The stimulation of angiogenesis and collagen deposition by copper

A spotlight on the role of copper in the epithelial to mesenchymal transition

The complex process known as epithelial to mesenchymal transition (EMT) plays a fundamental role in several biological settings, encompassing embryonic development, wound healing, and pathological conditions such as cancer and fibrosis. In recent years, a bulk of research has brought to light the key role of copper, a trace element with essential functions in cellular metabolism, cancer initiation and progression. Indeed, copper, besides functioning as cofactor of enzymes required for essential cellular processes, such as energy production and oxidation reactions, has emerged as an allosteric regulator of kinases whose activity is required to fulfill cancer dissemination through the EMT. In this comprehensive review, we try to describe the intricate relationship between the transition metal copper and EMT, spanning from the earliest foundational studies to the latest advancements. Our aim is to shed light on the multifaceted roles undertaken by copper in EMT in cancer and to unveil the diverse mechanisms by which copper homeostasis exerts its influence over EMT regulators, signaling pathways, cell metabolic reprogramming and transcription factors ultimately contributing to the spread of cancer. Therefore, this review not only may contribute to a deeper comprehension of copper-mediated mechanisms in EMT but also supports the hypothesis that targeting copper may contribute to counteract the progression of EMT-associated pathologies.

Copper ions-photo dual-crosslinked alginate hydrogel for angiogenesis and osteogenesis

Early healing of bone defects is still a clinical challenge. Many bone-filling materials have been studied, among which photocrosslinked alginate has received significant attention due to its good biocompatibility and morphological plasticity. Although it has been confirmed that photocrosslinked alginate can be used as an extracellular matrix for 3D cell culture, it lacks osteogenesis-related biological functions. This study constructed a copper ions-photo dual-crosslinked alginate hydrogel scaffold by controlling the copper ion concentration. The scaffolds were shaped by photocrosslinking and then endowed with biological functions by copper ions crosslinking. According to in vitro research, the dual-crosslinked hydrogel increased the compressive strength and favored copper dose-dependent osteoblast differentiation and cell surface adherence of rat bone marrow mesenchymal stem cells and the expression of type I collagen (Col1), runt-related transcription factor 2 (Runx2), osteocalcin (OCN), vascular endothelial growth factor (VEGF). In addition, hydrogel scaffolds were implanted into rat skull defects, and more angiogenesis and osteogenesis could be observed in in vivo studies. The above results show that the copper-photo-crosslinked hydrogel scaffold has excellent osseointegration properties and can potentially promote angiogenesis and early healing of bone defects, providing a reference solution for bone tissue engineering materials.

Electrochemical stability of biodegradable Zn-Cu alloys through machine-learning accelerated high-throughput discovery

Zn-Cu alloys have attracted great attention as biodegradable alloys owing to their excellent mechanical properties and biocompatibility, with corrosion characteristics being crucial for their suitability for biomedical applications. However, the unresolved identification of intermetallic compounds in Zn-Cu alloys affecting corrosion and the complexity of the application environment hamper the understanding of their electrochemical behavior. Utilizing high-throughput first-principles calculations and machine-learning accelerated evolutionary algorithms for screening the most stable compounds in Zn-Cu systems, a dataset encompassing the formation energy of 2033 compounds is generated. It reveals that most of the experimentally reported Zn-Cu compounds can be replicated, especially the structure of R32 CuZn5 is first discovered which possesses the lowest formation energy of -0.050 eV per atom. Furthermore, the simulated X-ray diffraction pattern matches perfectly with the experimental ones. By formulating 342 potential electrochemical reactions based on the binary compounds, the Pourbaix diagrams for Zn-Cu alloys are constructed to clarify the fundamental competition between different phases and ions. The calculated equilibrium potential of CuZn5 is higher than that of Zn through the forward reaction Zn + CuZn5 ⇌ CuZn5 + Zn2+ + 2e-, resulting in microcell formation owing to the stronger charge density localization in Zn compared to CuZn5. The presence of chlorine accelerates the corrosion of Zn through the reaction Zn + CuZn5 + 6Cl- + 6H2O ⇌ Cu + 6ZnOHCl + 6H+ + 12e-, where the formation of ZnOHCl disrupts the ZnO passive film and expands the corrosion pH range from 9.2 to 8.8. Our findings reveal an accurate quantitative corrosion mechanism for Zn-Cu alloys, providing an effective pathway to investigate the corrosion resistance of biodegradable alloys.

Photothermal Antibacterial and Osteoinductive Polypyrrole@Cu Implants for Biological Tissue Replacement

The treatment of bone defects caused by disease or accidents through the use of implants presents significant clinical challenges. After clinical implantation, these materials attract and accumulate bacteria and hinder the integration of the implant with bone tissue due to the lack of osteoinductive properties, both of which can cause postoperative infection and even lead to the eventual failure of the operation. This work successfully prepared a novel biomaterial coating with multiple antibacterial mechanisms for potent and durable and osteoinductive biological tissue replacement by pulsed PED (electrochemical deposition). By effectively regulating PPy (polypyrrole), the uniform composite coating achieved sound physiological stability. Furthermore, the photothermal analysis showcased exceptional potent photothermal antibacterial activity. The antibacterial assessments revealed a bacterial eradication rate of 100% for the PPy@Cu/PD composite coating following a 24 h incubation. Upon the introduction of NIR (near-infrared) irradiation, the combined effects of multiple antibacterial mechanisms led to bacterial reduction rates of 99% for E. coli and 98% for S. aureus after a 6 h incubation. Additionally, the successful promotion of osteoblast proliferation was confirmed through the application of the osteoinductive drug PD (pamidronate disodium) on the composite coating's surface. Therefore, the antimicrobial Ti-based coatings with osteoinductive properties and potent and durable antibacterial properties could serve as ideal bone implants.

Physico-Chemical Properties of Copper-Doped Hydroxyapatite Coatings Obtained by Vacuum Deposition Technique

The hydroxyapatite and copper-doped hydroxyapatite coatings (Ca10-xCux(PO4)6(OH)2; xCu = 0, 0.03; HAp and 3CuHAp) were obtained by the vacuum deposition technique. Then, both coatings were analyzed by the X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and water contact angle techniques. Information regarding the in vitro antibacterial activity and biological evaluation were obtained. The XRD studies confirmed that the obtained thin films consist of a single phase associated with hydroxyapatite (HAp). The obtained 2D and 3D SEM images did not show cracks or other types of surface defects. The FTIR studies' results proved the presence of vibrational bands characteristic of the hydroxyapatite structure in the studied coating. Moreover, information regarding the HAp and 3CuHAp surface wettability was obtained by water contact angle measurements. The biocompatibility of the HAp and 3CuHAp coatings was evaluated using the HeLa and MG63 cell lines. The cytotoxicity evaluation of the coatings was performed by assessing the cell viability through the MTT assay after incubation with the HAp and 3CuHAp coatings for 24, 48, and 72 h. The results proved that the 3CuHAp coatings exhibited good biocompatible activity for all the tested intervals. The ability of Pseudomonas aeruginosa 27853 ATCC (P. aeruginosa) cells to adhere to and develop on the surface of the HAp and 3CuHAp coatings was investigated using AFM studies. The AFM studies revealed that the 3CuHAp coatings inhibited the formation of P. aeruginosa biofilms. The AFM data indicated that P. aeruginosa's attachment and development on the 3CuHAp coatings were significantly inhibited within the first 24 h. Both the 2D and 3D topographies showed a rapid decrease in attached bacterial cells over time, with a significant reduction observed after 72 h of exposure. Our studies suggest that 3CuHAp coatings could be suitable candidates for biomedical uses such as the development of new antimicrobial agents.

A Double Network Composite Hydrogel with Self-Regulating Cu2+/Luteolin Release and Mechanical Modulation for Enhanced Wound Healing

Designing adaptive and smart hydrogel wound dressings to meet specific needs across different stages of wound healing is crucial. Here, we present a composite hydrogel, GSC/PBE@Lut, that offers self-regulating release of cupric ions and luteolin and modulates mechanical properties to promote chronic wound healing. The double network hydrogel, GSC, is fabricated through photo-cross-linking of gelatin methacrylate, followed by Cu2+-alginate coordination cross-linking. On one hand, GSC allows for rapid Cu2+ release to eliminate bacteria in the acidic pH environment during inflammation and reduces the hydrogel's mechanical strength to minimize tissue trauma during early dressing changes. On the other hand, GSC enables slow Cu2+ release during the proliferation stage, promoting angiogenesis and biocompatibility. Furthermore, the inclusion of pH- and reactive oxygen species (ROS)-responsive luteolin nanoparticles (PBE@Lut) in the hydrogel matrix allows for controlled release of luteolin, offering antioxidant and anti-inflammatory effects and promoting anti-inflammatory macrophage polarization. In a murine model of Staphylococcus aureus infected wounds, GSC/PBE@Lut demonstrates exceptional therapeutic benefits in antibacterial, anti-inflammatory, angiogenic, and tissue regeneration. Overall, our results suggest that smart hydrogels with controlled bioactive agent release and mechanical modulation present a promising solution for treating chronic wounds.

