Pro-inflammatory effects of silver nanoparticles in the intestine

Mitophagy protects against silver nanoparticle-induced hepatotoxicity by inhibiting mitochondrial ROS and the NLRP3 inflammasome

Silver nanoparticles (AgNPs) have wide clinical applications because of their excellent antibacterial properties; however, they can cause liver inflammation in animals. Macrophages are among the main cells mediating inflammation and are also responsible for the phagocytosis of nanomaterials. The NLRP3 inflammasome is a major mechanism of inflammation, and its activation both induces cytokine release and triggers inflammatory cell death (i.e., pyroptosis). In previous studies, we demonstrated that mitophagy activation plays a protective role against AgNP-induced hepatotoxicity. However, the exact molecular mechanisms underlying these processes are not fully understood. In this study, we demonstrate that AgNP exposure induces NLRP3 inflammasome activation, mitochondrial damage and pyroptosis in vivo and in vitro. NLRP3 silencing or inhibiting mitochondrial reactive oxygen species (ROS) overproduction reduces PINK1-Parkin-mediated mitophagy. Meanwhile, the inhibition of mitophagy ROS production, mitochondrial, NLRP3-mediated inflammation, and pyroptosis in RAW264.7 cells were more pronounced than in the control group. These results suggest that PINK1-Parkin-mediated mitophagy plays a protective role by reducing AgNP-induced mitochondrial ROS and subsequent NLRP3 inflammasome activation.

Nanotechnology in toothpaste: Fundamentals, trends, and safety

Several studies have revealed that healthcare nanomaterials are widely used in numerous areas of dentistry, including prevention, diagnosis, treatment, and repair. Nanomaterials in dental cosmetics are utilized to enhance the efficacy of toothpaste and other mouthwashes. Nanoparticles are added to toothpastes for a variety of reasons, including dental decay prevention, remineralization, hypersensitivity reduction, brightening, and antibacterial qualities. In this review, the benefits and uses of many common nanomaterials found in toothpaste are outlined. Additionally, the capacity and clinical applications of nanoparticles as anti-bacterial, whitening, hypersensitivity, and remineralizing agents in the treatment of dental problems and periodontitis are discussed.

Biodistribution and intestinal inflammatory response following voluntary oral intake of silver nanoparticles by C57BL/6J mice

Silver nanoparticles (AgNP) are among the most widely commercialized nanomaterials globally, with applications in medicine and the food industry. Consequently, the increased use of AgNP in the food industry has led to an unavoidable rise  in human exposure to these nanoparticles. Their widespread use raises concerns about potential hazards to human health, specifically their intestinal pro-inflammatory effects. Thus, the main objective of this study was to evaluate the biological effects of two subacute doses of 5 nm polyvinylpyrrolidone (PVP)-AgNP in C57BL/6J mice. One mg/kg body weight or 10 mg/kg bw was provided once a day for 14 days, using a new technology (HaPILLness) that allows voluntary, stress-free, and accurate oral dosing. It was observed that after oral ingestion, while AgNP is biodistributed throughout the entire organism, most of the ingested dose is excreted in the feces. The passage and accumulation of AgNP throughout the intestine instigated a prominent inflammatory response, marked by significant histological, vascular, and cellular transformations. This response was driven by the activation of the nuclear factor-кB (NF-кB) inflammatory pathway, ultimately leading to the generation of multiple cytokines and chemokines.

Transformation, Absorption and Toxicological Mechanisms of Silver Nanoparticles in the Gastrointestinal Tract Following Oral Exposure

Oral exposure is known as the primary way for silver nanoparticles (AgNPs), which are commonly used as food additives or antibacterial agents in commercial products, to enter the human body. Although the health risk of AgNPs has been a concern and extensively researched over the past few decades, there are still numerous knowledge gaps that need to be filled to disclose what AgNPs experience in the gastrointestinal tract (GIT) and how they cause oral toxicity. In order to gain more insight into the fate of AgNPs in the GIT, the main gastrointestinal transformation of AgNPs, including aggregation/disaggregation, oxidative dissolution, chlorination, sulfuration, and corona formation, is first described. Second, the intestinal absorption of AgNPs is presented to show how AgNPs interact with epithelial cells and cross the intestinal barrier. Then, more importantly, we make an overview of the mechanisms underlying the oral toxicity of AgNPs in light of recent advances as well as the factors affecting the nano-bio interactions in the GIT, which have rarely been thoroughly elaborated in published literature. At last, we emphatically discuss the issues that need to be addressed in the future to answer the question "How does oral exposure to AgNPs cause detrimental effects on the human body?".

Magnetic covalent organic framework for the adsorption of silver nanoparticles and recycled as surface-enhanced Raman substrate and high-efficiency catalysts for 4-nitrophenol degradation

A magnetic covalent organic framework Fe₃O₄@BM was prepared with melamine and 4-4'-biphenyldialdehyde as monomers and used as adsorbent for Ag NP removal. Fe₃O₄@BM was characterized by zeta potential analysis, transform infrared spectrometry, X-ray diffraction, thermogravimetric analysis, contact angle, and N₂ adsorption-desorption. Fe₃O₄@BM possessed plentiful amino groups, positive potential, and rapid separation performance, making it a promising adsorbent for silver nanoparticles. The adsorption process followed the pseudo-second-order kinetic equation and Langmuir isotherm model. The maximum adsorption capacity of Ag NPs calculated by the Langmuir isotherm model was 544.9 mg/g. The adsorption product Fe₃O₄@BM@Ag could be recycled and efficiently catalyze the degradation of 4-nitrophenol within 6 min. Meanwhile, the recycled Fe₃O₄@BM@Ag could also be used as a surface-enhanced Raman substrate for DTNB detection, and the limit of detection of DTNB reached as low as 10^-7 mol/L. This work prepared a promising adsorbent Fe₃O₄@BM for Ag NP adsorption and provided a sustainable approach for the recycling of the adsorption product Fe₃O₄@BM@Ag.