(Copyright NanoCMM Technology)
Antimicrobial Achievements –
Nano silver or Silver nanoparticles (AgNPs) have emerged as an alternative to antimicrobial agents and are capable of overcoming bacterial resistance to antibiotics. Therefore, there is a need to expand the use of AgNPs as an antimicrobial agent.
Among the various promising nanomaterials, nano-silver appears as a potential drug because of their large mass upper surface area and crystal surface structure.
The work of Sondi and Salopek-Sondi [39] confirmed the antibacterial activity of AgNPs against Escherichia coli when E. coli cells treated with AgNPs showed accumulation of AgNPs into cell walls and the formation of “pits” in the bacterial cell wall, and ultimately leading to cell death. In the same deformed E.coli, smaller particles with a larger surface-to-volume ratio showed more effective antimicrobial activity than larger particles [40].
Furthermore, the antibacterial activity of nano-silver was not only size-dependent but also shape-dependent [41]. Nano silver synthesized by four different saccharides with an average size of 25 nm, showed high antibacterial and bactericidal activity against Gram-positive and Gram-negative bacteria, including highly resistant strains such as methicillin-resistant Staphylococcus aureus. .
As previously predicted, not only is size important to determine efficiency, but shape is also important to determine effectiveness, as AgNPs undergo a shape-dependent interaction with Gram-negative microorganisms. coli [42].
Furthermore, a detailed study was performed to investigate the efficacy of the antibacterial effects of AgNPs against yeasts, E. coli and Staphylococcus aureus and concluded that, at low concentrations of AgNPs, inhibition Complete growth was observed in yeast and E. coli, while a mild effect was observed for S. aureus [43].
Bio-synthetic silver nanoparticles from culture fluids of Klebsiella pneumoniae were evaluated; the effectiveness of various antibiotics, such as penicillin G, amoxicillin, erythromycin, clindamycin and vancomycin against Staphylococcus aureus and E. coli was increased with AgNPs [25].
When compared with AgNPs, hydrogel-silver nanomaterials exhibit excellent antibacterial activity against E. coli. The general synthesis of nano-chitosan-nano Ag mixture was found to have higher antibacterial activity than its components at the respective concentrations, because the general synthesis supports the formation of small AgNPs, which bind to the polymer, can be dispersed in environment pH≤6,3 [44].
AgNPs are biologically produced using the surface culture method of Staphylococcus aureus, illustrating significant antibacterial activity against methicillin-resistant S. aureus, followed by methicillin-resistant Staphylococcus epidermidis (MRSE) and Streptococcus pyogenes, while only Moderate antibacterial activity was observed against Klebsiella pneumoniae and Salmonella typhi [45].
The mechanism of cell death due to nano-silver has been observed in E. coli through the leakage of reducing sugars and proteins. In addition, AgNP is capable of destroying the permeability of bacterial membranes by creating holes and voids, suggesting that AgNP can damage the structure of bacterial cell membranes [17].
Silver nanocrystalline chlorhexidine (AgCHX) complexes showing strong antibacterial activity against Gram-positive / negative and resistant to methicillin-resistant Staphylococcus aureus (MRSA) strains. Interestingly, the minimum inhibitory concentration (MIC) of Ag (III) CHX nanocrystals is much lower than the ligand (CHX), AgNO3, gold standard and silver sulfadiazine [46].
Biofilms not only lead to resistance, but have also been linked to the development of eye-related infectious diseases, such as bacterial keratitis [47]. Kalishwaralal et al. Demonstrated potential anti-biologic potential against Pseudomonas aeruginosa and Staphylococcus epidermidis.
