CeO2 Nanoparticle-Containing Polymers for Biomedical Applications: A Review

Investigation of the interaction mechanism and enzyme activity of trypsin with cerium oxide nanoparticles

In this study, the interaction mechanism and native conformational variation of trypsin (Try) affected by CeO2 nanoparticles (NPs) were systematically studied via various spectroscopic methods. The results of fluorescence spectroscopy revealed that CeO2 NPs markedly quenched the endogenous fluorescence of Try via the mechanism of static quenching. The main forces that contributed to the binding of Try and CeO2 NPs were van der Waals forces, hydrogen bonds, and electrostatic forces, as observed by the binding constants and significant thermodynamic characteristics of the two substances. The incorporation of CeO2 NPs lead to a slight change in the structure of Try, as shown by synchronized fluorescence spectroscopy, three-dimensional fluorescence spectroscopy and circular dichroism (CD) spectroscopy. Moreover, the enzyme activity of Try decreased with the addition of CeO2 NPs. This study is highly important for fully evaluating the use of CeO2 NPs in biomedical sciences and is helpful for clarifying the mechanism between Try and CeO2 NPs at the molecular level.

Diphasic CeO2 Nanocrystal/Bioactive Glass Nanosphere-Based Composite Hydrogel for Diabetic Wound Healing by Reactive Oxygen Species Scavenging and Inflammation Regulation

Background: Antioxidant therapy aimed at reducing excessive local oxidative stress is one of the most important strategies for promoting diabetic wound repair. The reversible transformation of Ce3+/Ce4+ in ceria (CeO2) can reduce excessive local oxidative stress. However, inducing angiogenesis, local anti-inflammatory effects, and other positive effects are challenging. Therefore, ideal dressings for chronic diabetic wound management must concurrently reduce excessive oxidative stress, promote angiogenesis, and have anti-inflammatory effects. Methods: In this study, Ce-doped borosilicate bioactive glasses (BGs) were prepared using the sol-gel method, and CeO2 nanocrystals (CeO2-NCs) were precipitated on the glass surface by heat treatment to obtain BG-xCe composite glass nanospheres. Subsequently, nanospheres were modified by amino group and combined with dopamine and acrylamide to obtain BG-xCe/polydopamine/polyacrylamide (PDA/PAM) composite hydrogel. Then, the morphology and properties of composite hydrogels were detected, and the properties to treat the diabetic wounds were also evaluated. Results: The results demonstrated that the BG-10Ce/PDA/PAM composite hydrogel possessed excellent tensile and adhesive properties. In vitro, the migration and angiogenesis of human umbilical vein endothelial cells (HUVECs) and fibroblasts (L929) were enhanced by reducing reactive oxygen species (ROS) levels in the conditioned medium. Animal experiments have shown that CeO2-NCs in hydrogels effectively scavenge ROS in diabetic wounds, and Sr dissolved from the glassy phase can modulate macrophage polarization to the M2 phenotype. Conclusions: The synergistic effect of both amorphous materials and nanocrystals provides the BG-10Ce/PDA/PAM composite hydrogel with great potential for diabetic wound healing.

Dual Crosslinked Antioxidant Mixture of Poly(vinyl alcohol) and Cerium Oxide Nanoparticles as a Bioink for 3D Bioprinting

Three-dimensional (3D) bioprinting has made it possible to fabricate structures with intricate morphologies and architectures, which is considered difficult to do when using other conventional techniques like electrospinning. Although the 3D printing of thermoplastics has seen a huge boom in the past few years, it has been challenging to translate this technology to cell-based printing. A major limitation in bioprinting is the lack of inks that allow for the printing of 3D structures that meet the biological requirements of a specific organ or tissue. A bioink is a viscous polymer solution that cells are incorporated into before printing. Therefore, a bioink must have specific characteristics to ensure both good printability and biocompatibility. Despite the progress that has been made in bioprinting, achieving a balance between these two properties has been difficult. In this work, we developed a multimodal bioink that serves as both a cell carrier and a free radical scavenger for treating peripheral nerve injury. This bioink comprises poly(vinyl alcohol) (PVA) and cerium oxide nanoparticles (also called nanoceria (NC)) and was developed with a dual crosslinking method that utilizes citric acid and sodium hydroxide. By employing this dual crosslinking method, good printability of the bioink and shape fidelity of the bioprinted structure were achieved. Additionally, a cell viability study demonstrated that the cells remained compatible and viable even after they underwent the printing process. The combination of this PVA/NC bioink and the dual crosslinking method proved to be effective in enhancing printability and cell biocompatibility for extrusion-based bioprinting applications.

Biopolymeric Innovations in Ophthalmic Surgery: Enhancing Devices and Drug Delivery Systems

The interface between material science and ophthalmic medicine is witnessing significant advances with the introduction of biopolymers in medical device fabrication. This review discusses the impact of biopolymers on the development of ophthalmic devices, such as intraocular lenses, stents, and various prosthetics. Biopolymers are emerging as superior alternatives due to their biocompatibility, mechanical robustness, and biodegradability, presenting an advance over traditional materials with respect to patient comfort and environmental considerations. We explore the spectrum of biopolymers used in ophthalmic devices and evaluate their physical properties, compatibility with biological tissues, and clinical performances. Specific applications in oculoplastic and orbital surgeries, hydrogel applications in ocular therapeutics, and polymeric drug delivery systems for a range of ophthalmic conditions were reviewed. We also anticipate future directions and identify challenges in the field, advocating for a collaborative approach between material science and ophthalmic practice to foster innovative, patient-focused treatments. This synthesis aims to reinforce the potential of biopolymers to improve ophthalmic device technology and enhance clinical outcomes.

The Highly Durable Antibacterial Gel-like Coatings for Textiles

Hospital-acquired infections are considered a priority for public health systems since they pose a significant burden for society. High-touch surfaces of healthcare centers, including textiles, provide a suitable environment for pathogenic bacteria to grow, necessitating incorporating effective antibacterial agents into textiles. This paper introduces a highly durable antibacterial gel-like solution, Silver Shell™ finish, which contains chitosan-bound silver chloride microparticles. The study investigates the coating's environmental impact, health risks, and durability during repeated washing. The structure of the Silver Shell™ finish was studied using transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDX). The TEM images showed a core-shell structure, with chitosan forming a protective shell around groupings of silver microparticles. The field-emission scanning electron microscopy (FESEM) demonstrated the uniform deposition of Silver Shell™ on the surfaces of the fabrics. AATCC Test Method 100 was employed to quantitatively analyze the antibacterial properties of the fabrics coated with silver microparticles. Two types of bacteria, Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli), were used in this study. The antibacterial results showed that after 75 wash cycles, a 100% reduction for both S. aureus and E. coli in the coated samples using crosslinking agents was observed. The coated samples without a crosslinking agent exhibited 99.88% and 99.81% reductions for S. aureus and E. coli after 50 washing cycles. To compare the antibacterial properties toward non-pathogenic and pathogenic strains of the same species, MG1655 model E. coli strain (ATCC 29213) and a multidrug-resistant clinical isolate were used. The results showed the antibacterial efficiency of the Silver ShellTM solution (up to 99.99% reduction) coated on cotton fabric. AATCC-147 was performed to investigate the coated samples' leaching properties and the crosslinking agent's effects against S. aureus and E. coli. All coated samples demonstrated remarkable antibacterial efficacy, even after 75 wash cycles. The crosslinking agent facilitated durable attachment between the silver microparticles and cotton substrate, minimizing the release of particles from the fabrics. Color measurements were conducted to assess the color differences resulting from the coating process. The results indicated fixation values of 44%, 32%, and 28% following 25, 50, and 75 washing cycles, respectively.

