Valence State Manipulation of Cerium Oxide Nanoparticles on a Titanium Surface for Modulating Cell Fate and Bone Formation

Near-infrared light-responsive copper-cerium bimetallic oxide nanozyme with antibacterial and antioxidant abilities for periodontitis therapy

Periodontitis, a chronic inflammatory disease of the supporting tissue around teeth, is triggered by periodontal pathogens. Clinical treatments face the problem of bacterial resistance and most therapies focus on a single function, lacking the multifunctional treatment of antibacterial, antioxidant, anti-inflammatory, and osteogenic properties. In our study, we developed a copper-cerium bimetallic oxide (CuCeOx) nanozyme with near-infrared (NIR) light responsiveness for the periodontitis therapy. Under the excitation of 808 nm NIR light, CuCeOx displayed excellent photodynamic and photothermal activities, efficiently generating reactive oxygen species (ROS) and heat. After the treatment of the CuCeOx/NIR system, the inhibition rate of Porphyromonas gingivalis (P. gingivalis), the main periodontitis pathogen, reached 98.69 ± 0.23 % in vitro. Without the NIR light irradiation, CuCeOx, acting as a nanozyme, exhibited enzyme-like activity in scavenging ROS, effectively alleviating the cellular oxidative stress. Furthermore, CuCeOx significantly mitigated the cellular inflammatory response induced by lipopolysaccharide (LPS) and promoted osteogenesis under the oxidative stress condition. Notably, the CuCeOx exhibited excellent blood compatibility (hemolysis < 5 %). The efficacy of the CuCeOx/NIR system in vivo was also investigated. H&E staining results demonstrated a significant reduction in periodontal tissue inflammation following treatment. Micro-CT analysis revealed that CuCeOx effectively inhibited the alveolar bone loss. Additionally, we found CuCeOx regulated the Nrf2/HO-1 signaling pathway both in vitro and in vivo. In conclusion, the multifunctional nanomaterial CuCeOx provides a promising strategy for the treatment of periodontitis.

Multifunctional Double-Loaded Oral Nanoplatform for Computed Tomography Imaging-Guided and Integrated Treatment of Inflammatory Bowel Disease

Excessive reactive oxygen species, disruption of the epithelial barrier, immune dysregulation, and gut microbiota imbalance are key factors driving the onset of inflammatory bowel disease (IBD) and complicating its treatment. Prompt diagnosis of diseases and precise delivery of therapeutic agents to inflamed intestinal sites offer promising targeted strategies for effectively treating IBD. Here, a barium sulfate-based nanoplatform (BaSO4@PDA@CeO2/DSP, BPCD) for synergistic delivery of nanozymes and drugs was developed. With enhanced colonic retention after oral drug delivery, this nanoplatform enables precise and effective targeting of inflammatory sites and CT imaging guidance to address multiple factors contributing to IBD. A comprehensive therapeutic effect was achieved through the synergistic action of cerium oxide with the optimized Ce3+/Ce4+ ratio and sustained release of dexamethasone sodium phosphate. Benefiting from superior gastrointestinal stability, the nanoplatform is highly effective in treating IBD by alleviating oxidative stress, modulating macrophage polarization balance, gut flora composition, and repairing the epithelial barrier. BPCD inhibits the development of IBD through multiple mechanisms and has superior biocompatibility, emerging as a practical alternative to traditional IBD therapies.

Impact of Vitamin D3 Functionalization on the Osteogenic Capacity of Bioinspired 3D Scaffolds Based on Ce-Doped Bioactive Glass and Spongia Agaricina

Reconstruction of extensive bone defects due to age, trauma, or post-illness conditions remains challenging. Biomimetic scaffolds with osteogenic capabilities have been proposed as an alternative to the classical autograft and allograft implants. Three-dimensional scaffolds were obtained based on Ce-doped mesoporous bioactive glass (MBG) and Spongia agaricina (SA) as sacrificial templates functionalized with vitamin D3. The study aimed to investigate the effect of vitamin D3 functionalization on the optimal variant of a 3D scaffold doped with 3 mol% ceria, selected in our previous work based on its biological and physicochemical properties. Scanning electron microscopy (SEM) images of the non-functionalized/functionalized scaffolds revealed a porous structure with interconnected pores ranging from 100 to 350 μm. Fourier transform infrared spectroscopy (FTIR) and SEM analysis confirmed the surface functionalization. Cytotoxicity evaluation showed that all investigated scaffolds do not exhibit cytotoxicity and genotoxicity toward the Saos-2 osteosarcoma cell line. Moreover, the study demonstrated that functionalization with vitamin D3 enhanced osteogenic activity in dental pulp stem cells (DPSCs) by increasing calcium deposition and osteocalcin secretion, as determined by Alizarin red stain and a colorimetric ELISA kit, as a result of its synergistic action with cerium ions. The results showed that the Ce-doped MBG scaffold functionalized with vitamin D3 had the potential for applications in bone regeneration.

High-Density Lipoprotein Biomimetic Inorganic-Organic Composite Nanosystem for Atherosclerosis Therapy

Atherosclerosis (AS) is an important causative agent of cardiovascular diseases, and the occurrence and development of AS is accompanied by oxidative stress, so antioxidant therapy has become one of the strategies for the treatment of AS. This study aimed to design and construct an apolipoprotein ApoA1-modified inorganic-organic composite nanosystem for AS therapy, in which ApoA1 was modified onto carboxylated CeO2/Mn3O4 by covalent bonding, resulting in an inorganic-organic nanocomplex with a structure similar to that of high-density lipoprotein. The nanocomplex could effectively deliver the antioxidant nanoparticles to the AS plaque through the specific recognition between ApoA1 and the macrophage at the AS lesion site. For one thing, the nanocomplex could alleviate the oxidative stress environment of the AS site through the highly efficient antioxidant effect of CeO2/Mn3O4, which played a therapeutic role in the treatment of AS. For another, it could effectively eliminate the formed lipid plaques and maximally alleviate and treat AS by utilizing the cholesterol efflux effect of ApoA1.

Nanoceria as a non-steroidal anti-inflammatory drug for endometriosis theranostics

Endometriosis, the growth of endometrial-like tissue outside the uterus, causes chronic pain and infertility in 10 % of reproductive-aged women worldwide. Unfortunately, no permanent cure exists, and current medical and surgical treatments offer only temporary relief. Endometriosis is a chronic inflammatory disease characterized by immune system dysfunction. Our previous study showed aberrant activation of signal transducer and activator of transcription 3 (STAT3) in endometriosis. Our transcriptomic analysis of uterine tissue from uterine-specific Stat3 knock-out mice identifies that STAT3 regulates inflammatory and immune-related genes. Here, we evaluate cerium-oxide nanoparticles (nanoceria) as a non-steroidal anti-inflammatory drug for endometriosis theranostics. Our in vitro studies validate the multi-enzymatic properties of nanoceria, enabling the transition of pro-inflammatory macrophages to an anti-inflammatory state in J774 macrophage cells. In vivo, treatment of endometriosis mice with nanoceria reveals its ability to passively accumulate at ectopic lesions. The nanoceria conjugated with indocyanine green are non-invasively trackable to ectopic lesions. Therefore, immune modulation and anti-inflammatory effects of nanoceria significantly reduce development of ectopic lesions while minimizing off-target effects, such as avoiding interference with pregnancy including implantation and decidualization. Our results suggest that aberrant STAT3 activation is a major contributor to endometriosis, and nanoceria offers a novel theranostic approach for endometriosis.

hCeO2@CA-074Me Nanoparticles Alleviate Inflammation and Improve Osteogenic Microenvironment by Regulating the CTSB-NLRP3 Signaling Pathway

Background

It is well established that the interaction between osteogenesis and inflammation can impact bone tissue regeneration. The use of nanoparticles to treat and alleviate inflammation at the molecular level has the potential to improve the osteogenic microenvironment and serve as a therapeutic approach.

