Label-free nanostructured biosensor for Schistosoma mansoni detection in complex biological fluids.

Schistosomiasis is a neglected tropical disease with a worldwide prevalence. Neuroschistosomiasis is the most severe presentation of the disease and affects the central nervous system. In this work, Schistosoma mansoni detection was based on self-assembled layers of 3-mercaptopropyltrimethoxysilane (MPTS) and electrosynthesized gold nanoparticles (AuNPs). The DNA probe was chemisorbed onto AuNPs. The biosensor was characterized by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). The impedimetric response of the MPTS-AuNPs-DNA system indicates an effective modification of the electrode surface. Topographical atomic force microscopy images were used to characterize the self-assembled layers on the gold electrode surface. The proposed biosystem was able to recognize the S. mansoni genome sequence at different concentrations in samples of urine, cerebrospinal fluid, and serum. Several concentration ranges were evaluated: urine (27-50 pg μL), cerebrospinal fluid (25-60 pg μL), and serum (27-42 pg μL). The limit detection (LOD) of the biosensor was 0.6 pg μL. The developed label-free genosensor was able to detect small concentrations of S. mansoni DNA in complex biological fluids.