Development of an electrochemical platform for the point-of-care diagnosis of infectious diseases

GLORIA LONGINOTTI; MIJAL MASS; LUCIANO MELLI; MARIANO ROBERTI; MARÍA EUGENIA CORTINA; MATÍAS LLORET; DIEGO BRENGI; DIEGO REY SERANTES; SALVADOR TROPEA; FRANCISCO SALOMÓN; JUAN E. UGALDE; LAURA MALATTO; GABRIEL YBARRA; ANDRÉS E. CIOCCHINI; LILIANA FRAIGI; DIEGO J. COMERCI; CARLOS MOINA

Melbourne

Congreso; 24th Anniversary World Congress on Biosensors; 2014

International Biosensors Society

As the final result of the work of an multidisciplinary group, we present a point-of-care platform for the serologic diagnosis of several diseases. The development of the platform has involved the convergence of biotechnology, nanochemistry, electrochemistry, electronics and computer programming. The principle of the diagnostic test is an electrochemical enzyme-linked immunoassay, as shown in the scheme below. Basically, superparamagnetic iron oxide nanoparticles were prepared and coated with silica via sol-gel process and then different recombinant antigens were covalently linked to the surface of the nanoparticles. The nanoparticles were incubated with sera for the diagnosis of specific diseases. In the case of infected sera, antigen-antibody complexes were formed. After incubation with horseradish peroxidase (HRP) conjugated antibodies, the nanoparticles were magnetically collected and transferred to an electrochemical cell where the enzymatic activity of HRP, if present, was amperometrically recorded. Disposable cartridges with eight electrochemical cells were designed and manufactured with dimensions fitting an 8-channel micropipette. Each electrochemical cell contains two carbon electrodes and one Ag│AgCl reference electrode screen printed onto 0.5 mm acrylic substrates. The central working electrodes were designed to be aligned with neodymium magnets incorporated in the housing so as to concentrate the magnetic particles. The eight electrochemical cells, each one with a total volume of about 35 µl, were completed with an acrylic top piece. The electronic instrumentation required to control the electrochemical system and process the resulting signal was also developed and connected to a computer via a USB port. A housing, which integrated the electronics and the measurement system, was designed and prototyped in ABS with a 3D printer in ABS. A software was developed with the capability of recording amperometric measurements with potential steps and cyclic voltammetries. The diagnostic platform was successfully tested for four different infectious diseases: foot-and-mouth disease, Chagas disease, human and bovine Brucellosis, and infections caused by STEC O157