Spectroscopic Study on Pseudomonas Aeruginosa Biofilm in the Presence of the Aptamer-DNA Scaffolded Silver Nanoclusters.

Bidisha Sengupta,Ronald Havner,Esther Mallet,Prabhakar Pradhan,Prakash Adhikari

doi:10.3390/molecules25163631

Bidisha Sengupta, Ronald Havner + Show 3 more

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https://doi.org/10.3390/molecules25163631

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Abstract

We report the effectiveness of silver nanocluster (Ag-NC) against the biofilm of Pseudomonas aeruginosa (PA). Two DNA aptamers specific for PA and part of their sequences were chosen as templates for growing the Ag-NC. While circular dichroism (CD) studies determined the presence of secondary structures, UV/Vis absorption, and fluorescence spectroscopic studies confirmed the formation of the fluorescent Ag-NC on the DNA templates. Furthermore, mesoscopic physics-based partial wave spectroscopy (PWS) was used to analyze the backscattered light signal that can detect the degree of nanoscale mass density/refractive index fluctuations to identify the biofilm formation, comparatively among the different aptamers with respect to the control sample. The importance of the secondary structure of the aptamer DNA in targeting, successfully binding with the cells and delivering the Ag-NC, is evidenced by the decrease in disorder strength (Ld) of the Ag-NC treated samples compared to the untreated PA cells, which showed the abundance of higher Ld in the PWS studies. The higher Ld value attributed to the higher mass density fluctuations and the formation of biofilm. We envision this study to open a new avenue in using a powerful optical microscopic technique like PWS in detection, and DNA aptamer enclosed silver nanoclusters to prevent biofilms for opportunist pathogens like Pseudomonas aeruginosa.

Highlights

IntroductionPseudomonas aeruginosa (Gram-negative bacteria) [3] forms biofilms by synthesizing three different polysaccharides—namely, alginate, Psl, and Pel—which help in the attachment of bacterial cells to the biotic or abiotic surface to make the highly structured multispecies communities [4,5,6,7] called biofilm
We have developed a novel method to detect the biofilm of Pseudonomas aeruginosa by using the backscattered photons—a technique called partial wave spectroscopy (PWS)—which has come into high prominence in recent years
We have proved that DNA aptamers can fruitfully be designed and exploited to make very small silver nanoclusters which can penetrate the exopolysaccharide matrix of the Pseudomonas aeruginosa (PA)

Summary

Introduction

Pseudomonas aeruginosa (Gram-negative bacteria) [3] forms biofilms by synthesizing three different polysaccharides—namely, alginate, Psl, and Pel—which help in the attachment of bacterial cells to the biotic or abiotic surface to make the highly structured multispecies communities [4,5,6,7] called biofilm. These exopolysaccharides (EPS) protect multicellular aggregates from environmental stresses such as mechanical desiccation, pH shifts, osmotic shock, and UV radiation [6,7]. These threats include loss of host immune responses followed by chronic infections and even death in humans as well as causes major contaminations in the hospital, food, and environmental industries [8,9]

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