Is sulfidation a true detoxification process for silver nanoparticles?: from the perspective of chronic exposure

Abstract

Sulfidation of silver nanoparticles may camouflage its long term effect with imperceptible acute toxicity.

Chronic Exposure to Titanium Dioxide Nanoparticles Induces Commensal-to-Pathogen Transition in Escherichia coli

“…5 As a consequence of cross-adaptation, E. coli exhibits tolerance to various antibiotics after exposure to 0.02 mg/L silver nanoparticles for more than 100 subcultures due to the coexpression of antioxidative responsive genes and multidrug resistance genes. 11 We recently reviewed the crossinduction of tolerance/resistance to various antibiotics in bacteria through pre-exposure to various nanoparticles (or related photocatalysis) and discussed the cross-adaptation mechanisms. 36 Notably, morphological changes were not commonly suggested in these studies, possibly because epistasis adaptive morphogenesis necessitates many subtle-effect modulations in regulatory DNA under relatively long-lasting selective events.…”

“…As a consequence of cross-adaptation, E. coli exhibits tolerance to various antibiotics after exposure to 0.02 mg/L silver nanoparticles for more than 100 subcultures due to the coexpression of antioxidative responsive genes and multidrug resistance genes . We recently reviewed the cross-induction of tolerance/resistance to various antibiotics in bacteria through pre-exposure to various nanoparticles (or related photocatalysis) and discussed the cross-adaptation mechanisms .…”

“…10 Although the bacteria reached a stationary phase in 12 h, a period of 48 h was adopted to ensure adequate time for the development of adaptation and the boosting of mutations. 11 Three independent cultures of each strain were maintained, which were used for subsequent bacterial morphological and physiological characterizations as three biological replicates to ensure that consistent phenotypic changes were obtained. Notably, we did not select the potential mutant strain on purpose; instead, the entire population was subjected to the assays to maintain heterogeneity, similar to a real-world setting.…”

“…The concentration 5 mg/L was selected because it exerted no discernible acute toxic effects (Figure S1) and is markedly lower than the TiO 2 concentration in the human intestine after the consumption of one to two pieces of gum or candy (100–200 mg/L) . Although the bacteria reached a stationary phase in 12 h, a period of 48 h was adopted to ensure adequate time for the development of adaptation and the boosting of mutations . Three independent cultures of each strain were maintained, which were used for subsequent bacterial morphological and physiological characterizations as three biological replicates to ensure that consistent phenotypic changes were obtained.…”

Copper(I) Promotes Silver Sulfide Dissolution and Increases Silver Phytoavailability

“…However, the discovery of elevated silver mobility and toxicity in silver mining areas , generated particular interest in the dissolution of silver sulfide. With the exception of a few studies that monitored dissolution of colloidal Ag 2 S at temperatures well in excess of those encountered in subsurface environments , or in the presence of strong oxidants, such as hypochlorite and ozone, in wastewater treatment plants, − Ag 2 S dissolution under natural conditions has long been overlooked . Indeed, Ag 2 S nanoparticles can undergo dissolution in the presence of Fe­(III) in irradiated surface waters, attributable to the formation of hydroxyl radicals. , A recent soil experiment demonstrates that the addition of a thiosulfate fertilizer promotes the dissolution of Ag 2 S originating from the municipal sewage sludge and enhances Ag accumulation in crop plants .…”