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.

Utilizing response surface methodology for the microstructural examination of CeO2/GNP composite coating applied via air plasma spraying and post-treated with spark plasma sintering

CeO2/GNP coatings were fabricated using a three-step process: high-energy ball milling, spray-drying, and air plasma spray (APS) deposition. Spark plasma sintering (SPS) was employed for post-treatment to densify the coatings. Response surface methodology (RSM) was employed to optimize SPS processing parameters, including temperature, pressure, and holding time, for minimizing porosity. A quadratic model was developed and validated using analysis of variance (ANOVA) to determine the influence of the independent variables. A regression equation was derived to predict porosity based on the process parameters. Scanning elctron microscopy(SEM) measurements revealed a significant 16 % porosity reduction in the densified coating. Interlamellar cracks and microcracks were significantly reduced, improving coating integrity and interface bonding. Enhancement of SPS parameters indicated that higher temperature and pressure combined with shorter holding times yielded minimal porosity. The study demonstrated that higher pressures exhibited a stronger impact on porosity at higher temperatures, while the effect of temperature was more pronounced at a holding time of 4 min. The interaction between pressure and holding time highlighted the importance of considering both parameters for effective porosity control in SPS. The constraints for each parameter have been defined through the optimization process. The set temperature is 950 °C, the pressure is established at 30 MPA, and the duration of the holding time is 4 min.

Gadolinium Doping Modulates the Enzyme-like Activity and Radical-Scavenging Properties of CeO2 Nanoparticles

Their unique physicochemical properties and multi-enzymatic activity make CeO2 nanoparticles (CeO2 NPs) the most promising active component of the next generation of theranostic drugs. When doped with gadolinium ions, CeO2 NPs constitute a new type of contrast agent for magnetic resonance imaging, possessing improved biocatalytic properties and a high level of biocompatibility. The present study is focused on an in-depth analysis of the enzyme-like properties of gadolinium-doped CeO2 NPs (CeO2:Gd NPs) and their antioxidant activity against superoxide anion radicals, hydrogen peroxide, and alkylperoxyl radicals. Using an anion-exchange method, CeO2:Gd NPs (~5 nm) with various Gd-doping levels (10 mol.% or 20 mol.%) were synthesized. The radical-scavenging properties and biomimetic activities (namely SOD- and peroxidase-like activities) of CeO2:Gd NPs were assessed using a chemiluminescent method with selective chemical probes: luminol, lucigenin, and L-012 (a highly sensitive luminol analogue). In particular, gadolinium doping has been shown to enhance the radical-scavenging properties of CeO2 NPs. Unexpectedly, both bare CeO2 NPs and CeO2:Gd NPs did not exhibit SOD-like activity, acting as pro-oxidants and contributing to the generation of reactive oxygen species. Gadolinium doping caused an increase in the pro-oxidant properties of nanoscale CeO2. At the same time, CeO2:Gd NPs did not significantly inhibit the intrinsic activity of the natural enzyme superoxide dismutase, and CeO2:Gd NPs conjugated with SOD demonstrated SOD-like activity. In contrast to SOD-like properties, peroxidase-like activity was observed for both bare CeO2 NPs and CeO2:Gd NPs. This type of enzyme-like activity was found to be pH-dependent. In a neutral medium (pH = 7.4), nanoscale CeO2 acted as a prooxidant enzyme (peroxidase), while in an alkaline medium (pH = 8.6), it lost its catalytic properties; thus, it cannot be regarded as a nanozyme. Both gadolinium doping and conjugation with a natural enzyme were shown to modulate the interaction of CeO2 NPs with the key components of redox homeostasis.

Diabetic wound healing function of PCL/cellulose acetate nanofiber engineered with chitosan/cerium oxide nanoparticles

The use of cerium oxide nanoparticles (CeO2NPs) in diabetic wound repair substances has shown promising results. Therefore, the study was conducted to introduce a novel nano-based wound dressing containing chitosan nanoparticles encapsulated with green synthesized cerium oxide nanoparticles using Thymus vulgaris extract (CeO2-CSNPs). The physical properties and structure of the nanoparticles were analyzed using XRD, DLS, FESEM and FTIR techniques. The electrospun PCL/cellulose acetate-based nanofiber was prepared and CeO2-CSNPs were integrated on the PCL/CA membrane by electrospraying. The physicochemical properties, morphology and biological characteristics of the electrospun nanocomposite were evaluated. The results showed that the nanocomposite with 0.1 % CeO2-CSNPs exhibited high antibacterial performance against S. aureus (<58.59 µg/mL). The PCL/CA/CeO2-CSNPs nanofiber showed significant antioxidant activity up to 89.59 %, cell viability improvement, and cell migration promotion up to 90.3 % after 48 h. The in vivo diabetic wound healing experiment revealed that PCL/CA/CeO2-CSNPs nanofibers can significantly increase the repair rate of diabetic wounds by up to 95.47 % after 15 days. The results of this research suggest that PCL/CA nanofiber mats functionalized with CeO2-CSNPs have the potential to be highly effective in treating diabetes-related wounds.

Antimicrobial Activity of Citrate-Coated Cerium Oxide Nanoparticles

The purpose of this study was to investigate the antimicrobial activity of citrate-stabilized sols of cerium oxide nanoparticles at different concentrations via different microbiological methods and to compare the effect with the peroxidase activity of nanoceria for the subsequent development of a regeneration-stimulating medical and/or veterinary wound-healing product providing new types of antimicrobial action. The object of this study was cerium oxide nanoparticles synthesized from aqueous solutions of cerium (III) nitrate hexahydrate and citric acid (the size of the nanoparticles was 3-5 nm, and their aggregates were 60-130 nm). Nanoceria oxide sols with a wide range of concentrations (10-1-10-6 M) as well as powder (the dry substance) were used. Both bacterial and fungal strains (Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Proteus vulgaris, Candida albicans, Aspergillus brasielensis) were used for the microbiological studies. The antimicrobial activity of nanoceria was investigated across a wide range of concentrations using three methods sequentially; the antimicrobial activity was studied by examining diffusion into agar, the serial dilution method was used to detect the minimum inhibitory and bactericidal concentrations, and, finally, gas chromatography with mass-selective detection was performed to study the inhibition of E. coli's growth. To study the redox activity of different concentrations of nanocerium, we studied the intensity of chemiluminescence in the oxidation reaction of luminol in the presence of hydrogen peroxide. As a result of this study's use of the agar diffusion and serial dilution methods followed by sowing, no significant evidence of antimicrobial activity was found. At the same time, in the current study of antimicrobial activity against E. coli strains using gas chromatography with mass spectrometry, the ability of nanoceria to significantly inhibit the growth and reproduction of microorganisms after 24 h and, in particular, after 48 h of incubation at a wide range of concentrations, 10-2-10-5 M (48-95% reduction in the number of microbes with a significant dose-dependent effect) was determined as the optimum concentration. A reliable redox activity of nanoceria coated with citrate was established, increasing in proportion to the concentration, confirming the oxidative mechanism of the action of nanoceria. Thus, nanoceria have a dose-dependent bacteriostatic effect, which is most pronounced at concentrations of 10-2-10-3 M. Unlike the effects of classical antiseptics, the effect was manifested from 2 days and increased during the observation. To study the antimicrobial activity of nanomaterials, it is advisable not to use classical qualitative and semi-quantitative methods; rather, the employment of more accurate quantitative methods is advised, in particular, gas chromatography-mass spectrometry, during several days of incubation.

