Albumin-Mediated Biomineralization of Shape-Controllable and Biocompatible Ceria Nanomaterials

Mitochondrial Targeted Cerium Oxide Nanoclusters for Radiation Protection and Promoting Hematopoiesis

Purpose

Mitochondrial oxidative stress is an important factor in cell apoptosis. Cerium oxide nanomaterials show great potential for scavenging free radicals and simulating superoxide dismutase (SOD) and catalase (CAT) activities. To solve the problem of poor targeting of cerium oxide nanomaterials, we designed albumin-cerium oxide nanoclusters (TPP-PCNLs) that target the modification of mitochondria with triphenyl phosphate (TPP). TPP-PCNLs are expected to simulate the activity of superoxide dismutase, continuously remove reactive oxygen species, and play a lasting role in radiation protection.

Methods

First, cerium dioxide nanoclusters (CNLs), polyethylene glycol cerium dioxide nanoclusters (PCNLs), and TPP-PCNLs were characterized in terms of their morphology and size, ultraviolet spectrum, dispersion stability and cellular uptake, and colocalization Subsequently, the anti-radiation effects of TPP-PCNLs were investigated using in vitro and in vivo experiments including cell viability, apoptosis, comet assays, histopathology, and dose reduction factor (DRF).

Results

TPP-PCNLs exhibited good stability and biocompatibility. In vitro experiments indicated that TPP-PCNLs could not only target mitochondria excellently but also regulate reactive oxygen species (ROS)levels in whole cells. More importantly, TPP-PCNLs improved the integrity and functionality of mitochondria in irradiated L-02 cells, thereby indirectly eliminating the continuous damage to nuclear DNA caused by mitochondrial oxidative stress. TPP-PCNLs are mainly targeted to the liver, spleen, and other extramedullary hematopoietic organs with a radiation dose reduction factor of 1.30. In vivo experiments showed that TPP-PCNLs effectively improved the survival rate, weight change, hematopoietic function of irradiated animals. Western blot experiments have confirmed that TPP-PCNLs play a role in radiation protection by regulating the mitochondrial apoptotic pathway.

Conclusion

TPP-PCNLs play a radiologically protective role by targeting extramedullary hematopoietic organ-liver cells and mitochondria to continuously clear ROS.

Focused ultrasound-mediated cerium-based nanoreactor against Parkinson's disease via ROS regulation and microglia polarization

Neuronal damage caused by oxidative stress and inflammatory microenvironment dominated by microglia are the main obstacles in the treatment of Parkinson's disease (PD). In this study, we developed an integrated nanoreactor Q@CeBG by encapsulating CeO2 nanozyme and quercetin (Que) into glutathione-modified bovine serum albumin, and then selected focused ultrasound (FUS) to temporarily open the blood-brain barrier (BBB) to enhance the accumulation level of Q@CeBG in the brain. Q@CeBG exhibited superior multi-ROS scavenging activity. Under the assistance of FUS, Q@CeBG nanoreactor can penetrate the BBB and act on neurons as well as microglia, reducing the neuron's oxidative stress level and polarizing microglia's phenotype from proinflammatory M1 to anti-inflammatory M2. In vitro and In vivo experiments demonstrated that Q@CeBG nanoreactor with good biocompatibility exhibit outstanding neuroprotection and immunomodulatory effects. In short, this dual synergetic nanoreactor will become a reliable platform against PD.

Phenolic Ligand-Metal Charge Transfer Induced Copper Nanozyme with Reactive Oxygen Species-Scavenging Ability for Chronic Wound Healing

Chronic wounds frequently arise as a complication in diabetic patients, and their management remains a significant clinical hurdle due to their nonhealing nature featured by heightened oxidative stress and impaired healing cells at the wound site. Herein, we present a 2D copper antioxidant nanozyme induced by phenolic ligand-metal charge transfer (LMCT) to eliminate reactive oxygen species (ROS) and facilitate the healing of chronic diabetic wounds. We found that polyphenol ligands coordinated on the Cu3(PO4)2 nanosheets led to a strong charge transfer at the interface and regulated the valence states of Cu. The obtained Cu nanozyme exhibited efficient scavenging ability toward different oxidative species and protected human cells from oxidative damage. The nanozyme enhanced the healing of diabetic wounds by promoting re-epithelialization, collagen deposition, angiogenesis, and immunoregulation. This work demonstrates the LMCT-induced ROS scavenging ability on a nanointerface, providing an alternative strategy of constructing metal-based nanozymes for the treatment of diabetic wounds as well as other diseases.

