Heterostructured piezocatalytic nanoparticles with enhanced ultrasound response for efficient repair of infectious bone defects

3D-printed zinc oxide nanoparticles modified barium titanate/hydroxyapatite ultrasound-responsive piezoelectric ceramic composite scaffold for treating infected bone defects

Clinically, infectious bone defects represent a significant threat, leading to osteonecrosis, severely compromising patient prognosis, and prolonging hospital stays. Thus, there is an urgent need to develop a bone graft substitute that combines broad-spectrum antibacterial efficacy and bone-inductive properties, providing an effective treatment option for infectious bone defects. In this study, the precision of digital light processing (DLP) 3D printing technology was utilized to construct a scaffold, incorporating zinc oxide nanoparticles (ZnO-NPs) modified barium titanate (BT) with hydroxyapatite (HA), resulting in a piezoelectric ceramic scaffold designed for the repair of infected bone defects. The results indicated that the addition of ZnO-NPs significantly improved the piezoelectric properties of BT, facilitating a higher HA content within the ceramic scaffold system, which is essential for bone regeneration. In vitro antibacterial assessments highlighted the scaffold's potent antibacterial capabilities. Moreover, combining the synergistic effects of low-intensity pulsed ultrasound (LIPUS) and piezoelectricity, results demonstrated that the scaffold promoted notable osteogenic and angiogenic potential, enhancing bone growth and repair. Furthermore, transcriptomics analysis results suggested that the early growth response-1 (EGR1) gene might be crucial in this process. This study introduces a novel method for constructing piezoelectric ceramic scaffolds exhibiting outstanding osteogenic, angiogenic, and antibacterial properties under the combined influence of LIPUS, offering a promising treatment strategy for infectious bone defects.

Biodegradable Janus sonozyme with continuous reactive oxygen species regulation for treating infected critical-sized bone defects

Critical-sized bone defects are usually accompanied by bacterial infection leading to inflammation and bone nonunion. However, existing biodegradable materials lack long-term therapeutical effect because of their gradual degradation. Here, a degradable material with continuous ROS modulation is proposed, defined as a sonozyme due to its functions as a sonosensitizer and a nanoenzyme. Before degradation, the sonozyme can exert an effective sonodynamic antimicrobial effect through the dual active sites of MnN4 and Cu2O8. Furthermore, it can promote anti-inflammation by superoxide dismutase- and catalase-like activities. Following degradation, quercetin-metal chelation exhibits a sustaining antioxidant effect through ligand-metal charge transfer, while the released ions and quercetin also have great self-antimicrobial, osteogenic, and angiogenic effects. A rat model of infected cranial defects demonstrates the sonozyme can rapidly eliminate bacteria and promote bone regeneration. This work presents a promising approach to engineer biodegradable materials with long-time effects for infectious bone defects.

Sodium alginate based piezoelectric hydrogel for promoting healing of infected wounds at movable parts

The frequent movement is an obstacle to the healing of wounds at movable parts. It would be highly beneficial if this characteristic could be utilized to accelerate wound healing process. Herein, we developed a sodium niobate (NNO) hydrogel (NNO-Gel) for promoting healing process of wounds at movable parts based on its photodynamic and piezoelectric properties. NNO-Gel is formed through incorporating NNO into polyvinyl alcohol‑sodium alginate hydrogel using calcium chloride as a cross-linking agent. NNO-Gel could not only produce reactive oxygen species for bacteria inactivation with simulated sunlight irradiation, but also generate electric field for promoting cell migration and proliferation through the frequent movement of necks. With simulated sunlight irradiation, NNO-Gel could kill 95.6 % ± 1.4 % of bacteria, 9.3 % higher than NNO nanomaterials. The cell proliferation rate reaches 148.41 ± 6.37 % by NNO nanomaterials with ultrasound irradiation through activating and phosphorylating phosphoinositide 3-kinase and protein kinase B. For infected neck wounds, NNO NMs and NNO-Gel show 23.6 ± 5.1 % and 25.3 ± 6.1 % higher healing rate than PBS treated ones. The development of NNO-Gel provides an opportunity for transforming the negative frequent movement which prevents wound healing into motive power for promoting healing of wound at movable parts, as well as the possibility of clinic applications for piezoelectric nanomaterials.