Influence of Nano-CeO2 and Graphene Nanoplatelets on the Conductivity and Dielectric Properties of Poly(vinylidene fluoride) Nanocomposite Films

Novel three-phase polymer nanocomposites (PNCs) based on cerium oxide (CeO2) nanoparticles (NPs) and graphene nanoplatelets (GNPs) incorporated in a poly(vinylidene fluoride) (PVDF) matrix were formulated using a solution-casting approach. To understand the structural and morphological features of PVDF/CeO2/GNP nanocomposites (NCs), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) analyses were accomplished. The PVDF/CeO2/GNP NCs displayed improved thermal stability which resulted from strong bonding between GNPs and CeO2 NPs and restriction of the polymer chain movement. The introduction of CeO2 NPs and GNPs within the PVDF matrix and good synergy between CeO2 NPs and GNPs led to variable mechanical properties of the prepared NCs. The PVDF/CeO2/GNP NCs portrayed reduced thermal stability, which could be due to the increased mobility of PVDF chains imposed by GNPs leading to the formation of volatile degradation products. Moreover, PVDF/CeO2/GNP NCs exhibited good electrical conductivity and high dielectric permittivity. The obtained dielectric permittivity value for the PVDF/CeO2/GNP NCs was 3-fold greater than PVDF/CeO2 NCs, making these novel tertiary composite materials a probable candidate for energy-storage applications.

α-Glucosidase Inhibitory Activity and Cytotoxicity of CeO2 Nanoparticles Fabricated Using a Mixture of Different Cerium Precursors

A mixture of three distinct cerium precursors (Ce(NO3)3·6H2O, CeCl3·7H2O, and Ce(CH3COO)3·H2O) was used to prepare cerium oxide nanoparticles (CeO2 NPs) in a polyol-mediated synthesis. Different ratios of diethylene glycol (DEG) and H2O were utilized in the synthesis. The properties of the synthesized CeO2 NPs, such as structural and morphological properties, were investigated to observe the effect of the mixed cerium precursors. Crystallite sizes of 7-8 nm were obtained for all samples, and all synthesized samples were confirmed to be in the cubic phase. The average particle sizes of the spherical CeO2 were between 9 and 13 nm. The successful synthesis of CeO2 can also be confirmed via the vibrational band of Ce-O from the FTIR. Antidiabetic properties of the synthesized CeO2 NPs were investigated using α-glucosidase enzyme inhibition assay, and the concentration of the synthesized CeO2 NPs was varied in the study. The biocompatibility properties of the synthesized CeO2 NPs were investigated via cytotoxicity tests, and it was found that all synthesized materials showed no cytotoxic properties at lower concentrations (62.5-125 μg/mL).

Enhancement of MXene optical properties towards medical applications via metal oxide incorporation

MXenes have garnered research attention in the field of biomedical applications due to their unique properties, such as a large surface area, low toxicity, biocompatibility, and stability. Their optical behavior makes them versatile for a wide range of biomedical applications, from diagnostics to therapeutics. Nonetheless, MXenes have some minor limitations, including issues with restacking, susceptibility to oxidation, and a non-semiconducting nature. These limitations have prompted researchers to explore the incorporation of metal oxides into MXene structures. Metal oxides possess advantageous properties such as a high surface area, biocompatibility, intriguing redox behavior, catalytic activity, semiconducting properties, and enhanced stability. Incorporating metal oxides into MXenes can significantly improve their conductivity, surface area, and mechanical strength. In this review, we emphasize the importance of incorporating metal oxides into MXenes for light-influenced biomedical applications. We also provide insights into various preparation methods for incorporating metal oxides into MXene structures. Furthermore, we discuss how the incorporation of metal oxides enhances the optical behavior of MXenes. Finally, we offer a glimpse into the future potential of metal oxide-incorporated MXenes for diverse biomedical applications.

Insight interactions of engineered nanoparticles with aquatic higher plants for phytoaccumulation, phytotoxicity, and phytoremediation applications: A review

With the growing age of human civilization, industrialization has paced up equally which is followed by the innovation of newer concepts of science and technology. One such example is the invention of engineered nanoparticles and their flagrant use in widespread applications. While ENPs serve their intended purposes, they also disrupt the ecological balance by contaminating pristine aquatic ecosystems. This review encompasses a comprehensive discussion about the potent toxicity of ENPs on aquatic ecosystems, with a particular focus on their impact on aquatic higher plants. The discussion extends to elucidating the fate of ENPs upon release into aquatic environments, covering aspects ranging from morphological and physiological effects to molecular-level phytotoxicity. Furthermore, this level of toxicity has been correlated with the determination of competent plants for the phytoremediation process towards the mitigation of this ecological stress. However, this review further illustrates the path of future research which is yet to be explored. Determination of the genotoxicity level of aquatic higher plants could explain the entire process comprehensively. Moreover, to make it suitable to be used in natural ecosystems phytoremediation potential of co-existing plant species along with the presence of different ENPs need to be evaluated. This literature will undoubtedly offer readers a comprehensive understanding of the stress induced by the irresponsible release of engineered nanoparticles (ENP) into aquatic environments, along with insights into the resilience characteristics of these pristine ecosystems.

Towards nanostructured red-ox active bio-interfaces: Bioinspired antibacterial hybrid melanin-CeO2 nanoparticles for radical homeostasis