Methods

We have synthesized new hollow cerium oxide nanoparticles and doped with cathepsin B inhibitor (CA-074Me) to create novel hCeO2@CA-074Me NPs. We characterized the surface morphology and physicochemical properties of hCeO2@CA-074Me NPs. Macrophage RAW 264.7 was cultured with hCeO2@CA-074Me NPs using P. gingivalis-LPS (P.g-LPS) stimulation as a model of inflammation. RT-PCR and Western blot analysis was employed to evaluate the effects of hCeO2@CA-074Me NPs on macrophage phenotype and the CTSB-NLRP3 signaling pathway. To further investigate the inflammatory osteogenic microenvironment, MC3T3-E1 cells were cultured with P.g-LPS to create an in vitro osteogenic conditions under inflammation. The cells were then co-cultured with hCeO2@CA-074Me NPs for 7, 14, and 21 d. The osteogenic ability was evaluated using ALP staining, ALP quantitative analysis, alizarin red staining, and RT-PCR analysis.

Results

Findings clearly demonstrated that hCeO2@CA-074Me NPs could effectively reduce the production of ROS and inhibited CTSB-NLRP3 signal pathway, thereby significantly attenuating the damage caused by the cellular inflammatory response. hCeO2@CA-074Me NPs could also induce the polarization of macrophages towards anti-inflammatory M2 phenotype. Additionally, results confirmed that hCeO2@CA-074Me NPs could inhibit inflammation and ameliorate osteogenic microenvironment, thus promoting the osteogenesis of MC3T3-E1 cells.

Conclusion

The synthetic hCeO2@CA-074Me NPs could able to modify the osteogenic microenvironment under inflammatory conditions by simultaneously inhibiting the CTSB-NLRP3 signaling pathway and regulating the macrophage phenotype through their ability to scavenge ROS. Based on these findings, our study may offer a promising approach for managing inflammatory bone damage.

Cerium Oxide Nanoparticles-Reinforced GelMA Hydrogel Loading Bone Marrow Stem Cells with Osteogenic and Inflammatory Regulatory Capacity for Bone Defect Repair

Effective bone defect repair has been a tough clinical challenge due to the complexity of the bone defect microenvironment. Hydrogels loaded with bone marrow mesenchymal stem cells (BMSCs) have been widely applied for bone regeneration. However, the low survival of BMSCs at the site of transplantation and lack of sufficient osteogenic induction capacity greatly limit their applications. In order to solve this puzzle, we fabricated gelatin methacryloyl (GelMA) hydrogels containing BMSCs with cerium oxide (CeO2) nanoparticles via photo-cross-linking to endow the composite hydrogel with osteogenic induction ability and immune induction ability. In vitro results demonstrated that the GelMA-CeO2-BMSC hydrogel presented with good biocompatibility and excellent osteogenic induction ability. In addition, the GelMA-CeO2-BMSC hydrogel could inhibit M1 polarization and promote M2 polarization, providing a good environment for the growth and osteogenic differentiation of BMSCs. Besides, the GelMA-CeO2-BMSC hydrogel was transplanted into critical-sized calvarial defects, and the results further confirmed its excellent bone regeneration capacity. In conclusion, the composite hydrogel provides a perspective for bone repair due to the remarkable potential for application in bone regeneration.

Cobalt ions-derived nanoenzyme array for endosseous neural network reconstruction and osseointegration

Interactions between bone cells and neurocytes are crucial for endosseous nerve and ensuing bone regeneration. However, absence of neural stem cells in bone makes the innervation of implant osseointegration a major challenge. Herein, a nanorod-like array of sodium hydrogen titanate (ST) co-doped with Co2+ and Co3+, namely STCh that behaves as a reactive oxygen species (ROS)-scavenging enzyme, was hydrothermally formed on Ti substrate. We show that the doped Co2+ and Co3+ locate at TiO6 octahedral interlayers and within octahedra of STCh lattice, appearing releasable and un-releasable, respectively, leading to an increase in Co3+/Co2+ ratio and enzyme activity of the array with immersion. The nanoenzyme-released Co2+ triggers macrophages (MΦs) towards M1 phenotype, then the nanoenzyme scavenges extracellular ROS inducing M1-to-M2 transition. The neurogenic factors secreted by STCh-regulated MΦs, in combination with the released Co2+, promote mesenchymal stem cells to differentiate into neurons and Schwann cells compared to sole Co2+and ST. STCh array greatly enhances nerve reconstruction, type-H capillary formation and ensuing osseointegration in normal rat bone, and antibacteria via engulfing S. aureus by MΦs and osteogenesis in infective case. This nanoenzyme provides an alternative strategy to orchestrate endosseous nerve regeneration for osseointegration without loading exogenous neurotrophins in implants.

Wnt 3a-Modified Scaffolds Improve Nerve Regeneration by Boosting Schwann Cell Function

A pivotal approach in engineering artificial peripheral nerve sheaths encompasses the augmentation of the regenerative microenvironment via the manipulation of Schwann cells (SCs). Our investigation employed single-cell sequencing analysis to elucidate the potential functions of Schwann cells and the Wnt pathway in facilitating peripheral nerve regeneration. In vitro studies showed that activating the Wnt signaling pathway promotes the transition to repair SCs, boosting their growth, movement, and immune functions. To better understand the peripheral nerve regeneration environment, we created a polymer scaffold using ammonization and electrospinning. The Wnt3a protein was incorporated into the polycaprolactone (PCL) electrospun fiber surface. In a rat sciatic nerve defect model, the Wnt3a-modified scaffold showed better nerve repair outcomes than traditional electrospun scaffolds. After a week, the test group showed better immune regulation and angiogenesis, with a significant increase in axon growth rate observed after 3 weeks. Three-month-long animal experiments revealed notable improvements in neuroelectrophysiology, reduced organ atrophy, and enhanced sciatic nerve recovery. In this nerve defect model, Wnt3a-modified neural scaffolds achieved repair effects.

Advances in the study of metal-organic frameworks and their biomolecule composites for osteoporosis therapeutic applications

With the population aging, osteoporosis (OP) is becoming more and more common, seriously affecting patients' quality of life and their families, and how to prevent and treat osteoporosis has become a hot topic. However, the current conventional method of treating OP is oral anti-osteoporosis medication, which has drawbacks such as first-pass elimination and gastrointestinal adverse effects. At the same time, osteoporosis can lead to microbial infections and the need to promote angiogenesis for bone healing, among other needs that often cannot be met with conventional treatments, and there is a risk of resistance to oral antibiotics for microbial infections. Metal-organic frameworks (MOFs) having a high specific surface area, high porosity, controlled degradation, and variable composition; they can not only be used as a carrier to control drug release, but can also play multiple roles in the treatment of OP and microbial infections by releasing metal ions, etc., so they have inherent advantages for OP, which is a disease that requires long-term treatment. Therefore, this paper reviews the research progress of MOFs and their biomacromolecular composites in therapeutic applications for osteoporosis, categorized by MOF type, and briefly describes the mechanism of osteoporosis, and different synthesis methods of MOFs and MOF-based composites, and finally presents the main existing problems and future perspectives, aiming to make MOFs more helpful for OP treatment.

Metal element-fusion peptide heterostructured nanocoatings endow polyetheretherketone implants with robust anti-bacterial activities and in vivo osseointegration

Polyetheretherketone (PEEK), renowned for its exceptional mechanical properties and bio-stability, is considered a promising alternative to traditional metal-based implants. However, the inferior bactericidal activity and the limited angiogenic and osteogenic properties of PEEK remain the three major obstacles to osseointegration in vivo. To overcome these obstacles, in this work, a versatile heterostructured nanocoating was conceived and equipped on PEEK. This nanocoating was designed to endow PEEK with the ability of photo-activated pathogen disinfection, along with enhanced angiogenesis and osteogenesis, effectively addressing the triple-barrier challenge towards osseointegration. The crafted nanocoating, encompassing diverse nutritional metal elements (Fe3+, Mg2+, and Sr2+) and a fusion peptide adept at promoting angiogenesis and osteogenesis, was seamlessly decorated onto PEEK. The engineered implant exhibited an antibacterial activity of over 94% upon near-infrared illumination by virtue of the photothermal conversion of the polyphenol nanocoating. Simultaneously, the decorated hierarchical nanocoatings synergistically promoted cellular adhesion and proliferation and up-regulated angiogenesis-/osteogenesis-associated cytokine expression in endothelial/osteoblast cells, resulting in superior angiogenic differentiation and osteoinductive capability in vitro. Moreover, an in vivo assay in a rabbit femoral defect model revealed that the decorated implant can achieve ameliorative osseointegrative fixation. Collectively, this work offers a practical and instructive clinical strategy to address the triple-barrier challenge associated with PEEK-based implants.

