An Electrochemical Platform for the Point-Of-Care Diagnosis of Infectious Diseases

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

Buenos Aires

Congreso; 15th International Meeting in Chemical Sensors; 2014

CNEA

Summary In this work, we present a point-of-care platform for the serologic diagnosis of infectious diseases. The principle of diagnosis can be regarded as an electrochemical enzyme-linked immunoassay. Different recombinant antigens were immobilized onto magnetic microparticles. After incubation with sera and horseradish peroxidase labeled conjugated antibodies, the magnetic particles were collected and placed in electrochemical cells where infected sera were amperometrically detected. All components of the platform were designed and developed during this project, including the electronic instrumentation and novel, disposable electrochemical cells, which allow eight simultaneous measurements. The platform was successfully tested for the diagnosis of foot-and-mouth disease, brucellosis, Chagas disease and infection by STEC O157.     The concept behind the device  The aim of this project was to develop a point-of-care platform to carry out serologic diagnosis of infectious diseases with a reliability comparable to ELISA tests. In contrast to optical detection, electrochemical transduction is easier to miniaturize and to integrate with electronic circuits. On the other hand, the immobilization of antigens onto magnetic microparticles has additional advantages over antigen immobilization in conventional wells, such as the possibility of using higher loads of antigens and the resulting shorter incubation times; nanoparticles present additional advantages, such as high surface to volume ratio and superparamagnetism, and are currently being tested as a replacement of microparticles. The point-of-care platform presented here is based on the combination of the use of magnetic particles and ELISA test with electrochemical detection. A schematic representation of the detection principle is shown in Fig. 1a. Antigen-coated magnetic particles were incubated with sera and, after rinsing, with horseradish peroxidase (HRP) conjugated antibodies. The particles were magnetically collected and placed onto the surface of an electrode, where the enzymatic activity of HRP, if present, was detected [1]. Electrochemical point-of-care platform All components of the point-of-care platform were developed in this project. Disposable, acrylic 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. The electrodes were screen printed onto 0.5 mm acrylic substrates. The central working electrodes were designed to be aligned with neodymium magnets so as to concentrate the magnetic particles. The eight electrochemical cells, each one with a volume of 40 µl, were completed with an acrylic top piece (Fig. 1b).  The electronic instrumentation required to control the electrochemical system and process the resulting signal was presented elsewhere [2]. The electronic circuits are connected to a computer via a USB port (Fig. 1c).  A software was developed with the capability of recording amperometric measurements with potential steps and cyclic voltammetries.