Silver Nanoparticles Induce Mitochondrial Protein Oxidation in Lung Cells Impacting Cell Cycle and Proliferation

Apoptosis and cell cycle arrest of bone marrow cells by green-synthesized silver but not albumin nanoparticles

Metallic nanoparticles (NPs) made by traditional means have a deleterious effect on bone marrow (BM) cells. Alternatively, green-synthesized NPs are cost-effective, ecofriendly, and may be less toxic. Also, albumin is a biocompatible blood protein involved in several physiological processes, employed in drug delivery without posing adverse effects, and is thought to be ideal NPs or coating for reducing the metallic NP's toxicity. We prepared albumin NPs (AlbNPs), biosynthesized silver NPs (AgNPs) using the metabolite of the Escherichia coli D8 strain and coated them with albumin (Ag/AlbNPs). These NPs were characterized and intraperitoneally administered to rats to compare their effect on rat BM cells. The flow cytometry results revealed that AgNPs significantly reduced viability, increased apoptosis, downregulated the antiapoptotic Bcl2 gene expression, and upregulated the apoptotic genes Bax and p53 in BM cells, while treatment with AlbNPs maintained these parameters. Principally, AgNPs caused significant DNA fragmentation, since all parameters observed by the comet assay (tail length, tail DNA content, tail moment, and olive moment) were significantly higher in AgNP-treated groups than in control and AlbNP-treated groups. Investigation of the cell cycle revealed that treatment with AgNP, but not AlbNPs, downregulated the expression of the regulatory genes Cdk2, Cdk4, and the cyclins A1 (Ccna1) and D1 (Ccnd1), which resulted in the arrest of the progression of the cell cycle at GO/G1, as demonstrated by flow cytometry. Coating AgNPs with albumin increased their size, and decreased their intracellular concentration, resulting in reduced apoptosis and cell cycle arrest. However, these results for the Ag/AlbNP-treated group were still not comparable to those treated with pure AlbNPs. In conclusion, in contrast to AlbNPs, green AgNPs are toxic to bone marrow cells. Their coating with albumin, however, reduces this toxicity. To avoid this metal NP toxicity, it is recommended to use compatible degradable NPs instead of metal NPs for medication delivery to BM.

Modification in Structures of Active Compounds in Anticancer Mitochondria-Targeted Therapy

Cancer is a multifaceted disease characterised by uncontrolled cellular proliferation and metastasis, resulting in significant global mortality. Current therapeutic strategies, including surgery, chemotherapy, and radiation therapy, face challenges such as systemic toxicity and tumour resistance. Recent advancements have shifted towards targeted therapies that act selectively on molecular structures within cancer cells, reducing off-target effects. Mitochondria have emerged as pivotal targets in this approach, given their roles in metabolic reprogramming, retrograde signalling, and oxidative stress, all of which drive the malignant phenotype. Targeting mitochondria offers a promising strategy to address these mechanisms at their origin. Synthetic derivatives of natural compounds hold particular promise in mitochondrial-targeted therapies. Innovations in drug design, including the use of conjugates and nanotechnology, focus on optimizing these compounds for mitochondrial specificity. Such advancements enhance therapeutic efficacy while minimizing systemic toxicity, presenting a significant step forward in modern anticancer strategies.

Polystyrene microplastics alleviate the developmental toxicity of silver nanoparticles in embryo-larval zebrafish (Danio rerio) at the transcriptomic level

Since silver nanoparticles (AgNPs) and polystyrene microplastics (PS-MP) share common environmental niches, their interactions can modulate their hazard impacts. Herein, we assessed the developmental toxicity of 1 mg/L PS-MP, 0.5 mg/L AgNPs and the mixtures of AgNPs and PS-MP on embryo-larval zebrafish. We found that AgNPs co-exposure with PS-MP remarkably decreased mortality rates, malformation rates, heart rates and yolk sac area, while it increased hatching rates and eye size compared to the AgNPs group. These phenomena revealed that the cell cycle, oxidative stress, apoptosis, lipid metabolism, ferroptosis and p53 signalling pathway were obviously affected by single AgNPs exposure at 96 hpf (hours post fertilization). Interestingly, all these effects were effectively ameliorated by co-exposure with PS-MP. The combination of transcriptomic and metabolomic analyses showed that the imbalance of DEGs (differentially expressed genes) and DEMs (differentially expressed metabolites) (PI, phosphatidylinositol and TAG-FA, triacylglycerol-fatty acid) disturbed both the cell cycle and lipid metabolism following single AgNPs exposure and co-exposure with PS-MP. These findings suggest that PS-MP attenuates the developmental toxicity of AgNPs on embryo-larval zebrafish. Overall, this study provides important insight into understanding the transcriptional responses and mechanisms of AgNPs alone or in combination with PS-MPs on embryo-larval zebrafish, providing a reference for ecological risk assessment of combined exposure to PS-MP and metal nanoparticles.

Enhancement of Triple-Negative Breast Cancer-Specific Induction of Cell Death by Silver Nanoparticles by Combined Treatment with Proteotoxic Stress Response Inhibitors

Metal nanoparticles have been tested for therapeutic and imaging applications in pre-clinical models of cancer, but fears of toxicity have limited their translation. An emerging concept in nanomedicine is to exploit the inherent drug-like properties of unmodified nanomaterials for cancer therapy. To be useful clinically, there must be a window between the toxicity of the nanomaterial to cancer and toxicity to normal cells. This necessitates identification of specific vulnerabilities in cancers that can be targeted using nanomaterials without inducing off-target toxicity. Previous studies point to proteotoxic stress as a driver of silver nanoparticle (AgNPs) toxicity. Two key cell stress responses involved in mitigating proteotoxicity are the heat shock response (HSR) and the integrated stress response (ISR). Here, we examine the role that these stress responses play in AgNP-induced cytotoxicity in triple-negative breast cancer (TNBC) and immortalized mammary epithelial cells. Furthermore, we investigate HSR and ISR inhibitors as potential drug partners to increase the anti-cancer efficacy of AgNPs without increasing off-target toxicity. We showed that AgNPs did not strongly induce the HSR at a transcriptional level, but instead decreased expression of heat shock proteins (HSPs) at the protein level, possibly due to degradation in AgNP-treated TNBC cells. We further showed that the HSR inhibitor, KRIBB11, synergized with AgNPs in TNBC cells, but also increased off-target toxicity in immortalized mammary epithelial cells. In contrast, we found that salubrinal, a drug that can sustain pro-death ISR signaling, enhanced AgNP-induced cell death in TNBC cells without increasing toxicity in immortalized mammary epithelial cells. Subsequent co-culture studies demonstrated that AgNPs in combination with salubrinal selectively eliminated TNBCs without affecting immortalized mammary epithelial cells grown in the same well. Our findings provide additional support for proteotoxic stress as a mechanism by which AgNPs selectively kill TNBCs and will help guide future efforts to identify drug partners that would be beneficial for use with AgNPs for cancer therapy.

Silver nanoparticles induces apoptosis of cancer stem cells in head and neck cancer

Background

Several nano formulations of silver nanoparticles with bioconjugates, herbal extracts and anti-cancerous drug coating have been vividly studied to target cancer. Despite of such extensive studies, AgNPs (silver nanoparticles) have not reached the stage of clinical use. Out of all possible reasons for this failure, the unexplored effect on Cancer Stem Cell (CSC) population and mechanism of action of AgNPs, are the most plausible ones and are worked upon in this study.

