chemistry*; D007118:Immunoassay / Q000295:instrumentation; D056656:Lab-On-A-Chip Devices; D046228:Microarray Analysis / Q000295:instrumentation*; D008839:Microelectrodes; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
keywords: Electrical redout; Immunoassay; Microarray; Microfluidics; Pesticide