Study of Biological Behavior and Antimicrobial Properties of Cerium Oxide Nanoparticles

An interdisciplinary approach to assessing the toxicity reduction of cerium oxide nanoparticles coated with polyethylene glycol and polyvinylpyrrolidone polymers: An in vitro study

OBJECTIVE

This study combines toxicology, analytical chemistry, and nanotechnology to develop cerium oxide nanoparticles, both uncoated and coated with Polyethylene Glycol and Polyvinylpyrrolidone polymers. The objective is to assess their toxicity reduction using cell-based assays.

METHODS

Nanoparticles were synthesized using the co-precipitation technique. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and dynamic light scattering (DLS) were employed to characterize their properties. The MTT assay evaluated cell viability, whereas reactive oxygen species and LPO assays were used to quantify oxidative stress.

FINDINGS

The chemical analysis of nanoparticles of the study revealed that cerium oxide nanoparticles exhibited better and more regular morphological characteristics compared to nanoparticles coated with PEG and PVP polymers in terms of size. In addition, cerium oxide nanoparticles combined with PVP polymer did not retain the morphology at the nano level. Toxicological studies demonstrated a reduction in the toxicity of cerium oxide nanoparticles when coated with PEG and PVP polymers.

DISCUSSION AND CONCLUSION

The study found that PEG coating significantly reduces the cytotoxicity of cerium oxide nanoparticles more effectively than PVP coating by mitigating oxidative stress. This approach presents a promising strategy for developing safer cerium oxide-based products for pharmaceutical and medical applications.

Photochemically Activated Microbubble Emulsion, Nd: Yap Laser, and Cerium Oxide Nanoparticles as Canal Disinfectants on Push-Out Bond Strength of Sealer to Root Dentin, Smear Layer, and Antibacterial Efficacy

Effect of different root canal irrigation regimes microbubble emulsion (MBE) via riboflavin photosensitizer (RFP), cerium oxide (CeO2) nanoparticles (NPs), and Nd: YAP laser on antibacterial efficiency, microhardness (MH), smear layer (SL) removal efficacy, and push-out bond strength (PBS) of AH plus sealer to canal dentin. Sixty single-rooted teeth were selected, disinfected, and categorized into four groups based on the type of disinfection. Following disinfection, a pair of samples were randomly selected and visualized under scanning electron microscope (SEM) for SL evaluation. Three samples from each disinfection group were mounted on a Vickers MH tester for hardness testing. A brain-heart infusion (BHI) agar plate was inoculated with a single colony of Enterococcus faecalis (E. faecalis), and their survival rate was measured following different disinfecting regimes. The remaining samples were filled with gutta-percha (GP) and sectioned to evaluate PBS via universal testing machine (UTM), followed by failure analysis. Data were analyzed using analysis of variance (ANOVA) and Tukey's post hoc test. The survival rate of E. faecalis was lowest for Group 3 (0.11 CFU/mL) with the highest MH values (49.72 ± 1.02 N/mm2). The PBS was highest for Group 3 cervical (11.54 ± 0.49 MPa) and middle third (11.12 ± 0.50 MPa). SL removal efficacy was comparable in groups 3 and 4 at the coronal and middle third. The application of CeO2NPs as a canal irrigant in conjunction with EDTA resulted in enhanced bond values, demonstrating superior SL removal capabilities. This type of disinfection notably enhances the MH of canal dentin while demonstrating significant sterilization efficacy against E. faecalis.