Methods

AgNPs were synthesized by chemical reduction method using sodium citrate and characterized by UV, FTIR, XRD and electron microscopy. CSC population was isolated from Cal33 cell line by MACS technique. MTT assay, trypan blue exclusion assay, Annexin V and PI based apoptosis assay and cell cycle assay were performed.

Results

The results showed that synthesized AgNPs have cytotoxic activity on all cancer cell lines tested with the IC50 value of a wide range (1.5-49.21 µg/ml for cell lines and 0.0643-0.1211 µg/ml for splenocytes and thymocytes). CSCs Cal33 showed higher resistance to AgNP treatment and arrest in G1/G0 phase upon cell cycle analysis.

Conclusion

AgNPs as an anti-cancer agent although have great potential but is limited by its off-target effects on normal cells and less effective on cancer stem cells at lower concentrations.

Application of High-Z Nanoparticles to Enhance Current Radiotherapy Treatment

Radiotherapy is an essential component of the treatment regimens for many cancer patients. Despite recent technological advancements to improve dose delivery techniques, the dose escalation required to enhance tumor control is limited due to the inevitable toxicity to the surrounding healthy tissue. Therefore, the local enhancement of dosing in tumor sites can provide the necessary means to improve the treatment modality. In recent years, the emergence of nanotechnology has facilitated a unique opportunity to increase the efficacy of radiotherapy treatment. The application of high-atomic-number (Z) nanoparticles (NPs) can augment the effects of radiotherapy by increasing the sensitivity of cells to radiation. High-Z NPs can inherently act as radiosensitizers as well as serve as targeted delivery vehicles for radiosensitizing agents. In this work, the therapeutic benefits of high-Z NPs as radiosensitizers, such as their tumor-targeting capabilities and their mechanisms of sensitization, are discussed. Preclinical data supporting their application in radiotherapy treatment as well as the status of their clinical translation will be presented.

Application of nano-radiosensitizers in non-small cell lung cancer

Radiotherapy stands as a cornerstone in the treatment of numerous malignant tumors, including non-small cell lung cancer. However, the critical challenge of amplifying the tumoricidal effectiveness of radiotherapy while minimizing collateral damage to healthy tissues remains an area of significant research interest. Radiosensitizers, by methods such as amplifying DNA damage and fostering the creation of free radicals, play a pivotal role in enhancing the destructive impact of radiotherapy on tumors. Over recent decades, nano-dimensional radiosensitizers have emerged as a notable advancement. Their mechanisms include cell cycle arrest in the G2/M phase, combating tumor hypoxia, and others, thereby enhancing the efficacy of radiotherapy. This review delves into the evolving landscape of nanomaterials used for radiosensitization in non-small cell lung cancer. It provides insights into the current research progress and critically examines the challenges and future prospects within this burgeoning field.

Silver-integrated EDM processing of TiAl6V4 implant material has antibacterial capacity while optimizing osseointegration

Periprosthetic joint infections (PJI) are a common reason for orthopedic revision surgeries. It has been shown that the silver surface modification of a titanium alloy (Ti-6Al-4V) by PMEDM (powder mixed electrical discharge machining) exhibits an antibacterial effect on Staphylococcus spp. adhesion. Whether the thickness of the silver-modified surface influences the adhesion and proliferation of bacteria as well as the ossification processes and in-vivo antibacterial capacity has not been investigated before. Therefore, the aim of this work is to investigate the antibacterial effect as well as the in vitro ossification process depending on the thickness of PMEDM silver modified surfaces. The attachment of S. aureus on the PMEDM modified surfaces was significantly lower than on comparative control samples, independently of the tested surface properties. Bacterial proliferation, however, was not affected by the silver content in the surface layer. We observed a long-term effect of antibacterial capacity in vitro, as well as in vivo. An induction of ROS, as indicator for oxidative stress, was observed in the bacteria, but not in osteoblast-like cells. No influence on the in vitro osteoblast function was observed, whereas osteoclast formation was drastically reduced on the silver surface. No changes in cell death, the metabolic activity and oxidative stress was measured in osteoblasts. We show that already small amounts of silver exhibit a significant antibacterial capacity while not influencing the osteoblast function. Therefore, PMEDM using silver nano-powder admixed to the dielectric represents a promising technology to shape and concurrently modify implant surfaces to reduce infections while at the same time optimizing bone ingrowth of endoprosthesis.

Silver nanoparticles induce a non-immunogenic tumor cell death

Immunogenic cell death (ICD) is a form of cell death characterized by the release of danger signals required to trigger an adaptive immune response against tumor-associated antigens. Silver nanoparticles (AgNP) display anti-proliferative and cytotoxic effects in tumor cells, but it has not been previously studied whether AgNP act as an ICD inductor. The present study evaluated the in vitro release of calreticulin as a damage-associated molecular pattern (DAMP) associated with the cytotoxicity of AgNP and their in vivo anti-cancer effects. In vitro, mouse CT26 colon carcinoma and MCA205 fibrosarcoma cells were exposed to AgNP and then cell proliferation, adhesion, and release of calreticulin were determined. The results indicated there were time- and concentration-related anti-proliferative effects of AgNP in both the CT26 and MCA205 lines. Concurrently, changes in cell adhesion were detected mainly in the CT26 cells. Regarding DAMP detection, a significant increase in calreticulin was observed only in CT26 cells treated with doxorubicin and AgNP; however, no differences were found in the MCA205 cells. In vivo, the survival and growth of subcutaneous tumors were monitored after vaccination of mice with cell debris from tumor cells treated with AgNP or after intra-tumoral administration of AgNP to established tumors. Consequently, anti-tumoral prophylactic immunization with AgNP-dead cells failed to protect mice from tumor re-challenge; intra-tumor injection of AgNP did not induce a significant effect. In conclusion, there was a noticeable anti-tumoral effect of AgNP in vitro in both CT26 and MCA205 cell lines, accompanied by the release of calreticulin in CT26 cells. In vivo, immunization with cell debris derived from AgNP-treated tumor cells failed to induce a protective immune response in the cancer model mice. Clearly, further research is needed to determine if one could combine AgNP with other ICD inducers to improve the anti-tumor effect of these nanoparticles in vivo.

The role of miRNA-26a-5p and target gene socs1a in flutolanil induced hepatotoxicity of zebrafish at environmental relevant levels

Flutolanil has been detected worldwide in aquatic environment and fish, which has become an undeniable stressor on ecosystem and human health. Flutolanil has been reported to be toxic to aquatic organisms. However, the pathophysiological and molecular mechanism behind the detrimental effects remains obscure. Here we reported hepatotoxicity induced by flutolanil in HepG2 cells and zebrafish, as revealed by toxicokinetic, HE staining, miRNAs-mRNAs sequencing, molecular dynamic simulations and dual luciferase reporter assays. Collectively, our results indicated that flutolanil could be absorbed by and accumulated in the liver of zebrafish, causing hepatic vacuolar degeneration, steatosis and nuclear condensation and abnormal liver function, where its exposure at environmental levels disrupted the expressions of miRNA-26a-5p and its target gene socs1a by mediating JAK-STAT signaling pathway, which was partially responsible for hepatotoxicity, correlated with oxidative stress, cell apoptosis, inflammation, cell cycle disorder and mitochondrial dysfunction. These findings suggest that miRNA-26a-5p/socs1a can serve as potential biomarkers of hepatotoxicity in zebrafish following exposure to flutolanil. This uncovered route will provide a new tool for the risk assessment of flutolanil and a guide to proper use of flutolanil and environmental remedy, and open up a new horizon for liver disease assessment.

