Copper Oxide Nanoparticles Exhibit Cell Death Through Oxidative Stress Responses in Human Airway Epithelial Cells: a Mechanistic Study

CuO-NPs Induce Apoptosis and Functional Impairment in BV2 Cells Through the CSF-1R/PLCγ2/ERK/Nrf2 Pathway

Copper oxide nanoparticles (CuO-NPs) induce neurological diseases, including neurobehavioral defects and neurodegenerative diseases. Direct evidence indicates that CuO-NPs induce inflammation in the central nervous system and cause severe neurotoxicity. However, the mechanism of CuO-NP-induced damage to the nervous system has rarely been studied, and the toxicity of different CuO-NP particle sizes and their copper ion (Cu2+) precipitation in microglia (BV2 cells) is worth exploring. Therefore, this study investigated CuO-NPs with different particle sizes (small particle size: S-CuO-NPs; large particle size: L-CuO-NPs), Cu2+ with equal molar mass (replaced by CuCl2 [Equ group]), and Cu2+ precipitated in a cell culture solution with CuO-NPs (replaced by CuCl2 [Pre group]), and examined the mechanism of action of each on BV2 microglia after co-culture for 12 h and 24 h. The activity of BV2 cells decreased, the morphology was damaged, and the apoptosis rate increased in all the exposed groups. Toxicity increased time- and dose-dependently, and was highest in the Equ group, followed by the S-CuO-NPs, L-CuO-NPs, and Pre groups, respectively. Subsequently, we investigated the mechanism of S-CuO-NP-induced cell injury, and revealed that S-CuO-NPs induced oxidative stress and inflammatory response and increased the membrane permeability of BV2 cells. Moreover, S-CuO-NPs reduced the ratio of p-CSF-1R/CSF-1R, p-PLCγ2/PLCγ2, p-extracellular signal-regulated kinase (ERK)/ERK, p-Nrf2/Nrf2, and Bcl-2/Bax protein expression in microglia, and elevated cleaved caspase-3 expression. The CSF-1R/PLCγ2/ERK/Nrf2 apoptotic pathway was activated. The downregulation of CX3CR1, CSF-1R, brain-derived neurotrophic factor (BDNF), and IGF-1 protein expression indicates impairment of the repair and protection functions of microglia in the nervous system. In summary, our results reveal that CuO-NPs promote an increase in inflammatory molecules in BV2 microglia through oxidative stress, activate the CSF-1R/PLCγ2/ERK/Nrf2 pathway, cause apoptosis, and ultimately result in neurofunctional damage to microglia.

Copper oxide nanoparticles induced reactive oxygen species generation: A systematic review and meta-analysis

Copper oxide nanoparticles (CuO NPs) are widely employed in various industrial and biomedical applications owing to their enhanced physicochemical characteristics. However, concerns regarding their adverse effects on biological systems upon entering the environment remain unexplored. The generation of reactive oxygen species (ROS) is one of the primary mechanisms in CuO NPs induced toxicity. This meta-analysis was conducted to assess the associative link between CuO NPs exposure and ROS generation. A literature survey was performed in PubMed, Web of Science, Scopus, and Google Scholar, following PRISMA guidelines. After comprehensive initial and primary screening, 28 in vitro studies were selected for meta-analysis. Overall, our results show a substantial increase of ROS in the experimental group when compared to control (SMD = 3.3; 95 % CI: 2.82-3.77, p = 0.00001), with substantial heterogeneity (82 %). Subgroup analysis revealed that larger-sized NPs, higher dosages, and longer exposure duration were associated with ROS generation. Meta-regression analysis identified size, and dosage as significant factors influencing ROS levels. Sensitivity analysis revealed an outlier study and the funnel plot results suggested potential publication bias. Overall, our results provide valuable insights of CuO NPs induced ROS generation, and the relation of variables such as size, dose, and duration in nanotoxicity assessments.