Use of Antimicrobial Nanoparticles for the Management of Dental Diseases

Dental diseases represent a significant global health concern, with traditional treatment methods often proving costly and lacking in long-term efficacy. Emerging research highlights nanoparticles as a promising, cost-effective therapeutic alternative, owing to their unique properties. This review aims to provide a comprehensive overview of the application of antimicrobial and antioxidant nanoparticles in the management of dental diseases. Silver and gold nanoparticles have shown great potential for inhibiting biofilm formation and thus preventing dental caries, gingivitis, and periodontitis. Various dental products can integrate copper nanoparticles, known for their antimicrobial properties, to combat oral infections. Similarly, zinc oxide nanoparticles enhance the antimicrobial performance of dental materials, including adhesives and cements. Titanium dioxide and cerium oxide nanoparticles possess antimicrobial and photocatalytic properties, rendering them advantageous for dental materials and oral hygiene products. Chitosan nanoparticles are effective in inhibiting oral pathogens and reducing inflammation in periodontal tissues. Additionally, curcumin nanoparticles, with their antimicrobial, anti-inflammatory, and antioxidant properties, can enhance the overall performance of dental materials and oral care products. Incorporating these diverse nanoparticles into dental materials and oral care products holds the potential to significantly reduce the risk of infection, control biofilm formation, and improve overall oral health. This review underscores the importance of continued research and development in this promising field to realize the full potential of nanoparticles in dental care.

Potential Applications of Rare Earth Metal Nanoparticles in Biomedicine

In recent years, the world scientific community has shown increasing interest in rare earth metals in general and their nanoparticles in particular. Medicine and pharmaceuticals are no exception in this matter. In this review, we have considered the main opportunities and potential applications of rare earth metal (gadolinium, europium, ytterbium, holmium, lutetium, dysprosium, erbium, terbium, thulium, scandium, yttrium, lanthanum, europium, neodymium, promethium, samarium, praseodymium, cerium) nanoparticles in biomedicine, with data ranging from single reports of effects found in vitro to numerous independent in vivo studies, as well as a number of challenges to their potential for wider application. The main areas of application of rare earth metals, including in the future, are diagnosis and treatment of malignant neoplasms, therapy of infections, as well as the use of antioxidant and regenerative properties of a number of nanoparticles. These applications are determined both by the properties of rare earth metal nanoparticles themselves and the need to search for new approaches to solve a number of urgent biomedical and public health problems. Oxide forms of lanthanides are most often used in biomedicine due to their greatest biocompatibility and nanoscale size, providing penetration through biological membranes. However, the existing contradictory or insufficient data on acute and chronic toxicity of lanthanides still make their widespread use difficult. There are various modification methods (addition of excipients, creation of nanocomposites, and changing the morphology of particles) that can reduce these effects. At the same time, despite the use of some representatives of lanthanides in clinical practice, further studies to establish the full range of pharmacological and toxic effects, as well as the search for approaches to modify nanoparticles remain relevant.

ROS Responsive Cerium Oxide Biomimetic Nanoparticles Alleviates Calcium Oxalate Crystals Induced Kidney Injury via Suppressing Oxidative Stress and M1 Macrophage Polarization

Emerging studies have demonstrated that M1 macrophage polarization and oxidative stress play important roles in calcium oxalate (CaOx) induced kidney injury, which leads to increased crystals deposition. ROS scavenging nanozymes and kidney-targeted nanoparticles for antioxidant drugs delivery have emerged as an arisen methodology for kidney injury therapy. However, cell membrane biomimetic-modified nanozymes as anti-inflammatory drug delivery systems for the treatment of kidney injury is rarely reported. Herein, the ROS responsive red blood cell-membrane-coated resatorvid-loaded cerium oxide nanoparticles (RBCM@CeO2/TAK-242) are constructed to suppress CaOx induced kidney injury and crystals deposition. In vitro, RBCM@CeO2/TAK-242 shows effective internalization by renal tubular epithelial cells, along with demonstrated antioxidative, anti-inflammatory, and macrophage reprogramming effects. Glyoxalate(Gly)-induced renal CaOx crystals mouse model is established, RBCM@CeO2/TAK-242 shows excellent injured kidney targeting and biosafety, and could effectively suppress CaOx induced kidney injury and crystals deposition. RBCM@CeO2/TAK-242 has a dual protective effect by both inhibiting oxidative stress and modulating macrophage polarization in vivo. In addition, RNA seq analysis reveals that RBCM@CeO2/TAK-242 protects against CaOx induced kidney injury via suppressing the TLR4/NF-κB pathway. This study provides an innovative strategy for RBCM@CeO2/TAK-242 as injured kidney targeting and dual protective effects for the treatment of CaOx induced kidney injury and crystals deposition.