Radiosterilized Pig Skin, Silver Nanoparticles and Skin Cells as an Integral Dressing Treatment for Burns: Development, Pre-Clinical and Clinical Pilot Study

Radiosterilized pig skin (RPS) has been used as a dressing for burns since the 1980s. Its similarity to human skin in terms of the extracellular matrix (ECM) allows the attachment of mesenchymal stem cells, making it ideal as a scaffold to create cellularized constructs. The use of silver nanoparticles (AgNPs) has been proven to be an appropriate alternative to the use of antibiotics and a potential solution against multidrug-resistant bacteria. RPS can be impregnated with AgNPs to develop nanomaterials capable of preventing wound infections. The main goal of this study was to assess the use of RPS as a scaffold for autologous fibroblasts (Fb), keratinocytes (Kc), and mesenchymal stem cells (MSC) in the treatment of second-degree burns (SDB). Additionally, independent RPS samples were impregnated with AgNPs to enhance their properties and further develop an antibacterial dressing that was initially tested using a burn mouse model. This protocol was approved by the Research and Ethics Committee of the INRLGII (INR 20/19 AC). Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis of the synthesized AgNPs showed an average size of 10 nm and rounded morphology. Minimum inhibitory concentrations (MIC) and Kirby-Bauer assays indicated that AgNPs (in solution at a concentration of 125 ppm) exhibit antimicrobial activity against the planktonic form of S. aureus isolated from burned patients; moreover, a log reduction of 1.74 ± 0.24 was achieved against biofilm formation. The nanomaterial developed with RPS impregnated with AgNPs solution at 125 ppm (RPS-AgNPs125) facilitated wound healing in a burn mouse model and enhanced extracellular matrix (ECM) deposition, as analyzed by Masson's staining in histological samples. No silver was detected by energy-dispersive X-ray spectroscopy (EDS) in the skin, and neither by Inductively Coupled Plasma Mass Spectrometry (ICP-MS) in different organs of the mouse burn model. Calcein/ethidium homodimer (EthD-1), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), and scanning electron microscopy (SEM) analysis demonstrated that Fb, Kc, and MSC could attach to RPS with over 95% cell viability. Kc were capable of releasing FGF at 0.5 pg above control levels, as analyzed by ELISA assays. An autologous RPS-Fb-Kc construct was implanted in a patient with SDB and compared to an autologous skin graft. The patient recovery was assessed seven days post-implantation, and the patient was followed up at one, two, and three months after the implantation, exhibiting favorable recovery compared to the gold standard, as measured by the cutometer. In conclusion, RPS effectively can be used as a scaffold for the culture of Fb, Kc, and MSC, facilitating the development of a cellularized construct that enhances wound healing in burn patients.

Preparation of injectable hydrophilic dextran/AgNPs nanocomposite product: White light active biomolecules as an antitumor agent

Incidence of various cancers including melanoma continues to rise worldwide. While treatment options have expanded in the recent years, the benefit of these treatments suffer from short period of duration for many patients. Hence, new treatment options are highly desired. Here, we propose a method combining a Dextran/reactive-copolymer/AgNPs nanocomposite and a harmless visible light approach to obtain a plasma substitute carbohydrate-based nanoproduct (D@AgNP) that shows strong antitumor activity. Light-driven polysaccharide-based nanocomposite provided essential conditions for extra small (8-12nm) AgNPs capping with subsequent specific self-assembly into spherical-like cloud nanostructures. Obtained biocompatible D@AgNP are stable over six months at room temperature and demonstrated absorbance peak at 406 nm. New formulated nanoproduct revealed efficient anticancer properties against A375 with IC50 0.0035 mg/mL following 24-h incubation; complete cell death is achieved at 0.001 mg/mL and 0.0005 mg/mL by 24- and 48-h time points, respectively. SEM examination shows that D@AgNP altered the shape of the cell structure and damaged the cell membrane. TEM finding shows that D@AgNP are mostly localized at vesicles such as the endosomes, lysosomes and mitochondria. It is anticipated that the introduced new method serves as the cornerstone for improving the generation of biocompatible hydrophilic carbohydrate-based anticancer drugs.

Innovative Eco-Friendly Microwave-Assisted Rapid Biosynthesis of Ag/AgCl-NPs Coated with Algae Bloom Extract as Multi-Functional Biomaterials with Non-Toxic Effects on Normal Human Cells

Harmful algal blooms impact human welfare and are a global concern. Sargassum spp., a type of algae or seaweed that can potentially bloom in certain regions of the sea around Thailand, exhibits a noteworthy electron capacity as the sole reducing and stabilizing agent, which suggests its potential for mediating nanoparticle composites. This study proposes an eco-friendly microwave-assisted biosynthesis (MAS) method to fabricate silver nanoparticles coated with Sargassum aqueous extract (Ag/AgCl-NPs-ME). Ag/AgCl-NPs-ME were successfully synthesized in 1 min using a 20 mM AgNO₃ solution without additional hazardous chemicals. UV-visible spectroscopy confirmed their formation through a surface plasmon resonance band at 400-500 nm. XRD and FTIR analyses verified their crystalline nature and involvement of organic molecules. TEM and SEM characterization showed well-dispersed Ag/AgCl-NPs-ME with an average size of 36.43 nm. The EDS results confirmed the presence of metallic Ag⁺ and Cl^- ions. Ag/AgCl-NPs-ME exhibited significant antioxidant activity against free radicals (DPPH, ABTS, and FRAP), suggesting their effectiveness. They also inhibited enzymes (tyrosinase and ACE) linked to diseases, indicating therapeutic potential. Importantly, the Ag/AgCl-NPs-ME displayed remarkable cytotoxicity against cancer cells (A375, A549, and Caco-2) while remaining non-toxic to normal cells. DNA ladder and TUNEL assays confirmed the activation of apoptosis mechanisms in cancer cells after a 48 h treatment. These findings highlight the versatile applications of Ag/AgCl-NPs-ME in food, cosmetics, pharmaceuticals, and nutraceuticals.

Functionalized and Nonfunctionalized Nanosystems for Mitochondrial Drug Delivery with Metallic Nanoparticles

Background: The application of metallic nanoparticles as a novel therapeutic tool has significant potential to facilitate the treatment and diagnosis of mitochondria-based disorders. Recently, subcellular mitochondria have been trialed to cure pathologies that depend on their dysfunction. Nanoparticles made from metals and their oxides (including gold, iron, silver, platinum, zinc oxide, and titanium dioxide) have unique modi operandi that can competently rectify mitochondrial disorders. Materials: This review presents insight into the recent research reports on exposure to a myriad of metallic nanoparticles that can alter the dynamic ultrastructure of mitochondria (via altering metabolic homeostasis), as well as pause ATP production, and trigger oxidative stress. The facts and figures have been compiled from more than a hundred PubMed, Web of Science, and Scopus indexed articles that describe the essential functions of mitochondria for the management of human diseases. Result: Nanoengineered metals and their oxide nanoparticles are targeted at the mitochondrial architecture that partakes in the management of a myriad of health issues, including different cancers. These nanosystems not only act as antioxidants but are also fabricated for the delivery of chemotherapeutic agents. However, the biocompatibility, safety, and efficacy of using metal nanoparticles is contested among researchers, which will be discussed further in this review.