Cerium oxide nanoparticles in wound care: a review of mechanisms and therapeutic applications

Skin wound healing is a complex and tightly regulated process. The frequent occurrence and reoccurrence of acute and chronic wounds cause significant skin damage to patients and impose socioeconomic burdens. Therefore, there is an urgent requirement to promote interdisciplinary development in the fields of material science and medicine to investigate novel mechanisms for wound healing. Cerium oxide nanoparticles (CeO2 NPs) are a type of nanomaterials that possess distinct properties and have broad application prospects. They are recognized for their capabilities in enhancing wound closure, minimizing scarring, mitigating inflammation, and exerting antibacterial effects, which has led to their prominence in wound care research. In this paper, the distinctive physicochemical properties of CeO2 NPs and their most recent synthesis approaches are discussed. It further investigates the therapeutic mechanisms of CeO2 NPs in the process of wound healing. Following that, this review critically examines previous studies focusing on the effects of CeO2 NPs on wound healing. Finally, it suggests the potential application of cerium oxide as an innovative nanomaterial in diverse fields and discusses its prospects for future advancements.

A xenogeneic extracellular matrix-based 3D printing scaffold modified by ceria nanoparticles for craniomaxillofacial hard tissue regeneration via osteo-immunomodulation

Hard tissue engineering scaffolds especially 3D printed scaffolds were considered an excellent strategy for craniomaxillofacial hard tissue regeneration, involving crania and facial bones and teeth. Porcine treated dentin matrix (pTDM) as xenogeneic extracellular matrix has the potential to promote the stem cell differentiation and mineralization as it contains plenty of bioactive factors similar with human-derived dentin tissue. However, its application might be impeded by the foreign body response induced by the damage-associated molecular patterns of pTDM, which would cause strong inflammation and hinder the regeneration. Ceria nanoparticles (CNPs) show a great promise at protecting tissue from oxidative stress and influence the macrophages polarization. Using 3D-bioprinting technology, we fabricated a xenogeneic hard tissue scaffold based on pTDM xenogeneic TDM-polycaprolactone (xTDM/PCL) and we modified the scaffolds by CNPs (xTDM/PCL/CNPs). Through series ofin vitroverification, we found xTDM/PCL/CNPs scaffolds held promise at up-regulating the expression of osteogenesis and odontogenesis related genes including collagen type 1, Runt-related transcription factor 2 (RUNX2), bone morphogenetic protein-2, osteoprotegerin, alkaline phosphatase (ALP) and DMP1 and inducing macrophages to polarize to M2 phenotype. Regeneration of bone tissues was further evaluated in rats by conducting the models of mandibular and skull bone defects. Thein vivoevaluation showed that xTDM/PCL/CNPs scaffolds could promote the bone tissue regeneration by up-regulating the expression of osteogenic genes involving ALP, RUNX2 and bone sialoprotein 2 and macrophage polarization into M2. Regeneration of teeth evaluated on beagles demonstrated that xTDM/PCL/CNPs scaffolds expedited the calcification inside the scaffolds and helped form periodontal ligament-like tissues surrounding the scaffolds.

Conformationally regulated "nanozyme-like" cerium oxide with multiple free radical scavenging activities for osteoimmunology modulation and vascularized osseointegration

Given post-operative aseptic loosening in orthopedic disease treatment, osteointegration occurs at the bone-implant interface as a holistic process, including immunoregulation (e.g., macrophage polarization), angiogenesis and osteogenesis in sequence. In order to achieve early rapid and satisfactory osseointegration, different nano-shaped (nanocone, nanopolyhedron and nanoflower abbr. NC, NP & NF) cerium oxide (CeO2-x) coatings, endowed with "nanozyme-like" activities for multiple free radical elimination and osteoimmunology regulation, were hydrothermally synthesized on titanium alloy (TC4). In vitro cell experiments showed that nano-CeO2-x coated TC4 not only induced polarization of RAW264.7 cells toward M2 phenotype, but also promoted angiogenesis and vascularization of endothelial cells along with differentiation and mineralization of osteogenic precursor cells. Improvements in M2-polarized macrophage, angiogenesis, and bone regeneration were further confirmed in a rat femoral condyle model. Among the above three nano-morphologies, NF exhibited the best osseoinetegration. RNA sequencing and mechanism exploration suggested that the inhibition of PI3K-AKT signaling pathway was essential for immunomodulatory capacity of NF. In conclusion, it provided promising insights into the immunomodulatory exploitation of orthopedic implants.

Advances in Immunomodulatory MOFs for Biomedical Applications

Given the crucial role of immune system in the occurrence and progression of various diseases such as cancer, wound healing, bone defect, and inflammation-related diseases, immunomodulation is recognized as a potential solution for treatment of these diseases. Immunomodulation includes both immunosuppression in hyperactive immune conditions and immune activation in hypoactive conditions. For these purposes, metal-organic frameworks (MOFs) are investigated to modulate immune responses either by their own bioactivities or by delivering immunomodulatory agents due to their excellent biodegradability and high delivery capacity. This review starts with an overview of the synthesis strategies of immunomodulatory MOFs, followed by a summarization on the latest applications of immunomodulatory MOFs in cancer immunomodulatory, wound healing, inflammatory disease, and bone tissue engineering. A variety of design considerations, in order to optimize immunomodulatory properties and efficacy of MOFs, is also involved. Last, the challenges and perspectives of future research, which are expected to provide researchers with new insight into the design and application of immunomodulatory MOFs, are discussed.

Unraveling Ros Conversion Through Enhanced Enzyme-Like Activity with Copper-Doped Cerium Oxide for Tumor Nanocatalytic Therapy

Nanozyme catalytic therapy for cancer treatments has become one of the heated topics, and the therapeutic efficacy is highly correlated with their catalytic efficiency. In this work, three copper-doped CeO2 supports with various structures as well as crystal facets are developed to realize dual enzyme-mimic catalytic activities, that is superoxide dismutase (SOD) to reduce superoxide radicals to H2 O2 and peroxidase (POD) to transform H2 O2 to ∙OH. The wire-shaped CeO2 /Cu-W has the richest surface oxygen vacancies, and a low level of oxygen vacancy (Vo) formation energy, which allows for the elimination of intracellular reactive oxygen spieces (ROS) and continuous transformation to ∙OH with cascade reaction. Moreover, the wire-shaped CeO2 /Cu-W displays the highest toxic ∙OH production capacity in an acidic intracellular environment, inducing breast cancer cell death and pro-apoptotic autophagy. Therefore, wire-shaped CeO2 /Cu nanoparticles as an artificial enzyme system can have great potential in the intervention of intracellular ROS in cancer cells, achieving efficacious nanocatalytic therapy.

The Preparation and Effects of Organic-Inorganic Antioxidative Biomaterials for Bone Repair

Reactive oxygen species (ROS) has great influence in many physiological or pathological processes in organisms. In the site of bone defects, the overproduced ROS significantly affects the dynamic balance process of bone regeneration. Many antioxidative organic and inorganic antioxidants showed good osteogenic ability, which has been widely used for bone repair. It is of great significance to summarize the antioxidative bone repair materials (ABRMs) to provide guidance for the future design and preparation of osteogenic materials with antioxidative function. Here, this review introduced the major research direction of ABRM at present in nanoscale, 2-dimensional coating, and 3-dimensional scaffolds. Moreover, the referring main active substances and antioxidative properties were classified, and the positive roles of antioxidative materials for bone repair have also been clearly summarized in signaling pathways, antioxidant enzymes, cellular responses and animal levels.

