Antimicrobial Activity of Silver and Gold Nanoparticles Prepared by Photoreduction Process with Leaves and Fruit Extracts of Plinia cauliflora and Punica granatum

Silver nanoparticles biosynthesis using mixture of Lactobacillus sp. and Bacillus sp. growth and their antibacterial activity

The biosynthesis of nanoparticles offers numerous advantages, including ease of production, cost-effectiveness, and environmental friendliness. In our research, we focused on the bioformation of silver nanoparticles (AgNPs) using a combination of Lactobacillus sp. and Bacillus sp. growth. These AgNPs were then evaluated for their biological activities against multidrug-resistant bacteria. Our study involved the isolation of Bacillus sp. from soil samples and Lactobacillus sp. from raw milk in Dhamar Governorate, Yemen. The synthesized AgNPs were characterized using various techniques such as UV-visible spectroscopy, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM). The antibacterial properties of the AgNPs were assessed using the modified Kirby Bauer disk diffusion method against multidrug-resistant strains of Staphylococcus aureus and Pseudomonas aeruginosa. Our results demonstrated that the use of a bacterial mixture for biosynthesis led to faster and more effective production of AgNPs compared to using a single bacterium. The UV-visible spectra showed characteristic peaks indicative of silver nanoparticles, while XRD analysis confirmed the crystalline nature of the synthesized particles. FTIR results suggested the presence of capping proteins that contribute to the synthesis and stability of AgNPs. Furthermore, TEM images revealed the size and morphology of the AgNPs, which exhibited spherical shapes with sizes ranging from 4.65 to 22.8 nm. Notably, the antibacterial activity of the AgNPs was found to be more pronounced against Staphylococcus aureus than Pseudomonas aeruginosa, indicating the potential of these nanoparticles as effective antimicrobial agents. Overall, our study highlights the promising antibacterial properties of AgNPs synthesized by a mixture of Lactobacillus sp. and Bacillus sp. growth. Further research is warranted to explore the potential of utilizing different bacterial combinations for enhanced nanoparticle synthesis.

Evaluation of Plant-Based Silver Nanoparticles for Antioxidant Activity and Promising Wound-Healing Applications

The current research focuses on the green synthesis of silver nanoparticles (AgNPs) using a polar extract of taro corms and the evaluation of its antioxidant properties and wound-healing applications. Taro corm extract (100 mL) was treated with a 5 mM AgNO3 solution (100 mL) at room temperature for the formation of AgNPs, and a color change was observed. The surface plasmon resonance (SPR) peaks in their UV-visible spectra appeared at a range of 438-445 nm. Fourier transform infrared, scanning electron microscopy, energy-dispersive X-ray, dynamic light scattering, and X-ray diffraction were used for the characterization of the taro corms extract-mediated AgNPs (TCE-AgNPs). The synthesized AgNPs were crystalline and spherical, with an average size of 244.9-272.2 nm with a polydispersity index of 0.530 and zeta potential of -18.8 mV, respectively. The antibacterial potential of TCE-AgNPs was tested, and the inhibition zones detected against Cronobacter sakazakii, Pseudomonas aeruginosa, Listeria monocytogenes, and Enterococcus faecalis were 28, 26, 18, and 13 mm, respectively. Furthermore, the antioxidant activity of TCE-AgNPs showed significant radical-scavenging activity compared to the standard used. Collagen content data collected from regenerated tissue and higher collagen content indicated rapid wound healing compared to others, which was seen in a group treated with TCE-AgNP film bandages.

