Diagnosis of dengue infection using a modified gold electrode with hybrid organic–inorganic nanocomposite and Bauhinia monandra lectin

AbstractA sensitive and selective biosensor for dengue serotyping was successfully developed. The biosensor uses a novel gold nanoparticles-polyaniline hybrid composite (AuNpPANI) for the immobilization of Bauhinia monandra lectin (BmoLL). The nanocomposite was applied to a bare gold electrode surface by chemical adsorption, and BmoLL was subsequently electrostatically adsorbed to the nanocomposite-modified surface. Atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance (EI) techniques were applied to evaluate the immobilization of BmoLL on AuNpPANI. The AFM images for AuNpPANI-BmoLL-DEN systems indicate a homogenous, compact and dense film of the conjugate. In the EI analyses, an obvious difference of the electron transfer resistance between the AuNpPANI-modified electrode and the bare gold electrode was observed. Among three dengue serotypes studied, dengue serotype 2 (DEN2) has higher values for RCT, and lower values for both n and Q. These are indications of a larger blocking effect and smaller capacitive dispersion, resulting from the higher agglutination of glycoproteins from the DEN2 sera. The selective BmoLL recognition for various dengue serotypes may be attributed to different patterns of glycoproteins in the sera produced by the glycoprotein immunoresponse from patients infected by the dengue virus

Saline extract from Malpighia emarginata DC leaves showed higher polyphenol presence, antioxidant and antifungal activity and promoted cell proliferation in mice splenocytes.

Abstract: Currently, the research of new natural compounds with biological potential demonstrates great ethnopharmacological importance. In this study, we evaluated the biological properties promoted by saline extract from Malpighia emarginata DC leaves, whose objective is to evaluate the antioxidant, antimicrobial and cytotoxicity potential. Phytochemical characterization was performed by UPLC-MS chromatography to identify the chemical compounds. For the antioxidant potential, DPPH, ATT and FRAP methods were used. The antibacterial and antifungal tests were performed evaluating the MIC50, MIC90, CMB and CMF parameters. Moreover, antibiofilm action was evaluated. Cytotoxicity and proliferation were performed using splenocytes from Balb/c mice and were evaluated by cytometry. We found a list of phenolic compounds among other bioactive compounds in the M. emarginata saline extract. In addition, higher antioxidant profile and antifungal activity against different strains of Candida spp. was promoted by the saline extract. Splenocytes showed greater cell viability (more than 90%) and showed higher proliferate index in 24 and 48 hours of incubation with the extract. Saline extract from Malpighia emarginata DC has potential action like antioxidant and antifungal agent without promote animal cell damage