Controlled Release of Ceria and Ferric Oxide Nanoparticles via Collagen Hydrogel for Enhanced Osteoarthritis Therapy

Osteoarthritis (OA), characterized by chronic inflammation and cartilage degeneration, significantly affects over 500 million people globally. Nanoparticles have emerged as promising treatments for OA; however, current strategies often employ a single type of nanoparticle targeting specific disease stages, limiting sustained therapeutic efficacy. In this study, a novel collagen hydrogel is introduced, thiol crosslinked collagen-cerium oxide-poly(D,L-lactic-co-glycolic acid) microspheres encapsulating nanoparticles (CSH-CeO2-pFe2O3), designed for the controlled release of cerium oxide (CeO2) and ferric oxide (Fe2O3) nanoparticles for comprehensive OA management. The sulfhydryl cross-linked collagen matrix embeds CeO2 nanoparticles and poly(D,L-lactic-co-glycolic acid) (PLGA) microspheres encapsulating Fe2O3 nanoparticles. The CSH-CeO2-pFe2O3 hydrogel exhibits enhanced mechanical strength and remarkable injectability, along with a significant promotion of cell adhesion, proliferation, and chondrogenic differentiation. Notably, the hydrogel demonstrates intelligent responsiveness to high levels of reactive oxygen species, initiating the rapid release of CeO2 nanoparticles to address the intense inflammatory responses of early-stage OA, followed by the sustained release of Fe2O3 nanoparticles to facilitate cartilage regeneration during the proliferative phase. In a rat model with cartilage defects, the hydrogel significantly alleviates inflammation and enhances cartilage regeneration, holding substantial potential for effectively managing the pathologically complex OA.

Development of Technology for the Synthesis of Nanocrystalline Cerium Oxide Under Production Conditions with the Best Regenerative Activity and Biocompatibility for Further Creation of Wound-Healing Agents

Background/Objectives: The issue of effective wound healing remains highly relevant. The objective of the study is to develop an optimal method for the synthesis of nanosized cerium oxide powder obtained via the thermal decomposition of cerium carbonate precipitated from aqueous nitrate solution for the technical creation of new drugs in production conditions; the select modification of synthesis under different conditions based on the evaluation of the physicochemical characteristics of the obtained material and its biological activity, and an evaluation of the broad-spectrum effect on cells involved in the regeneration of skin structure as well as antimicrobial properties. Methods: Several modes of the industrial synthesis of cerium dioxide nanoparticles (NPs) were carried out. The synthesis stages and the chemical and physical parameters of the obtained NPs were described using transmission electron microscopy (TEM), X-ray diffraction, Raman spectroscopy, and mass spectrometry. The cell cultures of human fibroblasts and keratinocytes were cultured with different concentrations of different nanoceria variations, and the cytotoxicity and the metabolic and proliferative activity were investigated. An MTT test and cell counting were performed. The antimicrobial activity of CeO2 variations at a concentration of 0.1-0.0001 M against Pseudomonas aeruginosa was studied. Results: The purity of the synthesized nanoceria powders in all the batches was >99.99%. According to TEM data, the size of the NPs varied from 1 nm to 70 nm under different conditions and methodologies. The most optimal technology for the synthesis of the nanoceria with the maximum biological effect was selected. A method for obtaining the most bioactive NPs of optimal size (up to 10 nm) was proposed. The repeatability of the results of the proposed method of nanoceria synthesis in terms of particle size was confirmed. It was proven that the more structural defects on the surface of the CeO2 crystal lattice, the higher the efficiency of the NPs due to oxygen vacancies. The strain provided the best redox activity and antioxidant properties of the nanoceria, which was demonstrated by better regenerative potential on various cell lines. The beneficial effect of synthesized nanoceria on the proliferative and metabolic activity of the cell lines involved in skin regeneration (human fibroblasts, human keratinocytes) was demonstrated. The antimicrobial effect of synthesized nanoceria on the culture of the most-resistant-to-modern-antibiotics microorganism Pseudomonas aeruginosa was confirmed. The optimal concentrations of the nanoceria to achieve the maximum biological effect were determined (10-3 M). Conclusions: It was possible to develop a method for the industrial synthesis of nanoceria, which can be used to produce drugs and medical devices containing CeO2 NPs.

