Nanostructured Biosensor Based on Multiwalled Carbon Nanotubes and Antimicrobial Peptide Temporin-PTA for Bacterial Detection

Abstract

Bacterial infections represent a major public health challenge due to treatment difficulties and resistance spread. Antimicrobial peptides (AMPs) offer innovative applications in biosensors, since their interaction with microbial membranes can be detected by electrochemical changes. This study developed a nanostructured sensor using multiwalled carbon nanotubes (MWCNTs) and the antimicrobial peptide Temporin-PTA (T-PTA), derived from Hylarana picturata skin secretion. MWCNTs were electrodeposited on electrodes via cyclic voltammetry (CV) in acidic dispersion, improving electron kinetics and enabling chemical immobilization of T-PTA. The system was applied to detect Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis and Staphylococcus aureus in a label-free electrochemical assay. Electrochemical impedance spectroscopy (EIS) and CV confirmed sensor assembly and interaction with different bacterial concentrations. Complementary analyses with atomic force microscopy (AFM) and Fourier-transform infrared spectroscopy (FTIR) evaluated gradual adhesion of platform components. The biosensor detected concentrations from 10¹ to 10⁵ CFU/mL within only 5 min. Notably, the electrochemical signal was stronger for Gram-negative bacteria, particularly P. aeruginosa, consistent with T-PTA's affinity for electronegative surfaces. This system demonstrated rapid, sensitive, and selective detection, distinguishing Gram-negative from Gram-positive species. Such characteristics highlight its potential as a valuable complement to gold-standard microbiological methods.