The potential of copper oxide nanoparticles in nanomedicine: A comprehensive review

Nanotechnology is a modern scientific discipline that uses nanoparticles of metals like copper, silver, gold, platinum, and zinc for various applications. Copper oxide nanoparticles (CuONPs) are effective in biomedical settings, such as killing bacteria, speeding up reactions, stopping cancer cells, and coating surfaces. These inorganic nanostructures have a longer shelf life than their organic counterparts and are chemically inert and thermally stable. However, commercial synthesis of NPs often involves harmful byproducts and hazardous chemicals. Green synthesis for CuONPs offers numerous benefits, including being clean, harmless, economical, and environmentally friendly. Using naturally occurring organisms like bacteria, yeast, fungi, algae, and plants can make CuONPs more environmentally friendly. CuONPs are expected to be used in nanomedicine due to their potent antimicrobial properties and disinfecting agents for infectious diseases. This comprehensive review looks to evaluate research articles published in the last ten years that investigate the antioxidant, anticancer, antibacterial, wound healing, dental application and catalytic properties of copper nanoparticles generated using biological processes. Utilising the scientific approach of large-scale data analytics. However, their toxic effects on vertebrates and invertebrates raise concerns about their use for diagnostic and therapeutic purposes. Therefore, biocompatibility and non-toxicity are crucial for selecting nanoparticles for clinical research.

Exploring the cytotoxicity mechanisms of copper ions and copper oxide nanoparticles in cells from the excretory system

Copper oxide nanoparticles (CuO NPs) are widely applied in various products, including food, cosmetic, biomedical, and environmental goods. Despite their broad use, potential risks are still associated with these NPs, therefore, the aim of this study is to delve deeper into the cytotoxic effects of 85 nm CuO NPs on kidney MDCK and liver AML-12 cells, representing cell models from the excretory system. Our findings pointed out that the viability of both cell lines decreased in a concentration-dependent manner when exposed to CuO NPs. Additionally, CuO NPs induced the overproduction of reactive oxygen species (ROS) and caused depolarization of the mitochondrial membrane, thereby arresting the cell cycle at the G2/M phase in MDCK and AML-12 cells. Importantly, unlike others our study uncovered distinctive forms of cellular death induced by CuO NPs in these cell lines. MDCK cells exhibited a combination of apoptosis and autophagy while early apoptosis was predominant in AML-12 cells. Moreover, the role of Cu2+ ions and CuO NPs in exerting cytotoxic effects was investigated, revealing that MDCK cells were affected by both copper ions and NPs. In contrast, AML-12 cells experienced toxic effects solely from CuO NPs. These findings provide crucial insights into the different cell death mechanisms caused either by CuO NPs or Cu2+ ions in excretory system cells in vitro. Nevertheless, further research is needed to explore the underlying mechanisms at the in vivo level, ensuring the safe use of CuO NPs. The results suggest that specific concentrations of metal oxide NPs can impact the physiology of cells within the excretory system of various mammals, including humans, and pave the way for comparing the toxic effects between ions and nanoparticles for further nanotoxicological studies.

Photothermal therapy of copper incorporated nanomaterials for biomedicine

Studies have reported on the significance of copper incorporated nanomaterials (CINMs) in cancer theranostics and tissue regeneration. Given their unique physicochemical properties and tunable nanostructures, CINMs are used in photothermal therapy (PTT) and photothermal-derived combination therapies. They have the potential to overcome the challenges of unsatisfactory efficacy of conventional therapies in an efficient and non-invasive manner. This review summarizes the recent advances in CINMs-based PTT in biomedicine. First, the classification and structure of CINMs are introduced. CINMs-based PTT combination therapy in tumors and PTT guided by multiple imaging modalities are then reviewed. Various representative designs of CINMs-based PTT in bone, skin and other organs are presented. Furthermore, the biosafety of CINMs is discussed. Finally, this analysis delves into the current challenges that researchers face and offers an optimistic outlook on the prospects of clinical translational research in this field. This review aims at elucidating on the applications of CINMs-based PTT and derived combination therapies in biomedicine to encourage future design and clinical translation.

