Biomechanochemical Solid-State Synthesis of Silver Nanoparticles with Antibacterial Activity Using Lichens

Abstract

A completely solid-state mechanochemical synthesis of silver nanoparticles overcoming the problem with water insolubility of lichen metabolites hampering their use for the classical green synthesis in water is shown herein. Four lichen species (Xanthoria elegans, Cetraria islandica, Usnea antarctica, and Leptogium puberulum) and AgNO3 were used as reducing agents and Ag(0) precursor, respectively. The reaction progress was rapid in the first two cases, whereas in the case of U. antarctica and L. puberulum, a significant amount of AgNO3 could still be detected after 6 h of milling. The products with a higher content of Ag(0) were shown to undergo a backward transformation documented by increasing content of AgNO3 with storage time; however, the repeated formation of Ag(0) could be observed upon remilling. Transmission electron microscopy analysis has shown bimodal nanocrystallite size distribution in all cases. However, the finer fraction was more abundant in the case of silver nanoparticles prepared using lichens with stronger reducing ability (X. elegans and C. islandica). All the products are excellent antibacterial agents. Whereas the as-received products exhibited higher activity against E. coli, the remilled samples were more active against S. aureus.

A Mini-Review on Lichen-Based Nanoparticles and Their Applications as Antimicrobial Agents

“…The biosynthesis of lichen-derived nanoparticles is gaining popularity these days: as the process does not involve use of any toxic chemicals, therefore, they can be safely used as pharmaceuticals (Kowalski et al, 2011). Researchers around the globe have been following different methodologies such as biomechanical and chemical solid-state synthesis for the synthesis of lichen-based nanoparticles (Baláž et al, 2020). Mie et al (2014) reported the synthesis of silver nanoparticles by the reduction of silver nitrate using aqueous extract of the lichen Parmotrema praesorediosum as a reductant as well as a stabilizer.…”

“…The characterization of nanoparticles, so formed, was carried out using techniques such as TEM, scanning electron microscopy (SEM), XRD, and FT-IR. Baláž et al (2020) reported the solid-state mechanochemical synthesis of silver nanoparticles using lichens Xanthoria elegans, C. islandica, Usnea antarctica, and Leptogium puberulum. The method involved milling of lichen sample and silver nitrate together in a pulverisette.…”

“…The nanoparticles exhibited significant bioactivity against E. coli and K. pneumoniae, but S. mutans, C. diphtheriae, and P. aeruginosa displayed resistance against them. Baláž et al (2020) reported that silver nanoparticles produced using Xanthoria elegans, Cetraria islandica, Usnea antarctica, and Leptogium puberulum were excellent antibacterial agents against E. coli and S. aureus. Alavi et al (2019) observed that Protoparmeliopsis muralisdriven metal (Ag and Cu) and metal oxide (TiO 2 , ZnO, and Fe 3 O 4 ) nanoparticles exhibited antibacterial, antibiofilm, antiquorum sensing, and antioxidant abilities against multidrug-resistant bacterium S. aureus and reference bacteria E. coli and P. aeruginosa.…”

“…Many reports are available on the synthesis of nanoparticles from different types of lichens, namely, Parmeliopsis ambigua, Punctelia subrudecta, Evernia mesomorpha, and Xanthoparmelia plitti (Dasari et al, 2013); Parmotrema praesorediosum (Mie et al, 2014); Cetraria islandica (Yıldız et al, 2014;Baláž et al, 2020); Ramalina dumeticola (Din et al, 2015); Acroscyphus sp. and Sticta sp.…”

“…and Sticta sp. (Debnath et al, 2016); Parmelia perlata (Leela and Anchana Devi, 2017); Usnea longissima (Siddiqi et al, 2018); Parmotrema tinctorum (Khandel et al, 2018); Parmelia sulcata (Gandhi et al, 2019); Protoparmeliopsis muralis (Alavi et al, 2019); Ramalina sinensis (Safarkar et al, 2020); Cladonia rangiferina (Devasena et al, 2014;Rai and Gupta, 2019); Pseudevernia furfuracea and Lobaria pulmonaria (Goga et al, 2020); Xanthoria elegans, Usnea antarctica, and Leptogium puberulum (Baláž et al, 2020); and Lecanora muralis (Abdullah et al, 2020).…”