Antioxidant nanozymes as next-generation therapeutics to free radical-mediated inflammatory diseases: A comprehensive review

Recent developments in exploring the biological enzyme mimicking properties in nanozymes have opened a separate avenue, which provides a suitable alternative to the natural antioxidants and enzymes. Due to high and tunable catalytic activity, low cost of synthesis, easy surface modification, and good biocompatibility, nanozymes have garnered significant research interest globally. Several inorganic nanomaterials have been investigated to exhibit catalytic activities of some of the key natural enzymes, including superoxide dismutase (SOD), catalase, glutathione peroxidase, peroxidase, and oxidase, etc. These nanozymes are used for diverse biomedical applications including therapeutics, imaging, and biosensing in various cells/tissues and animal models. In particular, inflammation-related diseases are closely associated with reactive oxygen and reactive nitrogen species, and therefore effective antioxidants could be excellent therapeutics due to their free radical scavenging ability. Although biological enzymes and other artificial antioxidants could perform well in scavenging the reactive oxygen and nitrogen species, however, suffer from several drawbacks such as the requirement of strict physiological conditions for enzymatic activity, limited stability in the environment beyond their optimum pH and temperature, and high cost of synthesis, purification, and storage make then unattractive for broad-spectrum applications. Therefore, this review systematically and comprehensively presents the free radical-mediated evolution of various inflammatory diseases (inflammatory bowel disease, mammary gland fibrosis, and inflammation, acute injury of the liver and kidney, mammary fibrosis, and cerebral ischemic stroke reperfusion) and their mitigation by various antioxidant nanozymes in the biological system. The mechanism of free radical scavenging by antioxidant nanozymes under in vitro and in vivo experimental models and catalytic efficiency comparison with corresponding natural enzymes has also been presented.

Fluorimetric determination of tetracycline antibiotics in animal derived foods using boron and nitrogen co-doped ceria-based nanoparticles

An innovative synthesis of boron and nitrogen co-doped ceria-based nanoparticles (B/N-CeFNPs) with bright blue fluorescence emission is reported using the hydrothermal method. Based on the aggregation-induced emission enhancement (AIEE) effect between B/N-CeFNPs and chlortetracycline (CTC), a rapid detection method for CTC through fluorescence enhancement was developed. In addition, through the electron transfer process (ET), fluorescence resonance energy transfer (FRET) effect and static quenching between B/N-CeFNPs and oxytetracycline (OTC), a ratio fluorescence strategy for detecting OTC was generated. The fluorescence of B/N-CeFNPs at 410 nm can be effectively quenched by OTC, and new fluorescence emission appears at a wavelength of 500 nm. B/N-CeFNPs showed good linear responses with CTC and OTC in the range 0.1-1 µM and 1-40 µM, respectively. This system was used to simultaneously detect the CTC and OTC in milk and honey, realizing multi-residues detection of TCs in actual samples by using the same ceria-based fluorescence nanomaterial.

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.

ROS-Scavenging Hydrogels Synergize with Neural Stem Cells to Enhance Spinal Cord Injury Repair via Regulating Microenvironment and Facilitating Nerve Regeneration

Although stem cell-based therapy is recognized as a promising therapeutic strategy for spinal cord injury (SCI), its efficacy is greatly limited by local reactive oxygen species (ROS)-abundant and hyper-inflammatory microenvironments. It is still a challenge to develop bioactive scaffolds with outstanding antioxidant capacity for neural stem cells (NSCs) transplantation. In this study, albumin biomimetic cerium oxide nanoparticles (CeO2 @BSA nanoparticles, CeNPs) are prepared in a simple and efficient manner and dispersed in gelatin methacryloyl to obtain the ROS-scavenging hydrogel (CeNP-Gel). CeNP-Gel synergistically promotes neurogenesis via alleviating oxidative stress microenvironments and improving the viability of encapsulated NSCs. More interestingly, in the presence of CeNP-Gel, microglial polarization to anti-inflammatory M2 subtype are obviously facilitated, which is further verified to be associated with phosphoinositide 3-kinase/protein kinase B pathway activation. Additionally, the injectable ROS-scavenging hydrogel is confirmed to induce the integration and neural differentiation of transplanted NSCs. Compared with the blank-gel group, the survival rate of NSCs in CeNP-Gel group is about 3.5 times higher, and the neural differentiation efficiency is about 2.1 times higher. Therefore, the NSCs-laden ROS-scavenging hydrogel represents a comprehensive strategy with great application prospect for the treatment of SCI through comprehensively modulating the adverse microenvironment.

Antioxidant Nanozymes: Mechanisms, Activity Manipulation, and Applications

Antioxidant enzymes such as catalase, superoxide dismutase, and glutathione peroxidase play important roles in the inhibition of oxidative-damage-related pathological diseases. However, natural antioxidant enzymes face some limitations, including low stability, high cost, and less flexibility. Recently, antioxidant nanozymes have emerged as promising materials to replace natural antioxidant enzymes for their stability, cost savings, and flexible design. The present review firstly discusses the mechanisms of antioxidant nanozymes, focusing on catalase-, superoxide dismutase-, and glutathione peroxidase-like activities. Then, we summarize the main strategies for the manipulation of antioxidant nanozymes based on their size, morphology, composition, surface modification, and modification with a metal-organic framework. Furthermore, the applications of antioxidant nanozymes in medicine and healthcare are also discussed as potential biological applications. In brief, this review provides useful information for the further development of antioxidant nanozymes, offering opportunities to improve current limitations and expand the application of antioxidant nanozymes.

