Amperometric Detection of Pathogen Causing Rheumatic Heart Disease

Rheumatic heart disease (RHD) is the damage of mitral or aortic heart valves due to delayed treatment of rheumatic fever. Streptococcus pyogenes, representative of Group A Streptococcus is the causative agent of the disease. The current diagnostic methods are either have some limitations or non-confirmatory due to single test. Hence, nucleotide based sensors may serve as reliable and rapid method for the diagnosis of the RHD disease. A 5´carboxyl labeled single stranded DNA probe complementary to mga gene of pathogen Streptococcus pyogenes was immobilized on screen printed gold electrode modified with mercaptopropionic acid and poly (amidoamine) dendrimer. Genomic DNA of pathogen was isolated from throat swab of suspected RHD patients and denatured at 94°C to make single strand DNA for hybridization with immobilized probe using redox indicator and electrochemical response was measured amperometrically using cyclic voltammetry. The sensitivity of the sensor was found 743 (μA/cm2)/ng and limit of detection was 0.18 pg/6 μL with regression coefficient (R2) 0.9622. The sensor was found highly specific to S. pyogenes and stable upto six months on storage at 4°C with only 10% loss in initial activity.