Development and characterization of polyethylene oxide and guar gum-based hydrogel; a detailed in-vitro analysis of degradation and drug release kinetics

Herein, we synthesized hydrogel films from crosslinked polyethylene oxide (PEO) and guar gum (GG) which can offer hydrophilicity, antibacterial efficacy, and neovascularization. This study focuses on synthesis and material/biological characterization of rosemary (RM) and citric acid (CA) loaded PEO/GG hydrogel films. Scanning Electron Microscopy images confirmed the porous structure of the developed hydrogel film matrix (PEO/GG) and the dispersion of RM and CA within it. This porous structure promotes moisture adsorption, cell attachment, proliferation, and tissue layer formation. Fourier Transform Infrared Spectroscopy (FTIR) further validated the crosslinking of the PEO/GG matrix, as confirmed by the appearance of C-O-C linkage in the FTIR spectrum. PEO/GG and PEO/GG/RM/CA revealed similar degradation and release kinetics in Dulbecco's Modified Eagle Medium, Simulated Body Fluid, and Phosphate Buffer Saline (degradation of ∼55 % and release of ∼60 % RM in 168 h.). The developed hydrogel film exhibited a zone of inhibition against Escherichia. coli (2 mm) and Staphylococcus. aureus (9 mm), which can be attributed to the presence of RM in the hydrogel film. Furthermore, incorporating CA in the hydrogel film promoted neovascularization, as confirmed by the Chorioallantoic Membrane Assay. The developed RM and CA-loaded PEO/GG-based hydrogel films offered suitable in-vitro properties that may aid in potential wound healing applications.

Oxygen tension regulating hydrogels for vascularization and osteogenesis via sequential activation of HIF-1α and ERK1/2 signaling pathways in bone regeneration

Angiogenesis plays a crucial role in bone regeneration. Hypoxia is a driving force of angiogenesis at the initial stage of tissue repair. The hypoxic microenvironment could activate the hypoxia-inducible factor (HIF)-1α signaling pathway in cells, thereby enhancing the proliferation, migration and pro-angiogenic functions of stem cells. However, long-term chronic hypoxia could inhibit osteogenic differentiation and even lead to apoptosis. Therefore, shutdown of the HIF-1α signaling pathway and providing oxygen at later stage probably facilitate osteogenic differentiation and bone regeneration. Herein, an oxygen tension regulating hydrogel that sequentially activate and deactivate the HIF-1α signaling pathway were prepared in this study. Its effect and mechanism on stem cell differentiation were investigated both in vitro and in vivo. We proposed a gelatin-based hydrogel capable of sequentially delivering a hypoxic inducer (copper ions) and oxygen generator (calcium peroxide). The copper ions released from the hydrogels significantly enhanced cell viability and VEGF secretion of BMSCs via upregulating HIF-1α expression and facilitating its translocation into the nucleus. Additionally, calcium peroxide promoted alkaline phosphatase activity, osteopontin secretion, and calcium deposition through the activation of ERK1/2. Both Cu2+ and calcium peroxide demonstrated osteogenic promotion individually, while their synergistic effect within the hydrogels led to a superior osteogenic effect by potentially activating the HIF-1α and ERK1/2 signaling pathways.

Atox1-cyclin D1 loop activity is critical for survival of tumor cells with inactivated TP53

The search for relevant molecular targets is one of the main tasks of modern tumor chemotherapy. To successfully achieve this, it is necessary to have the most complete understanding of the functioning of a transcriptional apparatus of the cell, particularly related to proliferation. The p53 protein plays an important role in regulating processes such as apoptosis, repair, and cell division, and the loss of its functionality often accompanies various types of tumors and contributes to the development of chemoresistance. Additionally, the proliferative activity of tumor cells is closely related to the metabolism of transition metals. For example, the metallochaperone Atox1 - a copper transporter protein - acts as a transcription activator for cyclin D1, promoting progression through the G1/S phase of the cell cycle. On the other hand, p53 suppresses cyclin D1 at the transcriptional level, thereby these proteins have divergent effects on cell cycle progression. However, the contribution of the interaction between these proteins to cell survival is poorly understood. This work demonstrates that not only exists a positive feedback loop between Atox1 and cyclin D1 but also that the activity of this loop depends on the status of the TP53 gene. Upon inactivation of TP53 in A549 and HepG2 cell lines, the expression of ATOX1 and CCND1 genes is enhanced, and their suppression in these cells leads to pronounced apoptosis. This fundamental observation may be useful in selecting more precise interventions for combined therapy of p53-negative tumors.

Metal Ion-Containing Hydrogels: Synthesis, Properties, and Applications in Bone Tissue Engineering

Hydrogel, as a unique scaffold material, features a three-dimensional network system that provides conducive conditions for the growth of cells and tissues in bone tissue engineering (BTE). In recent years, it has been discovered that metal ion-containing hybridized hydrogels, synthesized with metal particles as the foundation, exhibit excellent physicochemical properties, osteoinductivity, and osteogenic potential. They offer a wide range of research prospects in the field of BTE. This review provides an overview of the current state and recent advancements in research concerning metal ion-containing hydrogels in the field of BTE. Within materials science, it covers topics such as the binding mechanisms of metal ions within hydrogel networks, the types and fabrication methods of various metal ion-containing hydrogels, and the influence of metal ions on the properties of hydrogels. In the context of BTE, the review delves into the osteogenic mechanisms of various metal ions, the applications of metal ion-containing hydrogels in BTE, and relevant experimental studies in vitro and in vivo. Furthermore, future improvements in bone repair can be anticipated through advancements in bone bionics, exploring interactions between metal ions and the development of a wider range of metal ions and hydrogel types.

Biocompatible Copper-Based Nanocomposites for Combined Cancer Therapy

Copper (Cu) and Cu-based nanomaterials have received tremendous attention in recent years because of their unique physicochemical properties and good biocompatibility in the treatment of various diseases, especially cancer. To date, researchers have designed and fabricated a variety of integrated Cu-based nanocomplexes with distinctive nanostructures and applied them in cancer therapy, mainly including chemotherapy, radiotherapy (RT), photothermal therapy (PTT), chemodynamic therapy (CDT), photodynamic therapy (PDT), cuproptosis-mediated therapy, etc. Due to the limited effect of a single treatment method, the development of composite diagnostic nanosystems that integrate chemotherapy, PTT, CDT, PDT, and other treatments is of great significance and offers great potential for the development of the next generation of anticancer nanomedicines. In view of the rapid development of Cu-based nanocomplexes in the field of cancer therapy, this review focuses on the current state of research on Cu-based nanomaterials, followed by a discussion of Cu-based nanocomplexes for combined cancer therapy. Moreover, the current challenges and future prospects of Cu-based nanocomplexes in clinical translation are proposed to provide some insights into the design of integrated Cu-based nanotherapeutic platforms.

Enhancing Diabetic Wound Healing Through Improved Angiogenesis: The Role of Emulsion-Based Core-Shell Micro/Nanofibrous Scaffold with Sustained CuO Nanoparticle Delivery

Attempts are made to design a system for sustaining the delivery of copper ions into diabetic wounds and induce angiogenesis with minimal dose-dependent cytotoxicity. Here, a dual drug-delivery micro/nanofibrous core-shell system is engineered using polycaprolactone/sodium sulfated alginate-polyvinyl alcohol (PCL/SSA-PVA), as core/shell parts, by emulsion electrospinning technique to optimize sustained delivery of copper oxide nanoparticles (CuO NP). Herein, different concentrations of CuO NP (0.2, 0.4, 0.8, and 1.6%w/w) are loaded into the core part of the core-shell system. The morphological, biomechanical, and biocompatibility properties of the scaffolds are fully determined in vitro and in vivo. The 0.8%w/w CuO NP scaffold reveals the highest level of tube formation in HUVEC cells and also upregulates the pro-angiogenesis genes (VEGFA and bFGF) expression with no cytotoxicity effects. The presence of SSA and its interaction with CuO NP, and also core-shell structure sustain the release of the nanoparticles and provide a non-toxic microenvironment for cell adhesion and tube formation, with no sign of adverse immune response in vivo. The optimized scaffold significantly accelerates diabetic wound healing in a rat model. This study strongly suggests the 0.8%w/w CuO NP-loaded PCL/SSA-PVA as an excellent diabetic wound dressing with significantly improved angiogenesis and wound healing.