Neuro-bone tissue engineering: emerging mechanisms, potential strategies, and current challenges

The skeleton is a highly innervated organ in which nerve fibers interact with various skeletal cells. Peripheral nerve endings release neurogenic factors and sense skeletal signals, which mediate bone metabolism and skeletal pain. In recent years, bone tissue engineering has increasingly focused on the effects of the nervous system on bone regeneration. Simultaneous regeneration of bone and nerves through the use of materials or by the enhancement of endogenous neurogenic repair signals has been proven to promote functional bone regeneration. Additionally, emerging information on the mechanisms of skeletal interoception and the central nervous system regulation of bone homeostasis provide an opportunity for advancing biomaterials. However, comprehensive reviews of this topic are lacking. Therefore, this review provides an overview of the relationship between nerves and bone regeneration, focusing on tissue engineering applications. We discuss novel regulatory mechanisms and explore innovative approaches based on nerve-bone interactions for bone regeneration. Finally, the challenges and future prospects of this field are briefly discussed.

Ultrasound-Induced Abiotic and Biotic Interfacial Electron Transfer for Efficient Treatment of Bacterial Infection

Electron transfer plays an important role in various catalytic reactions and physiological activities, whose altered processes may change catalytic efficiency and interfere in physiological metabolic processes. In this study, we design an ultrasound (US)-activated piezoelectric responsive heterojunction (PCN-222-BTO, PCN: porous coordination network), which can change the electron transfer path at the abiotic and abiotic-biotic interfaces under US, thus achieving a rapid (15 min) and efficient bactericidal effect of 99.96%. US-induced polarization of BTO generates a built-in electric field, which promotes the electron transfer excited from PCN-222 to BTO at the PCN-222-BTO interface, thereby increasing the level of reactive oxygen species (ROS) production. Especially, we find that the biological electron transfer from the bacterial membrane to BTO is also activated at the MRSA-BTO interface. This antibacterial mode results in the down-regulated ribosomal, DNA and ATP synthesis related genes in MRSA, while the cell membrane and ion transport related genes are up-regulated due to the synergistic damage effect of ROS and disturbance of the bacterial electron transport chain. This US responsive dual-interface system shows an excellent therapeutic effect for the treatment of the MRSA-infected osteomyelitis model, which is superior to clinical vancomycin therapy.

Procedural Promotion of Multiple Stages in the Wound Healing Process by Graphene-Spiky Silica Heterostructured Nanoparticles

Background

Multiple stages including hemostasis, inflammation, proliferation, and remodeling were involved in the wound healing process. The increase in nanomaterials in recent years has extended the scope of tools for wound healing; however, it is still difficult to achieve the four multistage procedures simultaneously.

Materials and Methods

In this study, graphene-spiky silica heterostructured nanoparticles (GS) were synthesized for the procedural acceleration of the multistage in wound healing process. The nanobridge effect of GS was analyzed through the adhesion of two skins, the antibacterial effect was assessed in Gram-negative Escherichia coli (E. coli) and Gram-positive Staphylococcus aureus (S. aureus) bacteria, cell proliferation and migration were investigated in mouse embryonic fibroblast (NIH-3T3) cells, and the in vivo wound healing effect was examined in female BALB/c mice with a cutting wound and E. coli or S. aureus bacteria infection on the back.

Results

First, GS has a strong nanobridge effect on the rapid closure of wounds because the spiky architecture on the surface of GS facilitates the adhesion of skins, promoting the hemostasis stage. Second, graphene exhibits antimicrobial activities both in chemical and physical interactions, especially under simulated sunlight irradiation. Third, graphene plays an important role in scaffolding function, together with the spiky topographical architecture of GS, accelerating the proliferation and maturation stages.

Conclusion

By periodically promoting every stage of wound healing, GS combined with simulated sunlight irradiation could significantly accelerate wound healing. With a simple composition and compact structure but multiple functions, this strategy will be the guideline for the development of ideal wound-healing nanomaterials.

Study of Biological Behavior and Antimicrobial Properties of Cerium Oxide Nanoparticles

(1) Background: An element that has gained much attention in industrial and biomedical fields is Cerium (Ce). CeO2 nanoparticles have been proven to be promising regarding their different biomedical applications for the control of infection and inflammation. The aim of the present study was to investigate the biological properties and antimicrobial behavior of cerium oxide (CeO2) nanoparticles (NPs). (2) Methods: The investigation of the NPs' biocompatibility with human periodontal ligament cells (hPDLCs) was evaluated via the MTT assay. Measurement of alkaline phosphatase (ALP) levels and alizarine red staining (ARS) were used as markers in the investigation of CeO2 NPs' capacity to induce the osteogenic differentiation of hPDLCs. Induced inflammatory stress conditions were applied to hPDLCs with H2O2 to estimate the influence of CeO2 NPs on the viability of cells under these conditions, as well as to reveal any ROS scavenging properties. Total antioxidant capacity (TAC) of cell lysates with NPs was also investigated. Finally, the macro broth dilution method was the method of choice for checking the antibacterial capacity of CeO2 against the anaerobic pathogens Porphyromonas gingivalis and Prevotella intermedia. (3) Results: Cell viability assay indicated that hPDLCs increase their proliferation rate in a time-dependent manner in the presence of CeO2 NPs. ALP and ARS measurements showed that CeO2 NPs can promote the osteogenic differentiation of hPDLCs. In addition, the MTT assay and ROS determination demonstrated some interesting results concerning the viability of cells under oxidative stress conditions and, respectively, the capability of NPs to decrease free radical levels over the course of time. Antimicrobial toxicity was observed mainly against P. gingivalis. (4) Conclusions: CeO2 NPs could provide an excellent choice for use in clinical practices as they could prohibit bacterial proliferation and control inflammatory conditions.

The Impressive Anti-Inflammatory Activity of Cerium Oxide Nanoparticles: More than Redox?

Cerium oxide nanoparticles (CNPs) are biocompatible nanozymes exerting multifunctional biomimetic activities, including superoxide dismutase (SOD), catalase, glutathione peroxidase, photolyase, and phosphatase. SOD- and catalase-mimesis depend on Ce3+/Ce4+ redox switch on nanoparticle surface, which allows scavenging the most noxious reactive oxygen species in a self-regenerating, energy-free manner. As oxidative stress plays pivotal roles in the pathogenesis of inflammatory disorders, CNPs have recently attracted attention as potential anti-inflammatory agents. A careful survey of the literature reveals that CNPs, alone or as constituents of implants and scaffolds, strongly contrast chronic inflammation (including neurodegenerative and autoimmune diseases, liver steatosis, gastrointestinal disorders), infections, and trauma, thereby ameliorating/restoring organ function. By general consensus, CNPs inhibit inflammation cues while boosting the pro-resolving anti-inflammatory signaling pathways. The mechanism of CNPs' anti-inflammatory effects has hardly been investigated, being rather deductively attributed to CNP-induced ROS scavenging. However, CNPs are multi-functional nanozymes that exert additional bioactivities independent from the Ce3+/Ce4+ redox switch, such as phosphatase activity, which could conceivably mediate some of the anti-inflammatory effects reported, suggesting that CNPs fight inflammation via pleiotropic actions. Since CNP anti-inflammatory activity is potentially a pharmacological breakthrough, it is important to precisely attribute the described effects to one or another of their nanozyme functions, thus achieving therapeutic credibility.

Ultrasound-Responsive Nanobubbles for Combined siRNA-Cerium Oxide Nanoparticle Delivery to Bone Cells

This study aims to present an ultrasound-mediated nanobubble (NB)-based gene delivery system that could potentially be applied in the future to treat bone disorders such as osteoporosis. NBs are sensitive to ultrasound (US) and serve as a controlled-released carrier to deliver a mixture of Cathepsin K (CTSK) siRNA and cerium oxide nanoparticles (CeNPs). This platform aimed to reduce bone resorption via downregulating CTSK expression in osteoclasts and enhance bone formation via the antioxidant and osteogenic properties of CeNPs. CeNPs were synthesized and characterized using transmission electron microscopy and X-ray photoelectron spectroscopy. The mixture of CTSK siRNA and CeNPs was adsorbed to the surface of NBs using a sonication method. The release profiles of CTSK siRNA and CeNPs labeled with a fluorescent tag molecule were measured after low-intensity pulsed ultrasound (LIPUS) stimulation using fluorescent spectroscopy. The maximum release of CTSK siRNA and the CeNPs for 1 mg/mL of NB-(CTSK siRNA + CeNPs) was obtained at 2.5 nM and 1 µg/mL, respectively, 3 days after LIPUS stimulation. Then, Alizarin Red Staining (ARS) was applied to human bone marrow-derived mesenchymal stem cells (hMSC) and tartrate-resistant acid phosphatase (TRAP) staining was applied to human osteoclast precursors (OCP) to evaluate osteogenic promotion and osteoclastogenic inhibition effects. A higher mineralization and a lower number of osteoclasts were quantified for NB-(CTSK siRNA + CeNPs) versus control +RANKL with ARS (p < 0.001) and TRAP-positive staining (p < 0.01). This study provides a method for the delivery of gene silencing siRNA and CeNPs using a US-sensitive NB system that could potentially be used in vivo and in the treatment of bone fractures and disorders such as osteoporosis.