Recent advances in nanoantibiotics against multidrug-resistant bacteria

Multidrug-resistant (MDR) bacteria-caused infections have been a major threat to human health. The abuse of conventional antibiotics accelerates the generation of MDR bacteria and makes the situation worse. The emergence of nanomaterials holds great promise for solving this tricky problem due to their multiple antibacterial mechanisms, tunable antibacterial spectra, and low probabilities of inducing drug resistance. In this review, we summarize the mechanism of the generation of drug resistance, and introduce the recently developed nanomaterials for dealing with MDR bacteria via various antibacterial mechanisms. Considering that biosafety and mass production are the major bottlenecks hurdling the commercialization of nanoantibiotics, we introduce the related development in these two aspects. We discuss urgent challenges in this field and future perspectives to promote the development and translation of nanoantibiotics as alternatives against MDR pathogens to traditional antibiotics-based approaches.

Cuproptosis: emerging biomarkers and potential therapeutics in cancers

The sustenance of human life activities depends on copper, which also serves as a crucial factor for vital enzymes. Under typical circumstances, active homeostatic mechanisms keep the intracellular copper ion concentration low. Excess copper ions cause excessive cellular respiration, which causes cytotoxicity and cell death as levels steadily rise above a threshold. It is a novel cell death that depends on mitochondrial respiration, copper ions, and regulation. Cuproptosis is now understood to play a role in several pathogenic processes, including inflammation, oxidative stress, and apoptosis. Copper death is a type of regulatory cell death(RCD).Numerous diseases are correlated with the development of copper homeostasis imbalances. One of the most popular areas of study in the field of cancer is cuproptosis. It has been discovered that cancer angiogenesis, proliferation, growth, and metastasis are all correlated with accumulation of copper ions. Copper ion concentrations can serve as a crucial marker for cancer development. In order to serve as a reference for clinical research on the product, diagnosis, and treatment of cancer, this paper covers the function of copper ion homeostasis imbalance in malignant cancers and related molecular pathways.

Copper oxide nanoparticles: In vitro and in vivo toxicity, mechanisms of action and factors influencing their toxicology

Copper oxide nanoparticles (CuO NPs) have received increasing interest due to their distinctive properties, including small particle size, high surface area, and reactivity. Due to these properties, their applications have been expanded rapidly in various areas such as biomedical properties, industrial catalysts, gas sensors, electronic materials, and environmental remediation. However, because of these widespread uses, there is now an increased risk of human exposure, which could lead to short- and long-term toxicity. This review addresses the underlying toxicity mechanisms of CuO NPs in cells which include reactive oxygen species generation, leaching of Cu ion, coordination effects, non-homeostasis effect, autophagy, and inflammation. In addition, different key factors responsible for toxicity, characterization, surface modification, dissolution, NPs dose, exposure pathways and environment are discussed to understand the toxicological impact of CuO NPs. In vitro and in vivo studies have shown that CuO NPs cause oxidative stress, cytotoxicity, genotoxicity, immunotoxicity, neurotoxicity, and inflammation in bacterial, algal, fish, rodents, and human cell lines. Therefore, to make CuO NPs a more suitable candidate for various applications, it is essential to address their potential toxic effects, and hence, more studies should be done on the long-term and chronic impacts of CuO NPs at different concentrations to assure the safe usage of CuO NPs.

