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A simple nanostructured biosensor based on clavanin A antimicrobial peptide for gram-negative bacteria detection

de Miranda, Juliana L., Oliveira, Maria D.L., Oliveira, Idjane S., Frias, Isaac A.M., Franco, Octavio L., Andrade, Cesar A.S.
Biochemical engineering journal 2017 v.124 pp. 108-114
Enterococcus faecalis, Escherichia coli, Gram-negative bacteria, Salmonella Typhimurium, Staphylococcus aureus, adsorption, antimicrobial peptides, biosensors, death, dielectric spectroscopy, electrodes, microbial detection, morbidity, nanogold, patients
Nosocomial infections are the leading cause of morbidity and death among hospitalized patients. The main opportunistic bacteria are Escherichia coli, Salmonella typhimurium, Enterococcus faecalis and Staphylococcus aureus. In this work, the authors report the use of clavanin A (ClavA) peptide and cysteine-modified gold nanoparticles (AuNPsCys) for the development of a sensitive biosensor for Gram-negative (BGN) bacteria detection. The stages of electrode modification were evaluated by using electrochemical impedance spectroscopy (EIS) in the frequency range of 100mHz–100kHz, through the gradual increase of the charge transfer resistance (RCT) after adsorption of the system components. The higher levels of response were observed for S. typhimurium and E.coli. In addition, cyclic voltammetry technique (CV) in the scan range −0.2V–0.7V was also used. The gold bare electrode shows well-defined anodic and cathodic peak currents. Subsequently, a reduction of the peak currents was observed after adsorption of NpsCysClavA composite and being more expressed after adsorption of S. typhimurium and E. coli. Additionally, solutions with increasing concentration of each bacteria were tested. Our results indicate that the sensor effectively differentiates concentrations between 10¹ to 10⁴ CFU. Therefore, the proposed biosensor is a viable and simple alternative for bacterial detection with a possible use for quantitative detection.