Fluoride-activated photothermal system for promoting bacteria-infected wound healing

Although photothermal therapy (PTT) employing nanozymes has shown excellent antibacterial potential, excessive heating generally harms host cells and hinders recovery. Herein, we report an innovative technique for acquiring the programmed temperature by managing the catalytic activity of nanozymes. The photothermal system of CeO2 + F- + TMB can obtain precise photothermal temperature by adjusting the concentration of fluoride ions under near-infrared irradiation. At the optimized photothermal temperature, the photothermal system affords fine photothermal antibacterial treatment with high-efficiency antibacterial effects against Staphylococcus aureus and Escherichia coli in vitro. In vivo wound healing experiments confirm that the system can effectively promote fibroblast proliferation, angiogenesis and collagen deposition with remarkable wound healing efficiency. This strategy offers a novel design concept for creating a new generation of PTT and opens the way for the creation of alternative antibiotics.

Nanotechnology enabled radioprotectants to reduce space radiation-induced reactive oxidative species

Interest in space exploration has seen substantial growth following recent launch and operation of modern space technologies. In particular, the possibility of travel beyond low earth orbit is seeing sustained support. However, future deep space travel requires addressing health concerns for crews under continuous, longer-term exposure to adverse environmental conditions. Among these challenges, radiation-induced health issues are a major concern. Their potential to induce chronic illness is further potentiated by the microgravity environment. While investigations into the physiological effects of space radiation are still under investigation, studies on model ionizing radiation conditions, in earth and micro-gravity conditions, can provide needed insight into relevant processes. Substantial formation of high, sustained reactive oxygen species (ROS) evolution during radiation exposure is a clear threat to physiological health of space travelers, producing indirect damage to various cell structures and requiring therapeutic address. Radioprotection toward the skeletal system components is essential to astronaut health, due to the high radio-absorption cross-section of bone mineral and local hematopoiesis. Nanotechnology can potentially function as radioprotectant and radiomitigating agents toward ROS and direct radiation damage. Nanoparticle compositions such as gold, silver, platinum, carbon-based materials, silica, transition metal dichalcogenides, and ceria have all shown potential as viable radioprotectants to mitigate space radiation effects with nanoceria further showing the ability to protect genetic material from oxidative damage in several studies. As research into space radiation-induced health problems develops, this review intends to provide insights into the nanomaterial design to ameliorate pathological effects from ionizing radiation exposure. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Nanotechnology Approaches to Biology > Cells at the Nanoscale Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Advanced surface engineering of titanium materials for biomedical applications: From static modification to dynamic responsive regulation

Titanium (Ti) and its alloys have been widely used as orthopedic implants, because of their favorable mechanical properties, corrosion resistance and biocompatibility. Despite their significant success in various clinical applications, the probability of failure, degradation and revision is undesirably high, especially for the patients with low bone density, insufficient quantity of bone or osteoporosis, which renders the studies on surface modification of Ti still active to further improve clinical results. It is discerned that surface physicochemical properties directly influence and even control the dynamic interaction that subsequently determines the success or rejection of orthopedic implants. Therefore, it is crucial to endow bulk materials with specific surface properties of high bioactivity that can be performed by surface modification to realize the osseointegration. This article first reviews surface characteristics of Ti materials and various conventional surface modification techniques involving mechanical, physical and chemical treatments based on the formation mechanism of the modified coatings. Such conventional methods are able to improve bioactivity of Ti implants, but the surfaces with static state cannot respond to the dynamic biological cascades from the living cells and tissues. Hence, beyond traditional static design, dynamic responsive avenues are then emerging. The dynamic stimuli sources for surface functionalization can originate from environmental triggers or physiological triggers. In short, this review surveys recent developments in the surface engineering of Ti materials, with a specific emphasis on advances in static to dynamic functionality, which provides perspectives for improving bioactivity and biocompatibility of Ti implants.

Advances and Prospects in Materials for Craniofacial Bone Reconstruction

The craniofacial region is composed of 23 bones, which provide crucial function in keeping the normal position of brain and eyeballs, aesthetics of the craniofacial complex, facial movements, and visual function. Given the complex geometry and architecture, craniofacial bone defects not only affect the normal craniofacial structure but also may result in severe craniofacial dysfunction. Therefore, the exploration of rapid, precise, and effective reconstruction of craniofacial bone defects is urgent. Recently, developments in advanced bone tissue engineering bring new hope for the ideal reconstruction of the craniofacial bone defects. This report, presenting a first-time comprehensive review of recent advances of biomaterials in craniofacial bone tissue engineering, overviews the modification of traditional biomaterials and development of advanced biomaterials applying to craniofacial reconstruction. Challenges and perspectives of biomaterial development in craniofacial fields are discussed in the end.

Engineering Antioxidant Surfaces for Titanium-Based Metallic Biomaterials

Prolonged inflammation induced by orthopedic metallic implants can critically affect the success rates, which can even lead to aseptic loosening and consequent implant failure. In the case of adverse clinical conditions involving osteoporosis, orthopedic trauma and implant corrosion-wear in peri-implant region, the reactive oxygen species (ROS) activity is enhanced which leads to increased oxidative stress. Metallic implant materials (such as titanium and its alloys) can induce increased amount of ROS, thereby critically influencing the healing process. This will consequently affect the bone remodeling process and increase healing time. The current review explores the ROS generation aspects associated with Ti-based metallic biomaterials and the various surface modification strategies developed specifically to improve antioxidant aspects of Ti surfaces. The initial part of this review explores the ROS generation associated with Ti implant materials and the associated ROS metabolism resulting in the formation of superoxide anion, hydroxyl radical and hydrogen peroxide radicals. This is followed by a comprehensive overview of various organic and inorganic coatings/materials for effective antioxidant surfaces and outlook in this research direction. Overall, this review highlights the critical need to consider the aspects of ROS generation as well as oxidative stress while designing an implant material and its effective surface engineering.

Urchin-like ceria nanoparticles for enhanced gene therapy of osteoarthritis

Osteoarthritis (OA) is the most common degenerative joint disease in the world. Gene therapy based on delivering microRNAs (miRNAs) into cells has potential for the treatment of OA. However, the effects of miRNAs are limited by the poor cellular uptake and stability. Here, we first identify a type of microRNA-224-5p (miR-224-5p) from clinical samples of patients with OA that can protect articular cartilage from degeneration and further synthesize urchin-like ceria nanoparticles (NPs) that can load miR-224-5p for enhanced gene therapy of OA. Compared with traditional sphere ceria NPs, the thorns of urchin-like ceria NPs can efficiently promote the transfection of miR-224-5p. In addition, urchin-like ceria NPs have excellent performance of scavenging reactive oxygen species (ROS), which can regulate the microenvironment of OA to further improve the gene treatment of OA. The combination of urchin-like ceria NPs and miR-224-5p not only exhibits favorable curative effect for OA but also provides a promising paradigm for translational medicine.

