Search

Antibiotic resistance in bacteria is a major problem worldwide that costs 55 billion USD annually for extended hospitalization, resource utilization, and additional treatment expenditures in the United States. This review examines the roles and forms of silver (e.g., bulk Ag, silver salts (AgNO3), and colloidal Ag) from antiquity to the present, and its eventual incorporation as silver nanoparticles (AgNPs) in numerous antibacterial consumer products and biomedical applications. The AgNP fabrication methods, physicochemical properties, and antibacterial mechanisms in Gram-positive and Gram-negative bacterial models are covered. The emphasis is on the problematic ESKAPE pathogens and the antibiotic-resistant pathogens of the greatest human health concern according to the World Health Organization. This review delineates the differences between each bacterial model, the role of the physicochemical properties of AgNPs in the interaction with pathogens, and the subsequent damage of AgNPs and Ag+ released by AgNPs on structural cellular components. In closing, the processes of antibiotic resistance attainment and how novel AgNP–antibiotic conjugates may synergistically reduce the growth of antibiotic-resistant pathogens are presented in light of promising examples, where antibiotic efficacy alone is decreased. [ABSTRACT FROM AUTHOR]

Herein, Raman and surface-enhanced Raman spectroscopies (SERS) were successfully employed to establish the chemical interactions of citrate-capped silver nanoparticles (AgNPs, 10–15 nm) with human red blood cells (RBCs). The Raman/SERS spectra offered spectral evidence for the cellular uptake of AgNPs and the subsequent change in the conformation of the most abundant component, hemoglobin (Hb), from oxyhemoglobin to deoxyhemoglobin. The spectral characterization of AgNPs' interactions with other RBC biomarkers (membrane proteins and lipids) was impeded by the dominant Hb bands, even for non-resonant Hb conditions. CytoViva hyperspectral imaging and graphite furnace atomic absorption spectroscopy (GFAAS) served as complementary tools to effectively address the challenges related to a single excitation line (632.8 nm) and the resolution of the confocal Raman microscope (0.5–1.0 µm). CytoViva confirmed the RBC-AgNP interactions through hyperspectral signatures and facilitated the label-free localization of AgNPs extracellularly and intracellularly. Irreversible agglutination of RBCs was noted after 24 h of exposure, raising concerns about the toxicity of AgNPs of biocompatible citrate coatings. GFAAS validated the Raman/SERS results by quantifying the proportion of AgNPs absorbed by RBCs, which was significant (~48% AgNPs by mass), mostly at the membrane (60% RBCs), and size dependent (no large AgNPs or AgNP-aggregates in RBCs, after 12–24 h). [ABSTRACT FROM AUTHOR]

Green route is an economic, facile and eco-friendly method, employed for the synthesis of various types of nanoparticles, having it as a starting point biological entity, especially as a plant extract. The present study aims to obtain silver nanoparticles (AgNPs) starting from an ethanolic extract of Populi gemmae (Pg), by adjusting the reaction parameters. The morphological and structural characterization exhibited that both the reaction temperature and the concentration of metal salt, contributes to the obtaining of Pg-AgNPs with adjustable size and shape. The newly synthesized nanoparticles exhibited a good antibacterial activity on Gram-positive bacteria as well as antifungal activity. The in vitro antiproliferative activity of Pg-AgNPs was assessed on two different cancer cell lines (breast cancer cells—MCF7 and lung carcinoma epithelial cells—A549). Results have shown that the green-synthetized Pg-AgNPs_S2 (obtained at 60 °C, using AgNO3 of 5 M) induced a substantial decrease in tumor cell viability in a dose-dependent manner with an IC50 ranging from 5.03 to 5.07 µg/mL on A549 cell line and 3.24 to 4.93 µg/mL on MCF7 cell line. [ABSTRACT FROM AUTHOR]

The original version of this article unfortunately contained a mistake. The equation was incorrectly presented. [ABSTRACT FROM AUTHOR]

Although antimicrobial nanosilver finds numerous applications in the health and food industries, the in vivo toxicity of positively charged silver nanoparticles (AgNPs+) and relevant controls are largely unexplored. This study investigates the relationship between the biodistribution and toxicity of the well-known cetyltrimethylammonium bromide (CTAB)-capped AgNPs+ in 6-weeks old female Sprague-Dawley rats, at sublethal doses. Amounts comparative to those leaked from food products or considered for animal feed were administered through daily water intake, for an 18-day period: AgNPs+ (40 μg mL−1), Ag+ (40 μg mL−1), antimicrobial CTAB+ (24 μg mL−1) and tap water. All exposures except for the water control had adverse effects on the health and systemic functions of rats (e.g. , lethargy, hepatomegaly, splenomegaly, impediment of bone development, and/or heightened immune response). Although the total Ag accumulation in tissues (1.4–1.6 μg of Ag/g of liver, spleen, jejunum, and brain) was comparable for the two Ag species, AgNPs+ were generally more toxic than Ag+, particularly in spleen (0.8 μg Ag/g). Significantly reduced euthanasia time, alopecia, inflammatory responses in spleen, fragile veins, and enhanced lymphocytosis were observed only for AgNPs+. Overall, this study raises health concerns about the ingestion of capped-AgNPs+ or Ag+ by first-hand consumers and industry workers. [Display omitted] • Adverse effects of silver nanoparticles, capping agents, and silver ions on the health of Sprague-Dawley rats. • Lethargy, hepatomegaly, splenomegaly, impediment of bone development, and/or heightened immune response. • Exposure through water intake, in amounts comparable to those leaked from food products or considered for animal feed. • Total silver accumulation in liver, spleen, jejunum, and brain comparable for the two silver species. • Positively charged silver nanoparticles generally more toxic than the silver ions, particularly in spleen. [ABSTRACT FROM AUTHOR]