Additive manufacturing of degradable metallic scaffolds for material-structure-driven diabetic maxillofacial bone regeneration

The regeneration of maxillofacial bone defects associated with diabetes mellitus remains challenging due to the occlusal loading and hyperglycemia microenvironment. Herein, we propose a material-structure-driven strategy through the additive manufacturing of degradable Zn-Mg-Cu gradient scaffolds. The in situ alloying of Mg and Cu endows Zn alloy with admirable compressive strength for mechanical support and uniform degradation mode for preventing localized rupture. The scaffolds manifest favorable antibacterial, angiogenic, and osteogenic modulation capacity in mimicked hyperglycemic microenvironment, and Mg and Cu promote osteogenic differentiation in the early and late stages, respectively. In addition, the scaffolds expedite diabetic maxillofacial bone ingrowth and regeneration by combining the metabolic regulation effect of divalent metal cations and the hyperboloid and suitable permeability of the gradient structure. RNA sequencing further reveals that RAC1 might be involved in bone formation by regulating the transport and uptake of glucose related to GLUT1 in osteoblasts, contributing to cell function recovery. Inspired by bone healing and structural cues, this study offers an essential understanding of the designation and underlying mechanisms of the material-structure-driven strategy for diabetic maxillofacial bone regeneration.

Proanthocyanidins-based tandem dynamic covalent cross-linking hydrogel for diabetic wound healing

Wound healing in diabetic patients presents significant challenges in clinical wound care due to high oxidative stress, excessive inflammation, and a microenvironment prone to infection. In this study, we successfully developed a multifunctional tandem dynamic covalently cross-linked hydrogel dressing aimed at diabetic wound healing. This hydrogel was constructed using cyanoacetic acid functionalized dextran (Dex-CA), 2-formylbenzoylboric acid (2-FPBA) and natural oligomeric proanthocyanidins (OPC), catalyzed by histidine. The resulting Dex-CA/OPC/2-FPBA (DPOPC) hydrogel can be dissolved triggered by cysteine, thereby achieving "controllable and non-irritating" dressing change. Furthermore, the incorporation of OPC as a hydrogel building block endowed the hydrogel with antioxidant and anti-inflammatory properties. The cross-linked network of the DPOPC hydrogel circumvents the burst release of OPC, enhancing its biosafety. In vivo studies demonstrated that the DPOPC hydrogel significantly accelerated the wound healing process in diabetic mice compared to a commercial hydrogel, achieving an impressive wound closure rate of 98 % by day 14. The DPOPC hydrogel effectively balanced the disrupted inflammatory state during the healing process. This dynamic hydrogel based on natural polyphenols is expected to be an ideal candidate for dressings intended for chronic wounds.

Injectable hydrogels activated with copper sulfide nanoparticles for enhancing spatiotemporal sterilization and osteogenesis in periodontal therapy

Developing biomaterials capable of promoting bone regeneration in bacteria-infected sites is of utmost urgency for periodontal disease therapies. Here we produce a hybrid hydrogel by integrating CuS nanoparticles (CuSNPs), which could kill bacteria through photothermal therapy (PTT) triggered by a near infrared (NIR) light, and a gelatin methacryloyl (GelMA) hydrogel, which is injectable and biocompatible. Specifically, CuSNPs were precipitated by chitosan (CS) firstly, then grafted with methacrylic anhydride (MA) to form CuSNP@CS-MA, which was photo-crosslinked with GelMA to synthesize hybrid hydrogels (GelMA/CuSNP). The hybrid hydrogels exhibited a broad-spectrum antibacterial property that could be spatiotemprorally manipulated through applying a NIR light. Their mechanical properties were adjustable by controlling the concentration of CuSNPs, enabling the hydrogels to become more adapted to the oral diseases. Meanwhile, the hybrid hydrogels showed good cytocompatibility in vitro and improved hemostasis in vivo. Moreover, they accelerated alveolar osteogenesis and vascular genesis, successfully treating periodontis in four weeks in a rat model. GelMA/CuSNP hydrogels showed a broad-spectrum sterilization ability via PTT in vitro and outstanding antibacterial property in vivo, suggesting that the hybrid hydrogels could function in the challenging, bacteria-rich, oral environment. Such injectable hybrid hydrogels, capable of achieving both facilitated osteogenesis and NIR-inducible sterilization, represent a new biomaterial for treating periodontitis.

Turning Threat to Therapy: A Nanozyme-Patch in Surgical Bed for Convenient Tumor Vaccination by Sustained In Situ Catalysis

Complete surgical resection of tumor is difficult as the invasiveness of cancer, making the residual tumor a lethal threat to patients. The situation is deteriorated by the immune suppression state after surgery, which further nourishes tumor recurrence and metastasis. Immunotherapy is promising to combat tumor metastasis, but is limited by severe toxicity of traditional immunostimulants and complexity of multiple functional units. Here, it is reported that the simple "trans-surgical bed" delivery of Cu2- xSe nanozyme (CSN) by a microneedle-patch can turn the threat to therapy by efficient in situ vaccination. The biocompatible CSN exhibits both peroxidase and glutathione oxidase-like activities, efficiently exhausting glutathione, boosting free radical generation, and inducing immunogenic cell death. The once-for-all inserting of the patch on surgical bed facilitates sustained catalytic action, leading to drastic decrease of recurrence rate and complete suppression of tumor-rechallenge in cured mice. In vivo mechanism interrogation reveals elevated cytotoxic T cell infiltration, re-educated macrophages, increased dendritic cell maturation, and memory T cells formation. Importantly, preliminary metabolism and safety evaluation validated that the metal accumulation is marginable, and the important biochemical indexes are in normal range during therapy. This study has provided a simple, safe, and robust tumor vaccination approach for postsurgical metastasis control.

Bone Tissue Engineering and Nanotechnology: A Promising Combination for Bone Regeneration

Large bone defects are the leading contributor to disability worldwide, affecting approximately 1.71 billion people. Conventional bone graft treatments show several disadvantages that negatively impact their therapeutic outcomes and limit their clinical practice. Therefore, much effort has been made to devise new and more effective approaches. In this context, bone tissue engineering (BTE), involving the use of biomaterials which are able to mimic the natural architecture of bone, has emerged as a key strategy for the regeneration of large defects. However, although different types of biomaterials for bone regeneration have been developed and investigated, to date, none of them has been able to completely fulfill the requirements of an ideal implantable material. In this context, in recent years, the field of nanotechnology and the application of nanomaterials to regenerative medicine have gained significant attention from researchers. Nanotechnology has revolutionized the BTE field due to the possibility of generating nanoengineered particles that are able to overcome the current limitations in regenerative strategies, including reduced cell proliferation and differentiation, the inadequate mechanical strength of biomaterials, and poor production of extrinsic factors which are necessary for efficient osteogenesis. In this review, we report on the latest in vitro and in vivo studies on the impact of nanotechnology in the field of BTE, focusing on the effects of nanoparticles on the properties of cells and the use of biomaterials for bone regeneration.

Oxidized alginate-gelatin (ADA-GEL)/silk fibroin/Cu-Ag doped mesoporous bioactive glass nanoparticle-based hydrogels for potential wound care treatments

The present work focuses on developing 5% w/v oxidized alginate (alginate di aldehyde, ADA)-7.5% w/v gelatin (GEL) hydrogels incorporating 0.25% w/v silk fibroin (SF) and loaded with 0.3% w/v Cu-Ag doped mesoporous bioactive glass nanoparticles (Cu-Ag MBGNs). The microstructural, mechanical, and biological properties of the composite hydrogels were characterized in detail. The porous microstructure of the developed ADA-GEL based hydrogels was confirmed by scanning electron microscopy, while the presence of Cu-Ag MBGNs in the synthesized hydrogels was determined using energy dispersive x-ray spectroscopy. The incorporation of 0.3% w/v Cu-Ag MBGNs reduced the mechanical properties of the synthesized hydrogels, as investigated using micro-tensile testing. The synthesized ADA-GEL loaded with 0.25% w/v SF and 0.3% w/v Cu-Ag MBGNs showed a potent antibacterial effect againstEscherichia coliandStaphylococcus aureus. Cellular studies using the NIH3T3-E1 fibroblast cell line confirmed that ADA-GEL films incorporated with 0.3% w/v Cu-Ag MBGNs exhibited promising cellular viability as compared to pure ADA-GEL (determined by WST-8 assay). The addition of SF improved the biocompatibility, degradation rate, moisturizing effects, and stretchability of the developed hydrogels, as determinedin vitro. Such multimaterial hydrogels can stimulate angiogenesis and exhibit desirable antibacterial properties. Therefore further (in vivo) tests are justified to assess the hydrogels' potential for wound dressing and skin tissue healing applications.