Spontaneous formation of MXene-oxidized sono/chemo-dynamic sonosensitizer/nanocatalyst for antibacteria and bone-tissue regeneration

Prolonged and incurable bacterial infections in soft tissue and bone are currently causing large challenges in the clinic. Two-dimensional (2D) materials have been designed to address these issues, but materials with satisfying therapeutic effects are still needed. Herein, CaO₂-loaded 2D titanium carbide nanosheets (CaO₂-TiO_x@Ti₃C₂, C-T@Ti₃C₂) were developed. Surprisingly, this nanosheet exhibited sonodynamic ability, in which CaO₂ caused the in situ oxidation of Ti₃C₂ MXene to produce acoustic sensitiser TiO₂ on its surface. In addition, this nanosheet displayed chemodynamic features, which promoted a Fenton reaction triggered by self-supplied H₂O₂. We detected that C-T@Ti₃C₂ nanosheets increased reactive oxygen species (ROS) production in response to sonodynamic therapy, which displayed an ideal antibacterial effect. Furthermore, these nanoreactors facilitated the deposition of Ca²⁺, which promoted osteogenic transformation and enhanced bone quality in osteomyelitis models. Herein, a wound healing model and prosthetic joint infection (PJI) model were established, and the C-T@Ti₃C₂ nanosheets played a protective role in these models. Taken together, the results indicated that the C-T@Ti₃C₂ nanosheets function as a multifunctional instrument with sonodynamic features, which might reveal information regarding the treatment of bacterial infections during wound healing.

Fabrication and Characterisation of the Cytotoxic and Antibacterial Properties of Chitosan-Cerium Oxide Porous Scaffolds

Bone damage arising from fractures or trauma frequently results in infection, impeding the healing process and leading to complications. To overcome this challenge, we engineered highly porous chitosan scaffolds (S1, S2, and S3) by incorporating 30 (wt)% iron-doped dicalcium phosphate dihydrate (Fe-DCPD) minerals and different concentrations of cerium oxide nanoparticles (CeO₂) (10 (wt)%, 20 (wt)%, and 30 (wt)%) using the lyophilisation technique. The scaffolds were specifically designed for the controlled release of antibacterial agents and were systematically characterised by utilising Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy methodologies. Alterations in the physicochemical properties, encompassing pore size, swelling behaviour, degradation kinetics, and antibacterial characteristics, were observed with the escalating CeO₂ concentrations. Scaffold cytotoxicity and its impact on human bone marrow mesenchymal stem cell (BM-MSCs) proliferation were assessed employing the 2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide (XTT) assay. The synthesised scaffolds represent a promising approach for addressing complications associated with bone damage by fostering tissue regeneration and mitigating infection risks. All scaffold variants exhibited inhibitory effects on bacterial growth against Staphylococcus aureus and Escherichia coli strains. The scaffolds manifested negligible cytotoxic effects while enhancing antibacterial properties, indicating their potential for reducing infection risks in the context of bone injuries.

Potential application of inorganic nano-materials in modulation of macrophage function: Possible application in bone tissue engineering

Nanomaterials indicate unique physicochemical properties for drug delivery in osteogenesis. Benefiting from high surface area grades, high volume ratio, ease of functionalization by biological targeting moieties, and small size empower nanomaterials to pass through biological barriers for efficient targeting. Inorganic nanomaterials for bone regeneration include inorganic synthetic polymers, ceramic nanoparticles, metallic nanoparticles, and magnetic nanoparticles. These nanoparticles can effectively modulate macrophage polarization and function, as one of the leading players in osteogenesis. Bone healing procedures in close cooperation with the immune system. Inflammation is one of the leading triggers of the bone fracture healing barrier. Macrophages commence anti-inflammatory signaling along with revascularization in the damaged site to promote the formation of a soft callus, bone mineralization, and bone remodeling. In this review, we will discuss the role of macrophages in bone hemostasis and regeneration. Furthermore, we will summarize the influence of the various inorganic nanoparticles on macrophage polarization and function in the benefit of osteogenesis.

Targeting Endogenous Reactive Oxygen Species Removal and Regulating Regenerative Microenvironment at Annulus Fibrosus Defects Promote Tissue Repair

The excessive reactive oxygen species (ROS) level, inflammation, and weak tissue regeneration ability after annulus fibrosus (AF) injury constitute an unfavorable microenvironment for AF repair. AF integrity is crucial for preventing disc herniation after discectomy; however, there is no effective way to repair the AF. Herein, a composite hydrogel integrating properties of antioxidant, anti-inflammation, and recruitment of AF cells is developed through adding mesoporous silica nanoparticles modified by ceria and transforming growth factor β3 (TGF-β3) to the hydrogels. The nanoparticle loaded gelatin methacrylate/hyaluronic acid methacrylate composite hydrogels eliminate ROS and induce anti-inflammatory M2 type macrophage polarization. The released TGF-β3 not only plays a role in recruiting AF cells but is also responsible for promoting extracellular matrix secretion. The composite hydrogels can be solidified in situ in the defect area to effectively repair AF in rats. The strategies targeting endogenous ROS removal and improving the regenerative microenvironment by the nanoparticle-loaded composite hydrogels have potential applications in AF repair and intervertebral disc herniation prevention.

Mussel-inspired alkaline phosphatase-specific coating on orthopedic implants for spatiotemporal modulating local osteoimmune microenvironment to facilitate osseointegration

Inadequate initial osseointegration and consequent prosthesis loosening are the most severe complications after artificial arthroplasty. Proper immune responses are crucial for the successful implantation of artificial prostheses. Macrophages are central in osteoimmunomodulation because they exert distinct functions with highly plasticity. Herein, we developed an alkaline phosphatase (ALP) sensitive mussel-inspired coating on orthopedic implants for promoting osseointegration. First, the resveratrol-alendronate complexes were deposited on titanium implant surface through mussel-inspired interfacial interactions. Upon prosthesis implantation, macrophages first polarized towards M1 type to initiate inflammatory responses and bone regeneration. As osteogenesis progresses, increasing amounts of ALP secreted by osteoblasts was cleaved the resveratrol-alendronate complexes. Then, the released resveratrol further promoted osteogenic differentiation of BMSCs and induced locoregional macrophages M2 polarization. Our results demonstrated that the bioinspired osteoimmunomodulation coating remarkably facilitated the prosthesis-bone integration by spatiotemporally modulating macrophages switching from M1 to M2 polarization in response to a real-time healing signal during osteogenesis. In summary, the mussel-inspired osteoimmunomodulation coating technology may provide a new approach for promoting osseointegration after artificial arthroplasty.

Effects of Hyperlipidemia on Osseointegration of Dental Implants and Its Strategies

Hyperlipidemia refers to the abnormal increase in plasma lipid level exceeding the normal range. At present, a large number of patients require dental implantation. However, hyperlipidemia affects bone metabolism, promotes bone loss, and inhibits the osseointegration of dental implants through the mutual regulation of adipocytes, osteoblasts, and osteoclasts. This review summarized the effects of hyperlipidemia on dental implants and addressed the potential strategies of dental implants to promote osseointegration in a hyperlipidemic environment and to improve the success rate of dental implants in patients with hyperlipidemia. We summarized topical drug delivery methods to solve the interference of hyperlipidemia in osseointegration, which were local drug injection, implant surface modification and bone-grafting material modification. Statins are the most effective drugs in the treatment of hyperlipidemia, and they also encourage bone formation. Statins have been used in these three methods and have been found to be positive in promoting osseointegration. Directly coating simvastatin on the rough surface of the implant can effectively promote osseointegration of the implant in a hyperlipidemic environment. However, the delivery method of this drug is not efficient. Recently, a variety of efficient methods of simvastatin delivery, such as hydrogels and nanoparticles, have been developed to boost bone formation, but few of them were applied to dental implants. Applicating these drug delivery systems using the three aforementioned ways, according to the mechanical and biological properties of materials, could be promising ways to promote osseointegration under hyperlipidemic conditions. However, more research is needed to confirm.