Redox-active nano-biointerfaces are gaining weight in the field of regenerative medicine since they can act as enzymes in regulating physiological processes and enabling cell homeostasis, as well as the defense against pathogen aggression. In particular, cerium oxide nanoparticles (CeO2 NPs) stand as intriguing enzyme-mimicking nanoplatforms, owing to the reversible Ce+3/Ce+4 surface oxidation state. Moreover, surface functionalization leads to higher catalytic activity and selectivity, as well as more tunable enzyme-mimicking performances. Conjugation with melanin is an adequate strategy to boost and enrich CeO2 NPs biological features, because of melanin redox properties accounting for intrinsic antioxidant, antimicrobial and anti-inflammatory power. Herein, hybrid Melanin/CeO2 nanostructures were designed by simply coating the metal-oxide nanoparticles with melanin chains, obtained in-situ through ligand-to-metal charge transfer mechanism, according to a bioinspired approach. Obtained hybrid nanostructures underwent detailed physico-chemical characterization. Morphological and textural features were investigated through TEM, XRD and N2 physisorption. The nature of nanoparticle-melanin interaction was analyzed through FTIR, UV-vis and EPR spectroscopy. Melanin-coated hybrid nanostructures exhibited a relevant antioxidant activity, confirmed by a powerful quenching effect for DPPH radical, reaching 81 % inhibition at 33 μg/mL. A promising anti-inflammatory efficacy of the melanin-coated hybrid nanostructures was validated through a significant inhibition of BSA denaturation after 3 h. Meanwhile, the enzyme-mimicking activity was corroborated by a prolonged peroxidase activity after 8 h at 100 μg/mL and a relevant catalase-like action, by halving the H2O2 level in 30 min at 50 μg/mL. Antimicrobial assays attested that conjugation with melanin dramatically boosted CeO2 biocide activity against both Gram (-) and Gram (+) strains. Cytocompatibility tests demonstrated that the melanin coating not only enhanced the CeO2 nanostructures biomimicry, resulting in improved cell viability for human dermal fibroblast cells (HDFs), but mostly they proved that Melanin-CeO2 NPs were able to control the oxidative stress, modulating the production of nitrite and reactive oxygen species (ROS) levels in HDFs, under physiological conditions. Such remarkable outcomes make hybrid melanin-CeO2 nanozymes, promising redox-active interfaces for regenerative medicine.

Development and Characterization of Electrospun Composites Built on Polycaprolactone and Cerium-Containing Phases

The current study reports on the fabrication of composite scaffolds based on polycaprolactone (PCL) and cerium (Ce)-containing powders, followed by their characterization from compositional, structural, morphological, optical and biological points of view. First, CeO2, Ce-doped calcium phosphates and Ce-substituted bioglass were synthesized by wet-chemistry methods (precipitation/coprecipitation and sol-gel) and subsequently loaded on PCL fibres processed by electrospinning. The powders were proven to be nanometric or micrometric, while the investigation of their phase composition showed that Ce was present as a dopant within the crystal lattice of the obtained calcium phosphates or as crystalline domains inside the glassy matrix. The best bioactivity was attained in the case of Ce-containing bioglass, while the most pronounced antibacterial effect was visible for Ce-doped calcium phosphates calcined at a lower temperature. The scaffolds were composed of either dimensionally homogeneous fibres or mixtures of fibres with a wide size distribution and beads of different shapes. In most cases, the increase in polymer concentration in the precursor solution ensured the achievement of more ordered fibre mats. The immersion in SBF for 28 days triggered an incipient degradation of PCL, evidenced mostly through cracks and gaps. In terms of biological properties, the composite scaffolds displayed a very good biocompatibility when tested with human osteoblast cells, with a superior response for the samples consisting of the polymer and Ce-doped calcium phosphates.

Electrospun polyvinyl alcohol-chitosan dressing stimulates infected diabetic wound healing with combined reactive oxygen species scavenging and antibacterial abilities

Diabetic wounds (DW) are constantly challenged by excessive reactive oxygen species (ROS) accumulation and susceptibility to bacterial contamination. Therefore, the elimination of ROS in the immediate vicinity and the eradication of local bacteria are critical to stimulating the efficient healing of diabetic wounds. In the current study, we encapsulated mupirocin (MP) and cerium oxide nanoparticles (CeNPs) into a polyvinyl alcohol/chitosan (PVA/CS) polymer, and then a PVA/chitosan nanofiber membrane wound dressing was fabricated using electrostatic spinning, which is a simple and efficient method for fabricating membrane materials. The PVA/chitosan nanofiber dressing provided a controlled release of MP, which produced rapid and long-lasting bactericidal activity against both methicillin-sensitive S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA) strains. Simultaneously, the CeNPs embedded in the membrane exhibited the desired ROS scavenging capacity to maintain the local ROS at a normal physiological level. Moreover, the biocompatibility of the multifunctional dressing was evaluated both in vitro and in vivo. Taken together, PVA-CS-CeNPs-MP integrated the desirable features of a wound dressing, including rapid and broad-spectrum antimicrobial and ROS scavenging activities, easy application, and good biocompatibility. The results validated the effectiveness of our PVA/chitosan nanofiber dressing, highlighting its promising translational potential in the treatment of diabetic wounds.

Ce-based solid-phase catalysts for phosphate hydrolysis as new tools for next-generation nanoarchitectonics

This review comprehensively covers synthetic catalysts for the hydrolysis of biorelevant phosphates and pyrophosphates, which bridge between nanoarchitectonics and biology to construct their interdisciplinary hybrids. In the early 1980s, remarkable catalytic activity of Ce4+ ion for phosphate hydrolysis was found. More recently, this finding has been extended to Ce-based solid catalysts (CeO2 and Ce-based metal-organic frameworks (MOFs)), which are directly compatible with nanoarchitectonics. Monoesters and triesters of phosphates, as well as pyrophosphates, were effectively cleaved by these catalysts. With the use of either CeO2 nanoparticles or elegantly designed Ce-based MOF, highly stable phosphodiester linkages were also hydrolyzed. On the surfaces of all these solid catalysts, Ce4+ and Ce3+ coexist and cooperate for the catalysis. The Ce4+ activates phosphate substrates as a strong acid, whereas the Ce3+ provides metal-bound hydroxide as an eminent nucleophile. Applications of these Ce-based catalysts to practical purposes are also discussed.

Molecular Imaging Investigations of Polymer-Coated Cerium Oxide Nanoparticles as a Radioprotective Therapeutic Candidate

Cerium oxide nanoparticles (CONPs) have a unique surface redox chemistry that appears to selectively protect normal tissues from radiation induced damage. Our prior research exploring the biocompatibility of polymer-coated CONPs found further study of poly-acrylic acid (PAA)-coated CONPs was warranted due to improved systemic biodistribution and rapid renal clearance. This work further explores PAA-CONPs' radioprotective efficacy and mechanism of action related to tumor microenvironment pH. An ex vivo TUNEL assay was used to measure PAA-CONPs' protection of the irradiated mouse colon in comparison to the established radioprotector amifostine. [18F]FDG PET imaging of spontaneous colon tumors was utilized to determine the effects of PAA-CONPs on tumor radiation response. In vivo MRI and an ex vivo clonogenic assay were used to determine pH effects on PAA-CONPs' radioprotection in irradiated tumor-bearing mice. PAA-CONPs showed excellent radioprotective efficacy in the normal colon that was equivalent to uncoated CONPs and amifostine. [18F]FDG PET imaging showed PAA-CONPs do not affect tumor response to radiation. Normalization of tumor pH allowed some radioprotection of tumors by PAA-CONPs, which may explain their lack of tumor radioprotection in the acidic tumor microenvironment. Overall, PAA-CONPs meet the criteria for clinical application as a radioprotective therapeutic agent and are an excellent candidate for further study.