Current status of development and biomedical applications of peptide-based antimicrobial hydrogels

Microbial contamination poses a serious threat to human life and health. Through the intersection of material science and modern medicine, advanced bionic hydrogels have shown great potential for biomedical applications due to their unique bioactivity and ability to mimic the extracellular matrix environment. In particular, as a promising antimicrobial material, the synthesis and practical biomedical applications of peptide-based antimicrobial hydrogels have drawn increasing research interest. The synergistic effect of peptides and hydrogels facilitate the controlled release of antimicrobial agents and mitigation of their biotoxicity while achieving antimicrobial effects and protecting the active agents from degradation. This review reports on the progress and trends of researches in the last five years and provides a brief outlook, aiming to provide theoretical background on peptide-based antimicrobial hydrogels and make suggestions for future related work.

Advancements in incorporating metal ions onto the surface of biomedical titanium and its alloys via micro-arc oxidation: a research review

The incorporation of biologically active metallic elements into nano/micron-scale coatings through micro-arc oxidation (MAO) shows significant potential in enhancing the biological characteristics and functionality of titanium-based materials. By introducing diverse metal ions onto titanium implant surfaces, not only can their antibacterial, anti-inflammatory and corrosion resistance properties be heightened, but it also promotes vascular growth and facilitates the formation of new bone tissue. This review provides a thorough examination of recent advancements in this field, covering the characteristics of commonly used metal ions and their associated preparation parameters. It also highlights the diverse applications of specific metal ions in enhancing osteogenesis, angiogenesis, antibacterial efficacy, anti-inflammatory and corrosion resistance properties of titanium implants. Furthermore, the review discusses challenges faced and future prospects in this promising area of research. In conclusion, the synergistic approach of micro-arc oxidation and metal ion doping demonstrates substantial promise in advancing the effectiveness of biomedical titanium and its alloys, promising improved outcomes in medical implant applications.

Bio-response of copper-magnesium co-substituted mesoporous bioactive glass for bone tissue regeneration

Mesoporous bioactive glass (MBG) is widely acknowledged in bone tissue engineering due to its mesoporous structure, large surface area, and bioactivity. Recent research indicates that introduction of metallic ions has beneficial impacts on bone metabolism and angiogenesis. Thus, the features of MBG can be modified by incorporating combinations of ions, such as magnesium (Mg) and copper (Cu), which can play a considerable role in bone formation, influencing angiogenesis, osteogenesis, as well as antibacterial properties. In this study, Mg and Cu were co-doped for the first time (in a ratio of 1 : 1) in 80SiO2-5P2O5-(15 - 2x)CaO-xMgO-xCuO glass composition with x = 0, 0.5, 1, and 2 mol%, synthesized using the sol-gel and evaporation-induced self-assembly method. X-ray diffraction analysis confirmed the amorphous nature of the powders, while inductively coupled plasma-optical emission spectrometry verified the existence of dopant ions in the respective amounts. The nitrogen sorption method indicated the formation of uniform cylindrical mesopores which are open at both ends and a high surface area of the powders. TEM images show fringes, indicating an ordered mesoporous structure in all MgCu co-doped systems. In vitro bioactivity was observed in all MBG powders, confirmed by the formation of an apatite phase when placed in simulated body fluid (SBF). Flake-like microstructure characteristics of HAp crystals found on the surface of MBG powders were visualized using FESEM. Cytotoxicity tests at lower concentrations (0.1 and 1 wt/vol%) of co-doped 2MC MBG (co-doping up to 2 mol%) showed cell proliferation and viability of osteoblast-like MG-63 cells and normal human dermal fibroblast (NHDF) cells similar to the basic glass 80S. Antibacterial study of MBG pellets showed an increment in the zone of inhibition with the sequential addition of doping ions. The turbidity measurement of bacterial cultures revealed that the optimal concentration for effectively inhibiting bacterial growth was 1 wt/vol% (i.e., 10 mg mL-1) concentration of MBG extracts. The result suggested that the incorporation of Mg and Cu ions in MBG in lower concentrations of up to 2 mol% can be useful in bone regeneration owing to bioactivity, cell proliferation, and antibacterial characteristics.

Copper-doped magnesium phosphate nanopowders for critical size calvarial bone defect intervention

Calvarial defects of bone present difficult clinical situations, and their restoration using biocompatible materials requires special treatments that enable bone regeneration. Magnesium phosphate (MgP) is known as an osteoinductive biomaterial because it contains Mg2+ ions and P ions that enhance the activity of osteoplast cells and help in bone regeneration. In this study, MgP and CuO-doped MgP were fabricated and characterized for their physicomechanical properties, particle size, morphology, surface area, antibacterial test, and in vitro bioactivity evaluation using the following techniques: X-rays diffraction, Fourier-transformer infrared, TEM, and Brunauer, Emmett and Teller (BET) surface area, X-rays photoelectron spectroscopy (XPS), and Scanning electron microscopy (SEM). Furthermore, these nanopowders were implanted in adult inbred male Wistar rats and studied after two periods (28 and 56 days). The results demonstrated that the obtained semiamorphous powders are in nanoscale (≤ 50 nm). XPS analysis ensured the preparation of MgP as mono MgP and CuO were incorporated in the structure as Cu2+ . The bioactivity was supported by the observation of calcium phosphate layer on the nanopowders' surface. The in vivo study demonstrated success of MgP nanopowders especially those doped with CuO in restoration of calvarial defect bone. Therefore, fabricated biomaterials are of great potential in restoration of bone calvarial defects.

Research progress on cuproptosis in cancer

Cuproptosis is a recently discovered form of cell death that is mediated by copper (Cu) and is a non-apoptotic form of cell death related to oligomerization of lipoylated proteins and loss of Fe-S protein clusters. Since its discovery, cuproptosis has been extensively studied by researchers for its mechanism and potential applications in the treatment of cancer. Therefore, this article reviews the specific mechanism of cuproptosis currently studied, as well as its principles and strategies for use in anti-cancer treatment, with the aim of providing a reference for cuproptosis-based cancer therapy.

Enhanced healing of wounds that responded poorly to silver dressing by copper wound dressings: Prospective single arm treatment study

Background and Aims

Dressings containing silver ions are an accepted and common option for wound treatment. However, some wounds fail to heal at the desired rate despite optimal management. The aim of the study was to examine the effect of copper dressings in noninfected wounds.

Methods

The study included 20 patients aged 18-85 years with 2-30 cm2 noninfected wounds treated for 17-41 days with silver wound dressings that failed to reduce by >50% the wound size, who were then treated with copper dressings. Ten patients were diabetics, 10 suffered from hypertension, and six suffered from peripheral vascular disease (PVD). Two patients suffered from two wounds. Most were amputation wounds below the knee.

Results

Five patients dropped out from the study due to complications not related to the wound. The mean period of silver and copper dressings treatment was 25.6 and 29.6 days, respectively (p = 0.25; t test). None of the wounds became infected. Comparing a period of 25 days, during the copper dressings treatment, the mean wound area reduction was ~2.4 times higher than during the silver dressing treatment, 87.35 ± 22.4% versus 37.02 ± 25.11% (mean ± SD; p < 0.001; paired t test), respectively. The average decline during the silver and copper treatments were 1.2% and 2.14% per day (p = 0.002; multiple regression analysis), respectively.

Conclusions

The enhanced wound healing process observed with the copper dressings may be explained by the integral role of copper throughout all physiological skin repair processes. Silver in contrast has no physiological role in wound healing. The results of our study confirm case reports showing enhanced wound healing of hard-to-heal wounds with copper dressings, both of infected and noninfected wounds. Taken together, the results of the current study support the hypothesis that the application of copper dressings in situ for noninfected wounds results in the stimulation of the wound healing processes, as opposed to silver dressings.