Green Synthesized Gold and Silver Nanoparticles Increased Oxidative Stress and Induced Cell Death in Colorectal Adenocarcinoma Cells

The research investigated the effect of gold (Au-CM) and silver nanoparticles (Ag-CM) phytoreduced with Cornus mas fruit extract (CM) on a human colorectal adenocarcinoma (DLD-1) cell line. The impact of nanoparticles on the viability of DLD-1 tumor cells and normal cells was evaluated. Oxidative stress and cell death mechanisms (annexin/propidium iodide analysis, caspase-3 and caspase-8 levels, p53, BCL-2, BAX, NFkB expressions) as well as proliferation markers (Ki-67, PCNA and MAPK) were evaluated in tumor cells. The nanoparticles were characterized using UV-Vis spectroscopy and transmission electron microscopy (TEM) and by measuring zeta potential, hydrodynamic diameter and polydispersity index (PDI). Energy dispersive X-ray (EDX) and X-ray powder diffraction (XRD) analyses were also performed. The nanoparticles induced apoptosis and necrosis of DLD-1 cells and reduced cell proliferation, especially Ag-CM, while on normal cells, both nanoparticles maintained their viability up to 80%. Ag-CM and Au-CM increased the expressions of p53 and NFkB in parallel with the downregulation of BCL-2 protein and induced the activation of caspase-8, suggesting the involvement of apoptosis in cell death. Lipid peroxidation triggered by Ag-CM was correlated with tumor cell necrosis rate. Both nanoparticles obtained with phytocompounds from the CM extract protected normal cells and induced the death of DLD-1 tumor cells, especially by apoptosis.

Surface competition between osteoblasts and bacteria on silver-doped bioactive titanium implant

The rapid integration in the bone tissue and the prevention of bacterial infection are key for the success of the implant. In this regard, a silver (Ag)-doped thermochemical treatment that generate an Ag-doped calcium titanate layer on titanium (Ti) implants was previously developed by our group to improve the bone-bonding ability and provide antibacterial activity. In the present study, the biological and antibacterial potential of this coating has been further studied. In order to prove that the Ag-doped layer has an antibacterial effect with no detrimental effect on the bone cells, the behavior of osteoblast-like cells in terms of cell adhesion, morphology, proliferation and differentiation was evaluated, and the biofilm inhibition capacity was assessed. Moreover, the competition by the surface between cell and bacteria was carried out in two different co-culture methods. Finally, the treatment was applied to porous Ti implants to study in vivo osteointegration. The results show that the incorporation of Ag inhibits the biofilm formation and has no effect on the performance of osteoblast-like cells. Therefore, it can be concluded that the Ag-doped surface is capable of preventing bone bacterial infection and providing suitable osseointegration.

The Role of Silver Nanoparticles in the Diagnosis and Treatment of Cancer: Are There Any Perspectives for the Future?

Cancer is a fatal disease with a complex pathophysiology. Lack of specificity and cytotoxicity, as well as the multidrug resistance of traditional cancer chemotherapy, are the most common limitations that often cause treatment failure. Thus, in recent years, significant efforts have concentrated on the development of a modernistic field called nano-oncology, which provides the possibility of using nanoparticles (NPs) with the aim to detect, target, and treat cancer diseases. In comparison with conventional anticancer strategies, NPs provide a targeted approach, preventing undesirable side effects. What is more, nanoparticle-based drug delivery systems have shown good pharmacokinetics and precise targeting, as well as reduced multidrug resistance. It has been documented that, in cancer cells, NPs promote reactive oxygen species (ROS) production, induce cell cycle arrest and apoptosis, activate ER (endoplasmic reticulum) stress, modulate various signaling pathways, etc. Furthermore, their ability to inhibit tumor growth in vivo has also been documented. In this paper, we have reviewed the role of silver NPs (AgNPs) in cancer nanomedicine, discussing numerous mechanisms by which they render anticancer properties under both in vitro and in vivo conditions, as well as their potential in the diagnosis of cancer.

Naringenin attenuates inflammation, apoptosis, and ferroptosis in silver nanoparticle-induced lung injury through a mechanism associated with Nrf2/HO-1 axis: In vitro and in vivo studies

With the wide application of silver nanoparticles (AgNPs), their potential damage to human health needs to be investigated. Lung is one of the main target organs after inhalation of AgNPs. Naringenin has been reported to have anti-inflammatory and anti-oxidative properties. This study aims to evaluate the protective effects of naringenin against AgNPs-induced lung injury and determine the underlying mechanism. In in vivo experiments, AgNPs were intratracheally instilled into ICR mice (l mg/kg) to establish a lung injury model. These mice were then treated with naringenin by oral gavage (25, 50, 100 mg/kg) for three days. Naringenin treatment decreased the levels of white blood cells, neutrophils, and lymphocytes in the blood, ameliorated lung injury, suppressed the release of pro-inflammatory cytokines, normalized ferroptotic markers and prevented oxidative stress with elevating Nrf2 and HO-1 protein expressions in lung. In in vitro experiments, BEAS-2B cells were firstly treated with AgNPs (320 μg/mL) and then naringenin (25, 50, and 100 μM), respectively. Naringenin attenuated AgNPs-induced oxidative stress and inflammatory response. Moreover, naringenin attenuated AgNPs-induced apoptosis with modulated low BAX, CytC, cleaved Caspase9, cleaved Caspase3 but high Bcl2. Furthermore, naringenin effectively decreased ferroptotic markers and increased the protein expressions of Nrf2 and HO-1, as well as increased the nuclear translocation of Nrf2. Importantly, the anti-apoptotic and anti-ferroptotic effects of naringenin in BEAS-2B cells were found to be at least partially Nrf2-dependent. These results indicated that naringenin exerted anti-inflammation, anti-apoptosis, and anti-ferroptosis effects and protected against AgNPs-induced lung injury at least partly via activating Nrf2/HO-1 signaling pathway.

Mitophagy Induced by Metal Nanoparticles for Cancer Treatment

Research on nanoparticles, especially metal nanoparticles, in cancer therapy is gaining momentum. The versatility and biocompatibility of metal nanoparticles make them ideal for various applications in cancer therapy. They can bring about apoptotic cell death in cancer cells. In addition to apoptosis, nanoparticles mediate a special type of autophagy facilitated through mitochondria called mitophagy. Interestingly, nanoparticles with antioxidant properties are capable of inducing mitophagy by altering the levels of reactive oxygen species and by influencing signaling pathways like PINK/Parkin pathway and P13K/Akt/mTOR pathway. The current review presents various roles of metal nanoparticles in inducing mitophagy in cancer cells. We envision this review sheds some light on the blind spots in the research related to mitophagy induced by nanoparticles for cancer treatment.