Structural and functional insights in polysaccharides coated cerium oxide nanoparticles and their potential biomedical applications: A review

Cerium oxide nanoparticles have now significant presence in biomedical fields due to their wide applications; however, challenges regarding their safety and biocompatibility persist. Polysaccharides based biopolymers have inherent hydroxyl and carboxyl groups, enabling them to govern the surface functionalization of cerium oxide nanoparticles, hence their chemical and physical characteristics. Because of this, polysaccharides such as dextran, alginate, pullulan, chitosan, polylactic acid, starch, and pectin are practical substitutes for the conventional coatings used to synthesize cerium oxide nanoparticles. This review discusses the effect of biopolymer coatings on the properties of cerium oxide nanoparticles, such as size, stability, aggregation, and biocompatibility. Additionally, it also summarises various biomedical applications of polysaccharides coated cerium oxide nanoparticles, such as in bone tissue regeneration, liver inflammation, wound healing, and antibacterial and anticancer activities. Biocompatible cerium oxide nanoparticles will surely improve their applications in the biomedical field.

Synthesis and characterisation of a novel poly(2-hydroxyethylmethacrylate)-chitosan hydrogels loaded cerium oxide nanocomposites dressing on cutaneous wound healing on nursing care of chronic wound

This study was designed to establish the composition of wound dressing based on poly(2-hydroxyethylmethacrylate)-chitosan (PHEM-CS) hydrogels-loaded cerium oxide nanoparticle (CeONPs) composites for cutaneous wound healing on nursing care of the chronic wound. The as-synthesised PHEM-CS/CeONPs hydrogels nanocomposites were characterised by using UV-visible spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermo gravimetric analysis. The influence of PHEM-CS/CeONPs hydrogels nanocomposites on the gelation time, swelling ratio, in vitro degradation, and mechanical properties was investigated. The as-prepared PHEM-CS/CeONPs hydrogels nanocomposites dressing shows high antimicrobial activity against Staphylococcus aureus and Escherichia coli. Similar trends were observed for the treatment of biofilms where PHEM-CS/CeONPs hydrogels nanocomposites displayed better efficiency. Furthermore, the biological properties of PHEM-CS/CeONPs hydrogels nanocomposites had non-toxic in cell viability and excellent cell adhesion behaviour. After 2 weeks, the wounds treated with the PHEM-CS/CeONPs hydrogels nanocomposite wound dressing achieved a significant closure to 98.5 ± 4.95% compared with the PHEM-CS hydrogels with nearly 71 ± 3.55% of wound closure. Hence, this study strongly supports the possibility of using this novel PHEM-CS/CeONPs hydrogels nanocomposites wound dressing for efficient cutaneous wound healing on chronic wound infection and nursing care.

Combined cerium and zinc oxide nanoparticles induced hepato-renal damage in rats through oxidative stress mediated inflammation

The toxicity profiles of nanoparticles (NPs) used in appliances nowadays remains unknown. In this study, we investigated the toxicological consequences of exposure to cerium oxide (CeO₂) and zinc oxide (ZnO) nanoparticles given singly or in combination on the integrity of liver and kidney of male Wistar rats. Twenty (20) rats were allotted into four groups and treated as: Control (normal saline), CeO₂NPs (50 μg/kg), ZnONPs (80 μg/kg) and [CeO₂NPs (50 μg/kg) + ZnONPs (80 μg/kg)]. The nanoparticles were given to the animals through the intraperitoneal route, three times per week for four repeated weeks. Results revealed that CeO₂ and ZnO NPs (singly) increased serum AST and ALT by 29% & 57%; 41% & 18%, and co-administration by 53% and 23%, respectively. CeO₂ and ZnO NPs increased hepatic and renal malondialdehyde (MDA) by 33% and 30%; 38% and 67%, respectively, while co-administration increased hepatic and renal MDA by 43% and 40%, respectively. The combined NPs increased hepatic NO by 28%. Also, CeO₂ and ZnO NPs, and combined increased BAX, interleukin-1β and TNF-α by 45, 38, 52%; 47, 23, 82% and 41, 83, 70%, respectively. Histology revealed hepatic necrosis and renal haemorrhagic parenchymal in NPs-treated rats. Summarily, CeO₂ and ZnO NPs produced oxidative injury and induced inflammatory process in the liver and kidney of experimental animals.

A Brief Review on Cerium Oxide (CeO2NPs)-Based Scaffolds: Recent Advances in Wound Healing Applications

The process of wound healing is complex and involves the interaction of multiple cells, each with a distinct role in the inflammatory, proliferative, and remodeling phases. Chronic, nonhealing wounds may result from reduced fibroblast proliferation, angiogenesis, and cellular immunity, often associated with diabetes, hypertension, vascular deficits, immunological inadequacies, and chronic renal disease. Various strategies and methodologies have been explored to develop nanomaterials for wound-healing treatment. Several nanoparticles such as gold, silver, cerium oxide and zinc possess antibacterial properties, stability, and a high surface area that promotes efficient wound healing. In this review article, we investigate the effectiveness of cerium oxide nanoparticles (CeO₂NPs) in wound healing-particularly the effects of reducing inflammation, enhancing hemostasis and proliferation, and scavenging reactive oxygen species. The mechanism enables CeO₂NPs to reduce inflammation, modulate the immunological system, and promote angiogenesis and tissue regeneration. In addition, we investigate the efficacy of cerium oxide-based scaffolds in various wound-healing applications for creating a favorable wound-healing environment. Cerium oxide nanoparticles (CeO₂NPs) exhibit antioxidant, anti-inflammatory, and regenerative characteristics, enabling them to be ideal wound healing material. Investigations have shown that CeO₂NPs can stimulate wound closure, tissue regeneration, and scar reduction. CeO₂NPs may also reduce bacterial infections and boost wound-site immunity. However, additional study is needed to determine the safety and efficacy of CeO₂NPs in wound healing and their long-term impacts on human health and the environment. The review reveals that CeO₂NPs have promising wound-healing properties, but further study is needed to understand their mechanisms of action and ensure their safety and efficacy.

The Relationship between Photoluminescence Emissions and Photocatalytic Activity of CeO2 Nanocrystals

In this work, we focus on understanding the morphology and photocatalytic properties of CeO₂ nanocrystals (NCs) synthesized via a microwave-assisted solvothermal method using acetone and ethanol as solvents. Wulff constructions reveal a complete map of available morphologies and a theoretical-experimental match with octahedral nanoparticles obtained through synthesis using ethanol as solvent. NCs synthesized in acetone show a greater contribution of emission peaks in the blue region (∼450 nm), which may be associated with higher Ce³⁺ concentration, originating shallow-level defects within the CeO₂ lattice while for the samples synthesized in ethanol a strong orange-red emission (∼595 nm) suggests that oxygen vacancies may originate from deep-level defects within the optical bandgap region. The superior photocatalytic response of CeO₂ synthesized in acetone compared to that of CeO₂ synthesized in ethanol may be associated with an increase in long-/short-range disorder within the CeO₂ structure, causing the E_gap value to decrease, facilitating light absorption. Furthermore, surface (100) stabilization in samples synthesized in ethanol may be related to low photocatalytic activity. Photocatalytic degradation was facilitated by the generation of ·OH and ·O₂^- radicals as corroborated by the trapping experiment. The mechanism of enhanced photocatalytic activity has been proposed suggesting that samples synthesized in acetone tend to have lower e'─h· pair recombination, which is reflected in their higher photocatalytic response.