Bifunctional tissue-engineered composite construct for bone regeneration: The role of copper and fibrin

Bifunctional tissue engineering constructs promoting osteogenesis and angiogenesis are essential for bone regeneration. Metal ion-incorporated scaffolds and fibrin encapsulation attract much attention due to low cost, nontoxicity, and tunable control over ion and growth factor release. Herein, we investigated the effect of Cu.nHA/Cs/Gel scaffold and fibrin encapsulation on osteogenic and angiogenic differentiation of Wharton's jelly mesenchymal stem cells (WJMSCs) in vitro and in vivo. Cu-laden scaffolds were synthesized using salt leaching/freeze drying and were characterized using standard techniques. WJMSCs were isolated from the human umbilical cord and characterized. WJMSCs with or without encapsulating in fibrin were seeded onto scaffolds, followed by differentiating into the osteogenic lineage for 7 and 21 days. Osteogenic and angiogenic differentiation were evaluated using real-time polymerase chain reaction, western blot, and Alizarin red staining. Then, scaffolds were implanted into critical-sized calvarial bone defects in rats and histological assessments were performed using hematoxylin/eosin, Masson's trichrome, and CD31 immunohistochemical staining at 4 and 12 weeks. The scaffolds had good physicochemical and biological characteristics suitable for cell attachment and growth. Cu and fibrin increased the expression of ALP, RUNX2, OCN, COLI, VEGF, and HIF1α in differentiated WJMSCs. Implanted scaffolds were also biocompatible and were integrated well with the host tissue. Increased collagen condensation, mineralization, and blood vessel formation were observed in Cu-laden scaffolds. The fibrin-encapsulated groups showed the highest collagen and cell densities, immune cell infiltration, and bone trabeculae. CD31-positive cell population increased with fibrin encapsulation and seeding onto Cu-laden scaffolds. Adding Cu to scaffolds and encapsulating cells in fibrin are promising methods that guide osteogenesis and angiogenesis cellular signaling, leading to better bone regeneration.

Cuproptosis: A novel therapeutic target for overcoming cancer drug resistance

Cuproptosis is a newly identified form of cell death driven by copper. Recently, the role of copper and copper triggered cell death in the pathogenesis of cancers have attracted attentions. Cuproptosis has garnered enormous interest in cancer research communities because of its great potential for cancer therapy. Copper-based treatment exerts an inhibiting role in tumor growth and may open the door for the treatment of chemotherapy-insensitive tumors. In this review, we provide a critical analysis on copper homeostasis and the role of copper dysregulation in the development and progression of cancers. Then the core molecular mechanisms of cuproptosis and its role in cancer is discussed, followed by summarizing the current understanding of copper-based agents (copper chelators, copper ionophores, and copper complexes-based dynamic therapy) for cancer treatment. Additionally, we summarize the emerging data on copper complexes-based agents and copper ionophores to subdue tumor chemotherapy resistance in different types of cancers. We also review the small-molecule compounds and nanoparticles (NPs) that may kill cancer cells by inducing cuproptosis, which will shed new light on the development of anticancer drugs through inducing cuproptosis in the future. Finally, the important concepts and pressing questions of cuproptosis in future research that should be focused on were discussed. This review article suggests that targeting cuproptosis could be a novel antitumor therapy and treatment strategy to overcome cancer drug resistance.

Continuum of care in hard-to-heal wounds by copper dressings: a case series

OBJECTIVE

The quest for an ideal wound dressing has been a longstanding challenge due to the complex nature of wound healing, including stages of haemostasis, inflammation, maturation and remodelling, with overlapping timelines. This makes it difficult to find a single dressing that optimally supports all phases of wound healing. In addition, the ideal wound dressing should possess antibacterial properties and be capable of effectively debriding and lysing necrotic tissue. Copper is an essential trace element that participates in many of the key physiological wound healing processes.

METHOD

Copper stimulates secretion of various cytokines and growth factors, thus promoting angiogenesis, granulation tissue formation, extracellular matrix proteins secretion and re-epithelialisation. Harnessing this knowledge, we have used copper oxide-impregnated wound dressings in numerous cases and observed their benefits throughout the entire wound healing process.

RESULTS

This led us to postulate the 'continuum of care' hypothesis of copper dressings. In this study we describe four cases of hard-to-heal wounds of various aetiologies, in which we applied copper dressings consistently across all stages of wound healing, with rapid uneventful healing.

CONCLUSION

We believe we have successfully implemented the continuum of care principle.

3D Printing Assisted Fabrication of Copper-Silver Mesoporous Bioactive Glass Nanoparticles Reinforced Sodium Alginate/Poly(vinyl alcohol) Based Composite Scaffolds: Designed for Skin Tissue Engineering

Additive manufacturing (also known as 3D printing) is a promising method for producing patient-specific implants. In the present study, sodium alginate (Na-ALG)/poly(vinyl alcohol) (PVA) polymer blends of varying ratios (1:0, 3:1, 1:1, and 1:3) were used to produce tailored-designed skin scaffolds using a 3D bioprinter. Samples of skin scaffolds were printed at 20 layers with a layer height of 0.15 mm using a needle with an inner diameter of 330 μm while maintaining the extrusion speed, extrusion width, and fill density at 10 mm/s, 0.2 mm, and 85%, respectively. The Na-ALG/PVA blend with a 3:1 ratio showed the best printability due to its good viscosity and minimal nozzle leakage, allowing for the fabrication of skin scaffolds with high fidelity and the desired morphological characteristics. Then, copper-silver doped mesoporous bioactive glass nanoparticles (Cu-Ag MBGNs) were incorporated into the Na-ALG/PVA blend (which had already been prepared by using a Na-ALG:PVA ratio of 3:1) in order to obtain therapeutic (angiogenic and antibacterial) effects. The fabricated Na-ALG/PVA/Cu-Ag MBGNs biocomposite scaffolds with dimensions of 20 mm× 20 × 3 mm3 and pore size of 400 ± 60 μm exhibited a promising fidelity. The presence of chemical bonds attributed to Na-ALG, PVA, and Cu-Ag MBGNs and the uniform distribution of Na, C, and O elements within the microstructure of the scaffolds were confirmed by EDX, SEM, and FTIR analyses. The scaffolds were hydrophilic and exhibited proper swelling and degradation behavior for skin tissue engineering. According to the inhibition halo test, the scaffolds exhibited strong antibacterial activity against Staphylococcus aureus and Escherichia coli. The cytocompatibility to human-derived fibroblast cells was confirmed by the WST-8 assay and in vivo Chorioallantoic Membrane Assay. In addition, Na-ALG/PVA/Cu-Ag MBGNs showed angiogenic potential, exhibiting favorable wound healing properties.

Effect of Low Copper Doping on the Optical, Cytocompatible, Antibacterial, and SARS-CoV-2 Trapping Properties of Calcium Phosphate Glasses

Calcium phosphate glasses (CPGs) are acquiring great importance in the biomedical field because of their thermomechanical and bioresorbable properties. In this study, optically transparent copper (1 mol %)-doped calcium phosphate glasses (CPGs_Cu) were prepared through the melt-quenching method, and their biocompatibility and antibacterial and antiviral properties were evaluated and compared with undoped CPGs. Biocompatibility was evaluated on murine fibroblast NIH-3T3 cells as a preliminary study of cytocompatibility. The in vitro tests were performed through indirect and direct cytotoxicity analyses by MTT and Alamar Blue assays and supported by electron microscopy observations. Microbiological analyses were performed against the most common Gram-negative and Gram-positive pathogens that cause nosocomial infections: Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, and the methicillin-resistant Staphylococcus aureus strain. In addition, the bioglass samples were exposed to SARS-CoV-2 to assess their effects on viral survival. The obtained results assessed the biocompatibility of both bioglass types and their ability to reduce the viral load and trap the virus. In addition, Cu2+-doped bioglass was found to be antibacterial despite its low content (1 mol %) of copper, making this a promising candidate material for biomedical applications, e.g., surgery probes, drug delivery, and photodynamic therapy.

Multifunctional bioactive glasses with spontaneous degradation for simultaneous osteosarcoma therapy and bone regeneration

For the treatment of tumor-related bone defects resulting from surgical resection, simultaneous eradication of residual tumor cells and repair of bone defects represent a challenge. To date, photothermal therapy based on photothermal materials is used to remove residual tumor cells under near infrared light. However, most of photothermal materials have no function for bone repair, and even if combined with bioactive materials to enhance osteogenesis, they still cause potential harm to the body due to inability to degrade or poor degradability. Herein, multifunctional bioactive glasses (PGFe5-1100, PGCu5-1100) based on phosphate glass doped with transition metal elements were prepared for photothermal ablation, bone regeneration, and controllable degradation. The glasses exhibited excellent photothermal effect, which was derived from the electron in-band transition after light absorption due to energy level splitting of doped transition metal element and the subsequent electron nonradiative relaxation. The photothermal performance can be controlled by laser power density, element doping content and glass melting temperature. Moreover, the hyperthermia induced by the glasses can effectively kill tumor cells in vitro. In addition, the glasses degraded over time, and the released P, Ca, Na, Fe could promote bone cell proliferation and osteogenic differentiation. Therefore, these results successfully demonstrated that transition metal element-doped phosphate glasses have multifunctional abilities of tumor elimination, bone regeneration, and spontaneous degradation simultaneously with better biosecurity and bioactivity, which is believed to pave the way for the design of novel biomaterials for osteosarcoma treatment.