Spotlight on therapeutic efficiency of green synthesis metals and their oxide nanoparticles in periodontitis

Periodontitis, one of the most prevalent dental diseases, causes the loss of bone and gum tissue that hold teeth in place. Several bacteria, commonly present in clinically healthy oral cavities, may induce and perpetuate periodontitis when their concentration rises in the gingival sulcus. Antibacterial effect against various Gram-negative and Gram-positive bacteria, including pathogenic and drug-resistant ones, has been shown for several distinct transient metal and metal oxide NPs. Therefore, NPs may be used in biomedicine to treat periodontal problems and in nanotechnology to inhibit the development of microorganisms. Instead of using harmful chemicals or energy-intensive machinery, biosynthesis of metal and metal oxide nanoparticles (NPs) has been suggested. To produce metal and metal oxide NPs, the ideal technique is "Green" synthesis because of its low toxicity and safety for human health and the environment. Gold NPs (AuNPs) appear to be less toxic to mammalian cells than other nanometals because their antibacterial activity is not dependent on reactive oxygen species (ROS). AgNPs also possess chemical stability, catalytic activity, and superior electrical and thermal conductivity, to name a few of their other advantageous characteristics. It was observed that zinc oxide (ZnO) NPs and copper (Cu) NPs exhibited discernible inhibitory effects against gram-positive and gram-negative bacterial strains, respectively. ZnO NPs demonstrated bactericidal activity against the microorganisms responsible for periodontitis. Medications containing magnetic NPs are highly effective against multidrug-resistant bacterial and fungal infections. The titanium dioxide (TiO2) NPs are implicated in elevating salivary peroxidase activity in individuals diagnosed with chronic periodontitis. Furthermore, specific metallic NPs have the potential to enhance the antimicrobial efficacy of periodontitis treatments when combined. Therefore, these NPs, as well as their oxide NPs, are only some of the metals and metal oxides that have been synthesized in environmentally friendly ways and shown to have therapeutic benefits against periodontitis.

Synthesis, Bioactivity Evaluation and Application of Plant-Based Nanoparticles

Environmental and biomedical fields have various potential applications for the green synthesis of nanoparticles [...].

Antibacterial and anticancer activities of green-synthesized silver nanoparticles using Photinia glabra fruit extract

Aims: We prepared Photinia glabra (PG) aqueous fruit extract, utilized it to synthesize silver nanoparticles (PG-Ag NPs) and evaluated the antibacterial and anticancer activities of the nanoparticles (NPs). Materials & methods: Silver nitrate aqueous solution was reduced to PG-Ag NPs using aqueous PG fruit extract. NP shape, size, composition and functionalization were determined using transmission electron microscopy, x-ray photoelectron spectroscopy, Fourier transform infrared and x-ray diffraction. Results & conclusions: PG-Ag NPs were spherical, approximately 39-77 nm-sized, functionalized surfaces with notable antibacterial activity against both Escherichia coli and Staphylococcus aureus, with an MIC <30 ug/ml and cytotoxicity toward esophageal cancer cells, with IC50 values less than 20 ug/ml. PG-Ag@rt NPs have been shown to be a potent antibacterial and anticancer agent, and their enriched particle surfaces can be conjugated with other compounds for multibiomedical applications.

Evaluation of Antibacterial Mechanism of Action, Tyrosinase Inhibition, and Photocatalytic Degradation Potential of Sericin-Based Gold Nanoparticles

In recent times, numerous natural materials have been used for the fabrication of gold nanoparticles (AuNPs). Natural resources used for the synthesis of AuNPs are more environment friendly than chemical resources. Sericin is a silk protein that is discarded during the degumming process for obtaining silk. The current research used sericin silk protein waste materials as the reducing agent for the manufacture of gold nanoparticles (SGNPs) by a one-pot green synthesis method. Further, the antibacterial effect and antibacterial mechanism of action, tyrosinase inhibition, and photocatalytic degradation potential of these SGNPs were evaluated. The SGNPs displayed positive antibacterial activity (8.45-9.58 mm zone of inhibition at 50 μg/disc) against all six tested foodborne pathogenic bacteria, namely, Enterococcus feacium DB01, Staphylococcus aureus ATCC 13565, Listeria monocytogenes ATCC 33090, Escherichia coli O157:H7 ATCC 23514, Aeromonas hydrophila ATCC 7966, and Pseudomonas aeruginosa ATCC 27583. The SGNPs also exhibited promising tyrosinase inhibition potential, with 32.83% inhibition at 100 μg/mL concentration as compared to 52.4% by Kojic acid, taken as a reference standard compound. The SGNPs also displayed significant photocatalytic degradation effects, with 44.87% methylene blue dye degradation after 5 h of incubation. Moreover, the antibacterial mode of action of the SGNPs was also investigated against E. coli and E. feacium, and the results show that due to the small size of the nanomaterials, they could have adhered to the surface of the bacterial pathogens, and could have released more ions and dispersed in the bacterial cell wall surrounding environment, thereby disrupting the cell membrane and ROS production, and subsequently penetrating the bacterial cells, resulting in lysis or damage to the cell by the process of structural damage to the membrane, oxidative stress, and damage to the DNA and bacterial proteins. The overall outcome of the current investigation concludes the positive effects of the obtained SGNPs and their prospective applications as a natural antibacterial agent in cosmetics, environmental, and foodstuff industries, and for the management of environmental contagion.