Loading Nanoceria Improves Extracellular Vesicle Membrane Integrity and Therapy to Wounds in Aged Mice

Wound healing is a programmed process through which tissue restores its integrity after an injury. Advancing age is a risk factor for delayed cutaneous wound healing; however, ideal therapeutic approaches for aged wound have not been developed yet. By dissecting the harsh microenvironment of aged wound, we propose an integrated chemical and biological strategy to mitigate two main hostile factors including oxidative stress and ischemia. Mesenchymal stem cell-derived extracellular vesicles (EVs) are a rising star in regenerative medicine due to their powerful facilitation in tissue repair and regeneration. However, the fragile lipid membrane limits their function under the oxidative stress microenvironment. Nanoceria is an antioxidative nanozyme; here, we reveal that nanoceria-loaded EVs derived from mesenchymal stem cells facilitate cutaneous wound healing in aged mice. DG-CeO₂ was prepared via coating CeO₂ covalently with d-glucose to promote their cellular endocytosis. DG-CeO₂ was packaged into EVs under optimized hypoxic conditions (DG-CeO₂ EVs^Hyp). We further demonstrated that DG-CeO₂ EVs^Hyp had favorable biocompatibility and antioxidative and proangiogenic effects during the cutaneous wound healing in both young and aged mice. Further evidence revealed that DG-CeO₂ EVs^Hyp-transferred miR-92a-3p/125b-5p and their targets associated with aging degeneration may be the potential mechanisms. Collectively, these findings highlight that nanoceria-loaded EVs released by engineered stem cells may represent a potential therapeutic approach for tissue regeneration in aged population.

Nanozymes for Regenerative Medicine

Nanozymes refer to nanomaterials that catalyze enzyme substrates into products under relevant physiological conditions following enzyme kinetics. Compared to natural enzymes, nanozymes possess the characteristics of higher stability, easier preparation, and lower cost. Importantly, nanozymes possess the magnetic, fluorescent, and electrical properties of nanomaterials, making them promising replacements for natural enzymes in industrial, biological, and medical fields. On account of the rapid development of nanozymes recently, their application potentials in regeneration medicine are gradually being explored. To highlight the achievements in the regeneration medicine field, this review summarizes the catalytic mechanism of four types of representative nanozymes. Then, the strategies to improve the biocompatibility of nanozymes are discussed. Importantly, this review covers the recent advances in nanozymes in tissue regeneration medicine including wound healing, nerve defect repair, bone regeneration, and cardiovascular disease treatment. In addition, challenges and prospects of nanozyme researches in regeneration medicine are summarized.

Maternal exposure to CeO2NPs derails placental development through trophoblast dysfunction mediated by excessive autophagy activation

BACKGROUND

The increasing use of cerium dioxide nanoparticles (CeO₂NPs) in biomedical field has attracted substantial attention about their potential risks to human health. Recent studies have shown that nanoparticles can induce placental dysfunction and even fetal abortion, but a more detailed mechanism of nanoparticles affecting placental development remains elusive.

RESULTS

Here, we constructed a mouse exposure model with different doses of CeO₂NPs (2.5, 4, 5, 7.5, and 10 mg kg^-1 day^-1, average particle size 3-5 nm), finding that intravenous exposure to pregnant mice with CeO₂NPs could cause abnormal placental development. Deposited nanoparticles were able to be observed in the placental trophoblast at doses of 5 and 7.5 mg kg^-1 day^-1. Diving into molecular mechanisms indicated that CeO₂NPs exposure could lead to autophagy activation in placental trophoblast. At the cellular level, exposure to CeO₂NPs inhibited the migration and invasion of HTR-8/SVneo and activated the autophagy through mammalian target of rapamycin complex1 (mTORC1) signaling pathway. Furthermore, inhibition of autophagy initiation by 3-Methyladenine (3-MA) partially restored the function of HTR-8/SVneo, while blocking autophagic flow by Chloroquine (CQ) aggravated the functional damage.

CONCLUSIONS

Maternal exposure to CeO₂NPs impairs placental development through trophoblast dysfunction mediated by excessive autophagy activation. These results suggested that autophagy dysfunction may be a potential mechanism for the impairment of trophoblast by CeO₂NPs exposure. As above, our findings provide insights into the toxicity mechanism to the reproductive system induced by rare-earth nanoparticles exposure.