A prognostic and immunotherapy effectiveness model for pancreatic adenocarcinoma based on cuproptosis-related lncRNAs signature

Pancreatic adenocarcinoma (PAAD) results in one of the deadliest solid tumors with discouraging clinical outcomes. Growing evidence suggests that long non-coding RNAs (lncRNAs) play a crucial role in altering the growth, prognosis, migration, and invasion of pancreatic cancer cells. Cuproptosis is a novel type of cell death induced by copper (Cu) and is associated with mitochondrial respiration during the tricarboxylic acid cycle. However, the relationship between lncRNAs related to cuproptosis and PAAD is poorly studied. In this study, we investigated the association between a signature of cuproptosis-related lncRNAs and the diagnosis of PAAD. Genomic data and clinical information were obtained using the TCGA dataset, while cuproptosis-related genes (CRGs) from previous studies. Co-expression analysis was utilized to identify lncRNAs associated with cuproptosis. We developed and verified a prognostic risk model following a classification of patients into high- and low-risk categories. The prediction capacity of the risk model was assessed using a number of methods including Kaplan-Meier analysis, receiver operating characteristic (ROC) curves, nomograms, and principal component analysis (PCA). Furthermore, differentially expressed genes (DEGs) were used to perform functional enrichment analyses, and to examine the behaviors of various risk groups in terms of immune-related activities and medication sensitivity. We identified 7 cuproptosis-related lncRNA signatures, including CASC19, FAM83A-AS1, AC074099.1, AC007292.2, AC026462.3, AL358944.1, and AC009019.1, as overall survival (OS) predictors. OS and progression-free survival (PFS) showed significant differences among patients in different risk groups. Independent prognostic analysis revealed that the cuproptosis-related lncRNA signatures can independently achieve patient prognosis. The risk model demonstrated strong predictive ability for patient outcomes, as evidenced by ROC curves, nomograms, and PCA. Higher tumor mutation burden (TMB) and lower tumor immune dysfunction and exclusion (TIDE) scores were observed in the high-risk group. Additionally, the low-risk group was hypersensitive to 3 anti-cancer medications, whereas the high-risk group was hypersensitive to one. A prognostic risk model with a good predictive ability based on cuproptosis-related lncRNAs was developed, providing a theoretical basis for personalized treatment and immunotherapeutic responses in pancreatic cancer.

A phellinus igniarius polysaccharide/chitosan-arginine hydrogel for promoting diabetic wound healing

Inadequate angiogenesis and inflammation at the wound site have always been a major threat to skin wounds, especially for diabetic wounds that are difficult to heal. Therefore, hydrogel dressings with angiogenesis and antibacterial properties are very necessary in practical applications. This study reported a hydrogel (PCA) based on L-arginine conjugated chitosan (CA) and aldehyde functionalized polysaccharides of Phellinus igniarius (OPPI) as an antibacterial and pro-angiogenesis dressing for wound repair in diabetes for the first time. and discussed its possible mechanism for promoting wound healing. The results showed that PCA had good antioxidant, antibacterial, biological safety and other characteristics, and effectively promoted the healing course of diabetic wound model. In detail, the H&E and Masson staining results showed that PCA promoted normal epithelial formation and collagen deposition. The Western blot results confirmed that PCA decreased the inflammation by inhibiting the IKBα/NF-κB signaling pathway and enhanced angiogenesis by adjusting the level of HIF-1α. In conclusion, PCA is a promising candidate for promoting wound healing in diabetes. Graphic abstract.

Development and validation of a copper-related gene prognostic signature in hepatocellular carcinoma

Introduction: Reliable biomarkers are in need to predict the prognosis of hepatocellular carcinoma (HCC). Whilst recent evidence has established the critical role of copper homeostasis in tumor growth and progression, no previous studies have dealt with the copper-related genes (CRGs) signature with prognostic potential in HCC. Methods: To develop and validate a CRGs prognostic signature for HCC, we retrospectively included 353 and 142 patients as the development and validation cohort, respectively. Copper-related Prognostic Signature (Copper-PSHC) was developed using differentially expressed CRGs with prognostic value. The hazard ratio (HR) and the area under the time-dependent receiver operating characteristic curve (AUC) during 3-year follow-up were utilized to evaluate the performance. Additionally, the Copper-PSHC was combined with age, sex, and cancer stage to construct a Copper-clinical-related Prognostic Signature (Copper-CPSHC), by multivariate Cox regression. We further explored the underlying mechanism of Copper-PSHC by analyzing the somatic mutation, functional enrichment, and tumor microenvironment. Potential drugs for the high-risk group were screened. Results: The Copper-PSHC was constructed with nine CRGs. Patients in the high-risk group demonstrated a significantly reduced overall survival (OS) (adjusted HR, 2.65 [95% CI, 1.83-3.84] and 3.30, [95% CI, 1.27-8.60] in the development and validation cohort, respectively). The Copper-PSHC achieved a 3-year AUC of 0.74 [95% CI, 0.67-0.82] and 0.71 [95% CI, 0.56-0.86] for OS in the development and validation cohort, respectively. Copper-CPSHC yield a 3-year AUC of 0.73 [95% CI, 0.66-0.80] and 0.72 [95% CI, 0.56-0.87] for OS in the development and validation cohort, respectively. Higher tumor mutation burden, downregulated metabolic processes, hypoxia status and infiltrated stroma cells were found for the high-risk group. Six small molecular drugs were screened for the treatment of the high-risk group. Conclusion: Copper-PSHC services as a promising tool to identify HCC with poor prognosis and to improve disease outcomes by providing potential clinical decision support in treatment.

Antibacterial Biomaterial Based on Bioglass Modified with Copper for Implants Coating

Biofilm-related implant infections pose a substantial threat to patients, leading to inflammation in the surrounding tissue, and often resulting in implant loss and the necessity for additional surgeries. Overcoming this implantology challenge is crucial to ensure the success and durability of implants. This study shows the development of antibacterial materials for implant coatings by incorporating copper into 45S5 Bioglass^®. By combining the regenerative properties of Bioglass^® with the antimicrobial effects of copper, this material has the potential to prevent infections, enhance osseointegration and improve the long-term success of implants. Bioglasses modified with various concentrations of CuO (from 0 to 8 mol%) were prepared with the melt-quenching technique. Structural analysis using Raman and FTIR spectroscopies did not reveal significant alterations in the bioglasses structure with the addition of Cu. The antibacterial activity of the samples was assessed against Gram-positive and Gram-negative bacteria, and the results demonstrated significant inhibition of bacterial growth for the bioglass with 0.5 mol% of CuO. Cell viability studies indicated that the samples modified with up to 4 mol% of CuO maintained good cytocompatibility with the Saos-2 cell line at extract concentrations up to 25 mg/mL. Furthermore, the bioactivity assessment demonstrated the formation of a calcium phosphate (CaP)-rich layer on the surfaces of all bioglasses within 24 h. Our findings show that the inclusion of copper in the bioglass offers a significant enhancement in its potential as a coating material for implants, resulting in notable advancements in both antibacterial efficacy and osteointegration properties.

Janus porous polylactic acid membranes with versatile metal-phenolic interface for biomimetic periodontal bone regeneration

Conventional treatment to periodontal and many other bone defects requires the use of barrier membranes to guided tissue regeneration (GTR) and guided bone regeneration (GBR). However, current barrier membranes normally lack of the ability to actively regulate the bone repairing process. Herein, we proposed a biomimetic bone tissue engineering strategy enabled by a new type of Janus porous polylactic acid membrane (PLAM), which was fabricated by combining unidirectional evaporation-induced pore formation with subsequent self-assembly of a bioactive metal-phenolic network (MPN) nanointerface. The prepared PLAM-MPN simultaneously possesses barrier function on the dense side and bone-forming function on the porous side. In vitro, the presence of MPN nanointerface potently alleviated the proinflammatory polarization of mice bone marrow-derived macrophages (BMDMs), induced angiogenesis of human umbilical vein endothelial cells (HUVECs), and enhanced the attachment, migration and osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs). The implantation of PLAM-MPN into rat periodontal bone defects remarkably enhanced bone regeneration. This bioactive MPN nanointerface within a Janus porous membrane possesses versatile capacities to regulate cell physiology favoring bone regeneration, demonstrating great potential as GTR and GBR membranes for clinical applications.

