No abstract

The genusUsneaAdans. (Parmeliaceae; lichenized Ascomycetes) is a typical group of mostly pale grayish-green fruticoselichens that grow as leafless mini-shrubs.

The continuous use of silver nanoparticles (AgNPs) induces drug-resistance in pathogenic bacteria, resulting in the recurrence of biofilms, making them difficult to eradicate. AgNPs in higher concentrations are also toxic to cells. Therefore, an approach that can modulate bacterial quorum sensing (QS) signaling–NP interactions, thereby reducing the production of bacterial pathogenicity traits and minimizing the dose of NPs to suppress bacterial adhesion and colonization, is upmost welcomed. The present work follows an approach where AgNPs are decorated with endolichenic fungus-derived anti-QS chrysophanol (CP-AgNPs) that increases chrysophanol bacterial QS signaling interactions. The advantage of this approach lies in enhancing and long-term preventing bacterial adhesion and subsequent colonization of urinary catheters (UCs) mediated by CP-AgNPs through the inhibition of QS signaling as compared to that with citrate-capped AgNPs (Cc-AgNPs) alone. The anti-adhesion and anti-biofouling effects of CP-AgNPs-coated UC surfaces were assessed for the growth of Pseudomonas aeruginosa PAO1 and Escherichia coli under both static and flow conditions. The CP-AgNPs-coated latex and silicone surfaces showed greater than 9-fold anti-adhesion and anti-biofouling effects than the Cc-AgNPs-coated UCs, which shows the practical applicability of this strategy. These effects of CP-AgNPs influenced the surface hydrophobicity, eDNA content, lipopolysaccharide (LPS) production, and virulence gene expression of bacterial biofilm cells, which reduced biofilm invasion and formation. The CP-AgNPs-coated UCs did not induce toxicity in human bladder fibroblast cells, indicating massive biocompatibility. Eventually, the CP-AgNPs system was successfully applied to prevent bacterial biofilm formation in vivo. Thus, the CP-AgNPs reveal their strong use as anti-adhesion and anti-biofouling coating materials, demonstrating their great potential to prevent UC-associated urinary tract infections.

Herbo-metallic preparations such as bhasmas (ash) are used traditionally in Indian and Chinese medicinal systems.