Size and Shape-Dependent Antimicrobial Activities of Silver and Gold Nanoparticles: A Model Study as Potential Fungicides

Abstract

Plant-based pathogenic microbes hinder the yield and quality of food production. Plant diseases have caused an increase in food costs due to crop destruction. There is a need to develop novel methods that can target and mitigate pathogenic microbes. This study focuses on investigating the effects of luteolin tetraphosphate derived silver nanoparticles (LTP-AgNPs) and gold nanoparticles (LTP-AuNPs) as a therapeutic agent on the growth and expression of plant-based bacteria and fungi. In this study, the silver and gold nanoparticles were synthesized at room temperature using luteolin tetraphosphate (LTP) as the reducing and capping agents. The synthesis of LTP-AgNPs and LTP-AuNP was characterized by Transmission Electron Microscopy (TEM) and size distribution. The TEM images of both LTP-AgNPs and LTP-AuNPs showed different sizes and shapes (spherical, quasi-spherical, and cuboidal). The antimicrobial test was conducted using fungi: Aspergillus nidulans, Trichaptum biforme, Penicillium italicum, Fusarium oxysporum, and Colletotrichum gloeosporioides, while the class of bacteria employed include Pseudomonas aeruginosa, Aeromonas hydrophila, Escherichia coli, and Citrobacter freundii as Gram (−) bacteria, and Listeria monocytogenes and Staphylococcus epidermidis as Gram (+) bacterium. The antifungal study demonstrated the selective size and shape-dependent capabilities in which smaller sized spherical (9 nm) and quasi-spherical (21 nm) AgNPs exhibited 100% inhibition of the tested fungi and bacteria. The LTP-AgNPs exhibited a higher antimicrobial activity than LTP-AuNPs. We have demonstrated that smaller sized AgNPs showed excellent inhibition of A. nidulans growth compared to the larger size nanoparticles. These results suggest that LTP-AuNP and LTP-AgNPs could be used to address the detection and remediation of pathogenic fungi, respectively.

Nanoparticles as therapeutic options for treating multidrug-resistant bacteria: research progress, challenges, and prospects

“…Nanoparticles with size < 10 nm can penetrate to the interior of the bacterial cell and exert their antibacterial effect (Khalandi et al 2017), while that > 10 nm cannot penetrate the interior of the bacterial cell (Butler et al 2015;Wang et al 2011). A recent investigation by Osonga et al (2020) reported that the antimicrobial activities of AgNps and AuNps were dependent on size, with no associated toxicity. Furthermore, the surface charge of nanoparticles is also a crucial factor affecting their antimicrobial activity (Abbaszadegan et al 2015).…”

Cetyltrimethylammonium Bromide (CTAB)-Loaded SiO2–Ag Mesoporous Nanocomposite as an Efficient Antibacterial Agent

“…Silver nanoparticles (Ag NPs) are considered to be efficient antibacterial agents with prolonged activity against various pathogens [ 2 ]. Recent studies have demonstrated that Ag NPs exhibit size- and shape-dependent antimicrobial activity [ 3 , 4 , 5 ]. In summary, small-sized Ag NPs (up to ~20 nm) demonstrated the highest bactericidal effects compared to larger counterparts.…”

Citrate-silver nanoparticles and their impact on some environmental beneficial fungi

“…Due to the localized surface plasmon resonance effect, AgNPs have been used, for example, to color merino wool fibers, leading to novel AgNP-wool composite materials with different colors depending on AgNP size and their interaction with keratin from wool fibers ( Kelly and Johnston, 2011 ); nevertheless disinfectant features have been conferred to those fabrics ( Pietrzak et al, 2016 ). Numerous applications were developed in the life sciences research, based on AgNPs as source of silver, such as in pharmacy, cosmetics, sanitation, wastewater treatment, etc., ( Tylkowski et al, 2017 , Bapat et al, 2018 , Kaur et al, 2018 , Huang et al, 2020 , Al-Zubaidi et al, 2019 , Osonga et al, 2020 , Bernardo-Mazariegos et al, 2019 ). Generally silver ions were found to be the actual active agent, when released from silver nanoparticles (AgNPs) – since there is no final statement that nanoparticles themselves have antimicrobial or antifungal activity ( Ivask et al, 2014 , Mittelman et al, 2015 )).…”