Ceria nanoparticles: biomedical applications and toxicity

Ceria nanoparticles (CeO2 NPs) have become popular materials in biomedical and industrial fields due to their potential applications in anti-oxidation, cancer therapy, photocatalytic degradation of pollutants, sensors, etc. Many methods, including gas phase, solid phase, liquid phase, and the newly proposed green synthesis method, have been reported for the synthesis of CeO2 NPs. Due to the wide application of CeO2 NPs, concerns about their adverse impacts on human health have been raised. This review covers recent studies on the biomedical applications of CeO2 NPs, including their use in the treatment of various diseases (e.‍g., Alzheimer's disease, ischemic stroke, retinal damage, chronic inflammation, and cancer). CeO2 NP toxicity is discussed in terms of the different systems of the human body (e.‍g., cytotoxicity, genotoxicity, respiratory toxicity, neurotoxicity, and hepatotoxicity). This comprehensive review covers both fundamental discoveries and exploratory progress in CeO2 NP research that may lead to practical developments in the future.

Microenvironment Remodeling Self-Healing Hydrogel for Promoting Flap Survival

Random flap grafting is a routine procedure used in plastic and reconstructive surgery to repair and reconstruct large tissue defects. Flap necrosis is primarily caused by ischemia-reperfusion injury and inadequate blood supply to the distal flap. Ischemia-reperfusion injury leads to the production of excessive reactive oxygen species, creating a pathological microenvironment that impairs cellular function and angiogenesis. In this study, we developed a microenvironment remodeling self-healing hydrogel [laminarin-chitosan-based hydrogel-loaded extracellular vesicles and ceria nanozymes (LCH@EVs&CNZs)] to improve the flap microenvironment and synergistically promote flap regeneration and survival. The natural self-healing hydrogel (LCH) was created by the oxidation laminarin and carboxymethylated chitosan via a Schiff base reaction. We loaded this hydrogel with CNZs and EVs. CNZs are a class of nanomaterials with enzymatic activity known for their strong scavenging capacity for reactive oxygen species, thus alleviating oxidative stress. EVs are cell-secreted vesicular structures containing thousands of bioactive substances that can promote cell proliferation, migration, differentiation, and angiogenesis. The constructed LCH@EVs&CNZs demonstrated a robust capacity for scavenging excess reactive oxygen species, thereby conferring cellular protection in oxidative stress environments. Moreover, these constructs notably enhance cell migration and angiogenesis. Our results demonstrate that LCH@EVs&CNZs effectively remodel the pathological skin flap microenvironment and marked improve flap survival. This approach introduces a new therapeutic strategy combining microenvironmental remodeling with EV therapy, which holds promise for promoting flap survival.

Exploration of inorganic nanoparticles for revolutionary drug delivery applications: a critical review

The nanosystems for delivering drugs which have evolved with time, are being designed for greater drug efficiency and lesser side-effects, and are also complemented by the advancement of numerous innovative materials. In comparison to the organic nanoparticles, the inorganic nanoparticles are stable, have a wide range of physicochemical, mechanical, magnetic, and optical characteristics, and also have the capability to get modified using some ligands to enrich their attraction towards the molecules at the target site, which makes them appealing for bio-imaging and drug delivery applications. One of the strong benefits of using the inorganic nanoparticles-drug conjugate is the possibility of delivering the drugs to the affected cells locally, thus reducing the side-effects like cytotoxicity, and facilitating a higher efficacy of the therapeutic drug. This review features the direct and indirect effects of such inorganic nanoparticles like gold, silver, graphene-based, hydroxyapatite, iron oxide, ZnO, and CeO2 nanoparticles in developing effective drug carrier systems. This article has remarked the peculiarities of these nanoparticle-based systems in pulmonary, ocular, wound healing, and antibacterial drug deliveries as well as in delivering drugs across Blood-Brain-Barrier (BBB) and acting as agents for cancer theranostics. Additionally, the article sheds light on the plausible modifications that can be carried out on the inorganic nanoparticles, from a researcher's perspective, which could open a new pathway.