Similarly, guava leaf extract reduced AgNPs (Gr-Ag-NPs) which was evidence for significant antimicrobial activity and stability against E. coli compared to chemically synthesized AgNPs; The reason for this higher activity may be due to the adsorption of biological molecules on the surface of Gr-Ag-NPs [48]. Nano silver synthesized by Cryphonectria sp. demonstrated antibacterial activity against many infectious microorganisms, as well as E.coli, S. aureus, Candida albicans and Salmonella typhi. Interestingly, the AgNPs exhibited higher antibacterial activity against both S. aureus and E. coli in addition to S. typhi and C. albicans.
Potential silver nanoparticles for anti-biofilm activity are consistent with “Pseudomonas aeruginosa” and “Staphylococcus epidermidis”. Similarly, guava leaf extract reduced AgNPs (Gr-Ag-NPs) showing significant antibacterial activity and stability against E. coli in contrast to chemically synthesized AgNPs; The reason may be due to the higher adsorption of bio-molecules on the surface of Gr-Ag-NPs [48].
AgNPs synthesized by Cryphonectria sp. explains antimicrobial activity against diverse human pathogenic bacteria, enumerating S. aureus, E. coli, Salmonella typhi and Candida albicans. Interestingly, these particular AgNPs exhibited higher antibacterial activity against both S. aureus and E. coli compared with S. typhi and C. albicans.
Achievements against fungus – Fungal infections
occurs more often in immunosuppressed patients and overcoming fungal diseases is a tedious process, because there are currently a limited number of antifungal agents [30].
Therefore, there is a clear and consistent requirement for antifungal development to be biocompatible, non-toxic and environmentally friendly.
To overcome this problem, nano-silver plays an important role as an anti-fungal agent against various diseases caused by fungi. Nano-Ag illustrates effective antifungal activity alongside clinical isolates and “ATCC” strains of “Trichophyton mentagrophytes” and “Candida” species with concentrations of 1-7 μg / mL.
Esteban-Tejeda et al. [49] developed an inert substrate containing AgNPs with an average size of 20 nm into a glass of soda-lime to increase bactericidal activity. Monodisperse Nano-Ag sepiolite fiber exhibits significant antifungal activity against Issatchenkia orientalis.
AgNPs exhibited excellent antifungal activity against Aspergillus niger with an MIC of 25 μg / ml against Candida albicans [50]. Bio-synthesized AgNP shows outstanding antifungal activity with “fluconazole” against “Phoma glomerata”, “Phoma herbarum”, “Fusarium semitectum”, “Trichoderma sp.” And Candida albicans [51].
Silver nanoparticles stabilized by sodium dodecyl sulfate showed enhanced antifungal activity against Candida albicans compared with conventional antifungal agents [52]. The size-dependent antifungal activities of different AgNPs are performed alongside mature “Candida albicans” and “Candida glabrata” biofilms.
Bio-synthesized AgNP exhibits antifungal activity against a variety of pathogenic plant fungi, as well as alternative fungi Alternaria, Sclerotinia sclerotiorum, Macrophomina phaseolina, Rhizoctonia solani, Botrytis cinerea and Curvularia lunata at fifteen concentrations. mg [53-54].
Similarly, silver nanoparticles synthesized by Bacillus species exhibited strong antifungal activity against the fungal plant pathogen Fusarium oxysporum at a concentration of 8 g / mL [55]. The antifungal effect of Silver Nano is estimated when combined with “nystatin” (NYT) or “chlorhexidine” (CHX) against biofilm Candida albicans and Candida glabrata. Results from this investigation showed that AgNPs in combination with nystatin (NYT) or chlorhexidine digluconate (CHG) showed better synergistic activity against biofilm; however, activity was species and drug concentration dependent [56].
The biosynthetic silver nanoparticles showed antifungal activity in addition to “Bipolaris sorokiniana” by inhibiting spore germination [57]. Interestingly, nano silver not only inhibit human and plant pathogenic fungi, Penicillium brevicompactum, Aspergillus fumigatus, Cladosporium cladosporoides, Chaetomium globosum, Stachybotrys chartarum, and Mortierella alpine were cultured on agar [58].
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