Photodynamic and nitric oxide therapy-based synergistic antimicrobial nanoplatform: an advanced root canal irrigation system for endodontic bacterial infections.

BACKGROUND: The main issues faced during the treatment of apical periodontitis are the management of bacterial infection and the facilitation of the repair of alveolar bone defects to shorten disease duration. Conventional root canal irrigants are limited in their efficacy and are associated with several side effects. This study introduces a synergistic therapy based on nitric oxide (NO) and antimicrobial photodynamic therapy (aPDT) for the treatment of apical periodontitis. RESULTS: This research developed a multifunctional nanoparticle, CGP, utilizing guanidinylated poly (ethylene glycol)-poly (ε-Caprolactone) polymer as a carrier, internally loaded with the photosensitizer chlorin e6. During root canal irrigation, the guanidino groups on the surface of CGP enabled effective biofilm penetration. These groups undergo oxidation by hydrogen peroxide in the aPDT process, triggering the release of NO without hindering the production of singlet oxygen. The generated NO significantly enhanced the antimicrobial capability and biofilm eradication efficacy of aPDT. Furthermore, CGP not only outperforms conventional aPDT in eradicating biofilms but also effectively promotes the repair of alveolar bone defects post-eradication. Importantly, our findings reveal that CGP exhibits significantly higher biosafety compared to sodium hypochlorite, alongside superior therapeutic efficacy in a rat model of apical periodontitis. CONCLUSIONS: This study demonstrates that CGP, an effective root irrigation system based on aPDT and NO, has a promising application in root canal therapy.

Melatonin protects TEGDMA-induced preodontoblast mitochondrial apoptosis via the JNK/MAPK signaling pathway.

Resin monomer-induced dental pulp injury presents a pathology related to mitochondrial dysfunction. Melatonin has been regarded as a strong mitochondrial protective bioactive compound from the pineal gland. However, it remains unknown whether melatonin can prevent dental pulp from resin monomer-induced injury. The aim of this study is to investigate the effects of melatonin on apoptosis of mouse preodontoblast cells (mDPC6T) induced by triethylene glycol dimethacrylate (TEGDMA), a major component in dental resin, and to determine whether the JNK/MAPK signaling pathway mediates the protective effect of melatonin. A well-established TEGDMA-induced mDPC6T apoptosis model is adopted to investigate the preventive function of melatonin by detecting cell viability, apoptosis rate, expressions of apoptosis-related proteins, mitochondrial ROS (mtROS) production, mitochondrial membrane potential (MMP) and adenosine triphosphate (ATP) level. Inhibitors of MAPKs are used to explore which pathway is involved in TEGDMA-induced apoptosis. Finally, the role of the JNK/MAPK pathway is verified using JNK agonists and antagonists. Our results show that melatonin attenuates TEGDMA-induced mDPC6T apoptosis by reducing mtROS production and rescuing MMP and ATP levels. Furthermore, mitochondrial dysfunction and apoptosis are alleviated only by the JNK/MAPK inhibitor SP600125 but not by other MAPK inhibitors. Additionally, melatonin downregulates the expression of phosphorylated JNK and counteractes the activating effects of anisomycin on the JNK/MAPK pathway, mimicking the effects of SP600125. Our findings demonstrate that melatonin protects mDPC6T cells against TEGDMA-induced apoptosis partly through JNK/MAPK and the maintenance of mitochondrial function, offering a novel therapeutic strategy for the prevention of resin monomer-induced dental pulp injury.

Two dimensional monolayer rhombic silicene on the diamond (111) surface.

Two-dimensional rhombic silicene (named r-silicene) bonded on the diamond (111) surface with a (1 × 1) configuration is predicted by density functional theory. The planar structure of r-silicene has P6/mmm symmetry, and it is dynamically and thermodynamically stable on the diamond surface. r-Silicene has a metallic character, which is different to both bulk cubic Si and hexagonal silicene. The hybrid structure of r-silicene/diamond consists of a metallic surface and a wide band gap semiconductor diamond substrate, providing a novel low-dimensional composite based on silicon-diamond to realize high performance nanodevices. Moreover, a similar rhombic configuration of monolayer germanene has been theoretically constructed on the diamond (111) substrate.

Black Phosphorus Nanosheets-Loaded Mussel-Inspired Hydrogel with Wet Adhesion, Photothermal Antimicrobial, and In Situ Remineralization Capabilities for Caries Prevention.

The main features of early caries are the massive colonization of cariogenic bacteria and demineralization of tooth enamel by the acids that they produce. Owing to the lack of effective treatments, the development of anticaries therapeutics with both antimicrobial and remineralizing properties is urgently required. Black phosphorus nanosheets (BPNs) are ideal therapeutics for the treatment of early caries because they can mediate photothermal antibacterial activity and subsequently promote remineralization by generating PO4 3-. However, the dynamic and wet environment of the oral cavity prevents the long-term adhesion of BPNs to the tooth surface. In this study, using catechol-modified chitosan and PLGA-PEG-PLGA as raw materials, a mussel-inspired versatile hydrogel, BP@CP5, is presented that can be used to physically load BPNs. BP@CP5 has exceptional injectability and can firmly adhere to tooth surfaces for up to 24 h. Upon irradiation, BP@CP5 can quickly eliminate ≈99% of Streptococcus mutans and Streptococcus sanguinis; furthermore, the PO4 3- generated via degradation also promotes rapid remineralization of enamel slabs. Importantly, the vivo rodent caries modeling results further confirm the excellent caries-prevention properties of BP@CP5. This study demonstrates that BP@CP5 is a promising anticaries material for caries management.

Chitosan and polyhexamethylene guanidine dual-functionalized cotton gauze as a versatile bandage for the management of chronic wounds.

Development of versatile medical dressing with good immediate and long-lasting antibacterial, hygroscopic and moisturizing abilities is of great significance for management of chronic wounds. Cotton gauze (CG) can protect wounds and promote scabbing, but can cause wound dehydration and loss of biologically active substances, thereby greatly delays wound healing. Herein, a bi-functional CG dressing (CPCG) was developed by chemically grafting polyhexamethylene guanidine (PHMG) and physically adsorbing chitosan (CS) onto the CG surface. Due to the powerful microbicidal activity of PHMG, CPCG exhibited excellent immediate and long-lasting antibacterial activity against gram-positive and gram-negative bacteria. Moreover, the abundant hydroxyl and amino groups in CS endowed CPCG with good biocompatibility, moisture absorption, moisturizing and cell scratch healing performances. Importantly, CPCG can be easily fabricated into a bandage to conveniently manage infected full-skin wounds. Together, this study suggests that CPCG is a versatile wound dressing, having enormous application potential for management chronic wounds.

Nanodiamonds: a critical component of anodes for high performance lithium-ion batteries.

Detonation nanodiamonds (DNDs) have been introduced into a carbonaceous anode for improving the performance of lithium ion batteries (LIBs). The lithium storage capacity, cycling performance and stability of the LIBs are increased and this is related to the DNDs' unique characteristics of chemical inertness, a larger surface area, low expansion, and high lithium adsorption capacity.