Nanocatalytic medicine enabled next-generation therapeutics for bacterial infections

The rapid rise of antibiotic-resistant strains and the persistence of biofilm-associated infections have significantly challenged global public health. Unfortunately, current clinical high-dose antibiotic regimens and combination therapies often fail to completely eradicate these infections, which can lead to adverse side effects and further drug resistance. Amidst this challenge, however, the burgeoning development in nanotechnology and nanomaterials brings hopes. This review provides a comprehensive summary of recent advancements in nanomaterials for treating bacterial infections. Firstly, the research progress of catalytic therapies in the field of antimicrobials is comprehensively discussed. Thereafter, we systematically discuss the strategies of nanomaterials for anti-bacterial infection therapies, including endogenous response catalytic therapy, exogenous stimulation catalytic therapy, and catalytic immunotherapy, in order to elucidate the mechanism of nanocatalytic anti-infections. Based on the current state of the art, we conclude with insights on the remaining challenges and future prospects in this rapidly emerging field.

Near-Infrared Carbon Dots With Antibacterial and Osteogenic Activities for Sonodynamic Therapy of Infected Bone Defects

Repairing infected bone defects is hindered by the presence of stubborn bacterial infections and inadequate osteogenic activity. The incorporation of harmful antibiotics not only fosters the emergence of multidrug-resistant bacteria, but also diminishes the osteogenic properties of scaffold materials. In addition, it is essential to continuously monitor the degradation kinetics of scaffold materials at bone defect sites, yet the majority of bone repair materials lack imaging capability. To address these issues, this study reports for the first time the development of a single nanomaterial with triple functionality: efficient sonodynamic antibacterial activity, accelerated bone defect repair capability, and NIR imaging ability for visualized therapy of infected bone defects. Through rationally regulating the surface functional groups, the obtained multifunctional NIR carbon dots (NIR-CD) exhibit p-n junction-enhanced sonodynamic activity, narrow bandgap-facilitated NIR imaging capability, and negative charge-augmented osteogenic activity. The validation of NIR-CDs antibacterial and osteogenic activities in vivo is conducted by constructing 3D injectable hydrogels encapsulated by NIR-CDs (NIR-CD/GelMA). The implantation of multifunctional NIR-CD/GelMA hydrogel scaffolds in a model of MRSA-infected craniotomy defects results in almost complete restoration of the infected bone defects after 60 days. These findings will provide traceable, renewable, repairable and antibacterial candidate biomaterials for bone tissue engineering.

Time-Dependent Electrical Active and Ultrasound-Responsive Calcium Titanate Implant Coating with Immunomodulation, Osteogenesis, and Customized Antibacterial Activity

Surgical site infection and insufficient osseointegration are notable risks factors associated with oral implant surgery. In this study, the development of a polarized calcium titanate (CT-P) coating for titanium surfaces is proposed as a solution to these problems. The coating generated electrical stimulation (ES) can inhibit pro-inflammatory M1-type macrophage polarization and promote anti-inflammatory M2-type macrophage polarization, resulting in favorable bone immunomodulation. The ES generated by the coating can match the physiological electrical potential that will change during bone repair, thereby promoting osseointegration in vivo. In addition, the system can also achieve on-demand antibacterial activity, mainly depending on the CT-P coating responding to ultrasound (US) irradiation to produce reactive oxygen species (ROS) and remove Staphylococcus aureus (S. aureus) on the surface of the implant. In conclusion, this work provides valuable insights for the development and clinical application of highly efficient electroactive coatings, as well as novel solutions for the selective treatment of bacterial infections in the surgical area.

A 3D in vitro model of biphasic calcium phosphate (BCP) scaffold combined with human osteoblasts, osteoclasts, and endothelial cells as a platform to mimic the oral microenvironment for tissue regeneration

OBJECTIVES

This study aimed to develop an innovative 3D in vitro model based on the biphasic calcium phosphate (BCP) scaffold combined with human osteoblasts (hOBs), osteoclasts (hOCs), and endothelial cells to evaluate its effects on bone and vascular cells behavior.

METHODS

To this end, an optimized mixture of hydroxyapatite (HA) and β-tricalcium phosphate (TCP) with a weight ratio of 30/70 was employed to develop a BCP scaffold using the computer-aided design (CAD) approach. The BCP scaffold was combined with primary cultures of hOBs, hOCs and human umbilical vein endothelial cells (HUVECs).

RESULTS

Morphometric analyses using scanning electron microscopy (SEM) and X-ray micro-computed tomography, along with biomechanical testing, revealed that BCP scaffold exhibited a regular 3D structure with large interconnected internal pores (700 µm) and high mechanical strength. In terms of biological behavior, after 14 days of tri-culture with hOBs, hMCs and HUVECs, SEM, immunofluorescence, and histological analyses showed that all cell types were viable and adhered well to the entire surface of the scaffold. Interestingly, SEM and energy-dispersive X-ray spectroscopy analyses also revealed on the BCP scaffold the presence of mineralized matrix crystals of Ca, P, O and C within a tissue-like cell layer produced by the interaction of the three cell types.

