title: Reusable conductimetric array of interdigitated microelectrodes for the readout of low-density microarrays.
abstract: Low-density protein microarrays are emerging tools in diagnostics whose deployment could be primarily limited by the cost of fluorescence detection schemes. This paper describes an electrical readout system of microarrays comprising an array of gold interdigitated microelectrodes and an array of polydimethylsiloxane microwells, which enabled multiplexed detection of up to thirty six biological events on the same substrate. Similarly to fluorescent readout counterparts, the microarray can be developed on disposable glass slide substrates. However, unlike them, the presented approach is compact and requires a simple and inexpensive instrumentation. The system makes use of urease labeled affinity reagents for developing the microarrays and is based on detection of conductivity changes taking place when ionic species are generated in solution due to the catalytic hydrolysis of urea. The use of a polydimethylsiloxane microwell array facilitates the positioning of the measurement solution on every spot of the microarray. Also, it ensures the liquid tightness and isolation from the surrounding ones during the microarray readout process, thereby avoiding evaporation and chemical cross-talk effects that were shown to affect the sensitivity and reliability of the system. The performance of the system is demonstrated by carrying out the readout of a microarray for boldenone anabolic androgenic steroid hormone. Analytical results are comparable to those obtained by fluorescent scanner detection approaches. The estimated detection limit is 4.0 ng mL(-1), this being below the threshold value set by the World Anti-Doping Agency and the European Community.
authors.affiliation: Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), Campus UAB, Bellaterra 08193, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Mallén
authors.affiliation: Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), Campus UAB, Bellaterra 08193, Spain.
authors.forename: María
authors.initials: M
authors.lastname: Díaz-González
authors.affiliation: Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), Campus UAB, Bellaterra 08193, Spain.
authors.forename: Diana
authors.initials: D
authors.lastname: Bonilla
authors.affiliation: Nanobiotechnology for Diagnostics group (Nb4D), IQAC-CSIC, Jordi Girona 18-26, Barcelona 08034, Spain; CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Spain.
authors.forename: Juan P
authors.initials: JP
authors.lastname: Salvador
authors.affiliation: Nanobiotechnology for Diagnostics group (Nb4D), IQAC-CSIC, Jordi Girona 18-26, Barcelona 08034, Spain; CIBER de Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Spain.
authors.forename: María P
authors.initials: MP
authors.lastname: Marco
authors.affiliation: Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), Campus UAB, Bellaterra 08193, Spain. Electronic address: antoni.baldi@imb-cnm.csic.es.
authors.forename: Antoni
authors.initials: A
authors.lastname: Baldi
authors.affiliation: Instituto de Microelectrónica de Barcelona, IMB-CNM (CSIC), Campus UAB, Bellaterra 08193, Spain. Electronic address: cesar.fernandez@imb-cnm.csic.es.
authors.forename: César
authors.initials: C
authors.lastname: Fernández-Sánchez
mesh_terms: D004553:Electric Conductivity; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods; D008839:Microelectrodes; D040081:Protein Array Analysis / Q000295:instrumentation* / Q000379:methods; D012680:Sensitivity and Specificity; D013739:Testosterone / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D013739:Testosterone; C013915:boldenone
keywords: Conductivity; Impedance; Interdigitated electrode; Microarray; Microwell; Transducer array