The use of Trojan-horse drug delivery system in managing periodontitis

The aim of this review is to evaluate the possibility of delivering a silver-acid complex via a Trojan-horse mechanism for managing periodontits. We theroised that the complex could be an effective treatment option for bacterial inflammatory processes in the oral cavity. Searches were conducted using MEDLINE, Embase, Web of Science Core Collection, and Google Scholar search engines. We also reviewed several reference lists of the included studies or relevant reviews identified by the search. By using Medical Subject Headings (MeSH) terminology, a comprehensive search was performed for the following keywords: silver, folic acid, periodontitis, macrophages, Trojan-horse mechanism, toxicity, and targeting. Using the keywords mentioned earlier, we selected 110 articles and after appropriate elimination the review was written based on 37 papers. Accordingly the we noted that silver isons were an effective approach to kill oral pathogens. Secondly the Trojan-horse mechanism. could be used by macrophages (as the Trojan horse) to deliver silver ions in large quantities to the inflammatory focus to kill the periodontopathogens. The Trojan-horse mechanism has never been described in the field of dentistry before. The proposed novel approach using the principle of Trojan Horse delivery of drugs/chemicals could be used to manage oral inflammatory conditions. This method can be used to supplement regular treatments.

Metal-Polymer Nanoconjugates Application in Cancer Imaging and Therapy

Metallic-based nanoparticles present a unique set of physicochemical properties that support their application in different fields, such as electronics, medical diagnostics, and therapeutics. Particularly, in cancer therapy, the plasmonic resonance, magnetic behavior, X-ray attenuation, and radical oxygen species generation capacity displayed by metallic nanoparticles make them highly promising theragnostic solutions. Nevertheless, metallic-based nanoparticles are often associated with some toxicological issues, lack of colloidal stability, and establishment of off-target interactions. Therefore, researchers have been exploiting the combination of metallic nanoparticles with other materials, inorganic (e.g., silica) and/or organic (e.g., polymers). In terms of biological performance, metal-polymer conjugation can be advantageous for improving biocompatibility, colloidal stability, and tumor specificity. In this review, the application of metallic-polymer nanoconjugates/nanohybrids as a multifunctional all-in-one solution for cancer therapy will be summarized, focusing on the physicochemical properties that make metallic nanomaterials capable of acting as imaging and/or therapeutic agents. Then, an overview of the main advantages of metal-polymer conjugation as well as the most common structural arrangements will be provided. Moreover, the application of metallic-polymer nanoconjugates/nanohybrids made of gold, iron, copper, and other metals in cancer therapy will be discussed, in addition to an outlook of the current solution in clinical trials.

Antibacterial and Cytocompatible: Combining Silver Nitrate with Strontium Acetate Increases the Therapeutic Window

Microbial infection and insufficient tissue formation are considered to be the two main causes of dental implant failure. Novel studies have focused on designing dual-functional strategies to promote antibacterial properties and improve tissue cell response simultaneously. In this study, we investigated the antibacterial properties and cytocompatibility of silver nitrate (AgNO₃) and strontium acetate (SrAc) in a mono-culture setup for dental application. Additionally, we defined the therapeutic window between the minimum inhibitory concentration against pathogenic bacteria and maximum cytocompatible dose in the case of combined applications in a co-culture setup. Antibacterial properties were screened using Aggregatibacter actinomycetemcomitans and cell response experiments were performed with osteoblastic cells (MC3T3) and fibroblastic cells (NIH3T3). The osteoinductive behavior was investigated separately on MC3T3 cells using alizarin red staining. A therapeutic window for AgNO₃ as well as SrAc applications could be defined in the case of MC3T3 cells while the cytocompatibility of NIH3T3 cells was compromised for all concentrations with an antibacterial effect. However, the combined application of AgNO₃/SrAc caused an enhanced antibacterial effect and opened a therapeutic window for both cell lines. Enhanced mineralization rates could be observed in cultures containing SrAc. In conclusion, we were able to demonstrate that adding SrAc to AgNO₃ not only intensifies antibacterial properties but also exhibits bone inductive characteristics, thereby offering a promising strategy to combat peri-implantitis and at the same time improve osseointegration in implant therapy.

Lung Models to Evaluate Silver Nanoparticles’ Toxicity and Their Impact on Human Health

Nanomaterials (NMs) solve specific problems with remarkable results in several industrial and scientific areas. Among NMs, silver nanoparticles (AgNPs) have been extensively employed as drug carriers, medical diagnostics, energy harvesting devices, sensors, lubricants, and bioremediation. Notably, they have shown excellent antimicrobial, anticancer, and antiviral properties in the biomedical field. The literature analysis shows a selective cytotoxic effect on cancer cells compared to healthy cells, making its potential application in cancer treatment evident, increasing the need to study the potential risk of their use to environmental and human health. A large battery of toxicity models, both in vitro and in vivo, have been established to predict the harmful effects of incorporating AgNPs in these numerous areas or those produced due to involuntary exposure. However, these models often report contradictory results due to their lack of standardization, generating controversy and slowing the advances in nanotoxicology research, fundamentally by generalizing the biological response produced by the AgNP formulations. This review summarizes the last ten years’ reports concerning AgNPs’ toxicity in cellular respiratory system models (e.g., mono-culture models, co-cultures, 3D cultures, ex vivo and in vivo). In turn, more complex cellular models represent in a better way the physical and chemical barriers of the body; however, results should be used carefully so as not to be misleading. The main objective of this work is to highlight current models with the highest physiological relevance, identifying the opportunity areas of lung nanotoxicology and contributing to the establishment and strengthening of specific regulations regarding health and the environment.

Silver Nanoparticles Selectively Treat Neurofibromatosis Type 1-Associated Malignant Peripheral Nerve Sheath Tumors in a Neurofibromin-Dependent Manner

Neurofibromatosis type 1 (NF1) is among the most common neurogenic disorders, characterized by loss of function mutations in the neurofibromin gene (NF1). NF1 patients are extremely susceptible to developing neurofibromas, which can transform into deadly malignant peripheral nerve sheath tumors (MPNSTs). At the center of these tumors are NF1-null Schwann cells. Here, we found that nanomedicine shows promise in the treatment of NF1-associated MPNSTs. We assessed the cytotoxicity of silver nanoparticles (AgNPs) in NF1-null NF1-associated MPNSTs, NF1-wildtype sporadic MPNST, and normal Schwann cells. Our data show that AgNP are selectivity cytotoxic to NF1-associated MPNSTs relative to sporadic MPNST and Schwann cells. Furthermore, we found that sensitivity to AgNPs is correlated with the expression levels of functional neurofibromin. The restoration of functional neurofibromin in NF1-associated MPNSTs reduces AgNP sensitivity, and the knockdown of neurofibromin in Schwann cells increases AgNP sensitivity. This finding is unique to AgNPs, as NF1 restoration does not alter sensitivity to standard of care chemotherapy doxorubicin in NF1-associated MPNSTs. Using an in vitro model system, we then found that AgNP can selectively eradicate NF1-associated MPNSTs in co-culture with Schwann cells at doses tolerable to normal cells. AgNP represents a novel therapy for the treatment of NF1-associated MPNSTs and addresses significant unmet clinical need.

