Effective inhibition and eradication of pathogenic biofilms by titanium dioxide nanoparticles synthesized using Carum copticum extract.

Most bacteria exist in nature in the form of biofilms. One of the key survival strategies by bacteria to withstand chemical and physical stresses is by forming biofilms on biotic and abiotic surfaces. A different set of genes are expressed in biofilms compared to the planktonic mode of bacterial growth. According to data from the National Institutes of Health (NIH) and Centers for Disease Control and Prevention (CDC), nearly 80 percent of all human infections are encouraged by biofilms and roughly 65 percent of all hospital-acquired infections are associated with biofilms. Hence, considering the role of biofilms in clinical settings, there is an urgent need for the discovery/development of novel antibiofilm agents. In this study, we have tested the effect of freshly prepared titanium dioxide nanoparticles (TiO2-NPs) synthesized using Carum copticum extract on biofilms, both against Gram +ve and Gram -ve bacteria. Being environment friendly in nature, the green route of nanoparticle synthesis is believed to be advantageous over chemical synthesis of metal nanoparticles. The synthesized nanoparticles were found to be predominantly spherical or spheroidal in shape with an average size of 12.01 ± 5.58 nm. As evident from data, more than 70% inhibition of biofilms of test bacteria was achieved in the presence of TiO2-NPs. Electron microscopic analysis revealed that the adherence and colonization of bacteria on the glass surface were remarkably reduced by the treatment of TiO2-NPs. The EPS secretion of E. coli ATCC 25922 and P. aeruginosa PAO1 were inhibited by 62.08 and 74.94%, respectively. The EPS secretion of S. aureus MTCC 3160 was least inhibited (<55%) compared to other test bacteria. Moreover, TiO2-NPs successfully eradicated the preformed biofilms of E. coli ATCC 25922, P. aeruginosa PAO1, and S. aureus MTCC 3160 by 60.09, 64.14, and 48.30%, respectively. The findings demonstrate the efficacy of green synthesized titanium dioxide nanoparticles in inhibiting and eradicating the biofilms of bacterial pathogens and they may be further exploited for the development of a new alternative antibiofilm agent.

Biofabricated silver nanoparticles exhibit broad-spectrum antibiofilm and antiquorum sensing activity against Gram-negative bacteria.

The emergence and spread of antimicrobial resistance (AMR) among bacterial pathogens have created a global threat to human health and the environment. Targeting the quorum sensing (QS) linked virulent traits of bacteria is considered to be a novel approach for addressing the problem of AMR. In this study, green synthesized silver nanoparticles (AgNPs-MK) were evaluated for the inhibition of the formation of biofilms and quorum sensing controlled virulence factors against three Gram negative bacteria. Remarkable inhibition (>80%) of QS-mediated violacein production was recorded in C. violaceum 12472. Up to 90% inhibition of the QS-mediated virulent traits of S. marcescens MTCC 97 was observed. The virulence factors of P. aeruginosa PAO1 also decreased in a dose dependent manner in the presence of AgNPs-MK. Moreover, the development of biofilms of C. violaceum 12472, S. marcescens MTCC 97, and P. aeruginosa PAO1 was reduced by 87.39, 81.54, and 71.34%, respectively. Biofilms on glass surfaces were remarkably reduced, with less aggregation of bacterial cells and the reduced formation of extra polymeric substances. The findings clearly show the efficacy of AgNPs-MK against the development of biofilms and the QS mediated virulent traits of Gram negative bacterial pathogens. AgNPs-MK may be further exploited for the development of alternative antimicrobial agents after careful scrutiny in animal models for the management of bacterial infections, especially for topical applications.