Antibacterial Potential of Gold Nanoparticles Synthesized From Leaf Extract of Syzygium cumini Against Multidrug-Resistant Urinary Tract Pathogens

BACKGROUND

Urinary tract infection (UTI) is one of the most commonly encountered bacterial infections. Due to the misuse or excessive use of antibiotics, the upsurge of multidrug-resistance cases in UTIs has now become a global threat to public health. Exploring a newer or safer treatment using green synthesized nanoparticles (NPs) is another substitute for eliminating multidrug-resistant pathogens.

METHODOLOGY

Leaf extract of Syzygium cumini was used for green synthesis of gold NPs. Synthesis of Syzygium cumini gold nanoparticles (ScAu-NPs) was achieved by optimizing various reaction parameters. These ScAu-NPs were characterized through UV-visible spectroscopy, transmission electron microscope, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction. ScAu-NPs were then processed for antibacterial activity against clinically isolated multidrug-resistant pathogens like Escherichia coli, Klebsiella pneumoniae, Proteus vulgaris, Acinetobacter baumannii, Staphylococcus aureus, and Enterococcus faecalis.

RESULTS

Characterization of NPs revealed that biosynthesized NPs were spherical in shape. FTIR spectroscopy showed the presence of phenolics and aromatic compounds. Biosynthesized NPs exhibit good antibacterial activity with a significant bacterial reduction seen against all bacterial isolates compared to the controls.

CONCLUSION

From the results of the present study, the formulation of biosynthesized ScAu-NPs can be utilized in drug development for eliminating infections caused by multidrug-resistant pathogens.

Green Synthesis of Silver Nanoparticles Using Salvia verticillata and Filipendula ulmaria Extracts: Optimization of Synthesis, Biological Activities, and Catalytic Properties

The study's objective was to obtain silver nanoparticles (SVAgNP and FUAgNP) using aqueous extracts of Salvia verticillata and Filipendula ulmaria. The optimal conditions for nanoparticle synthesis were determined and obtained; nanoparticles were then characterized using UV-Vis, Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), Dynamic Light Scattering (DLS), Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS). SVAgNP and FUAgNP possessed a crystalline structure with 48.42% and 60.41% silver weight, respectively. The highest percentage of nanoparticles in the solution had a diameter between 40 and 70 nm. In DPPH˙ and ABTS˙⁺ methods, FUAgNP (IC₅₀ 15.82 and 59.85 µg/mL, respectively) demonstrated a higher antioxidant capacity than SVAgNP (IC₅₀ 73.47 and 79.49 µg/mL, respectively). Obtained nanoparticles also showed pronounced antibacterial activity (MIC ˂ 39.1 µg/mL for most of the tested bacteria), as well as high biocompatibility with the human fibroblast cell line MRC-5 and significant cytotoxicity on some cancer cell lines, especially on the human colon cancer HCT-116 cells (IC₅₀ 31.50 and 66.51 µg/mL for SVAgNP and FUAgNP, respectively). The nanoparticles demonstrated high catalytic effectiveness in degrading Congo red dye with NaBH₄. The results showed a rapid and low-cost methodology for the synthesis of AgNPs using S. verticillata and F. ulmaria with promising biological potential.