Current Trends and Prospects for Application of Green Synthesized Metal Nanoparticles in Cancer and COVID-19 Therapies

Cancer and COVID-19 have been deemed as world health concerns due to the millions of lives that they have claimed over the years. Extensive efforts have been made to develop sophisticated, site-specific, and safe strategies that can effectively diagnose, prevent, manage, and treat these diseases. These strategies involve the implementation of metal nanoparticles and metal oxides such as gold, silver, iron oxide, titanium oxide, zinc oxide, and copper oxide, formulated through nanotechnology as alternative anticancer or antiviral therapeutics or drug delivery systems. This review provides a perspective on metal nanoparticles and their potential application in cancer and COVID-19 treatments. The data of published studies were critically analysed to expose the potential therapeutic relevance of green synthesized metal nanoparticles in cancer and COVID-19. Although various research reports highlight the great potential of metal and metal oxide nanoparticles as alternative nanotherapeutics, issues of nanotoxicity, complex methods of preparation, biodegradability, and clearance are lingering challenges for the successful clinical application of the NPs. Thus, future innovations include fabricating metal nanoparticles with eco-friendly materials, tailor making them with optimal therapeutics for specific disease targeting, and in vitro and in vivo evaluation of safety, therapeutic efficiency, pharmacokinetics, and biodistribution.

Chitosan Composites with Bacterial Cellulose Nanofibers Doped with Nanosized Cerium Oxide: Characterization and Cytocompatibility Evaluation

In this work, new composite films were prepared by incorporating the disintegrated bacterial cellulose (BCd) nanofibers and cerium oxide nanoparticles into chitosan (CS) matrices. The influence of the amount of nanofillers on the structure and properties of the polymer composites and the specific features of the intermolecular interactions in the materials were determined. An increase in film stiffness was observed as a result of reinforcing the CS matrix with BCd nanofibers: the Young’s modulus increased from 4.55 to 6.3 GPa with the introduction of 5% BCd. A further increase in Young’s modulus of 6.7 GPa and a significant increase in film strength (22% increase in yield stress compared to the CS film) were observed when the BCd concentration was increased to 20%. The amount of nanosized ceria affected the structure of the composite, followed by a change in the hydrophilic properties and texture of the composite films. Increasing the amount of nanoceria to 8% significantly improved the biocompatibility of the films and their adhesion to the culture of mesenchymal stem cells. The obtained nanocomposite films combine a number of favorable properties (good mechanical strength in dry and swollen states, improved biocompatibility in relation to the culture of mesenchymal stem cells), which allows us to recommend them for use as a matrix material for the culture of mesenchymal stem cells and wound dressings.

Biocomposite films based on chitosan and cerium oxide nanoparticles with promising regenerative potential

Polymeric nanocomposite materials have great potential in the development of tissue-engineered scaffolds because they affect the structure and properties of polymeric materials and regulate cell proliferation and differentiation. In this work, cerium oxide nanoparticles (CeONPs) were incorporated into a chitosan (CS) film to improve the proliferation of multipotent mesenchymal stem cells (MSCs). The citrate-stabilized CeONPs with a negative ζ-potential (-25.0 mV) were precoated with CS to obtain positively charged particles (+20.3 mV) and to prevent their aggregation in the composite solution. The composite CS-CeONP films were prepared in the salt and basic forms using a dry-cast process. The films obtained in both forms were characterized by a uniform distribution of CeONPs. The incorporation of CeONPs into the salt form of CS increased the stiffness of the CS-CeONP film, while the subsequent conversion of the film to the basic form resulted in a decrease in both the Young's modulus and the yield stress. The redox activity (Ce⁴⁺ ⇌ Ce³⁺) of cerium oxide in the CS-CeONP film was confirmed by thermal oxidative degradation. In vitro culture of MSCs showed that the CS-CeONP film has good biocompatibility, and in vivo experiments demonstrated its substantial regenerative potential.

Shear Bond Strength and Color Stability of Novel Antibacterial Nanofilled Dental Adhesive Resins

Experimental adhesives containing co-doped metaloxide nanoparticles were demonstrated to display strong and long-term antibacterial properties against Streptococcus mutans biofilms. The present study represents an effort to characterize the shear-bond strength (SBS) and color stability (CS) of these novel biomaterials. Experimental adhesives were obtained by dispersing nitrogen and fluorine co-doped titanium dioxide nanoparticles (NF_TiO2, 10%, 20% or 30%, v/v%) into OptiBond Solo Plus (OPTB). Dentin surfaces were wet-polished (600-Grit). Specimens (n = 5/group) of Tetric EvoCeram were fabricated and bonded using either OPTB or experimental (OPTB + NF_TiO2) adhesives. Specimens were stored in water (37 °C) for twenty-four hours (T1), three months (T2), and six months (T3). At T1, T2, or T3, specimens were removed from water storage and were tested for SBS. Disc-shaped specimens (n = 10/group; d = 6.0 mm, t = 0.5 mm) of adhesives investigated were fabricated and subjected to thermocycling (10,000 cycles, 5−55 °C, 15 s dwell time). Specimens’ colors were determined with a VITA Easyshade® V spectrophotometer (after every 1000 cycles). SBS data was analyzed using two-way ANOVA and post-hoc Tukey tests, while CS data was analyzed using one-way ANOVA and post-hoc Tukey tests (α = 0.05). Mean values of SBS ranged from 16.39 ± 4.20 MPa (OPTB + 30%NF_TiO2) to 19.11 ± 1.11 MPa (OPTB), from 12.99 ± 2.53 MPa (OPTB + 30% NF_TiO2) to 14.87 ± 2.02 (OPTB) and from 11.37 ± 1.89 (OPTB + 20% NF_TiO2) to 14.19 ± 2.24 (OPTB) after twenty-four hours, three months, and six months of water storage, respectively. Experimental materials had SBS values that were comparable (p > 0.05) to those from OPTB independently of nanoparticle concentration or time-point considered. Experimental materials with higher NF_TiO2 concentrations had less intense color variations and were more color stable than OPTB even after 10,000 thermocycles. In combination, the results reported have demonstrated that experimental adhesives can establish strong and durable bonds to human dentin while displaying colors that are more stable, thereby suggesting that the antibacterial nanotechnology investigated can withstand the harsh conditions within the oral cavity without compromising the esthetic component of dental restorations.

Smart biomaterials for enhancing cancer therapy by overcoming tumor hypoxia: a review

Hypoxia is a distinctive feature of most solid tumors due to insufficient oxygen supply of the abnormal vasculature, which cannot work with the demands of the fast proliferation of cancer cells. One of the main obstacles to limiting the efficacy of cancer medicines is tumor hypoxia. Thus, oxygen is a vital parameter for controlling the efficacy of different types of cancer therapy, such as chemotherapy (CT), photodynamic therapy (PDT), photothermal therapy (PTT), immunotherapy (IT), and radiotherapy (RT). Numerous technologies have attracted much attention for enhancing oxygen distribution in humans and improving the efficacy of cancer treatment. Such technologies include treatment with hyperbaric oxygen therapy (HBO), delivering oxygen by polysaccharides (e.g., cellulose, gelatin, alginate, and silk) and other biocompatible synthetic polymers (e.g., PMMA, PLA, PVA, PVP and PCL), decreasing oxygen consumption, producing oxygen in situ in tumors, and using polymeric systems as oxygen carriers. Herein, this review provides an overview of the relationship between hypoxia in tumor cells and its role in the limitation of different cancer therapies alongside the numerous strategies for oxygen delivery using polysaccharides and other biomaterials as carriers and for oxygen generation.