Sequential Therapy for Bone Regeneration by Cerium Oxide-Reinforced 3D-Printed Bioactive Glass Scaffolds

Rational design of multifunctional biomaterials with customized architecture and on demand bioactivity is of great significance for bone tissue engineering (BTE) in modern society. Herein, a versatile therapeutic platform has been established by integrating cerium oxide nanoparticles (CeO₂ NPs) into bioactive glass (BG) to fabricate three-dimensional (3D)-printed scaffolds, achieving a sequential therapeutic effect against inflammation and promoting osteogenesis toward bone defect. The antioxidative activity of CeO₂ NPs plays a crucial role in alleviating the oxidative stress upon formation of bone defects. Subsequently, CeO₂ NPs exert a promotion effect on the proliferation and osteogenic differentiation of rat osteoblasts through enhancing mineral deposition and alkaline phosphatase and osteogenic gene expression. Strikingly, the incorporation of CeO₂ NPs bestows on the BG scaffolds greatly reinforced mechanical properties, improved biocompatibility, adequate cell adhesion, elevated osteogenic capability, and multifunctional performance in a single platform. In vivo studies on the treatment of rat tibial defect confirmed the better osteogenic properties of CeO₂-BG scaffolds compared with pure BG scaffolds. Additionally, the employment of the 3D printing technique creates a proper porous microenvironment around the bone defect, which further facilitates the cell in-growth and new bone formation. This report provides a systematic study on CeO₂-BG 3D-printed scaffolds prepared by simple ball milling method, achieving sequential and integral treatment in BTE based on a single platform.

Redox Homeostasis Strategy for Inflammatory Macrophage Reprogramming in Rheumatoid Arthritis Based on Ceria Oxide Nanozyme-Complexed Biopolymeric Micelles

The synovial tissues under rheumatoid arthritis conditions are usually infiltrated by inflammatory cells, particularly M1 macrophages with aberrant redox homeostasis, which causes rapid deterioration of articular structure and function. Herein, we created an ROS-responsive micelle (HA@RH-CeO_X) through the in situ host-guest complexation between ceria oxide nanozymes and hyaluronic acid biopolymers, which precisely delivered nanozyme and clinically approved rheumatoid arthritis drug Rhein (RH) to proinflammatory M1 macrophage populations in inflamed synovial tissues. The abundant cellular ROS could cleave the thioketal linker to trigger the release of RH and Ce. Specifically, the Ce³⁺/Ce⁴⁺ redox pair could present SOD-like enzymatic activity to rapidly decompose ROS and alleviate the oxidative stress in M1 macrophages, while RH could inhibit the TLR4 signaling in M1 macrophages, both of which could act in a concerted manner to induce their repolarization into anti-inflammatory M2 phenotype to ameliorate local inflammation and promote cartilage repair. Notably, rats bearing rheumatoid arthritis showed a drastic increase in the M1-to-M2 macrophage ratio from 1:0.48 to 1:1.91 in the inflamed tissue and significantly reduced inflammatory cytokine levels including TNF-α and IL-6 following the intra-articular injection of HA@RH-CeO_X, accompanied by efficient cartilage regeneration and restored articular function. Overall, this study revealed an approach to in situ modulate the redox homeostasis in inflammatory macrophages and reprogram their polarization states through micelle-complexed biomimetic enzymes, which offers alternative opportunities for the treatment of rheumatoid arthritis.

A mace-like heterostructural enriched injectable hydrogel composite for on-demand promotion of diabetic wound healing

Wound healing is a multifaceted process that involves hemostasis, inflammation, proliferation, and remodeling stages. Diabetic wounds affect the transition of the organized phases and result in delayed healing due to impaired angiogenesis, chronic inflammation, bacterial infection, and insufficient growth factors. Multifunctional heterostructural nanoparticles enriched minimally invasive hydrogels for on-demand procedural distribution to aid wound healing at various stages has become a promising strategy. Herein, silk fibroin-hyaluronic acid based injectable hydrogels incorporated with mace-like Au-CuS heterostructural nanoparticles (gAu-CuS HSs) were used to cure diabetic wounds. SF-HA and the rough surface of gAu-CuS HSs confer a synergistic hemostatic phase with a nano-bridge effect and rapidly close the wounds. During the inflammation stage, gAu-CuS HSs perform in-space resonance energy transfer under 808 nm laser irradiation which in return produces reactive oxygen species for bacterial destruction. The unusual mace-like rough structure of nanoparticles causes macrophage transfer to the M2 phenotype, regulates cytokine expression (interleukin 6, transforming factor-β1, interferon γ, and interleukin-10), promotes angiogenesis, and promotes cell multiplication and fibroblast emigration to the wound area during the proliferation and remodeling phase. Overall, the gAu-CuS HSs reinforced injectable hydrogel programmatically accelerates wound healing and could represent a versatile strategy for advanced diabetic wound healing.

Preparation of MOF/polypyrrole and flower-like MnO2 electrodes by electrodeposition: High-performance materials for hybrid capacitive deionization defluorination

Fluorine pollution has become a global public health problem due to its adverse health effects. Adsorption is the primary method for removing fluoride from drinking water. However, the adsorption method has disadvantages such as difficulty in recovering the adsorbent, and the need to add additional chemicals for regeneration, thereby causing secondary pollution, which limits further industrial applications. Capacitive deionization (CDI), as an emerging water treatment technology, has attracted widespread attention due to its advantages of simple operation, low energy consumption and less environmental impact. In this study, a polypyrrole (PPy) film was prepared on a graphite substrate by electrodeposition, and then metal-organic framework Ce/Zn-BDC-NH₂ (CZBN) was deposited on the PPy film by electrophoretic deposition to obtain CZBN/PPy electrode was obtained. The CZBN/PPy anode was then coupled with the MnO₂ cathode for capacitive removal of fluoride in a CDI cell. Both CZBN/PPy and MnO₂ electrodes exhibit pseudocapacitive behavior, which can selectively and reversibly intercalate F^- (CZBN/PPy) and Na⁺ (MnO₂) ions. As expected, the CZBN/PPy-MnO₂ system exhibits excellent fluorine removal performance. In 1.2 V, 100 mg/L F^- solution, the F^- removal capacity can reach 55.12 mg/g. It has high F^- selectivity in the presence of some common anions, and can maintain high F^- removal ability even after five adsorption regeneration processes. The mechanism of F^- removal was studied by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). F^- was mainly removed by electrostatic interaction and ion exchange with hydroxyl. The excellent defluorination performance of the CZBN/PPy-MnO₂ system makes it have good practical application prospects.

Electrical stimulation of piezoelectric BaTiO3 coated Ti6Al4V scaffolds promotes anti-inflammatory polarization of macrophages and bone repair via MAPK/JNK inhibition and OXPHOS activation

Bone regeneration is a highly synchronized process that requires multiple biochemical, bioelectrical, mechanical, and other physiological cues. The restoration and delivery of electrical cues locally through piezoelectric materials have been demonstrated to facilitate osteogenesis in vitro and bone repair in vivo. However, the underlying mechanism by which piezoelectric stimulation promotes osteogenesis and bone repair remains unclear yet, limiting the design and clinical application of piezoelectric materials for bone repair. Herein, a piezoelectric BaTiO3/Ti6Al4V (BT/Ti) scaffold was prepared by hydrothermal synthesis of a uniform BaTiO3 layer on three dimensionally printed Ti6Al4V scaffold. The BT/Ti scaffolds exhibited piezoelectricity and favorable biocompatibility with RAW264.7 macrophages after polarization. In vitro results demonstrated that the piezoelectric effects of the poled BT/Ti scaffolds promoted M2 polarization of macrophages and immunoregulatory osteogenesis of MC-3T3 osteoblasts. In a subcutaneous implantation model, a higher proportion of CD68⁺ CD206⁺ M2 macrophages was observed in the tissues around the poled BT/Ti scaffolds under low intensity pulsed ultrasound (LIPUS) stimulation. Improvements in macrophage M2 polarization and bone regeneration were further identified in a sheep cervical corpectomy model. RNA sequencing and mechanistic investigation revealed that the piezoelectric BT/Ti (poled) scaffolds inhibited the inflammatory MAPK/JNK signaling cascade and activated oxidative phosphorylation (OXPHOS) and ATP synthesis in macrophages. Collectively, our study provides a promising method for regulating the immune microenvironment and enhancing bone regeneration using polarized piezoelectric BT/Ti scaffolds.

