Fabrication of cerium doped carbon dots with highly radical scavenging activity alleviates ferroptosis-induced oxidative damage

Cerium oxide nanoparticles: Chemical properties, biological effects and potential therapeutic opportunities (Review)

The chemistry of pure cerium oxide (CeO2-x) nanoparticles has been widely studied since the 1970s, especially for chemical catalysis. CeO2-x nanoparticles have been included in an important class of industrial metal oxide nanoparticles and have been attributed a range of wide applications, such as ultraviolet absorbers, gas sensors, polishing agents, cosmetics, consumer products, high-tech devices and fuel cell conductors. Despite these early applications in the field of chemistry, the biological effects of CeO2-x nanoparticles were only explored in the 2000s. Since then, CeO2-x nanoparticles have gained a spot in research related to various diseases, especially the ones in which oxidative stress plays a part. Due to an innate oxidation state variation on their surface, CeO2-x nanoparticles have exhibited redox activities in diseases, such as cancer, acting either as an oxidizing agent, or as an antioxidant. In biological models, CeO2-x nanoparticles have been shown to modulate cancer cell viability and, more recently, cell death pathways. However, a deeper understanding on how the chemical structure of CeO2-x nanoparticles (including nanoparticle size, shape, suspension, agglomeration in the medium used, pH of the medium, type of synthesis and crystallite size) influences the cellular effects observed remains to be elucidated. In the present review, the chemistry of CeO2-x nanoparticles and their impact on biological models and modulation of cell signalling, particularly focusing on oxidative and cell death pathways, were investigated. The deeper understanding of the chemical activity of CeO2-x nanoparticles may provide the rationale for further biomedical applications towards disease treatment and drug delivery purposes.

Carbon dots with selective fluorescence response to hydroxyl radical for sensitive detection of bleomycin

In this work, antioxidant carbon dots (ACDs) with high quantum yield (63.98%) were developed through a one-step strategy using citric acid, ethylenediamine, and L-arginine as sources. The ACDs demonstrated excellent in vitro antioxidant activity. Additionally, ACDs displayed a unique fluorescence response to hydroxyl radical (OH). Leveraging this distinctive feature, a selective and sensitive fluorescence-based sensor was developed for detecting bleomycin (BLM) in the presence of ferrous ions (Fe2+). The studies on the oxidizing properties and dynamic quenching mechanism of ACDs by OH suggested that OH reduced the contents of the amino and hydroxyl groups of ACDs, leading to a decreased electron cloud density of ACDs for dynamic quenching of ACDs. Under optimally refined conditions, the detection limit of this strategy for BLM was 0.58 μg/mL, with a linear range spanning from 1 to 24 μg/mL when employing ACDs as the probe. This fluorescence sensing strategy provides a promising method for the detection of BLM in clinical samples.

Biomimetic Nanozymes Suppressed Ferroptosis to Ameliorate Doxorubicin-Induced Cardiotoxicity via Synergetic Effect of Antioxidant Stress and GPX4 Restoration

Mitochondria-dependent ferroptosis plays an important role in the pathogenesis of doxorubicin (DOX)-induced cardiotoxicity (DIC), which remains a clinical challenge due to the lack of effective interventions. Cerium oxide (CeO₂), a representative nanozyme, has attracted much attention because of its antioxidant properties. This study evaluated CeO₂-based nanozymes for the prevention and treatment of DIC in vitro and in vivo by adding nanoparticles (NPs), which were synthesized by biomineralization, to the culture or giving them to the mice, and the ferroptosis-specific inhibitor ferrostatin-1 (Fer-1) was used as control. The prepared NPs exhibited an excellent antioxidant response and glutathione peroxidase 4 (GPX4)-depended bioregulation, with the additional merits of bio-clearance and long retention in the heart. The experiments showed that NP treatment could significantly reverse myocardial structural and electrical remodeling, and reduce myocardial necrosis. These cardioprotective therapeutic effects were associated with their ability to alleviate oxidative stress, mitochondrial lipid peroxidation, and mitochondrial membrane potential damage, with a superior efficiency to the Fer-1. The study also found that the NPs significantly restored the expression of GPX4 and mitochondrial-associated proteins, thereby restoring mitochondria-dependent ferroptosis. Therefore, the study provides some insights into the role of ferroptosis in DIC. It also shows that CeO₂-based nanozymes could be a promising prevention and treatment candidate as a novel cardiomyocyte ferroptosis protector to mitigate DIC and improve prognosis and quality of life in cancer patients.

Fabrication of manganese-coordinated polyphenol carbon dots for photothermal therapy and immune activation

Background

Nanoparticle-based photothermal therapy (PTT) is capable of inducing immunogenic cell death (ICD) and eradicating local tumor via hyperthermia. However, it can hardly prevent tumor recurrence and metastasis owing to inadequate immune activation.

Results

To this end, manganese-coordinated polyphenol carbon dots (MP-CDs) were synthesized by hydrothermal carbonization and metal–polyphenol coordination. This prepared MP-CDs had ultra-small particle size of 5 nm, excellent optical performance, good dispersibility in water and favorable biocompatibility. Under 808 nm near-infrared laser irradiation, the MP-CDs with high photothermal conversion efficiency could kill tumor cells and induce the release of damage-associated molecular patterns (DAMPs) from tumor cells. Notably, the MP-CDs can promote the maturation and antigen presentation ability of dendritic cells (DCs) via manganese-mediated immune activation.

Conclusion

The present work offers a versatile strategy to integrate functional metal into CDs via metal–polyphenol coordination for photothermal/immune therapy.

Folic Acid-Modified Cerium-Doped Carbon Dots as Photoluminescence Sensors for Cancer Cells Identification and Fe(III) Detection

Carbon dots (CDs) are a new class of carbon-based luminescence materials with fascinating properties. They have been given great expectations on superseding traditional semiconductor quantum dots due to their good dispersity and stability, relatively low toxicity, superior resistance to photobleaching, and excellent biocompatibility. The diversified luminescence properties of CDs are largely due to the synthetic strategies and precursors. In view of those described above, this study has explored the possibility to establish a facile one-step hydrothermal method for the one-pot synthesis of folic acid-modified cerium-doped CDs (Ce-CDs-FA), which could be further utilized as a sensitive fluorescent nanoprobe for biosensing. This investigation demonstrates that the Ce-CDs-FA nanocomposites have nice biocompatibility and bright fluorescent properties, which can be readily utilized to detect cancer cells through recognizing overexpressing folate receptors by virtue of folic acid. Meanwhile, it is noted that the Fe3+ ion can actualize a specific and hypersensitive quenching effect for these Ce-CDs-FA nanocomposites, which can be further explored for special ion recognition, including iron ions. It raises the possibility that the as-prepared Ce-CDs-FA nanocomposites could be extended as a dual fluorescence sensor for targeted cell imaging and Fe3+ ion detection.