Antimicrobial warnericin RK peptide functionalized GaAs/AlGaAs biosensor for highly sensitive and selective detection of Legionella pneumophila

Abstract

Detection of pathogenic Legionella pneumophila by culture-based methods is not efficient in predicting outbreaks of the Legionnaires’ disease. The main problem is the relatively slow time-to-result and the inability of some culture media to support the growth of viable bacteria. One strategy to alleviate these issues is developing biosensors functionalized with mammalian antibodies designed to capture bacteria. However, mammalian antibodies are known to suffer from batch-to-batch variations, as well as limited stability, which reduce the consistent utility of antibody-based biosensors. In an attempt to address this problem, we investigated antimicrobial peptides (AMPs) for capture of L. pneumophila with GaAs/AlGaAs biochips. The Fourier-transform infrared spectroscopy measurements revealed that the peptides were covalently immobilized on the 1-ethyl-3-(-3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide activated −COOH terminals of mercaptohexadecanoic acid self-assembled monolayer functionalized GaAs surface. The efficiency of the specific interaction between the peptide and L. pneumophila, E. coli, B. subtilis and P. fluorescens was investigated with fluorescence microscopy and a digital photocorrosion GaAs/AlGaAs biosensor. We found that the warnericin RK peptides exhibited ∼5 times greater binding affinity towards L. pneumophila than to the other bacteria investigated. Furthermore, detection level as low as 103 CFU/mL was possible with the proposed biosensor architecture. We argue that a biosensor based on warnericin RK AMP peptides offers an attractive alternative solution in comparison to antibody-based devices towards detection of L. pneumophila.