Bacterial Cellulose Composites with Polysaccharides Filled with Nanosized Cerium Oxide: Characterization and Cytocompatibility Assessment

A new biocompatible nanocomposite film material for cell engineering and other biomedical applications has been prepared. It is based on the composition of natural polysaccharides filled with cerium oxide nanoparticles (CeONPs). The preparative procedure consists of successive impregnations of pressed bacterial cellulose (BC) with a sodium alginate (ALG) solution containing nanoparticles of citrate-stabilized cerium oxide and a chitosan (CS) solution. The presence of CeONPs in the polysaccharide composite matrix and the interaction of the nanoparticles with the polymer, confirmed by IR spectroscopy, change the network architecture of the composite. This leads to noticeable changes in a number of properties of the material in comparison with those of the matrix's polysaccharide composition, viz., an increase in mechanical stiffness, a decrease in the degree of planar orientation of BC macrochains, an increase in hydrophilicity, and the shift of the processes of thermo-oxidative destruction of the material to a low-temperature region. The latter effect is considered to be caused by the redox activity of cerium oxide (reversible transitions between the states Ce⁴⁺ and Ce³⁺) in thermally stimulated processes in the nanocomposite films. In the equilibrium swollen state, the material retains a mechanical strength at the level of ~2 MPa. The results of in vitro tests (cultivation of multipotent mesenchymal stem cells) have demonstrated the good biocompatibility of the BC-ALG(CeONP)-CS film as cell proliferation scaffolds.

Protective effect of cerium oxide on testicular function and oxidative stress after torsion/detorsion in adult male rats

Testicular torsion (T)/detorsion (D) can cause testicular injury due to the rotation of the spermatic cord and its vessels, therefore it represents an urological emergency that is surgically treated. Oxidative damage occurs in the testis and distant organs because of the overproduction of free radicals and overexpression of proinflammatory cytokines by reperfusion after surgery. Cerium oxide (CeO₂) nanoparticles, a material also known as nanoceria, have regenerative antioxidant properties on oxidative stress. The present study aimed to investigate the effects of nanoceria on testis tissues in testicular T/D in rats. A total of 24 rats were equally and randomly divided into four groups: Control, CeO₂, T/D and CeO2-T/D groups. Left inguinoscrotal incision was performed in the control group. In the CeO₂ group, 0.5 mg/kg CeO₂ was given intraperitoneally 30 min before inguinoscrotal incision. In the T/D group, unilateral testicular T/D was performed through an inguinoscrotal incision and rotating the left testis 720˚ clockwise, which was then left ischemic for 120 min, followed by 120 min of reperfusion. In the CeO₂-T/D group, 0.5 mg/kg CeO₂ was given intraperitoneally 30 min before testicular T/D. At the end of the experiment, testis tissues were removed for histopathological and biochemical examinations. The samples were histologically examined, Glutathione-s transferase (GST), catalase (CAT), paraoxonase (PON) activities and malondialdehyde (MDA) levels were measured via biochemical analysis methods, while the expression levels of p53, Bax and Bcl-2 were detected using immunohistochemistry. The present results revealed statistically significant inter-group differences in PON, CAT and GST activities and MDA levels. GST, CAT and PON activities were significantly higher, whereas MDA levels in the CeO₂-T/D group were significantly lower compared with those in the T/D group. The T/D group had increased Bax and decreased Bcl-2 expression levels in their seminiferous tubules compared with the control and CeO₂ groups. CeO₂ treatment led to downregulation of Bax and upregulation of Bcl-2. The expression of p53 was high in the T/D group compared with that in the control and CeO2 groups, and was upregulated in all germinal cells. However, compared with that in the T/D group, p53 expression was significantly decreased in the CeO₂-T/D group. The testicular injury score significantly increased in the CeO₂-T/D group compared with the control and CeO₂ groups. Rats in the CeO₂-T/D group demonstrated significantly milder tissue lesions compared with those in T/D group. The present findings indicated that nanoceria may protect testis in rats against the harmful effects of T/D. Further studies are required to evaluate how CeO₂ reduces oxidative stress and cell death in testis tissue that underwent T/D-related injury.

Antioxidant Activity of New Copolymer Conjugates of Methoxyoligo(Ethylene Glycol)Methacrylate and Betulin Methacrylate with Cerium Oxide Nanoparticles In Vitro

The synthesis of two new copolymer conjugates of methoxyoligo(ethylene glycol)methacrylate MPEGMA and betulin methacrylate BM was developed via RAFT polymerization. The molar content of BM units was equal to 9–10 and 13–16 mol%, respectively (HPLC, ¹H and ¹³C NMR); molar weights were equal to 75000–115000. CeO₂ NPs as a component of the hybrid material were synthesized for the preparation of the composition with copolymer conjugates of MPEGMA and BM. We showed a significant increase in G6PDH and GR activities by 21–51% and 9–132%, respectively, which was due to the increase in NADPH concentration under the action of copolymers in vitro. The actions of copolymers and CeO₂ NPs combination were stronger than those of the individual components: the SOD activity increased by more than 30%, the catalase activity increased dose-dependently from 13 to 45%, and the GR activity increased to 49%. The maximum increase in enzyme activity was observed for the G6PDH from 54% to 151%. The MDA level dose-dependently increased by 3–15% under the action of copolymers compared with the control, and dose-dependently decreased by 3–12% in samples containing CeO₂ NPs only. CeO₂ NP–copolymer compositions can be used for the design of new biomimetic medical products with controlled antioxidant properties.

The Strong Protective Action of Ce3+/F- Combined Treatment on Tooth Enamel and Epithelial Cells

We studied the toxic effects of cerium and fluoride species on human dental pulp stem cells and epithelial cells of Cercopithecus aethiops as a surrogate for the human oral mucosa. The sequential use of CeCl₃ and NH₄F solutions in equimolar sub-toxic concentrations enabled the possible toxic effects of individual components to be avoided, ensuring the preservation of the metabolic activity of the cells due to the formation of CeF₃ nanoparticles. Cerium fluoride nanoparticles and terbium-doped cerium fluoride nanoparticles exhibited neither cytotoxicity nor genotoxicity to dental pulp stem cells, even at high concentrations (10^-4 M). In millimolar concentrations (from 10^-5-10^-6 M), these nanoparticles significantly increased the expression of genes responsible for the cell cycle, differentiation and proliferation. The formation of cerium fluoride on the surface of the mucous membrane and teeth provided protection against the development of carious lesions, periodontitis, ROS attacks and other inflammatory diseases of the oral cavity. Luminescent CeF₃: Tb nanoparticles enabled the visualization of tooth enamel microcracks.

