Impedimetric Screen-Printed Immunosensor for the Rapid Detection of Chagas Disease

Chagas disease (CD) is an endemic parasitic condition affecting Latin America and recently Europe caused by the Trypanosoma cruzi (T. cruzi). This work proposes a new impedimetric immunosensor for the rapid, cost-effective, label-free, and low-volume detection of specific anti- T. cruzi antibodies, used as biomarkers of CD in human serum. The biosensor is based on gold screen-printed electrodes that are functionalized with isolated cruzipain (CrP) proteins by adsorption, following a highly reproducible 40 min chemical procedure. The biosensor is tested with clinical serum samples from patients with (positive) or without (negative) anti- T. cruzi antibodies as previously verified by ELISA testing. The detection is performed through electrochemical impedance spectroscopy (EIS), showing ~22% variation of the charge transfer resistance (
${R}_{\text {ct}}$
) for positive human serum due to the immunoreaction between the immobilized CrP and the specific antibodies contained in the samples. Based on the cutoff value of
${R}_{\text {ct}}$
ratios, the developed immunosensor is capable of successfully discriminating positive and negative human serum samples at a dilution factor of 1/6400 in phosphate-buffered saline (PBS) solution, showing an excellent agreement with the ELISA results.