Application of Nanomaterials in the Prevention, Detection, and Treatment of Methicillin-Resistant Staphylococcus aureus (MRSA)

Due to differences in geographic surveillance systems, chemical sanitization practices, and antibiotic stewardship (AS) implementation employed during the COVID-19 pandemic, many experts have expressed concerns regarding a future surge in global antimicrobial resistance (AMR). A potential beneficiary of these differences is the Gram-positive bacteria MRSA. MRSA is a bacterial pathogen with a high potential for mutational resistance, allowing it to engage various AMR mechanisms circumventing conventional antibiotic therapies and the host’s immune response. Coupled with a lack of novel FDA-approved antibiotics reaching the clinic, the onus is on researchers to develop alternative treatment tools to mitigate against an increase in pathogenic resistance. Mitigation strategies can take the form of synthetic or biomimetic nanomaterials/vesicles employed in vaccines, rapid diagnostics, antibiotic delivery, and nanotherapeutics. This review seeks to discuss the current potential of the aforementioned nanomaterials in detecting and treating MRSA.

Nano Silver-Induced Toxicity and Associated Mechanisms

Nano silver is one of the most widely used engineering nanomaterials with antimicrobial activity against bacteria, fungi, and viruses. However, the widespread application of nano silver preparations in daily life raises concerns about public health. Although several review articles have described the toxicity of nano silver to specific major organs, an updated comprehensive review that clearly and systematically outlines the harmful effects of nano silver is lacking. This review begins with the routes of exposure to nano silver and its distribution in vivo. The toxic reactions are then discussed on three levels, from the organ to the cellular and subcellular levels. This review also provides new insights on adjusting the toxicity of nano silver by changing their size and surface functionalization and their combination with other materials to form a composite formulation. Finally, future development, challenges, and research directions are discussed.

Antitumor Activity against A549 Cancer Cells of Three Novel Complexes Supported by Coating with Silver Nanoparticles

A novel biologically active organic ligand L (N’-benzylidenepyrazine-2-carbohydrazonamide) and its three coordination compounds have been synthesized and structurally described. Their physicochemical and biological properties have been thoroughly studied. Cu(II), Zn(II), and Cd(II) complexes have been analyzed by F-AAS spectrometry and elemental analysis. The way of metal–ligand coordination was discussed based on FTIR spectroscopy and UV-VIS-NIR spectrophotometry. The thermal behavior of investigated compounds was studied in the temperature range 25–800 °C. All compounds are stable at room temperature. The complexes decompose in several stages. Magnetic studies revealed strong antiferromagnetic interaction. Their cytotoxic activity against A549 lung cancer cells have been studied with promising results. We have also investigated the biological effect of coating studied complexes with silver nanoparticles. The morphology of the surface was studied using SEM imaging.

Proteome-wide analysis reveals molecular pathways affected by AgNP in a ROS-dependent manner

The use of mass spectrometry-based proteomics has been increasingly applied in nanomaterials risk assessments as it provides a proteome-wide overview of the molecular disturbances induced by its exposure. Here, we used this technique to gain detailed molecular insights into the role of ROS as an effector of AgNP toxicity, by incubating Bend3 cells with AgNP in the absence or presence of an antioxidant N-acetyl L-cystein (NAC). ROS generation is a key player in AgNP-induced toxicity, as cellular homeostasis was kept in the presence of NAC. By integrating MS/MS data with bioinformatics tools, in the absence of NAC, we were able to pinpoint precisely which biological pathways were affected by AgNP. Cells respond to AgNP-induced ROS generation by increasing their antioxidant pool, via NRF2 pathway activation. Additionally, cell proliferation-related pathways were strongly inhibited in a ROS-dependent manner. These findings reveal important aspects of the AgNP mechanism of action at the protein level.

In Vivo Effects of Silver Nanoparticles on Development, Behavior, and Mitochondrial Function are Altered by Genetic Defects in Mitochondrial Dynamics

Silver nanoparticles (AgNPs) are extensively used in consumer products and biomedical applications, thus guaranteeing both environmental and human exposures. Despite extensive research addressing AgNP safety, there are still major knowledge gaps regarding AgNP toxicity mechanisms, particularly in whole organisms. Mitochondrial dysfunction is frequently described as an important cytotoxicity mechanism for AgNPs; however, it is still unclear if mitochondria are the direct targets of AgNPs. To test this, we exposed the nematodeCaenorhabditis elegans to sublethal concentrations of AgNPs and assessed specific mitochondrial parameters as well as organismal-level endpoints that are highly reliant on mitochondrial function, such as development and chemotaxis behavior. All AgNPs tested significantly delayed nematode development, disrupted mitochondrial bioenergetics, and blocked chemotaxis. However, silver was not preferentially accumulated in mitochondria, indicating that these effects are likely not due to direct mitochondria-AgNP interactions. Mutant nematodes with deficiencies in mitochondrial dynamics displayed both greater and decreased susceptibility to AgNPs compared to wild-type nematodes, which was dependent on the assay and AgNP type. Our study suggests that AgNPs indirectly promote mitochondrial dysfunction, leading to adverse outcomes at the organismal level, and reveals a role of gene-environment interactions in the susceptibility to AgNPs. Finally, we propose a novel hypothetical adverse outcome pathway for AgNP effects to guide future research.

Cancer Therapy by Silver Nanoparticles: Fiction or Reality?

As an emerging new class, metal nanoparticles and especially silver nanoparticles hold great potential in the field of cancer biology. Due to cancer-specific targeting, the consequently attenuated side-effects and the massive anti-cancer features render nanoparticle therapeutics desirable platforms for clinically relevant drug development. In this review, we highlight those characteristics of silver nanoparticle-based therapeutic concepts that are unique, exploitable, and achievable, as well as those that represent the critical hurdle in their advancement to clinical utilization. The collection of findings presented here will describe the features that distinguish silver nanoparticles from other anti-cancer agents and display the realistic opportunities and implications in oncotherapeutic innovations to find out whether cancer therapy by silver nanoparticles is fiction or reality.

The mechanism of cell death induced by silver nanoparticles is distinct from silver cations

Background

Precisely how silver nanoparticles (AgNPs) kill mammalian cells still is not fully understood. It is not clear if AgNP-induced damage differs from silver cation (Ag⁺), nor is it known how AgNP damage is transmitted from cell membranes, including endosomes, to other organelles. Cells can differ in relative sensitivity to AgNPs or Ag⁺, which adds another layer of complexity to identifying specific mechanisms of action. Therefore, we determined if there were specific effects of AgNPs that differed from Ag⁺ in cells with high or low sensitivity to either toxicant.

Methods

Cells were exposed to intact AgNPs, Ag⁺, or defined mixtures of AgNPs with Ag⁺, and viability was assessed. The level of dissolved Ag⁺ in AgNP suspensions was determined using inductively coupled plasma mass spectrometry. Changes in reactive oxygen species following AgNP or Ag⁺ exposure were quantified, and treatment with catalase, an enzyme that catalyzes the decomposition of H₂O₂ to water and oxygen, was used to determine selectively the contribution of H₂O₂ to AgNP and Ag⁺ induced cell death. Lipid peroxides, formation of 4-hydroxynonenol protein adducts, protein thiol oxidation, protein aggregation, and activation of the integrated stress response after AgNP or Ag⁺ exposure were quantified. Lastly, cell membrane integrity and indications of apoptosis or necrosis in AgNP and Ag⁺ treated cells were examined by flow cytometry.

