Favorably orienting recombinant proteins to develop amperometric biosensors to diagnose Chagas' disease.
Clinical immunoassays often display suitable sensitivity but some lack of specificity or vice versa. As a trade-off between specificity improvement and sensitivity loss, biosensors were designed to perform indirect immunoassays with amperometric detection using tailor-made chimeric receptors to react with the analyte, specific anti-Trypanosoma cruzi immunoglobulin G (IgG). Recombinant chimeras were designed to favor their oriented covalent attachment. This allows the chimeras to properly expose their epitopes, to efficiently capture the analyte, and to withstand severe chemical treatment to reuse the biosensors. By further binding the secondary antibody, horseradish peroxidase-labeled anti-human IgG, in the presence of the soluble mediator and the enzyme substrate, a current that increased with the analyte concentration was measured. Biosensors using the chimeric constructions showed 100% specificity with samples that had revealed false-positive results when using other bioreceptors. A protein bearing a poly-Lys chain and thioredoxin as directing elements displayed the highest signal-to-noise ratio (P<0.05). The limit of detection was 62 ng ml⁻¹, which is eight times lower than that obtained with a currently used commercial Chagas enzyme-linked immunosorbent assay (ELISA) kit. Reusability of the biosensor was assessed. The signal was approximately 80% of the original one after performing 10 consecutive determinations.
Belluzo
María Soledad
MS
Departamento de Química Analítica, Universidad Nacional de Rosario, Argentina.
Ribone
María Élida
MÉ
Camussone
Cecilia
C
Marcipar
Iván Sergio
IS
Lagier
Claudia Marina
CM
D000595:Amino Acid Sequence; D000913:Antibodies, Protozoan / Q000276:immunology; D000953:Antigens, Protozoan / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015374:Biosensing Techniques / Q000379:methods*; D014355:Chagas Disease / Q000175:diagnosis*; D055664:Electrochemical Techniques / Q000379:methods*; D004566:Electrodes; D006801:Humans; D007118:Immunoassay / Q000379:methods; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D014349:Trypanosoma cruzi / Q000378:metabolism
D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D011994:Recombinant Proteins