Rapid Colorimetric Detection of <i>Pseudomonas aeruginosa</i> in Clinical Isolates Using a Magnetic Nanoparticle Biosensor

Abstract

A rapid, sensitive, and specific colorimetric biosensor based on the use of magnetic nanoparticles (MNPs) was designed for the detection of <i>Pseudomonas aeruginosa</i> in clinical samples. The biosensing platform was based on the measurement of <i>P. aeruginosa</i> proteolytic activity using a specific protease substrate. At the N-terminus, this substrate was covalently bound to MNPs and was linked to a gold sensor surface via cystine at the C-terminus of the substrates. The golden sensor appears black to naked eyes because of the coverage of the MNPs. However, upon proteolysis, the cleaved peptide-MNP moieties will be attracted by an external magnet, revealing the golden color of the sensor surface, which can be observed by the naked eye. In vitro, the biosensor was able to detect specifically and quantitatively the presence of <i>P. aeruginosa</i> with a detection limit of 10² cfu/mL in less than 1 min. The colorimetric biosensor was used to test its ability to detect in situ <i>P. aeruginosa</i> in clinical isolates from patients. This biochip is anticipated to be useful as a rapid point-of-care device for the diagnosis of <i>P. aeruginosa</i>-related infections.