Results

We identified AgNPs with negligible Ag⁺ contamination. We found that SUM159 cells, which are a triple-negative breast cancer cell line, were more sensitive to AgNP exposure less sensitive to Ag⁺ compared to iMECs, an immortalized, breast epithelial cell line. This indicates that high sensitivity to AgNPs was not predictive of similar sensitivity to Ag⁺. Exposure to AgNPs increased protein thiol oxidation, misfolded proteins, and activation of the integrated stress response in AgNP sensitive SUM159 cells but not in iMEC cells. In contrast, Ag⁺ cause similar damage in Ag⁺ sensitive iMEC cells but not in SUM159 cells. Both Ag⁺ and AgNP exposure increased H₂O₂ levels; however, treatment with catalase rescued cells from Ag⁺ cytotoxicity but not from AgNPs. Instead, our data support a mechanism by which damage from AgNP exposure propagates through cells by generation of lipid peroxides, subsequent lipid peroxide mediated oxidation of proteins, and via generation of 4-hydroxynonenal (4-HNE) protein adducts.

Conclusions

There are distinct differences in the responses of cells to AgNPs and Ag⁺. Specifically, AgNPs drive cell death through lipid peroxidation leading to proteotoxicity and necrotic cell death, whereas Ag⁺ increases H₂O₂, which drives oxidative stress and apoptotic cell death. This work identifies a previously unknown mechanism by which AgNPs kill mammalian cells that is not dependent upon the contribution of Ag⁺ released in extracellular media. Understanding precisely which factors drive the toxicity of AgNPs is essential for biomedical applications such as cancer therapy, and of importance to identifying consequences of unintended exposures.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12989-021-00430-1.

Lack of Detectable Direct Effects of Silver and Silver Nanoparticles on Mitochondria in Mouse Hepatocytes

Silver nanoparticles (AgNPs) are well-proven antimicrobial nanomaterials, yet little is elucidated regarding the mechanism underlying cytotoxicity induced by these nanoparticles. Here, we tested the hypothesis that mitochondria are primary intracellular targets of two AgNPs and silver ions in mouse hepatocytes (AML12) cultured in glucose- and galactose-based media. AML12 cells were more sensitive to mitochondrial uncoupling when grown with galactose rather than glucose. However, 24 h treatments with 15 nm AgNPs and 6 nm GA-AgNPs (5 and 10 μg/mL) and AgNO3 (1 and 3 μg/mL), concentrations that resulted in either 10 or 30% cytotoxicity, failed to cause more toxicity to AML12 cells grown on galactose than glucose. Furthermore, colocalization analysis and subcellular Ag quantification did not show any enrichment of silver content in mitochondria in either medium. Finally, the effects of the same exposures on mitochondrial respiration were mild or undetectable, a result inconsistent with mitochondrial toxicity causing cell death. Our results suggest that neither ionic Ag nor the AgNPs that we tested specifically target mitochondria and are inconsistent with mitochondrial dysfunction being the primary cause of cell death after Ag exposure under these conditions.

Detection of Oxidative Stress Induced by Nanomaterials in Cells-The Roles of Reactive Oxygen Species and Glutathione

The potential of nanomaterials use is huge, especially in fields such as medicine or industry. Due to widespread use of nanomaterials, their cytotoxicity and involvement in cellular pathways ought to be evaluated in detail. Nanomaterials can induce the production of a number of substances in cells, including reactive oxygen species (ROS), participating in physiological and pathological cellular processes. These highly reactive substances include: superoxide, singlet oxygen, hydroxyl radical, and hydrogen peroxide. For overall assessment, there are a number of fluorescent probes in particular that are very specific and selective for given ROS. In addition, due to the involvement of ROS in a number of cellular signaling pathways, understanding the principle of ROS production induced by nanomaterials is very important. For defense, the cells have a number of reparative and especially antioxidant mechanisms. One of the most potent antioxidants is a tripeptide glutathione. Thus, the glutathione depletion can be a characteristic manifestation of harmful effects caused by the prooxidative-acting of nanomaterials in cells. For these reasons, here we would like to provide a review on the current knowledge of ROS-mediated cellular nanotoxicity manifesting as glutathione depletion, including an overview of approaches for the detection of ROS levels in cells.

Potential cytotoxicity of silver nanoparticles: Stimulation of autophagy and mitochondrial dysfunction in cardiac cells

In the present study, we elucidated the potential cytotoxicity of AgNPs in H9c2 rat cardiomyoblasts and assessed the underlying toxicological manifestations responsible for their toxicity thereof. The results indicated that the exposure of AgNPs to H9c2 cardiac cells decreased cell viability in a dose-dependent manner and caused cell cycle arrest followed by induction of apoptosis. The AgNPs treated cardiac cells showed a generation of reactive oxygen species (ROS) and mitochondrial dysfunction where mitochondrial ATP was reduced and the expression of AMPK1α increased. AgNPs also induced ROS-mediated autophagy in H9c2 cells. There was a significant time-dependent increase in intracellular levels of Atg5, Beclin1, and LC3BII after exposure to AgNPs, signifying the autophagic response in H9c2 cells. More importantly, the addition of N-acetyl-L-cysteine (NAC) inhibited autophagy and significantly reduced the cytotoxicity of AgNPs in H9c2 cells. The study highlights the prospective toxicity of AgNPs on cardiac cells, collectively signifying a potential health risk.

Integrated Redox Proteomic Analysis Highlights New Mechanisms of Sensitivity to Silver Nanoparticles

Silver nanoparticles (AgNPs) are widely used nanomaterials in both commercial and clinical biomedical applications, but the molecular mechanisms underlying their activity remain elusive. In this study we profiled proteomics and redox proteomics changes induced by AgNPs in two lung cancer cell lines: AgNPs-sensitive Calu-1 and AgNPs-resistant NCI-H358. We show that AgNPs induce changes in protein abundance and reversible oxidation in a time and cell-line-dependent manner impacting critical cellular processes such as protein translation and modification, lipid metabolism, bioenergetics, and mitochondrial dynamics. Supporting confocal microscopy and transmission electron microscopy (TEM) data further emphasize mitochondria as a target of AgNPs toxicity differentially impacting mitochondrial networks and morphology in Calu-1 and NCI-H358 lung cells. Proteomics data are available via ProteomeXchange with identifier PXD021493.

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AgNP-sensitive cells experience broader changes in protein abundance.

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Redox proteomics reveals increased reversible oxidation in AgNP-sensitive cells.

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AgNPs alter protein translation, lipid metabolism, and bioenergetics.

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Mitochondria is identified as key target underlying AgNP toxicity.

Combined Photothermal and Ionizing Radiation Sensitization of Triple-Negative Breast Cancer Using Triangular Silver Nanoparticles

Background

Ionizing radiation (IR) is commonly used in triple-negative breast cancer (TNBC) treatment regimens. However, off-target toxicity affecting normal tissue and grueling treatment regimens remain major limitations. Hyperthermia is one of the greatest IR sensitizers, but only if heat is administered simultaneously or immediately prior to ionizing radiation. Difficulty in co-localizing ionizing radiation (IR) in rapid succession with hyperthermia, and confining treatment to the tumor have hindered widespread clinical adoption of combined thermoradiation treatment. Metal nanoparticle-based approaches to IR sensitization and photothermal heat generation may aid in overcoming these issues and improve treatment specificity.

