Reduction of the Cytotoxicity of Copper (II) Oxide Nanoparticles by Coating with a Surface-Binding Peptide

Investigating the biocompatibility, flexural strength, and surface roughness of denture base resin containing copper oxide nanoparticles: An in vitro study

Aim

This study aimed to evaluate the biocompatibility, flexural strength, and surface roughness of polymethyl methacrylate (PMMA) containing Copper Oxide Nanoparticles (CuO NPs) at different concentrations.

Methods

25 heat-polymerized PMMA wax patterns fabricated in 5 groups containing 0.5, 5, 50, and 500 μg/ml CuO NPs and nanoparticle (NP)-free PMMA discs were prepared. 5 growth mediums (DMEM with 10% FBS and 1% penicillin-streptomycin) without disks were also incubated similarly to serve as the control groups. The cytotoxicity of the discs was measured by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay on cultured Human Gingival Fibroblasts. The number of 1.3 × 104 cells were seeded in each well of 96-well plates (5 wells for the extract of each specimen). Days 1, 3, 5, and 7 were the intervals that the culture media were in direct contact with the PMMA discs for either 24 or 72 h. After that, a total of 40 specimens with 65 × 10 × 2.5 mm dimensions were prepared in five groups (n = 8). The specimens were subjected to a rugosimeter for the evaluation of surface roughness. The flexural strength test was performed using a universal testing machine. Microscopic evaluation was performed for the dispersion of the NPs. Non-parametric Kruskal-Wallis test and parametric one-way ANOVA test were used for data analysis.

Results

The samples containing 500 μg/ml NPs showed the lowest percentage of cell viability at all incubation periods, while the highest cell viability was observed in NP-free PMMA 24 h after the seventh day of incubation. NPs at 50 and 500 μg/ml concentrations showed strongly significant differences in cytotoxicity compared to the 0 concentration and the control group (p < 0.001). Although all the samples demonstrated an increasing pattern of cell viability on the third, fifth, and seventh days, the percentage of cell viability was significantly lower after 72 h than after 24 h in all incubation periods (p < 0.001). NPs significantly increased flexural strength (p = 0.005) but did not affect the surface roughness of the PMMA discs (p = 0.396).

Significance

The CuO NPs were cytotoxic only when applied in high concentrations, but presented a descending trend over time. No cytotoxic effect was observed in the experimental groups after seven days of incubation. Furthermore, CuO NPs increased flexural strength, but the surface roughness of the PMMA discs was not affected.

Environmentally Benign Nanoparticles for the Photocatalytic Degradation of Pharmaceutical Drugs

A rapid rise in industrialization has led to the release of pharmaceutical pollutants into water bodies, rendering water inappropriate for consumption by humans and animals, challenging our efforts to achieve the clean water sustainable development goal. These pharmaceutical pollutants include antibiotics, anticancer drugs, antidepressants, etc., which are highly stable and persistent in water, in addition to being harmful to life. At times, the secondary pollutant that is formed after degradation is more potent than the parent drug. Conventional water purification methods cannot completely remove these pollutants. Hence, efficient and robust methods are required to degrade pharmaceutical waste. Photocatalytic degradation of drugs is deemed an efficient and effective method for environmental remediation, along with recovery of photocatalysts, which are important for recycling and sustainable use. Herein, we present the synthesis of nanoparticles (NPs) and their application for photocatalytic degradation of pharmaceutical waste as a preferred water treatment method. Additionally, green synthesis of photocatalytic nanomaterials offers the benefit of avoiding secondary pollution. The green synthesis of NPs is employed by using plant extracts that offer a number of metabolites as reducing agents or capping agents, as well as the use of microbes as green nanofactories to tackle the issue of water cleanliness with respect to pharmaceutical waste. Despite regulations concerning drug disposal, some underdeveloped countries do not enforce and practice these guidelines in letter and spirit. Hence, the current work presenting a promising water cleanliness method is expected to contribute to the assurance of strict policy compliance and enforcement, resulting in the resolution of the health concerns with respect to hazardous pharmaceutical waste disposal in water bodies.

Copper-containing nanoparticles: Mechanism of antimicrobial effect and application in dentistry-a narrative review

Copper has been used as an antimicrobial agent long time ago. Nowadays, copper-containing nanoparticles (NPs) with antimicrobial properties have been widely used in all aspects of our daily life. Copper-containing NPs may also be incorporated or coated on the surface of dental materials to inhibit oral pathogenic microorganisms. This review aims to detail copper-containing NPs' antimicrobial mechanism, cytotoxic effect and their application in dentistry.

