Biopolymer-assisted green synthesis of functional cerium oxide nanoparticles

Biosafe cerium oxide nanozymes protect human pluripotent stem cells and cardiomyocytes from oxidative stress

BACKGROUND

Cardiovascular diseases (CVDs) have the highest mortality worldwide. Human pluripotent stem cells (hPSCs) and their cardiomyocyte derivatives (hPSC-CMs) offer a valuable resource for disease modeling, pharmacological screening, and regenerative therapy. While most CVDs are linked to significant over-production of reactive oxygen species (ROS), the effects of current antioxidants targeting excessive ROS are limited. Nanotechnology is a powerful tool to develop antioxidants with improved selectivity, solubility, and bioavailability to prevent or treat various diseases related to oxidative stress. Cerium oxide nanozymes (CeONZs) can effectively scavenge excessive ROS by mimicking the activity of endogenous antioxidant enzymes. This study aimed to assess the nanotoxicity of CeONZs and their potential antioxidant benefits in stressed human embryonic stem cells (hESCs) and their derived cardiomyocytes (hESC-CMs).

RESULTS

CeONZs demonstrated reliable nanosafety and biocompatibility in hESCs and hESC-CMs within a broad range of concentrations. CeONZs exhibited protective effects on the cell viability of hESCs and hESC-CMs by alleviating excessive ROS-induced oxidative stress. Moreover, CeONZs protected hESC-CMs from doxorubicin (DOX)-induced cardiotoxicity and partially ameliorated the insults from DOX in neonatal rat cardiomyocytes (NRCMs). Furthermore, during hESCs culture, CeONZs were found to reduce ROS, decrease apoptosis, and enhance cell survival without affecting their self-renewal and differentiation potential.

CONCLUSIONS

CeONZs displayed good safety and biocompatibility, as well as enhanced the cell viability of hESCs and hESC-CMs by shielding them from oxidative damage. These promising results suggest that CeONZs may be crucial, as a safe nanoantioxidant, to potentially improve the therapeutic efficacy of CVDs and be incorporated into regenerative medicine.

Removal of fluoride ions from water by cerium-carboxymethyl cellulose beads doped with CeO2 nanoparticles

A novel adsorbent for fluoride ions (F^-) removal was prepared from cerium ion cross-linked carboxymethyl cellulose (CMC) biopolymer beads loaded with CeO₂ nanoparticles (NPs). The characterization of the beads was performed by swelling experiments, scanning electron microscopy and Fourier transforms infrared spectroscopy. The adsorption of fluoride ions from aqueous solutions was carried out with both cerium ion cross-linked CMC beads (CMCCe) and CeO₂-NPs added beads (CeO₂-CMC-Ce) in a batch system. Optimized adsorption conditions were obtained by testing the parameters such as pH, contact time, adsorbent dose, and shaking rate at 25 °C. The adsorption process is well described by the Langmuir isotherm and pseudo-second-order kinetics. The maximum adsorption capacity was found as 105 and 312 mg/g F^- for CMC-Ce and CeO₂-CMC-Ce beads, respectively. Reusability studies showed that, the adsorbent beads have exhibited excellent sustainable properties up to 9 cycle usage. This study suggests that, CMC-Ce composite with CeO₂ nanoparticles is a very effective adsorbent in removing fluoride from water.

Efficient Photocatalytic Degradation of Methylene Blue Dye from Aqueous Solution with Cerium Oxide Nanoparticles and Graphene Oxide-Doped Polyacrylamide

A cerium oxide nanoparticles (CeO₂-NPs)/graphene oxide (GO)/polyacrylamide (PAM) ternary composite was synthesized through free-radical polymerization of acrylamide in the presence of CeO₂ nanoparticles and GO in an aqueous system. The synthesized composite material was characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) spectroscopy techniques and applied for the photocatalytic degradation of methylene blue (MB) dye from an aqueous solution. Tauc's model for direct transition was used to model for the optical band gap. The key operating parameters such as the amounts of CeO₂-NPs and GO, pH, initial MB concentration, type of light irradiation, and contact time have been optimized to achieve the highest MB degradation percentage. The photocatalysis process was pH-dependent, and the optimum pH value was found to be 12.0. Under UV-A light, 90% dye degradation occurred in 90 min. The degradation of MB was also specified in terms of total organic carbon (TOC) and chemical oxygen demand (COD). Free-radical capture experiments were also performed to determine the role of radical species during the photocatalytic oxidation process. The photocatalytic process showed that the equilibrium data is in good agreement with the Langmuir-Hinshelwood kinetic model. A rate constant of 0.0259 min^-1 was obtained. The hydrogel was also tested to assess its reusability, which is an important key factor in practical wastewater treatment. The photocatalytic activity only decreased to 75% after nine uses.