CONCLUSIONS

Data confirmed the high performance of the BCP scaffold through biomechanical studies. Notably, for the first time, this study demonstrated the feasibility of combining BCP scaffold with hOBs, hOCs, and HUVEC, which remained viable and maintained their native phenotypes, creating also tissue-like cell layer.

CLINICAL SIGNIFICANCE

Although further investigation is needed, these results underscore the potential to develop a 3D in vitro model that mimics the oral microenvironment, which could be valuable for BTE approaches in vivo studies.

Doping-Engineered Piezoelectric Ultrathin Nanosheets for Synergistically Piezo-Chemocatalytic Antitumor and Antibacterial Therapies Against Cutaneous Melanoma

The post-surgical melanoma recurrence and wound infections have persistently troubled clinical management. Piezocatalytic therapy features high efficiency in generating reactive oxygen species (ROS) for tumor therapy, but it faces limitations in piezoelectricity and redox-active site availability. Herein, Fe-doped ultrathin Bi4Ti3O12 nanosheets (designated as Fe-UBTO NSs) with synergistically piezo-chemocatalytic activity are engineered for antitumor and antibacterial treatment against cutaneous melanoma. The doping-engineered strategy induces oxygen vacancies and lattice distortions in Fe-UBTO NSs, which narrows bandgap to enhance piezocatalytic 1O2 and H2O2 generation by improving the electron-hole pairs separation, hindering their recombination, and increasing oxygen adsorption. Moreover, Fe doping establishes a piezo-chemocatalytic system, in which the piezocatalysis enables the self-supply of H2O2 and expedites electron transfer in Fenton reactions, inducing increased ·OH production. Besides, the atomic-level thickness and expanded surface area enhance the sensitivity to ultrasound stimuli and expose more redox-active sites, augmenting the piezo-chemocatalytic efficiency, and ultimately leading to abundant ROS generation. The Fe-UBTO-mediated piezo-chemocatalytic therapy causes intracellular oxidative stress, triggering apoptosis and excessive autophagy of tumor cells. Moreover, this strategy accelerates wound healing by facilitating sterilization, angiogenesis, and collagen deposition. This work provides distinct options to develop doping-engineered ultrathin nanosheets with augmented piezo-chemocatalytic activity for postoperative management of cutaneous melanoma.

Unveiling Green Synthesis and Biomedical Theranostic paradigms of Selenium Nanoparticles (SeNPs) - A state-of-the-art comprehensive update

The advancements in nanotechnology, pharmaceutical sciences, and healthcare are propelling the field of theranostics, which combines therapy and diagnostics, to new heights; emphasizing the emergence of selenium nanoparticles (SeNPs) as versatile theranostic agents. This comprehensive update offers a holistic perspective on recent developments in the synthesis and theranostic applications of SeNPs, underscoring their growing importance in nanotechnology and healthcare. SeNPs have shown significant potential in multiple domains, including antioxidant, anti-inflammatory, anticancer, antimicrobial, antidiabetic, wound healing, and cytoprotective therapies. The review highlights the adaptability and biocompatibility of SeNPs, which are crucial for advanced disease detection, monitoring, and personalized treatment. Special emphasis is placed on advancements in green synthesis techniques, underscoring their eco-friendly and cost-effective benefits in biosensing, diagnostics, imaging and therapeutic applications. Additionally, the appraisal scrutinizes the progressive trends in smart stimuli-responsive SeNPs, conferring their role in innovative solutions for disease management and diagnostics. Despite their promising therapeutic and prophylactic potential, SeNPs also present several challenges, particularly regarding toxicity concerns. These challenges and their implications for clinical translation are thoroughly explored, providing a balanced view of the current state and prospects of SeNPs in theranostic applications.

An oxidized dextran-composite self-healing coated magnesium scaffold reduces apoptosis to induce bone regeneration

Self-healing coatings have shown promise in controlling the degradation of scaffolds and addressing coating detachment issues. However, developing a self-healing coating for magnesium (Mg) possessing multiple biological functions in infectious environments remains a significant challenge. In this study, a self-healing coating was developed for magnesium scaffolds using oxidized dextran (OD), 3-aminopropyltriethoxysilane (APTES), and nano-hydroxyapatite (nHA) doped micro-arc oxidation (MHA), named OD-MHA/Mg. The results demonstrated that the OD-MHA coating effectively addresses coating detachment issues and controls the degradation of Mg in an infectious environment through self-healing mechanisms. Furthermore, the OD-MHA/Mg scaffold exhibits antibacterial, antioxidant, and anti-apoptotic properties, it also promotes bone repair by upregulating the expression of osteogenesis genes and proteins. The findings of this study indicate that the OD-MHA coated Mg scaffold possessing multiple biological functions presents a promising approach for addressing infectious bone defects. Additionally, the study showcases the potential of polysaccharides with multiple biological functions in facilitating tissue healing even in challenging environments.