Portable Handheld "SkinPen" Loaded with Biomaterial Ink for In Situ Wound Healing

In situ bioprinting has emerged as an attractive tool for directly depositing therapy ink at the defective area to adapt to the irregular wound shape. However, traditional bioprinting exhibits an obvious limitation in terms of an unsatisfactory bioadhesive effect. Here, a portable handheld bioprinter loaded with biomaterial ink is designed and named "SkinPen". Gelatin methacrylate (GelMA) and Cu-containing bioactive glass nanoparticles (Cu-BGn) serve as the main components to form the hydrogel ink, which displays excellent biocompatibility and antibacterial and angiogenic properties. More importantly, by introducing ultrasound and ultraviolet in a sequential programmed manner, the SkinPen achieves in situ instant gelation and amplified (more than threefold) bioadhesive shear strength. It is suggested that ultrasound-induced cavitation and the resulting topological entanglement contribute to the enhanced bioadhesive performance together. Combining the ultrasound-enhanced bioadhesion with the curative role of the hydrogel, the SkinPen shows a satisfactory wound-healing effect in diabetic rats. Given the detachable property of the SkinPen, the whole device can be put in a first-aid kit. Therefore, the application scenarios can be expanded to many kinds of accidents. Overall, this work presents a portable handheld SkinPen that might provide a facile but effective approach for clinical wound management.

Fabrication of Cu2+-loaded phase-transited lysozyme nanofilm on bacterial cellulose: Antibacterial, anti-inflammatory, and pro-angiogenesis for bacteria-infected wound healing

Bacterial overgrowth in injured wounds causes wound infection and excessive inflammation, leading to delayed wound healing. Successful treatment of delayed infected wound healing demands dressings, which can inhibit bacterial growth and inflammation and simultaneously induce vascularization, collagen deposition, and re-epithelialization of wounds. In this study, bacterial cellulose (BC) deposited with Cu²⁺-loaded phase-transited lysozyme (PTL) nanofilm (BC/PTL/Cu) was prepared for healing infected wounds. The results confirm that PTL were successfully self-assembled on BC matrix, and Cu²⁺ were loaded into PTL through electrostatic coordination. The tensile strength and the elongation at break of the membranes were not significantly changed after modification with PTL and Cu²⁺. Compared with BC, the surface roughness of BC/PTL/Cu significantly increased while the hydrophilicity decreased. Moreover, BC/PTL/Cu displayed slower release rate of Cu²⁺ compared with BC directly loaded with Cu²⁺. BC/PTL/Cu exhibited good antibacterial activity against Staphylococcus aureus, Escherichia coli, Bacillus subtilis, and Pseudomonas aeruginosa. By controlling copper concentration, BC/PTL/Cu were not cytotoxic to mouse fibroblast cell line L929. In vivo, BC/PTL/Cu accelerated wound healing and promoted re-epithelialization, collagen deposition, and angiogenesis while inhibiting inflammation of the infected full-thickness skin wounds of rats. Collectively, these results demonstrate that BC/PTL/Cu composites are promising dressings for healing infected wounds.

Acid-degradable nanocomposite hydrogel and glucose oxidase combination for killing bacterial with photothermal augmented chemodynamic therapy

Bacterial infection often delays diabetic wound healing, and even causes serious life-threatening complications. Herein, we successfully developed a Cu₂O/Pt nanocubes-dopping alginate (ALG)- hyaluronic acid (HA) hydrogel (Cu₂O/Pt hydrogel) by simple assembly of the Cu₂O/Pt nanocubes and the ALG-HA mixture. The Cu₂O/Pt hydrogel combined with the glucose oxidase (GOx) can be used for photothermal- and starving-enhanced chemodynamic therapy (CDT) against Gram-negative and Gram-positive bacteria. The GOx can catalyze the glucose to produce gluconic acid and H₂O₂ for starvation therapy, following which the released Cu₂O/Pt nanocubes react with H₂O₂ in the acidic microenvironment to generate highly cytotoxic hydroxyl radicals (·OH) for CDT. Additionally, the Cu₂O/Pt hydrogel can release copper ions gradually with the decrease of pH induced by gluconic acid, which can increase the protein expression and secretion of vascular endothelial growth factor (VEGF) and promote endothelial cell proliferation, migration and angiogenesis, subsequently promoting diabetic wound healing in rats. Our results suggested that the Cu₂O/Pt hydrogel combined with GOx may be a potential therapeutic approach for treating the infected diabetic wound.

How to Promote Skin Repair? In-Depth Look at Pharmaceutical and Cosmetic Strategies

Skin repair encompasses epidermal barrier repair and wound healing which involves multiple cellular and molecular stages. Therefore, many skin repair strategies have been proposed. In order to characterize the usage frequency of skin repair ingredients in cosmetics, medicines, and medical devices, commercialized in Portuguese pharmacies and parapharmacies, a comprehensive analysis of the products' composition was performed. A total of 120 cosmetic products, collected from national pharmacies online platforms, 21 topical medicines, and 46 medical devices, collected from INFARMED database, were included in the study, revealing the top 10 most used skin repair ingredients in these categories. A critical review regarding the effectiveness of the top ingredients was performed and an in-depth analysis focused on the top three skin repair ingredients pursued. Results demonstrated that top three most used cosmetic ingredients were metal salts and oxides (78.3%), vitamin E and its derivatives (54.2%), and Centella asiatica (L.) Urb. extract and actives (35.8%). Regarding medicines, metal salts and oxides were also the most used (47.4%) followed by vitamin B5 and derivatives (23.8%), and vitamin A and derivatives (26.3%). Silicones and derivatives were the most common skin repair ingredients in medical devices (33%), followed by petrolatum and derivatives (22%) and alginate (15%). This work provides an overview of the most used skin repair ingredients, highlighting their different mechanisms of action, aiming to provide an up-to-date tool to support health professionals' decisions.

Influence of Silver Nanoparticles on the Growth of Ascitic and Solid Ehrlich Adenocarcinoma: Focus on Copper Metabolism

The link between copper metabolism and tumor progression motivated us to use copper chelators for suppression of tumor growth. We assume that silver nanoparticles (AgNPs) can be used for lowering bioavailable copper. Our assumption is based on the ability of Ag(I) ions released by AgNPs in biological media and interfere with Cu(I) transport. Intervention of Ag(I) into copper metabolism leads to the replacement of copper by silver in ceruloplasmin and the decrease in bioavailable copper in the bloodstream. To check this assumption, mice with ascitic or solid Ehrlich adenocarcinoma (EAC) were treated with AgNPs using different protocols. Copper status indexes (copper concentration, ceruloplasmin protein level, and oxidase activity) were monitored to assess copper metabolism. The expression of copper-related genes was determined by real-time PCR in the liver and tumors, and copper and silver levels were measured by FAAS. Intraperitoneal AgNPs treatment beginning on the day of tumor inoculation enhanced mice survival, reduced the proliferation of ascitic EAC cells, and suppressed the activity of HIF1α, TNF-α and VEGFa genes. Topical treatment by the AgNPs, which was started together with the implantation of EAC cells in the thigh, also enhanced mice survival, decreased tumor growth, and repressed genes responsible for neovascularization. The advantages of silver-induced copper deficiency over copper chelators are discussed.

Dually Crosslinked Copper-Poly(tannic acid) Nanoparticles with Microenvironment-Responsiveness for Infected Wound Treatment

Reducing the burden of death due to wound infection is an urgent global public health priority. Metal-phenolic networks (MPNs) have received widespread attention in antimicrobial infections due to their facile synthesis process, excellent biocompatibility, and antimicrobial properties brought about by polyphenols and metal ions. However, typical therapeutic MPNs show rapid release of metal ions due to their poor solution stability, impeding long-acting efficacy in multiple wound healing stages. To address these issues, copper-poly (tannic acid) nanoparticles (Cu-PTA NPs): robust (dually crosslinked), microenvironment-responsive, antibacterial, antioxidative, and anti-inflammatory are prepared, which hierarchically modulate the infected wound healing process. Covalently polymerized via phenol-formaldehyde condensation and crosslinked with bioactive Cu²⁺ , reactive polyphenols are preserved, and Cu²⁺ is efficiently entrapped in the PTA scaffold. The proposed strategy relieves the systemic toxicity, and only high reactive oxygen species (ROS)level as stimuli can "turn on" the catalytic activity of Cu²⁺ to implement antibacterial therapy specifically in an infected wound. Systematic tissue regeneration assessment on the infected full-thickness skin wounds of rats demonstrates enhanced wound healing rate. Cu-PTA NPs enables the direct application in infected wound and exertion of long-acting healing efficacy. This synergetic therapy strategy will pave the way for more complicated infections and inflammatory diseases.