Density Functional Theory Investigation of the Biocatalytic Mechanisms of pH-Driven Biomimetic Behavior in CeO2

There is considerable interest in the pH-dependent, switchable, biocatalytic properties of cerium oxide (CeO₂) nanoparticles in biomedicine, where these materials exhibit beneficial antioxidant activity against reactive oxygen species (ROS) at a basic physiological pH but cytotoxic prooxidant activity in an acidic cancer cell pH microenvironment. While the general characteristics of the role of oxygen vacancies are known, the mechanism of their action at the atomic scale under different pH conditions has yet to be elucidated. The present work applies density functional theory (DFT) calculations to interpret, at the atomic scale, the pH-induced behavior of the stable {111} surface of CeO₂ containing oxygen vacancies. Analysis of the surface-adsorbed media species reveals the critical role of pH on the interaction between ROS (^•O₂^- and H₂O₂) and the defective CeO₂ {111} surface. Under basic conditions, the superoxide dismutase (SOD) and catalase (CAT) biomimetic reactions can be performed cyclically, scavenging and decomposing ROS to harmless products, making CeO₂ an excellent antioxidant. However, under acidic conditions, the CAT biomimetic reaction is hindered owing to the limited reversibility of Ce³⁺ ↔ Ce⁴⁺ and formation ↔ annihilation of oxygen vacancies. A Fenton biomimetic reaction (H₂O₂ + Ce³⁺ → Ce⁴⁺ + OH^- + ^•OH) is predicted to occur simultaneously with the SOD and CAT biomimetic reactions, resulting in the formation of hydroxyl radicals, making CeO₂ a cytotoxic prooxidant.

Perfluorooctyl bromide nanoemulsions holding MnO2 nanoparticles with dual-modality imaging and glutathione depletion enhanced HIFU-eliciting tumor immunogenic cell death

Tumor-targeted immunotherapy is a remarkable breakthrough, offering the inimitable advantage of specific tumoricidal effects with reduced immune-associated cytotoxicity. However, existing platforms suffer from low efficacy, inability to induce strong immunogenic cell death (ICD), and restrained capacity of transforming immune-deserted tumors into immune-cultivated ones. Here, an innovative platform, perfluorooctyl bromide (PFOB) nanoemulsions holding MnO₂ nanoparticles (MBP), was developed to orchestrate cancer immunotherapy, serving as a theranostic nanoagent for MRI/CT dual-modality imaging and advanced ICD. By simultaneously depleting the GSH and eliciting the ICD effect via high-intensity focused ultrasound (HIFU) therapy, the MBP nanomedicine can regulate the tumor immune microenvironment by inducing maturation of dendritic cells (DCs) and facilitating the activation of CD8⁺ and CD4⁺ T cells. The synergistic GSH depletion and HIFU ablation also amplify the inhibition of tumor growth and lung metastasis. Together, these findings inaugurate a new strategy of tumor-targeted immunotherapy, realizing a novel therapeutics paradigm with great clinical significance.

Self-Cascade Uricase/Catalase Mimics Alleviate Acute Gout

Uricase-based therapies are limited for gout partially due to the accumulation of H2O2 in an arthrosis environment with slow metabolism. To tackle this limitation, previous studies adopted a cascade reaction between the degradation of uric acid (UA) and timely elimination of H2O2 using complicated composites of uricase and catalase (CAT)/CAT-like nanozyme. Herein, the self-cascade nanozyme Pt/CeO2 with high efficiency toward simultaneous UA degradation and H2O2 elimination is demonstrated on the basis of both uricase- and CAT-like activities in Pt, Ir, Rh, and Pd platinum-group metals. With an optimized molar ratio of Pt and CeO2, Pt/CeO2 (1/5) not only does better in degrading UA but also has excellent reactive oxygen species (ROS) and reactive nitrogen species (RNS) scavenging activities. In monosodium urate (MSU)-induced acute gout rats, Pt/CeO2 nanozyme markedly alleviates pain along with joint edema, thus improving gait claudication and tissue inflammation. These results provide novel insights into strategies of an efficient enzyme-mimetic treatment for gout.

BSA-templated Ultrasmall Ag/Gd2O3 as A Self-enabled Nanotheranostics for MR/CT/PA tri-modality Imaging and Photothermal Therapy

It is becoming more and more important to effectively integrate multiple complementary diagnostic imaging and synergistic therapy into a nano-platform, but it is still challenging. Here, we used bovine serum...

