Biogenic Synthesis of Antibacterial, Hemocompatible, and Antiplatelets Lysozyme Functionalized Silver Nanoparticles through the One-Step Process for Therapeutic Applications

Bacteriocin isolated from Ralstonia mannitolilytica and bacteriocin-capped silver nanoparticles: Comparative effects on biofilm formation and LuxS Gene's expressions by Proteus mirabilis as an approach to counter MDR catheter infection

Among undesirables in treating certain infections and diseases is the contamination of catheters, especially of the microbes' resistance to drugs. The situation has necessitated the search for alternative antimicrobial agents. Bacteriocin category, antibiotic-originate, peptide-natured, Ralstonia mannitolilytica microbes-produced, bacteriocin material, and the semi-pure bacteriocin capped silver metal nanoparticles (AgNPs) were used for combating the MDR (multi drug resistance) organism, Proteus mirabilis, which is the third-most common cause of UTI (urinary tract infection), and that is linked to catheter use, are being recommended for clinical use with certain development. The crude microbial product was isolated from the microbial entity, Ralstonia mannitolilytica, which grows in crude petroleum-contaminated soil, and was semi-purified for use in the synthesis of the bacteriocin-capped AgNPs. The prepared nanoparticles were characterized using X-ray diffraction, indicating the silver element's presence; field emission scanning electron microscopy, revealing near-spherical but irregular shapes of the bacteriocin-capped AgNPs with a size range of 34-46 nm; and atomic force microscopic analysis, which demonstrated the nanoparticles surface characteristics. The DLS analysis established the negative charge, and an average hydrodynamic size of 51 nm, while the UV-Vis spectroscopic analysis showed the absorption maxima (λmax) at 454 nm. The P. mirabilis isolates were numbered according to MDR detection by the VITEK 2 system (A to J), and the microbes appeared as a pale-coloured colony on MacConkey agar. The biofilm formation screening revealed the highest biofilm-producing isolates, identified as A, B, C, and D. The treatments with both bacteriocin and the bacteriocin-capped AgNPs showed that bacteriocin inhibited the biofilm formation for isolates A, B, and C, but isolate D was less affected, while bacteriocin capped AgNPs inhibited the film formation in isolates A, C, and D more than the bacteriocin alone. However, the activity level was low to moderate. In addition, the LuxS gene-down-regulating effects of bacteriocin and bacteriocin-capped AgNPs were also observed. The expression of the LuxS gene in P. mirabilis was lowered by bacteriocin-capped AgNPs during biofilm formation, while the isolates B and C lowered their expressions of the LuxS gene more effectively when the bacteriocin was used. The study finds the use of bacteriocin and bacteriocin-capped AgNPs of value for developing these products, especially bacteriocin-capped AgNPs, for managing the catheter infections. The products need further development and clinical testings.

Mechanistic insight of lysozyme transport through the outer bacteria membrane with dendronized silver nanoparticles for peptidoglycan degradation

Drug resistance has become a global problem, prompting the entire scientific world to seek alternative methods of dealing with resistant pathogens. Among the many alternatives to antibiotics, two appear to be the most promising: membrane permeabilizers and enzymes that destroy bacterial cell walls. Therefore, in this study, we provide insight into the mechanism of lysozyme transport strategies using two types of carbosilane dendronized silver nanoparticles (DendAgNPs), non-polyethylene glycol (PEG)-modified (DendAgNPs) and PEGylated (PEG-DendAgNPs), for outer membrane permeabilization and peptidoglycan degradation. Remarkably, studies have shown that DendAgNPs can build up on the surface of a bacterial cell, destroying the outer membrane, and thereby allowing lysozymes to penetrate inside the bacteria and destroy the cell wall. PEG-DendAgNPs, on the other hand, have a completely different mechanism of action. PEG chains containing a complex lysozyme resulted in bacterial aggregation and an increase in the local enzyme concentration near the bacterial membrane, thereby inhibiting bacterial growth. This is due to the accumulation of the enzyme in one place on the surface of the bacteria and penetration into it through slight damage of the membrane due to interactions of NPs with the membrane. The results of this study will help propel more effective antimicrobial protein nanocarriers.

Combined Anti-Bacterial Actions of Lincomycin and Freshly Prepared Silver Nanoparticles: Overcoming the Resistance to Antibiotics and Enhancement of the Bioactivity

Bacterial drug resistance to antibiotics is growing globally at unprecedented levels, and strategies to overcome treatment deficiencies are continuously developing. In our approach, we utilized metal nanoparticles, silver nanoparticles (AgNPs), known for their wide spread and significant anti-bacterial actions, and the high-dose regimen of lincosamide antibiotic, lincomycin, to demonstrate the efficacy of the combined delivery concept in combating the bacterial resistance. The anti-bacterial actions of the AgNPs and the lincomycin as single entities and as part of the combined mixture of the AgNPs-lincomycin showed improved anti-bacterial biological activity in the Bacillus cereus and Proteus mirabilis microorganisms in comparison to the AgNPs and lincomycin alone. The comparison of the anti-biofilm formation tendency, minimum bactericidal concentration (MBC), and minimum inhibitory concentration (MIC) suggested additive effects of the AgNPs and lincomycin combination co-delivery. The AgNPs' MIC at 100 μg/mL and MBC at 100 μg/mL for both Bacillus cereus and Proteus mirabilis, respectively, together with the AgNPs-lincomycin mixture MIC at 100 + 12.5 μg/mL for Bacillus cereus and 50 + 12.5 μg/mL for Proteus mirabilis, confirmed the efficacy of the mixture. The growth curve test showed that the AgNPs required 90 min to kill both bacterial isolates. The freshly prepared and well-characterized AgNPs, important for the antioxidant activity levels of the AgNPs material, showed radical scavenging potential that increased with the increasing concentrations. The DPPH's best activity concentration, 100 μg/mL, which is also the best concentration exhibiting the highest anti-bacterial zone inhibition, was chosen for evaluating the combined effects of the antibiotic, lincomycin, and the AgNPs. Plausible genotoxic effects and the roles of AgNPs were observed through decreased Bla gene expressions in the Bacillus cereus and Bla_CTX-M-15 gene expressions in the Proteus mirabilis.

Biologically Synthesized Silver Nanoparticles and Their Diverse Applications

Nanotechnology has become the most effective and rapidly developing field in the area of material science, and silver nanoparticles (AgNPs) are of leading interest because of their smaller size, larger surface area, and multiple applications. The use of plant sources as reducing agents in the fabrication of silver nanoparticles is most attractive due to the cheaper and less time-consuming process for synthesis. Furthermore, the tremendous attention of AgNPs in scientific fields is due to their multiple biomedical applications such as antibacterial, anticancer, and anti-inflammatory activities, and they could be used for clean environment applications. In this review, we briefly describe the types of nanoparticle syntheses and various applications of AgNPs, including antibacterial, anticancer, and larvicidal applications and photocatalytic dye degradation. It will be helpful to the extent of a better understanding of the studies of biological synthesis of AgNPs and their multiple uses.