α-tocopherol ameliorates copper II oxide nanoparticles-induced cytotoxic, biochemical, apoptotic, and genotoxic damages in the rainbow trout gonad cells-2 (RTG-2) culture

We investigated the effects of α-tocopherol on oxidative stress-caused damage caused by copper II oxide nanoparticles (CuO NPs) on Oncorhynchus mykiss gonadal cells (RTG-2) for 24 and 48 h. α-Tocopherol reversed the cell death and alterations in the expressions of genes such as sod1, gpx1a, gpx4b, and igf2 caused by CuO NPs; it also supported the expressions of cat, igf1, and gapdh genes caused by CuO NPs for 24 h and promoted alterations in the expressions of the sod2, gh1, and igf1 genes for 48 h. Additionally, α-tocopherol reversed the caspase 3/7 activity increased by CuO NPs for 24 h and supported it's decrease for 48 h. α-Tocopherol supported the increase in tail DNA (%) affected by CuO NPs for 24 h and reversed it for 48 h. Therefore, α-tocopherol may have the potential to protect against cellular alterations induced by CuO NPs in a time-dependent manner.

Synthesis, biomedical applications, and toxicity of CuO nanoparticles

Versatile nature of copper oxide nanoparticles (CuO NPs) has made them an imperative nanomaterial being employed in nanomedicine. Various physical, chemical, and biological methodologies are in use for the preparation of CuO NPs. The physicochemical and biological properties of CuO NPs are primarily affected by their method of fabrication; therefore, selectivity of a synthetic technique is immensely important that makes these NPs appropriate for a specific biomedical application. The deliberate use of CuO NPs in biomedicine questions their biocompatible nature. For this reason, the present review has been designed to focus on the approaches employed for the synthesis of CuO NPs; their biomedical applications highlighting antimicrobial, anticancer, and antioxidant studies; and most importantly, the in vitro and in vivo toxicity associated with these NPs. This comprehensive overview of CuO NPs is unique and novel as it emphasizes on biomedical applications of CuO NPs along with its toxicological assessments which would be useful in providing core knowledge to researchers working in these domains for planning and conducting futuristic studies. KEY POINTS: • The recent methods for fabrication of CuO nanoparticles have been discussed with emphasis on green synthesis methods for different biomedical approaches. • Antibacterial, antioxidant, anticancer, antiparasitic, antidiabetic, and antiviral properties of CuO nanoparticles have been explained. • In vitro and in vivo toxicological studies of CuO nanoparticles exploited along with their respective mechanisms.

Modulation mechanism of phytotoxicity on Ipomoea aquatica Forssk. by surface coating-modified copper oxide nanoparticles and its health risk assessment

To evaluate the influence of surface coatings on nano-fertilizers uptake and their phytotoxicity to crops and its health risk to Chinese adults, trisodium citrate (TC) and polyethylene glycol (PEG) coatings were prepared on the surface of copper oxide nanoparticles (CuO NPs), respectively, with 100 and 500 mg/L of bare CuO NPs, TC-CuO NPs, and PEG-CuO NPs were exposed to soil-grown Ipomoea aquatica Forssk. Combined bio-transmission electron microscopy and micro-CT observed cellular migration of coated CuO NPs in symplastic and apoplastic pathways, as well as nanoparticles transported through vascular tissues to the above-ground parts. Since TC-CuO NPs had less inhibition on vascular phylogeny of I. aquatica roots which was determined by RT-qPCR, their migration in plants was more efficient, thus exhibiting greater phytotoxicity to shoots. Meanwhile, coatings significantly reduced the phytotoxicity of CuO NPs by stimulating plant antioxidant defense. The risk of CuO nano-fertilizers on human dietary safety was evaluated, the HQ > 1 in the 500 mg/L CuO NPs treatment indicated a potential health risk to Chinese adults, which was reduced by the coatings. This work explored for the first time the mechanism of coating effects on nanoparticles migration efficiency and phytotoxicity at the molecular level and demonstrated that the migration of nanoparticles between tissues could have an impact on phytotoxicity. It implied that coating can be tailored to target nanoparticles to specific regions of the plant. In addition, this study highlights the potential health risks associated with the consumption of I. aquatica fertilized with CuO NPs and provides valuable insights into the environmental applications of nano-fertilizers.