Metal-Phenolic Networks Assembled on TiO2 Nanospikes for Antimicrobial Peptide Deposition and Osteoconductivity Enhancement in Orthopedic Applications

The lack of antimicrobial and osteoconductive activities of titanium (Ti) for orthopedic implants has led to problems such as infection and structural looseness, which bring physical and psychological sufferings to patients as well as economic burden on the healthcare system. To endow Ti implants with anti-infective function and bioactivity, in this study, we successfully constructed TiO2 nanospike (TNS) structure on the surface of Ti followed by assembling metal-polyphenol networks (MPNs) and depositing antimicrobial peptides (AMPs). The TNSs' structure can disrupt the bacteria by physical puncture, and it was also proved to have excellent photothermal conversion performance upon near-infrared light irradiation. Furthermore, with the assistance of contact-active chemo bactericidal efficacy of AMPs, TNS-MPN-AMP nanocoating achieved physical/photothermal/chemo triple-synergistic therapy against pathogenic bacteria. The anti-infective efficiency of this multimodal treatment was obviously improved, with an antibacterial ratio of >99.99% in vitro and 95.03% in vivo. Moreover, the spike-like nanostructure of TNSs and the bioactive groups from MPNs and AMPs not only demonstrated desirable biocompatibility but also promoted the surface hydroxyapatite formation in simulated body fluid for further osseointegration enhancement. Altogether, this multifaceted TNS-MPN-AMP nanocoating endowed Ti implants with enhanced antibacterial activity, excellent cytocompatibility, and desirable osteoconductive ability.

Ceria-based coatings on magnesium alloys for biomedical applications: a literature review

Magnesium alloys are being studied for use in temporary orthopedic implants because of their mechanical properties, which are similar to those of human bone, and their good biocompatibility. However, their application is limited due to their rapid degradation, and early loss of their mechanical properties, decreasing the stability of the implant and its proper synchronization with tissue regeneration. In this regard, various surface coatings have been used to improve their biological, physico-chemical and biodegradation properties. Currently, one of the most explored strategies is using smart coatings because of their self-healing properties that can slow down the corrosion process of Mg and its alloys. Ceria-based materials show promise as coatings for these alloys. Their unique redox capacity not only provides Mg alloys with good self-healing properties but also interesting biological properties, which are described in this paper. Despite this, some problems and challenges related to the biocompatibility and application of these materials in coatings remain unsolved. In this article, a critical review is presented summarizing the most representative literature on ceria-based coatings on Mg alloys for their potential use as biomaterials. The results show that ceria is a versatile material that may be used in industrial and biomedical applications.

Bone regeneration strategies based on organelle homeostasis of mesenchymal stem cells

The organelle modulation has emerged as a crucial contributor to the organismal homeostasis. The mesenchymal stem cells (MSCs), with their putative functions in maintaining the regeneration ability of adult tissues, have been identified as a major driver to underlie skeletal health. Bone is a structural and endocrine organ, in which the organelle regulation on mesenchymal stem cells (MSCs) function has most been discovered recently. Furthermore, potential treatments to control bone regeneration are developing using organelle-targeted techniques based on manipulating MSCs osteogenesis. In this review, we summarize the most current understanding of organelle regulation on MSCs in bone homeostasis, and to outline mechanistic insights as well as organelle-targeted approaches for accelerated bone regeneration.

Defective Homojunction Porphyrin-Based Metal-Organic Frameworks for Highly Efficient Sonodynamic Therapy

Sonodynamic therapy (SDT) with non-invasiveness and high tissue-penetrating ability has attracted widespread interest in treating deep-seated tumors or infections. To enhance the treatment efficacy of SDT, the development of high-efficiency and stable sonosensitizers are still needed. Herein, a defective homojunction porphyrin-based metal-organic framework (MOF) with greatly enhanced sonocatalytic ability is easily prepared and used for SDT of osteomyelitis infected by methicillin-resistant Staphylococcus aureus (MRSA). Acetic acid and benzoic acid are chosen as modulators during the hydrothermal synthesis of porphyrin-based MOF. It is found that the crystal structure of MOF shifts from PCN-222 to PCN-224 as the amount of acetic acid increases. Interestingly, the defective PCN (D-PCN) contains a two-phase homojunction structure of PCN-222/PCN-224. The sonocatalytic reactive oxygen species production presents a volcano-type trend with increased acetic acid, among which D-PCN-2 with more content of PCN-224 has the best sonocatalytic antibacterial ability. The reduced band gap introduced a defect, and type-II homojunction structures of D-PCN-2 improve the separation of the ultrasound-triggered electron hole, which significantly enhances the SDT effect. Through a mixed linker approach, this work develops a new defect-induced homojunction MOF with great performance for SDT of MRSA-infected osteomyelitis.

A drug delivery system constructed by a fusion peptide capturing exosomes targets to titanium implants accurately resulting the enhancement of osseointegration peri-implant

BACKGROUND

Exosomes derived from bone marrow mesenchymal stem cells (BMSC-exos) have been shown triggering osteogenic differentiation and mineralization of MSCs, but exosomes administered via bolus injections are rapidly sequestered and cleared. Therefore, we considered the implant as a new organ of patient's body and expected to find a method to treat implant with BMSC-exos in vivo directly.

METHODS

A fusion peptide (PEP), as a drug delivery system (DDS) which contained a titanium-binding peptide (TBP) possessing the ability to selectively bind to the titanium surface and another peptide CP05 being able to capture exosomes expertly, is constructed to modify the titanium surface.

RESULTS

Both in vitro and in vivo experiments prove PEP retains the ability to bind titanium and exosome simultaneously, and the DDS gain the ability to target exosomes to titanium implants surface following enhancing osseointegration post-implantation. Moreover, the DDS constructed by exosomes of diverse origins shows the similar combination rate and efficiency of therapy.

CONCLUSION

This drug delivery system demonstrates the concept that EXO-PEP system can offer an accurate and efficient therapy for treating implants with long-term effect.

Alginate/Gelatin Hydrogel Scaffold Containing nCeO2 as a Potential Osteogenic Nanomaterial for Bone Tissue Engineering

Background

Clinicians frequently face difficulties when trying to fix bone abnormalities. Gelatin-Alginate (GA) is frequently employed as a carrier because it is non-toxic, biodegradable, and has a three-dimensional network structure. Meanwhile, cerium oxide nanoparticles (nCeO₂) demonstrated high antioxidant enzyme simulation activity. Therefore, in order to develop a porous hydrogel scaffold for the application of bone tissue engineering, an appropriate-type GA-nCeO₂ hydrogel scaffold was developed and evaluated.

Methods

 GA-nCeO₂ hydrogel scaffold was prepared by the lyophilized method and characterized. The surface morphology and cell adhesion of the scaffold were observed by the scanning electron microscope. CCK8 and live-dead staining methods were used to evaluate its biological safety and cell proliferation. Then the osteogenic differentiation in early and late stages was discussed. The expression of osteogenic genes was also detected by RT-PCR. Finally, a bone defect model was made in SD rats, and bone formation in vivo was detected.

Results

 The results showed that GA-nCeO₂ hydrogel scaffold exhibited a typical three-dimensional porous structure with a mean pore ratio of 70.61 ± 1.94%. The GA-nCeO₂ hydrogel was successfully endowed with simulated enzyme activity including superoxide dismutase (SOD) and catalase (CAT) after the addition of nCeO₂. Osteoblasts demonstrated superior cell proliferation and adhesion on composite scaffolds, and both mineralization test and gene expression demonstrated the strong osteogenic potential of GA-nCeO₂ hydrogel. The outcomes of hematoxylin and eosin (H&E) staining and Masson trichrome staining in the femoral defect model of SD rats further supported the scaffold's favorable biocompatibility and bone-promoting capacity.

Conclusion

Due to its favorable safety, degradability, and bone formation property, GA-nCeO₂ hydrogel was anticipated to be used as a potential bone defect healing material.

Introducing Nanozymes: New Horizons in Periodontal and Dental Implant Care

The prevalence of periodontal and peri-implant diseases has been increasing worldwide and has gained a lot of attention. As multifunctional nanomaterials with enzyme-like activity, nanozymes have earned a place in the biomedical field. In periodontics and implantology, nanozymes have contributed greatly to research on maintaining periodontal health and improving implant success rates. To highlight this progress, we review nanozymes for antimicrobial therapy, anti-inflammatory therapy, tissue regeneration promotion, and synergistic effects in periodontal and peri-implant diseases. The future prospects of nanozymes in periodontology and implantology are also discussed along with challenges.