Development of Folate-Group Impedimetric Biosensor Based on Polypyrrole Nanotubes Decorated with Gold Nanoparticles.

In this study, polypyrrole nanotubes (PPy-NT) and gold nanoparticles (AuNPs) were electrochemically synthesized to form a hybrid material and used as an electroactive layer for the attachment of proteins for the construction of a high-performance biosensor. Besides the enhancement of intrinsic conductivity of the PPy-NT, the AuNPs act as an anchor group for the formation of self-assembly monolayers (SAMs) from the gold-sulfur covalent interaction between gold and Mercaptopropionic acid (MPA). This material was used to evaluate the viability and performance of the platform developed for biosensing, and three different biological approaches were tested: first, the Avidin-HRP/Biotin couple and characterizations were made by using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), wherein we detected Biotin in a linear range of 100-900 fmol L-1. The studies continued with folate group biomolecules, using the folate receptor α (FR-α) as a bioreceptor. Tests with anti-FR antibody detection were performed, and the results obtained indicate a linear range of detection from 0.001 to 6.70 pmol L-1. The same FR-α receptor was used for Folic Acid detection, and the results showed a limit of detection of 0.030 nmol L-1 and a limit of quantification of 90 pmol L-1. The results indicate that the proposed biosensor is sensitive and capable of operating in a range of clinical interests.

A brief review on the strategy of developing SPR-based biosensors for application to the diagnosis of neglected tropical diseases.

The phenomenon of surface plasmon resonance (SPR) through optical sensors was developed from initial studies involving excitation of surface plasmons on metallic substrates. From the beginning, these optical systems have attracted increasing interest for application in different areas, ranging from physics, chemistry, and materials science to biology. Although numerous applications have been explored, the use of SPR in the development of biosensors is by far the most prominent. This review provides a brief account of fundamental aspects related to the recent applications of SPR as a tool for the development of new clinical diagnosis methods. The applications of SPR biosensors were illustrated through recent studies published in the field of neglected tropical diseases, with an emphasis on the contributions achieved in visceral leishmaniasis. It was possible to demonstrate the real benefits and the difficulties that the SPR biosensors have encountered in this important and complex system. Finally, future trends in the use of nanomaterials for the development of SPR-based portable devices for application to neglected tropical diseases have been demonstrated.