Green Approach Towards Morphology-Controlled Synthesis of Zein-Functionalized TiO2 Nanoparticles for Cosmeceutical Application

Biomolecular approaches for synthesis of inorganic nanoparticle are very popular among researchers and exhibit significant shape-directing morphologies in classified condition. The proteins are the most abundant macromolecules and employed for the hybrid synthesis as well as shape-directing agent. The present study is designed to investigate the potential role of a plant protein 'zein' to synthesize hybrid TiO₂ nanoparticles. This versatile amphiphilic protein paves a unique path towards shape directing synthesis and act as template in the biomineralization process. The structural changes occurred in protein structure is thoroughly characterized using the circular dichroism (CD) and FTIR spectroscopy. UV, XPS and HRTEM analysis confirms the presence of zein on the nanoparticle surface. The proposed approach provides finely engineered nano-cuboidal (22.75±5.07 nm) geometry with homogenous dispersion, curved edged cuboids (403.51±0.05 nm) and spherical (97.85±0.62 nm) shaped from different modification, as evidenced by TEM. We also discussed in-vitro method for the detection of antimicrobial activity of nanocuboids against acne causing microorganisms such as Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Streptococcus agalactiae. Our results demonstrate that hybrid nanocuboids could be an efficient green material and provide cognitive antimicrobial evidence that could be deployed for cosmeceutical application.

The Synthesis of Protein-Encapsulated Ceria Nanorods for Visible-Light Driven Hydrogen Production and Carbon Dioxide Reduction

1D rare earth-based nanomaterials have attracted significant attention due to their excellent photo/electro-catalytic performance. The corresponding challenge is how to synthesize shape and size-controlled nanostructures in an easy scale-up way. Herein, the authors present a facile one-step strategy to design 1D multifunctional protein-encapsulated cerium oxide nanorods (PCNRs) by utilizing bovine serum albumin as an efficient biotemplate. Remarkably, the PCNRs exhibit high chemical and interfacial adhesion stability with intriguing properties, resulting in an exceptionally high activity towards H₂ evolution and CO₂ reduction. The photocatalytic activity of PCNRs to produce H₂ is about 10 times higher than conventional CeO₂ nanorods. The incorporation of rhodamine B into the PCNRs brings unprecedentedly high photocatalytic H₂ evolution rate being 123 times higher than that of conventional CeO₂ nanorods. Further the presence of the -NH₂ groups on the PCNRs facilitated the adsorption and activation of CO₂ and efficiently suppressed the proton reduction, and as a result, the PCNRs photocatalyst is highly active in converting CO₂ to CO and CH₄ , with the evolution rates being 50 and 83 times higher than those of conventional CeO₂ nanorods, respectively. Achieving such efficient photocatalyst is a critical step toward practical production of high-value renewable fuels using solar energy.

Alendronate-Modified Nanoceria with Multiantioxidant Enzyme-Mimetic Activity for Reactive Oxygen Species/Reactive Nitrogen Species Scavenging from Cigarette Smoke

Highly toxic radicals including reactive oxygen species (ROS) and reactive nitrogen species (RNS) in cigarette smoke play an important role in oxidative damage of the lungs, which cannot be efficiently scavenged by current filter techniques. Herein, a novel alendronate-coated nanoceria (CeAL) nanozyme is explored for cigarette filter modification for ROS/RNS scavenging. The CeAL nanozyme with an adjustable oxidation state and high thermal stability exhibits an excellent superoxide dismutase (SOD)-like activity, hydroxyl radical elimination capacity, catalase-mimicking activity, and nitric oxide radical scavenging ability. These synergistic antioxidant abilities make the CeAL nanozyme a lucrative additive for cigarette filters. The filter incorporated with the CeAL nanozyme can efficiently scavenge ROS/RNS in the hot smoke generated by burned commercial cigarettes, resulting in reduction of oxidative stress-induced pulmonary injury and acute inflammation of mice. The developed CeAL nanozyme opens up new opportunities for cigarette filter modification to decrease the toxicity of cigarette smoke and expands the application fields of nanoceria.

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.

Sonochemically Prepared BSA Microspheres as Adsorbents for the Removal of Organic Pollutants from Water

This work investigates, for the first time, the application of sonochemically prepared bovine serum albumin (BSA) microspheres (BSAMS) as adsorbents of industrial organic pollutant dyes, such as rhodamine B (RhB), rhodamine 6G (Rh6G), and methylene blue (MB). These dyes also serve as model compounds for other organic pollutants such as bisphenol A and 2-nitrophenol. Adsorption kinetics of the dyes by the BSAMS was studied using pseudo-first-order (PFO) and pseudo-second-order (PSO) kinetic models. It was found that RhB follows PFO, with an adsorption capacity, qe,cal, of 7.9 mg/g, which was closer to the experimental adsorption capacity of qe,exp. of 7.6 mg/g. However, MB and Rh6G were controlled by PSO kinetics, with a qe,cal of 5.6 mg/g for MB and 6.6 mg/g for Rh6G, closer to the experimental adsorption capacity of 5.7 and 6.4 mg/g, respectively. The intraparticle diffusion (ID) model applied to the three dyes indicated multi-linearity with ID as the rate-limiting step in the adsorption process. Furthermore, the adsorption equilibria for each of the organic pollutants were studied through various isotherm models such as Langmuir, Freundlich, Temkin, and Halsey, which indicated physical interaction between the BSAMS and the dye pollutants, thus suggesting the applicability of the BSAMS as pollutant adsorbent materials. It was found that the BSAMS can effectively remove RhB, MB, and Rh6G from wastewater with efficiencies of 95.5, 83.3, and 97.9%, respectively.