Recent trends and advances in polyindole-based nanocomposites as potential antimicrobial agents: a mini review

Infections caused by multi-drug resistant microbes are a big challenge to the medical field and it necessitates the need for new biomedical agents that can act as potential candidates against these pathogens. Several polyindole based nanocomposites were found to exhibit the ability to release reactive oxygen species (ROS) and hence they show excellent antimicrobial properties. The features of polyindole can be fine-tuned to make them potential alternatives to antibiotics and antifungal medicines. This review clearly portrays the antimicrobial properties of polyindole based nanocomposites, reported so far for biomedical applications. This review will give a clear insight into the scope and possibilities for further research on the biomedical applications of polyindole based nanocomposites.

Exosomes for diabetes syndrome: ongoing applications and perspective

Diabetes mellitus, ranking the ninth death cause in the world, is a kind of metabolic disease characterized by hyperglycemia. Without timely and effective treatment, many ensuing complications involved with heart,...

PLLA-gelatin composite fiber membranes incorporated with functionalized CeNPs as a sustainable wound dressing substitute promoting skin regeneration and scar remodelling

The need of wound dressing material that can accelerate wound healing is increasing and will last a long time. In this study, Cerium Oxide Nanoparticles (CeNPs) incorporated poly-L-lactic acid (PLLA)-gelatin...

Solvent Extraction of Lanthanides(III) in the Presence of the Acetate Ion Acting as a Complexing Agent Using Mixtures of Cyanex 272 and Caprylic Acid in Hexane

A new extraction system containing a mixture of Cyanex 272 and caprylic acid is proposed for the extraction and separation of lanthanides(III). It was shown that this system possesses a high level of extraction ability and capacity. The extraction of lanthanides(III) from chloride-acetate and nitrate-acetate media was investigated on an example of La(III). The composition of the extracted species was confirmed, based on the analysis of lanthanum(III) extraction isotherms. In the case of acetic-acetate aqueous solutions, a decrease in lanthanum(III) extraction efficiency was observed, due to the decreasing equilibrium pH of the aqueous phase in accordance with the cation-exchange mechanism. The composition of the synergistic mixture of Cyanex 272-caprylic acid established demonstrates highly efficient separation of rare-earth metal ions.

New facets of nanozyme activity of ceria: lipo- and phospholipoperoxidase-like behaviour of CeO2 nanoparticles

Cerium dioxide nanoparticles have a special place among engineered nanomaterials due to the wide range of their enzyme-like activities. They possess SOD-, catalase- and peroxidase-like properties, as well as recently discovered phosphatase-, photolyase-, phospholipase- and nuclease-like properties. Advancing biomedical applications of CeO₂-based nanozymes requires an understanding of the features and mechanisms of the redox activity of CeO₂ nanoparticles when entering the vascular bed, especially when interacting with lipid-protein supramolecular complexes (biomembranes and lipoproteins). In this paper, CeO₂ nanoparticles are shown to possess two further types of nanozyme activity, namely lipo- and phospholipoperoxidase-like activities. Compared to a strong blood prooxidant, hemoglobin, CeO₂ nanoparticles act as a mild oxidising agent, since they exhibit a 10⁶ times lower, and 20 times lower, prooxidant capacity towards linoleic acid and phosphatidylcholine hydroperoxides, respectively. Compared to the widespread pharmacological preparation of iron, Fe(iii) carboxymaltose (antianemic preparation Ferinject®), the prooxidant capacity of CeO₂ nanoparticles towards lipid and phospholipid substrates has been shown to be 10² times lower, and 4 times higher, respectively. The data obtained on the mechanism of the interaction of nanodisperse CeO₂ with the main components of biological membranes, lipids and phospholipids enable the substantial expansion of the scope of biomedical applications of CeO₂ nanozymes.

CeO₂ nanoparticles were shown to possess two novel types of enzyme-like activity, namely lipoperoxidase and phospholipoperoxidase activity.

Synthesis and Characterization of Thin Films Based on Azobenzene Derivative Anchored to CeO2 Nanoparticle for Photoswitching Applications

Azobenzene has attracted substantial attention as a photoswitchable molecule since its applications range from energy and data storage to biomedical applications. This work reports a new type of thin-film based on azobenzene derivative anchored to cerium oxide nanoparticles CeO₂ NPs for photoswitching applications. The trans-cis isomerization and reverse isomerization occur by UV-light exposure and thermal relaxation process, respectively. The photoisomerization and reverse isomerization kinetics for CeO₂ NPs-MR thin films are studied, investigated, and analyzed using UV-Vis absorbance spectra, FTIR spectroscopy, XRD, and scanning electron microscopy (SEM), in addition to differential scanning calorimetry (DSC) measurement to study the energy storage capacity. The results found that anchoring azobenzene to CeO₂ NPs is successful in multisource storage of solar energy applications.

Poly (Ethylene Glycol) Methyl Ether Methacrylate-Based Hydrogel and Cerium(IV) Oxide Nanoparticles as Ophthalmic Lens Material

The functional hydrogel lens containing 2-hydroxyethylmethacrylate (HEMA) was manufactured by thermal polymerization. The physical properties of the produced hydrogel lens were measured and analyzed. In this study, HEMA, ethylene glycol dimethacrylate (EGDMA), and azobisisobutyronitrile (AIBN) were used for thermal copolymerization. Additionally, poly (ethylene glycol) methyl ether methacrylate (PEGMEMA), 3-(Triethoxysilyl) propyl isocyanate (TEPI), and cerium(Ⅳ) oxide nanoparticles were used as additives to make a functional hydrogel lens. The mixture was heated at 100 °C for 90 min to produce the hydrogel ophthalmic lens by the cast mold method. The resulting physical properties showed that the water content and refractive index of the sample were in the ranges of 38.06~42.11% and 1.426~1.436, respectively. The addition of cerium oxide nanoparticles lowered the contact angle and allowed the hydrogel lens to block UV light. The tensile strength was also improved by 52.13% through cerium oxide nanoparticles, and up to 123.4% by using TEPI. Based on the results of this study, the produced ophthalmic lens is suitable for durable, UV-blocking high-performance lenses.

Bacterial Cellulose-Based Nanocomposites Containing Ceria and Their Use in the Process of Stem Cell Proliferation

A technique for the fabrication of bacterial cellulose-based films with CeO₂ nanofiller has been developed. The structural and morphological characteristics of the materials have been studied, their thermal and mechanical properties in dry and swollen states having been determined. The preparation methodology makes it possible to obtain composites with a uniform distribution of nanoparticles. The catalytic effect of ceria, regarding the thermal oxidative destruction of cellulose, has been confirmed by TGA and DTA methods. An increase in CeO₂ content led to an increase in the elastic modulus (a 1.27-fold increase caused by the introduction of 5 wt.% of the nanofiller into the polymer) and strength of the films. This effect is explained by the formation of additional links between polymer macro-chains via the nanoparticles’ surface. The materials fabricated were characterized by a limited ability to swell in water. Swelling caused a 20- to 30-fold reduction in the stiffness of the material, the mechanical properties of the films in a swollen state remaining germane to their practical use. The application of the composite films in cell engineering as substrates for the stem cells’ proliferation has been studied. The increase in CeO₂ content in the films enhanced the proliferative activity of embryonic mouse stem cells. The cells cultured on the scaffold containing 5 wt.% of ceria demonstrated increased cell survival and migration activity. An analysis of gene expression confirmed improved cultivation conditions on CeO₂-containing scaffolds.