Tea polyphenols mediated biogenic synthesis of chitosan-coated cerium oxide (CS/CeO2) nanocomposites and their potent antimicrobial capabilities

In the present study, we hypothesized that novel nanocomposites of chitosan-coated cerium oxide (CS/CeO₂ NCs) derived from aqueous extracts of tea polyphenols would be stabilized and reduced by using green chemistry. The UV-visible spectrum of the synthesized material revealed an SPR peak at 279 nm, and the morphological characteristics of nanoparticles (NPs) as a uniformly distributed spherical shape with a size range of 20 nm were confirmed by field emission scanning electron microscopy (FESEM). The Fourier transform infrared spectroscopy (FTIR) spectrum illustrated the amino groups of chitosan-coated with CeO₂ NPs on the surface. While, the hydrodynamic size (376 nm) and surface charge (+ 25.0 mV) of particles were assessed by dynamic light scattering (DLS), and the existence of oxidation state elements Ce 3d, O 1 s, and C 1 s was identified by employing X-ray photoelectron spectroscopy (XPS). A cubic fluorite polycrystalline structure with a crystallite size of (5.24 nm) NPs was determined using an X-ray Diffractometer (XRD). The developed CS/CeO₂ NCs demonstrated excellent antibacterial and antifungal efficacy against foodborne pathogens such as Escherichia coli, Staphylococcus aureus, and Botrytis cinerea with zone of inhibition of 13.5 ± 0.2 and 11.7 ± 0.2 mm, respectively. The results elucidated the potential of biosynthesized CS/CeO₂ NCs could be utilized as potent antimicrobial agents in the food and agriculture industries.

Nanostructured Ceria: Biomolecular Templates and (Bio)applications

Ceria (CeO2) nanostructures are well-known in catalysis for energy and environmental preservation and remediation. Recently, they have also been gaining momentum for biological applications in virtue of their unique redox properties that make them antioxidant or pro-oxidant, depending on the experimental conditions and ceria nanomorphology. In particular, interest has grown in the use of biotemplates to exert control over ceria morphology and reactivity. However, only a handful of reports exist on the use of specific biomolecules to template ceria nucleation and growth into defined nanostructures. This review focusses on the latest advancements in the area of biomolecular templates for ceria nanostructures and existing opportunities for their (bio)applications.

Synthesis and characterization of nanoceria for electrochemical sensing applications

Nanoceria (cerium oxide nanoparticles: CeO2-NPs) has received significant attention due to its biocompatibility, good conductivity, and the ability to transfer oxygen. Nanoceria has been widely used to develop electrochemical sensors and biosensors as it could increase response time, sensitivity, and stability of the sensor. In this review, we discussed synthesis methods, and the recent applications employing CeO2-NPs for electrochemical detection of various analytes reported in the most recent four years.

The Advances of Ceria Nanoparticles for Biomedical Applications in Orthopaedics

The ongoing biomedical nanotechnology has intrigued increasingly intense interests in cerium oxide nanoparticles, ceria nanoparticles or nano-ceria (CeO2-NPs). Their remarkable vacancy-oxygen defect (VO) facilitates the redox process and catalytic activity. The verification has illustrated that CeO2-NPs, a nanozyme based on inorganic nanoparticles, can achieve the anti-inflammatory effect, cancer resistance, and angiogenesis. Also, they can well complement other materials in tissue engineering (TE). Pertinent to the properties of CeO2-NPs and the pragmatic biosynthesis methods, this review will emphasize the recent application of CeO2-NPs to orthopedic biomedicine, in particular, the bone tissue engineering (BTE). The presentation, assessment, and outlook of the orthopedic potential and shortcomings of CeO2-NPs in this review expect to provide reference values for the future research and development of therapeutic agents based on CeO2-NPs.