Superoxide dismutase nanozymes: an emerging star for anti-oxidation

Superoxide dismutases (SODs) are a group of metalloenzymes that catalyze the dismutation of superoxide radicals (O2˙-) into hydrogen peroxide (H2O2) and oxygen (O2). As the first line of defense against reactive oxygen species (ROS)-mediated damage, SODs are expected to play an important role in the treatment of oxidative stress-related diseases. However, the clinical applications of SODs have been severely limited by their structural instability and high cost. Compared with natural enzymes, nanozymes, nanomaterials with enzyme-like activity, are more stable, and economical, can be easily modified and their activities can be adjusted. Due to their excellent characteristics, nanozymes have attracted widespread attention in recent years and are expected to become effective substitutes for natural enzymes in many application fields. Importantly, some nanozymes with SOD-like activity have been developed and proved to have a mitigating effect on diseases caused by oxidative stress. These studies on SOD-like nanozymes provide a feasible strategy for breaking through the dilemma of SOD clinical applications. However, at present, the specific catalytic mechanism of SOD-like nanozymes is still unclear, and many important issues need to be resolved. Although there are many comprehensive reviews to introduce the overall situation of the nanozyme field, the research on SOD-like nanozymes still lacks a systematic review. From the structure and mechanism of natural SOD enzymes to the structure and regulation of SOD-like nanozymes, and then to the measurement and application of nanozymes, this review systematically summarizes the recent progress in SOD-like nanozymes. The existing shortcomings and possible future research hotspots in the development of SOD-like nanozymes are summarized and prospected. We hope that this review would provide ideas and inspirations for further research on the catalytic mechanism and rational design of SOD-like nanozymes.

Combined Antioxidant-Antibiotic Treatment for Effectively Healing Infected Diabetic Wounds Based on Polymer Vesicles

Infected diabetic wounds are difficult to heal due to high reactive oxygen species (ROS) concentrations and recurrent infections. Such wounds can easily deteriorate into a diabetic ulcer, a chronic diabetic complication with a very high mortality rate. Herein, we propose a combined antioxidant-antibiotic therapy based on poly(ε-caprolactone)-block-poly(glutamic acid) polymer vesicle to treat infected diabetic wounds. This was realized by in situ decoration of stable, well-dispersed ceria nanoparticles onto ciprofloxacin (CIP)-loaded polymer vesicles. These resulting CIP-loaded and ceria-decorated polymer vesicles (CIP-Ceria-PVs) exhibited high superoxide dismutase mimetic activity to inhibit superoxide free radicals (the inhibition rate reached ∼50% at an extremely low cerium concentration of 1.25 μg/mL). When the cerium content is in the range of 5-20 μg/mL, the CIP-Ceria-PVs showed the highest protective capability to normal L02 cells from damage of superoxide free radicals. In addition, the CIP-Ceria-PVs exhibited enhanced antibacterial activity (the dosage of CIP in CIP-Ceria-PVs was reduced by 25-50% compared to free CIP). In vivo treatment of infected diabetic wounds was performed on a diabetic mice model. The CIP-Ceria-PVs could effectively cure infected diabetic wounds within 14 days. Overall, a combined antioxidant-antibiotic therapy was proposed by introducing ceria nanoparticles and CIP into polymer vesicles for the treatment of infected diabetic wounds.

A multifunctional nano system based on DNA and CeO2 for intracellular imaging of miRNA and enhancing photodynamic therapy

An increased content of reactive oxygen species (ROS) is a primary feature of tumor cells. When the new homeostasis established by cancer cells with a high ROS level is destroyed, this leads to oxidative stress and apoptosis. In this study, a composite nanosystem was designed in which the DNA structure with the functions of miRNA detection and drug delivery is connected to CeO₂ nanoclusters that exhibit enzyme-like activity to enable them to load drugs together. In addition, based on the concept of sequential catalysis, we used CeO₂ to decompose H₂O₂ into O₂ with low cytotoxicity, which provides raw materials for the photodynamic therapy (PDT) of the Cy5 fluorescent group modified on the DNA. Subsequently, this is transformed into highly cytotoxic free radicals (OH), and we used PDT to further stimulate the therapeutic ability of doxorubicin (DOX) to improve its effectiveness in killing cancer cells. This composite nanosystem can perform fluorescence detection for miRNA-21 in vitro, intracellular fluorescence imaging, and PDT treatment, and can enhance the effect of DOX.

Ceria-based nanotheranostic agent for rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease that affects 1-2% of the human population worldwide, and effective therapies with targeted delivery for local immune suppression have not been described. We address this problem by developing a novel theranostic nanoparticle for RA and assessed its therapeutic and targeting effects under image-guidance.

