A Comparative Study of Cancer Cells Susceptibility to Silver Nanoparticles Produced by Electron Beam

Silver nanoparticles enhance neutron radiation sensitivity in cancer cells: An in vitro study

Growing interest in cancer radiotherapy has led to the application of nanoparticles as radiosensitizers. Here, we, for the first time, present the results of the radiosensitizing properties of silver nanoparticles (AgNPs) (possessing low toxicity towards human body) against cancer cells under neutron irradiation. Five standard cancer cultures (including glioblastoma, known for its resistance to conventional photon radiation) were used to evaluate the radiosensitizing properties of AgNPs suing MTT test, flow cytometry, and optical fluorescence microscopy. Neutron irradiation was applied in the absorbed dose of 0.5-1.5 Gy with an average neutron energy of 7.5 MeV. AgNPs increased the irradiation efficiency with the radiosensitivity enhancement ratios 1.02-2.32, for glioblastoma with ratios 1.22-1.47. It was revealed that at 1.5 Gy, AgNP-induced cytotoxicity made a significant contribution to the total observed radiosensitizer effect: on average, for five cell types, 29.8 and 96.2 % at the AgNP concentration of 0.2 and 1.6 μg/mL, respectively.

Potential Antibiotic Resurgence: Consecutive Silver Nanoparticle Applications Gradually Increase Bacterial Susceptibility to Antibiotics

The increasing prevalence of resistant bacteria has emerged as a critical public health concern due to their ability to resist multiple antibiotics. This study aimed to investigate whether repeated treatments with silver nanoparticles (AgNPs) could gradually decrease bacterial resistance to antibiotics. The methodology involved three consecutive applications of AgNPs on six bacterial strains, followed by assessing their susceptibility to 38 different antibiotics. To our knowledge, the following three phenomena were observed for the first time. (1) During three consecutive AgNP applications, it was revealed that all the studied bacteria gradually became more susceptible to 38 antibiotics; by the end of the treatments, susceptibility had doubled for five bacteria and tripled for Klebsiella pneumoniae compared to the susceptibility before the first AgNP application. (2) Three consecutive AgNP treatments led to 27-47% restoration of bacterial susceptibility to antibiotics, which had already completely lost their activity before the initial AgNP application. (3) Unlike previous studies, we discovered a novel effect: the repeated AgNP applications increased the susceptibility of Salmonella enteritidis and Staphylococcus aureus to AgNPs themselves. Obtained results suggest that AgNP treatments may offer a new promising strategy to combat antibiotic resistance.

Protective Effect of Silver Nanoparticles Against Cytosine Arabinoside Genotoxicity: An In Vivo Micronucleus Assay

Cancer treatments have harmful side effects, including genotoxic ones. Our previous research discovered that a specific silver nanoparticle (AgNPs) formulation could reduce the genotoxic effects of an alkylating agent, cyclophosphamide. This study aims to evaluate if this protective effect is observed against an antimetabolite anticancer agent, cytosine arabinoside (Ara-C). An erythrocyte micronucleus assay was conducted on BALB/c mice. A most significant effect was observed after the application scheme, including three doses of Ara-C and three subsequent doses of AgNPs, resulting in a 3.7 and 2.0-fold decrease in the frequency of micronucleated reticulocytes and accumulated erythrocytes, respectively. Current and previous studies reveal that AgNPs could be used as a genoprotector against the genotoxic damage produced by the currently used antineoplastic antimetabolites and alkylating agents. It was revealed that AgNPs could be considered a new class of promising synthetic antineoplastic genoprotectants along with the known class of derivatives from natural sources.

Green Synthesis of Silver Oxide Nanoparticles from Mauritia flexuosa Fruit Extract: Characterization and Bioactivity Assessment

The increasing prevalence of multidrug-resistant (MDR) pathogens, persistent biofilms, oxidative stress, and cancerous cell proliferation poses significant challenges in healthcare and environmental settings, highlighting the urgent need for innovative and sustainable therapeutic solutions. The exploration of nanotechnology, particularly the use of green-synthesized nanoparticles, offers a promising avenue to address these complex biological challenges due to their multifunctional properties and biocompatibility. Utilizing a green synthesis approach, Mauritia flexuosa Mf-Ag2ONPs were synthesized and characterized using dynamic light scattering (DLS), transmission electron microscopy (TEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy coupled with scanning electron microscopy (EDS-SEM), UV-Vis spectroscopy, and Fourier transform infrared spectroscopy (FTIR). The Mf-Ag2ONPs exhibited potent antibacterial effects against both non-resistant and MDR bacterial strains, with minimum inhibitory concentrations (MICs) ranging from 11.25 to 45 µg/mL. Mf-Ag2ONPs also demonstrated significant antifungal efficacy, particularly against Candida glabrata, with an MIC of 5.63 µg/mL. Moreover, the nanoparticles showed strong biofilm inhibition capabilities and substantial antioxidant properties, underscoring their potential to combat oxidative stress. Additionally, Mf-Ag2ONPs exhibited pronounced anticancer properties against various cancer cell lines, displaying low IC50 values across various cancer cell lines while maintaining minimal hemolytic activity at therapeutic concentrations. These findings suggest that Mf-Ag2ONPs synthesized via an eco-friendly approach offer a promising alternative for biomedical applications, including antimicrobial, antifungal, antioxidant, and anticancer therapies, warranting further in vivo studies to fully exploit their therapeutic potential.

Nanoparticles Partially Restore Bacterial Susceptibility to Antibiotics

The growing resistance of bacteria to antibiotics is one of the main public health problems nowadays. The influence of silver nanoparticle (AgNP) pretreatment of 220 cows with mastitis on the susceptibility of Staphylococcus epidermidis bacteria to 31 antibiotics was studied. The obtained results were compared with the previous results for Escherichia coli, Streptococcus dysgalactiae, and Staphylococcus aureus. For all four bacteria, an increase in susceptibility (9.5-21.2%) to 31 antibiotics after cow treatment with AgNPs was revealed, while after first-line antibiotic drug treatment as expected, the susceptibility decreased (11.3-27.3%). These effects were explained by (1) the increase in the contribution of isolates with efflux effect after antibiotic treatments and its decrease after AgNP treatment and (2) the changes in bacteria adhesion and anti-lysozyme activity after these treatments. The effect of the increasing antibacterial activity of antibiotics after AgNP treatment was the most pronounced in the case of E. coli and was minimal in the case of S. epidermidis. With AgNP treatment, the time of recovery decreased by 26.8-48.4% compared to the time of recovery after treatment with the first-line antibiotic drugs. The AgNP treatment allows for achieving the partial restoration of the activity of antibiotics.