Photoluminescence-Based Bioassay With Cysteamine-Capped TiO2 Nanoparticles for the Selective Recognition of N-Acyl Homoserine Lactones.

Sahana Vasudevan,John Bosco Balaguru Rayappan,Adline Princy Solomon,Parthasarathy Srinivasan,Parthasarathy Srinivasan,Prasanna Neelakantan

doi:10.3389/fbioe.2021.750933

Sahana Vasudevan, John Bosco Balaguru Rayappan + Show 4 more

Open Access

https://doi.org/10.3389/fbioe.2021.750933

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Abstract

Currently available diagnostic procedures for infections are laborious and time-consuming, resulting in a substantial financial burden by increasing morbidity, increased costs of hospitalization, and mortality. Therefore, innovative approaches to design diagnostic biomarkers are imperative to assist in the rapid and sensitive diagnosis of microbial infections. Acyl homoserine lactones (AHLs) are ubiquitous bacterial signaling molecules that are found to be significantly upregulated in infected sites. In this pioneering work, we have developed a simple photoluminescence-based assay using cysteamine-capped titanium oxide (TiO2) nanoparticles for AHL detection. The PL intensity variation of the oxygen defect state of TiO2 was used for the biosensing measurements. The bioassays were validated using two well-studied AHL molecules (C4-HSL and 3-oxo-C12 HSL) of an important human pathogen, Pseudomonas aeruginosa. The developed system has a maximum relative response of 98%. Furthermore, the efficacy of the system in simulated host urine using an artificial urine medium showed a linear detection range of 10–160 nM. Also, we confirmed the relative response and specificity of the system in detecting AHLs produced by P. aeruginosa in a temporal manner.

Highlights

Quorum sensing (QS) is a well-synchronized communication process that exists among bacteria to mediate the infection process in the host niches (Azimi et al, 2020)
The position of diffraction peaks corresponding to both TiO2 and cysteamine-capped TiO2 nanoparticles was shifted to the lower angles 2θ ±0.2° due to the lattice mismatching, which, in turn, induce the lattice distortion
The alarming increase in life-threatening infections necessitates the growing need for immediate infection diagnosis. This requires the advent of point-of-care diagnostics that are rapid and non-invasive with minimal or no sample processing. This is the first study to report the bioassay based on cysteamine-capped TiO2 nanoparticles to identify the quorum sensing signaling molecule, Acyl homoserine lactones (AHLs)

Summary

Introduction

Quorum sensing (QS) is a well-synchronized communication process that exists among bacteria to mediate the infection process in the host niches (Azimi et al, 2020). A classic example of AHL-based communication is Pseudomonas aeruginosa, which is the predominant infectious agent of cystic fibrosis (Lee and Zhang, 2015) and is a dominant pathogen found in chronic wound infections (Klockgether and Tümmler, 2017), urinary tract infections (Mittal et al, 2009), and bacteremia (Tuon et al, 2012). This bacterium produces two AHL signals, C4-HSL and 3-oxo-C12 HSL. 3-oxo-C12 HSL is synthesized and determined by LasI and LasR, respectively (Papenfort and Bassler, 2016)

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