Multifunctional Three-Dimensional Printed Copper Loaded Calcium Phosphate Scaffolds for Bone Regeneration

Bone regeneration using inorganic nanoparticles is a robust and safe approach. In this paper, copper nanoparticles (Cu NPs) loaded with calcium phosphate scaffolds were studied for their bone regeneration potential in vitro. The pneumatic extrusion method of 3D printing was employed to prepare calcium phosphate cement (CPC) and copper loaded CPC scaffolds with varying wt% of copper nanoparticles. A new aliphatic compound Kollisolv MCT 70 was used to ensure the uniform mixing of copper nanoparticles with CPC matrix. The printed scaffolds were studied for physico-chemical characterization for surface morphology, pore size, wettability, XRD, and FTIR. The copper ion release was studied in phosphate buffer saline at pH 7.4. The in vitro cell culture studies for the scaffolds were performed using human mesenchymal stem cells (hMSCs). The cell proliferation study in CPC-Cu scaffolds showed significant cell growth compared to CPC. The CPC-Cu scaffolds showed improved alkaline phosphatase activity and angiogenic potential compared to CPC. The CPC-Cu scaffolds showed significant concentration dependent antibacterial activity in Staphylococcus aureus. Overall, the CPC scaffolds loaded with 1 wt% Cu NPs showed improved activity compared to other CPC-Cu and CPC scaffolds. The results showed that copper has improved the osteogenic, angiogenic and antibacterial properties of CPC scaffolds, facilitating better bone regeneration in vitro.

Melatonin ameliorates chronic copper-induced lung injury

Copper (Cu) is an important trace element required for several biological processes. The use of copper is increasing gradually in several applications. Previous studies suggest that excess levels of copper are attributed to induce oxidative stress and inflammation, mediating tissue damage. Inline, melatonin the hormone of darkness has been reported to exhibit various therapeutic effects including strong free radical scavenging properties and anti-inflammatory effects. However, its effects against pulmonary injury promoted by copper are not explored and remain unclear so far. Therefore, the present study was aimed to investigate the protective effect of melatonin against copper-induced lung damage. Female Sprague Dawley (SD) rats were exposed to 250 ppm of copper in drinking water for 16 weeks and treated with melatonin (i.p.) 5 and 10 mg/kg from the week (13-16th). The extent of tissue damage was assessed by tissue oxidative stress parameters, metal estimation and histological analysis. Copper-challenged rats showed altered oxidative stress variables. In addition, metal analysis revealed increased copper accumulation in the lungs and histological staining results further indicated severe tissue injury and inflammatory cell infiltration in copper-exposed rats. To this side, treatment with melatonin showed antioxidant and anti-inflammatory activities evidenced by reduced oxidative stress, tissue inflammation and collagen deposition as compared to copper-exposed animals. Moreover, spectral findings suggested melatonin treatment modulated the frequency sift, as compared to copper-challenged animals. Altogether, the present results suggest that melatonin might play a potential role in preventing copper-induced lung aberrations via inhibiting the ROS-mediated oxidative stress and inflammation.

Nanomaterials and nanomaterials-based drug delivery to promote cutaneous wound healing

Various factors could damage the structure and integrity of skin to cause wounds. Nonhealing or chronic wounds seriously affect the well-being of patients and bring heavy burdens to the society. The past few decades have witnessed application of numerous nanomaterials to promote wound healing. Owing to the unique physicochemical characteristics at nanoscale, nanomaterials-based therapy has been regarded as a potential approach to promote wound healing. In this review, we first overview the wound categories, wound healing process and critical influencing factors. Then applications of nanomaterials with intrinsic therapeutic effect and nanomaterials-based drug delivery systems to promote wound healing are addressed in detail. Finally, current limitations and future perspectives of nanomaterials in wound healing are discussed.

Investigating the structure, solubility, and antibacterial properties of silver- and copper-doped hydroxyapatite

Hydroxyapatite (HA) powders were synthesized by the wet precipitation method in which two experimental compositions were synthesized (10 mol% Ag-HA and Cu-HA) where the CaNO₃ content was partially substituted with AgNO₃ and Cu(NO₃ )₂ . X-ray diffraction (XRD) was employed to characterize changes to the HA structure as the dopants (Cu²⁺ , Ag⁺ ) were incorporated into the materials structure. Energy-dispersive X-ray spectroscopy (EDS) determined confirmed the compositions and found that the Ca/P ratio was 1.63 for the control (HA) while Ag-HA and Cu-HA exhibited (X + Ca)/P ratios of 1.79 and 1.65, respectively. Antibacterial efficacies were evaluated against E. coli and S. aureus, as a function of surface area and incubation time. The more prominent antibacterial effects were observed with both Ag-HA and Cu-HA and the materials antibacterial influence was maintained with respect to time. Ion release studies of each HA composition (15, 30, and 45 days) showed that Cu-HA released significantly more Cu²⁺ (36.1 ± 5.1 mg/L) than Ag⁺ (2.9 ± 1.2 mg/L) from Ag-HA. Analysis of each composition incubated in simulated body fluid (SBF) exhibited surface depositions that are likely calcium phosphate (CaP). Cytocompatibility testing in MC 3T3 Osteoblasts showed slight reductions in cell viability when tested using MTT assay, however cell adhesion studies were positive for each composition.

A review on borate bioactive glasses (BBG): effect of doping elements, degradation, and applications

Because of their excellent biologically active qualities, bioactive glasses (BGs) have been extensively used in the biomedical domain, leading to better tissue-implant interactions and promoting bone regeneration and wound healing. Aside from having attractive characteristics, BGs are appealing as a porous scaffold material. On the other hand, such porous scaffolds should enable tissue proliferation and integration with the natural bone and neighboring soft tissues and degrade at a rate that allows for new bone development while preventing bacterial colonization. Therefore, researchers have recently become interested in a different BG composition based on borate (B₂O₃) rather than silicate (SiO₂). Furthermore, apatite synthesis in the borate-based bioactive glass (BBG) is faster than in the silicate-based bioactive glass, which slowly transforms to hydroxyapatite. This low chemical durability of BBG indicates a fast degradation process, which has become a concern for their utilization in biological and biomedical applications. To address these shortcomings, glass network modifiers, active ions, and other materials can be combined with BBG to improve the bioactivity, mechanical, and regenerative properties, including its degradation potential. To this end, this review article will highlight the details of BBGs, including their structure, properties, and medical applications, such as bone regeneration, wound care, and dental/bone implant coatings. Furthermore, the mechanism of BBG surface reaction kinetics and the role of doping ions in controlling the low chemical durability of BBG and its effects on osteogenesis and angiogenesis will be outlined.

Toward Smart Biomimetic Apatite-Based Bone Scaffolds with Spatially Controlled Ion Substitutions

Biomimetic apatites exhibit a high reactivity allowing ion substitutions to modulate their in vivo response. We developed a novel approach combining several bioactive ions in a spatially controlled way in view of subsequent releases to address the sequence of events occurring after implantation, including potential microorganisms' colonization. Innovative micron-sized core-shell particles were designed with an external shell enriched with an antibacterial ion and an internal core substituted with a pro-angiogenic or osteogenic ion. After developing the proof of concept, two ions were particularly considered, Ag⁺ in the outer shell and Cu²⁺ in the inner core. In vitro evaluations confirmed the cytocompatibility through Ag-/Cu-substituting and the antibacterial properties provided by Ag⁺. Then, these multifunctional "smart" particles were embedded in a polymeric matrix by freeze-casting to prepare 3D porous scaffolds for bone engineering. This approach envisions the development of a new generation of scaffolds with tailored sequential properties for optimal bone regeneration.

The Oncopig as an Emerging Model to Investigate Copper Regulation in Cancer

Emerging evidence points to several fundamental contributions that copper (Cu) has to promote the development of human pathologies such as cancer. These recent and increasing identification of the roles of Cu in cancer biology highlights a promising field in the development of novel strategies against cancer. Cu and its network of regulatory proteins are involved in many different contextual aspects of cancer from driving cell signaling, modulating cell cycle progression, establishing the epithelial-mesenchymal transition, and promoting tumor growth and metastasis. Human cancer research in general requires refined models to bridge the gap between basic science research and meaningful clinical trials. Classic studies in cultured cancer cell lines and animal models such as mice and rats often present caveats when extended to humans due to inherent genetic and physiological differences. However, larger animal models such as pigs are emerging as more appropriate tools for translational research as they present more similarities with humans in terms of genetics, anatomical structures, organ sizes, and pathological manifestations of diseases like cancer. These similarities make porcine models well-suited for addressing long standing questions in cancer biology as well as in the arena of novel drug and therapeutic development against human cancers. With the emergent roles of Cu in human health and pathology, the pig presents an emerging and valuable model to further investigate the contributions of this metal to human cancers. The Oncopig Cancer Model is a transgenic swine model that recapitulates human cancer through development of site and cell specific tumors. In this review, we briefly outline the relationship between Cu and cancer, and how the novel Oncopig Cancer Model may be used to provide a better understanding of the mechanisms and causal relationships between Cu and molecular targets involved in cancer.