Methods: Albumin-cerium oxide nanoparticles were synthesized by the biomineralization process and further conjugated with near-infrared, indocyanine green (ICG) dye. Enzymatic-like properties and reactive oxygen species (ROS) scavenging activities, as well as the ability to reprogram macrophages, were determined on a monocyte cell line in culture. The therapeutic effect and systemic targeting potential were evaluated in collagen-induced arthritis (CIA) mouse model using optical/optoacoustic tomographic imaging.

Results: Small nanotheranostics with narrow size distribution and high colloidal stability were fabricated and displayed high ROS scavenging and enzymatic-like activity, as well as advanced efficacy in a converting pro-inflammatory macrophage phenotype into anti-inflammatory phenotype. When administrated into affected animals, these nanoparticles accumulated in inflamed joints and revealed a therapeutic effect similar to the gold-standard therapy for RA, methotrexate.

Conclusions: The inflammation-targeting, inherent contrast and therapeutic activity of this new albumin-cerium oxide nanoparticle may make it a relevant agent for assessing severity in RA, and other inflammatory diseases, and controlling inflammation with image-guidance. The design of these nanotheranostics will enable potential clinical translation as systemic therapy for RA.

Protein-Based Artificial Nanosystems in Cancer Therapy

Proteins, like actors, play different roles in specific applications. In the past decade, significant achievements have been made in protein-engineered biomedicine for cancer therapy. Certain proteins such as human serum albumin, working as carriers for drug/photosensitizer delivery, have entered clinical use due to their long half-life, biocompatibility, biodegradability, and inherent nonimmunogenicity. Proteins with catalytic abilities are promising as adjuvant agents for other therapeutic modalities or as anticancer drugs themselves. These catalytic proteins are usually defined as enzymes with high biological activity and substrate specificity. However, clinical applications of these kinds of proteins remain rare due to protease-induced denaturation and weak cellular permeability. Based on the characteristics of different proteins, tailor-made protein-based nanosystems could make up for their individual deficiencies. Therefore, elaborately designed protein-based nanosystems, where proteins serve as drug carriers, adjuvant agents, or therapeutic drugs to make full use of their intrinsic advantages in cancer therapy, are reviewed. Up-to-date progress on research in the field of protein-based nanomedicine is provided.

Maternal exposure to CeO2NPs during early pregnancy impairs pregnancy by inducing placental abnormalities

Cerium dioxide nanoparticles (CeO₂NPs) has been widely used in many fields, and also recommended as a promising carrier for cancer targeted drugs in human medicine for its excellent properties. However, its biological safety to human health remains controversial. In this study, we propose a mouse model exposed to CeO₂NPs during early pregnancy, to clarify the effect of maternal CeO₂NPs exposure and related molecular mechanism. Pregnant mice are injected intravenously with CeO₂NPs by once a day on D5, D6, and D7. The effects of CeO₂NPs exposure on pregnancy outcomes are observed on D8, D9, D10 and D12. The results show that CeO₂NPs exposure during early pregnancy would lead to poor pregnancy outcomes. Further study find that low-quality decidualization, including the imbalance of trophoblast invasion regulators secreted by decidual cells and abnormal recruitment and differentiation of uNK cells, leads to subsequent biological negative "ripple effects", including placental dysfunction, fetal loss or growth restriction. This study broadens the understanding of the biological safety of CeO₂NPs, and provide clues for the prevention of its negative biological effects. Improving the function of uNK cells can be used as one of the therapeutic targets to prevent negative effects of CeO₂NPs on pregnancy.

Biomineralized Bimetallic Oxide Nanotheranostics for Multimodal Imaging-Guided Combination Therapy

The hypoxia of the tumor microenvironment (TME) often hinders the effectiveness of cancer treatments, especially O₂-dependent photodynamic therapy (PDT).

Methods: An integrated iridium oxide (IrO₂)-manganese dioxide (MnO₂) nanotheranostic agent was fabricated through bovine serum albumin (BSA)-based biomineralization of Ir³⁺ and Mn²⁺. BSA was first covalently modified with chlorin e6 (Ce6), and used to fabricate multifunctional BSA-Ce6@IrO₂/MnO₂ nanoparticles (NPs) for computed X-ray tomography (CT) and photoacoustic (PA) imaging-guided PDT and photothermal (PTT) therapy of cancer. Extensive in vitro and in vivo studies were performed.

Results: The theranostic agent produced can relieve tumor hypoxia by the decomposition of endogenous H₂O₂ in cancer cells to oxygen. The oxygen generated can be exploited for improved PDT. Paramagnetic Mn²⁺ released from the NPs in the acidic TME permits magnetic resonance imaging (MRI) to be performed. The exceptional photothermal conversion efficiency (65.3%) and high X-ray absorption coefficient of IrO₂ further endow the NPs with the ability to be used in computed CT and PA imaging. Extensive antitumor studies demonstrated that the BSA-Ce6@IrO₂/MnO₂ nanoplatform inhibits cancer cell growth, particularly after combined PTT and PDT. Systematic in vivo biosafety evaluations confirmed the high biocompatibility of the nanoplatform.