Methods

We assessed the potential to selectively treat MDA-MB-231 TNBC cells without affecting non-malignant MCF-10A breast cells using a multimodal approach based upon combined photothermal therapy, IR sensitization, and specific cytotoxicity using triangular silver nanoparticles (TAgNPs) with peak absorbance in the near-infrared light (NIR) spectrum.

Results

We found that TAgNP-mediated photothermal therapy and radiosensitization offer a high degree of specificity for treatment of TNBC without affecting non-malignant mammary epithelial cells.

Discussion

If given at a high enough dose, IR, heat, or TAgNPs alone could be sufficient for tumor treatment. However, when the dose of one or all of these modalities increases, off-target effects also increase. The challenge lies in identifying the minimal doses of each individual treatment such that when combined they provide maximum selectivity for treatment of TNBC cells with minimum off-target effects on non-malignant breast cells. Our results provide proof of concept that this combination is highly selective for TNBC cells while sparing non-malignant mammary epithelial cells. This treatment would be particularly important for patients undergoing breast conservation therapy and for treatment of invasive tumor margins near the periphery where each individual treatment might be at a sub-therapeutic level.

Mitophagy-lysosomal pathway is involved in silver nanoparticle-induced apoptosis in A549 cells

With the increasing use of silver nanoparticles (AgNPs) in biological materials, the cytotoxicity caused by these particles has attracted much attention. However, the molecular mechanism underlying AgNP cytotoxicity remains unclear. In this study, we aimed to systematically investigate the toxicity induced by AgNP exposure to the lung adenocarcinoma A549 cell line at the subcellular and signaling pathway levels and elucidate the related molecular mechanism. The survival rate of cells exposed to AgNPs at 0, 20, 40, 80, and 160 μg/mL for 24 or 48 h decreased in a dose- and time-dependent manner. AgNPs induced autophagy and mitophagy, determined by the transmission electron microscopy investigation and upregulation of LC3 II/I, p62, PINK1, and Parkin expression levels. AgNP treatment induced lysosomal injury, including the decline of lysosomal membrane integrity and increase in cathepsin B level. The decreased in mitochondrial membrane potential, along with upregulation of cytochrome c, caspases 9 and 3, and BAX/BCL2, further suggested that mitochondrial injury were involved in AgNP-induced apoptosis. In addition, mitochondrial injury may further lead to excessive production of reactive oxygen species and oxidative/ antioxidant imbalance. The results suggested that AgNPs could regulate autophagy via mitochondrial and lysosome injury in A549 cells. The information of the molecular mechanism will provide an experimental basis for the safe application of nanomaterials.

Roles of ROS and cell cycle arrest in the genotoxicity induced by gold nanorod core/silver shell nanostructure

To understand the genotoxicity induced in the liver by silver nanoparticles (AgNPs) and silver ions, an engineered gold nanorod core/silver shell nanostructure (Au@Ag NR) and humanized hepatocyte HepaRG cells were used in this study. The involvement of oxidative stress and cell cycle arrest in the DNA and chromosome damage induced by 0.4-20 µg mL^-1 Au@Ag NR were investigated by comet assay, γ-H2AX assay and micronucleus test. Further, the distribution of Au@Ag NR was analyzed. Our results demonstrated that both Ag⁺ and Au@Ag NR led to DNA cleavage and chromosome damage (clastogenicity) in HepaRG cells and that the Au@Ag NR retained in the nucleus may further release Ag⁺, aggravating the damages, which are mainly caused by cell cycle arrest and ROS formation. The results reveal the correlation between the intracellular accumulation, Ag⁺ ion release and the potential genotoxicity of AgNPs.

Silver Nanoparticle-Induced Apoptosis in ARPE-19 Cells Is Inhibited by Toxoplasma gondii Pre-Infection Through Suppression of NOX4-Dependent ROS Generation

Purpose

External and internal stimuli easily affect the retina. Studies have shown that cells infected with Toxoplasma gondii are resistant to multiple inducers of apoptosis. Nanoparticles (NPs) have been widely used in biomedical fields; however, little is known about cytotoxicity caused by NPs in the retina and the modulators that inhibit nanotoxicity.

Materials and Methods

ARPE-19 cells from human retinal pigment epithelium were treated with silver nanoparticles (AgNPs) alone or in combination with T. gondii. Then, the cellular toxicity, apoptosis, cell cycle analysis, autophagy, ROS generation, NOX4 expression, and MAPK/mTOR signaling pathways were investigated. To confirm the AgNP-induced cytotoxicity in ARPE-19 cells and its modulatory effects caused by T. gondii infection, the major experiments carried out in ARPE-19 cells were performed again using human foreskin fibroblast (HFF) cells and bone marrow-derived macrophages (BMDMs) from NOX4^−/− mice.

Results

AgNPs dose-dependently induced cytotoxicity and cell death in ARPE-19 cells. Apoptosis, sub-G1 phase cell accumulation, autophagy, JNK phosphorylation, and mitochondrial apoptotic features, such as caspase-3 and PARP cleavages, mitochondrial membrane potential depolarization, and cytochrome c release into the cytosol were observed in AgNP-treated cells. AgNP treatment also increased the Bax, Bik, and Bim protein levels as well as NOX4-dependent ROS generation. However, T. gondii-infected ARPE-19 cells inhibited AgNP-induced apoptosis, JNK phosphorylation, sub-G1 phase cell accumulation, autophagy, NOX4-mediated ROS production, and mitochondrial apoptosis. Furthermore, mitochondrial apoptosis was found in AgNP-treated HFF cells and BMDMs, and AgNP-induced mitochondrial apoptosis inhibition via NOX4-dependent ROS suppression in T. gondii pre-infected HFF cells and BMDMs was also confirmed.

Conclusion

AgNPs induced mitochondrial apoptosis in human RPE cells combined with cell cycle dysregulation and autophagy; however, these effects were significantly inhibited by T. gondii pre-infection by suppression of NOX4-mediated ROS production, suggesting that T. gondii is a strong inhibitory modulator of nanotoxicity in in vitro models.

Controlled Release of Thymol from Poly(Lactic Acid)-Based Silver Nanocomposite Films with Antibacterial and Antioxidant Activity

Thymol and silver nanoparticles (Ag-NPs) were used to develop poly(lactic acid) (PLA)-based films with antioxidant and antibacterial performance. Different amounts of thymol (6 and 8 wt%) and 1 wt% Ag-NPs were added to PLA to produce the active films. Ag-NPs and thymol were successfully identified in the nanocomposite structures using spectroscopic techniques. A kinetic study was performed to evaluate the release of thymol and Ag-NPs from the nanocomposites to an aqueous food simulant (ethanol 10%, v/v) at 40 °C. The diffusion of thymol from the polymer matrix was affected by the presence of non-migrating Ag-NPs, which showed non-Fickian release behavior. The ternary system including 1 wt% Ag-NPs and 8 wt% thymol showed clear antibacterial performance by reducing the cell viability of Escherichia coli and Staphylococcus aureus by around 40% after 3 and 24 h of storage at 4, 25, and 37 °C compared to neat PLA. Significant antioxidant behavior of all active films was also confirmed using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. The obtained nanocomposite films based on PLA and the addition of Ag-NPs and thymol were proven to have combined antioxidant and antibacterial performance, with controlled release of thymol. These formulations have potential applications in the development of innovative and customized active packaging systems to increase the shelf-life of food products.