Nanocomposite coatings for the prevention of surface contamination by coronavirus

The current Covid-19 pandemic has a profound impact on all aspects of our lives. Aside from contagion by aerosols, the presence of the SARS-CoV-2 is ubiquitous on surfaces that millions of people handle daily. Therefore, controlling this pandemic involves the reduction of potential infections via contaminated surfaces. We developed antiviral surfaces by preparing suspensions of copper and cupric oxide nanoparticles in two different polymer matrices, poly(methyl methacrylate) and polyepoxide. For total copper contents as low as 5%, the composite material showed remarkable antiviral properties against the HCoV‐OC43 human coronavirus and against a model lentivirus and proved well-resistant to accelerated aging conditions. Importantly, we showed that the Cu/CuO mixture showed optimal performances. This product can be implemented to produce a simple and inexpensive coating with long-term antiviral properties and will open the way to developing surface coatings against a broad spectrum of pathogens including SARS-CoV-2.

Nanostructured Antimicrobial Peptides: Crucial Steps of Overcoming the Bottleneck for Clinics

The security issue of human health is faced with dispiriting threats from multidrug-resistant bacteria infections induced by the abuse and misuse of antibiotics. Over decades, the antimicrobial peptides (AMPs) hold great promise as a viable alternative to treatment with antibiotics due to their peculiar antimicrobial mechanisms of action, broad-spectrum antimicrobial activity, lower drug residue, and ease of synthesis and modification. However, they universally express a series of disadvantages that hinder their potential application in the biomedical field (e.g., low bioavailability, poor protease resistance, and high cytotoxicity) and extremely waste the abundant resources of AMP database discovered over the decades. For all these reasons, the nanostructured antimicrobial peptides (Ns-AMPs), based on a variety of nanosystem modification, have made up for the deficiencies and pushed the development of novel AMP-based antimicrobial therapies. In this review, we provide an overview of the advantages of Ns-AMPs in improving therapeutic efficacy and biological stability, reducing side effects, and gaining the effect of organic targeting and drug controlled release. Then the different material categories of Ns-AMPs are described, including inorganic material nanosystems containing AMPs, organic material nanosystems containing AMPs, and self-assembled AMPs. Additionally, this review focuses on the Ns-AMPs for the effect of biological activities, with emphasis on antimicrobial activity, biosecurity, and biological stability. The "state-of-the-art" antimicrobial modes of Ns-AMPs, including controlled release of AMPs under a specific environment or intrinsic antimicrobial properties of Ns-AMPs, are also explicated. Finally, the perspectives and conclusions of the current research in this field are also summarized.

Should Nano-Particles be Weighed or Counted? Technical Considerations to In Vitro Testing Originated from Corpuscular Nature of Nano-Particles

The abundance of nanoparticles introduced to household products created the great expectations towards the application of nanotechnology in biology and medicine. That calls for cost-effective preliminary assessment of its cytotoxicity and biological activity. There are many attempts for creating proper guidance and standards for performing studies regarding nanoparticles. But still some important aspects crucial for in vitro testing of nanomaterials need more attention. Particulate nature is an obvious and widely unappreciated property of nanoparticles. In the context of in vitro studies, this property is critical, and it should be, but rarely is, considered when designing, performing, describing or interpreting the experiments involving the solid nanoparticles. First, we should be aware of relatively small and limited number of nanoparticles in the experimental setup. Even crude estimation of its number will be useful for proper interpretation of results. Second, we should not presume even distribution of particles in the solution, moreover we should expect that sedimentation and aggregation play an important role in interactions of nanoparticles with cells. In that case, expressing the dose in mass/volume units may lead as astray. Finally, the relation of size, weight, and number of nanoparticles makes comparisons of activity of nanoparticles of different sizes very complex. Estimations of number of nanoparticles in the dose should be an integral part of experiment design, its validation and interpretation.

In Vitro and In Vivo Models for Evaluating the Oral Toxicity of Nanomedicines

Toxicity studies for conventional oral drug formulations are standardized and well documented, as required by the guidelines of administrative agencies such as the US Food & Drug Administration (FDA), the European Medicines Agency (EMA) or European Medicines Evaluation Agency (EMEA), and the Japanese Pharmaceuticals and Medical Devices Agency (PMDA). Researchers tend to extrapolate these standardized protocols to evaluate nanoformulations (NFs) because standard nanotoxicity protocols are still lacking in nonclinical studies for testing orally delivered NFs. However, such strategies have generated many inconsistent results because they do not account for the specific physicochemical properties of nanomedicines. Due to their tiny size, accumulated surface charge and tension, sizeable surface-area-to-volume ratio, and high chemical/structural complexity, orally delivered NFs may generate severe topical toxicities to the gastrointestinal tract and metabolic organs, including the liver and kidney. Such toxicities involve immune responses that reflect different mechanisms than those triggered by conventional formulations. Herein, we briefly analyze the potential oral toxicity mechanisms of NFs and describe recently reported in vitro and in vivo models that attempt to address the specific oral toxicity of nanomedicines. We also discuss approaches that may be used to develop nontoxic NFs for oral drug delivery.