Conclusion: This work not only provides a novel strategy for designing albumin-based nanohybrids for theranostic applications but also provides a facile approach for extending the biomedical applications of iridium-based materials.

Albumin-functionalized CuFeS2/photosensitizer nanohybrid for single-laser-induced folate receptor-targeted photothermal and photodynamic therapy

Multimodal therapy is an emerging medical intervention to overcome the current limitation in cancer therapy combining treatment modalities with different mechanisms of action to eradicate tumors. This study demonstrates a targeted multifunctional bovine serum albumin (BSA)-functionalized CuFeS₂/chlorin e6 (Ce6) for synergistic photothermal therapy (PTT) and photodynamic therapy (PDT) effects. The CuFeS₂ nanocrystals were synthesized through a simple heating-up approach and transferred into an aqueous phase using BSA in an ultrasonic-assisted microemulsion method. The as-prepared CuFeS₂@BSA nanoparticles further conjugated with folic acid (FA) followed by attachment of Ce6 to form the Ce6:CuFeS₂@BSA-FA nanohybrid with improved solubility and strong near-infrared (NIR) absorbance and fluorescence. It is the first report to fabricate the targeted Ce6:CuFeS₂@BSA-FA hybrid and evaluates their synergistic PTT/PDT effect using a single laser. The Ce6:CuFeS₂@BSA-FA hybrid showed lower toxicity in vitro (HeLa and HepG2 cells) and in vivo (zebrafish embryos), while they are selectively recognized and internalized by HeLa cells that over-express folate receptors. Compared to each modality applied separately, the combined single-laser-induced PTT and PDT treatment showed the enhanced generation of heat and reactive oxygen species (ROS) with synergistic cancer killing under 671 nm laser irradiation (10 min, 1 W/cm²). As a biocompatible targeted nanoprobe, the multifunctional nanohybrid holds promise in combined PDT/PTT synergistic therapy to achieve better efficacy.

Hyaluronic acid mediated biomineralization of multifunctional ceria nanocomposites as ROS scavengers and tumor photodynamic therapy agents

A novel HA@ceria nanoquantum dots (HA@CQDs) exhibit efficient protective effects against damage induced by ROS. More importantly, aided by H₂O₂, the HA@CQDs-Ce6/H₂O₂ significantly enhanced PDT efficacy for the tumor therapy.

Albumin-Stabilized Metal-Organic Nanoparticles for Effective Delivery of Metal Complex Anticancer Drugs

Many metal-organic complexes showed potent anticancer efficacy, but their clinical applications were limited by the lack of administration route because of their poor solubility. To make metal-organic nanoparticles (MONPs) comprising metal complex drugs is a new formulation strategy for their administration. Herein, we developed a facile synthesis of an MONP composed of bovine serum albumin (BSA), Cu²⁺, and an anticancer agent, 5-nitro-8-hydroxyquinoline (NQ) with albumin as a nanoreactor. The resultant BSA/Cu/NQ nanoparticle (BSA/Cu/NQ NP) showed good stability in different physiological buffers and could target tumors through the enhanced permeability and retention effect and receptor-mediated cellular uptake. As the BSA/Cu/NQ NP could be readily and efficiently internalized by cancer cells, it showed much higher cytotoxic cancer cells than the NQ + Cu(II) complex and NQ. Therefore, the treatment with BSA/Cu/NQ NP noticeably enhanced the anticancer efficacy without causing systemic toxicity, indicating that such a facile preparation method has great potential to prepare other metal complex nanoparticles for drug delivery.

Single Enzyme Direct Biomineralization of CdSe and CdSe-CdS Core-Shell Quantum Dots

Biomineralization is the process by which biological systems synthesize inorganic materials. Herein, we demonstrate an engineered cystathionine γ-lyase enzyme, smCSE that is active for the direct aqueous phase biomineralization of CdSe and CdSe-CdS core-shell nanocrystals. The nanocrystals are formed in an otherwise unreactive buffered solution of Cd acetate and selenocystine through enzymatic turnover of the selenocystine to form a reactive precursor, likely H₂Se. The particle size of the CdSe core nanocrystals can be tuned by varying the incubation time to generated particle sizes between 2.74 ± 0.63 nm and 4.78 ± 1.16 nm formed after 20 min and 24 h of incubation, respectively. Subsequent purification and introduction of l-cysteine as a sulfur source facilitates the biomineralization of a CdS shell onto the CdSe cores. The quantum yield of the resulting CdSe-CdS core-shell particles is up to 12% in the aqueous phase; comparable to that reported for more traditional chemical synthesis routes for core-shell particles of similar size with similar shell coverage. This single-enzyme route to functional nanocrystals synthesis reveals the powerful potential of biomineralization processes.