Nanomaterials-Enabled Physicochemical Antibacterial Therapeutics: Toward the Antibiotic-Free Disinfections.

Bacterial infection continues to be an increasing global health problem with the most widely accepted treatment paradigms restricted to antibiotics. However, the overuse and misuse of antibiotics have triggered multidrug resistance of bacteria, frustrating therapeutic outcomes, and leading to higher mortality rates. Even worse, the tendency of bacteria to form biofilms on living and nonliving surfaces further increases the difficulty in confronting bacteria because the extracellular matrix can act as a robust barrier to prevent the penetration of antibiotics and resist environmental damage. As a result, the inability to eliminate bacteria and biofilms often leads to persistent infection, implant failure, and device damage. Therefore, it is of paramount importance to develop alternative antimicrobial agents while avoiding the generation of bacterial resistance to prevent the large-scale growth of bacterial resistance. In recent years, nano-antibacterial materials have played a vital role in the antibacterial field because of their excellent physical and chemical properties. This review focuses on new physicochemical antibacterial strategies and versatile antibacterial nanomaterials, especially the mechanism and types of 2D antibacterial nanomaterials. In addition, this advanced review provides guidance on the development direction of antibiotic-free disinfections in the antibacterial field in the future.

Cascade and Ultrafast Artificial Antioxidases Alleviate Inflammation and Bone Resorption in Periodontitis.

Periodontitis, one of the most common, challenging, and rapidly expanding oral diseases, is an oxidative stress-related disease caused by excessive reactive oxygen species (ROS) production. Developing ROS-scavenging materials to regulate the periodontium microenvironments is essential for treating periodontitis. Here, we report on creating cobalt oxide-supported Ir (CoO-Ir) as a cascade and ultrafast artificial antioxidase to alleviate local tissue inflammation and bone resorption in periodontitis. It is demonstrated that the Ir nanoclusters are uniformly supported on the CoO lattice, and there is stable chemical coupling and strong charge transfer from Co to Ir sites. Benefiting from its structural advantages, CoO-Ir presents cascade and ultrafast superoxide dismutase-catalase-like catalytic activities. Notably, it displays distinctly increased Vmax (76.249 mg L-1 min-1) and turnover number (2.736 s-1) when eliminating H2O2, which surpasses most of the by-far-reported artificial enzymes. Consequently, the CoO-Ir not only provides efficient cellular protection from ROS attack but also promotes osteogenetic differentiation in vitro. Furthermore, CoO-Ir can efficiently combat periodontitis by inhibiting inflammation-induced tissue destruction and promoting osteogenic regeneration. We believe that this report will shed meaningful light on creating cascade and ultrafast artificial antioxidases and offer an effective strategy to combat tissue inflammation and osteogenic resorption in oxidative stress-related diseases.

Catalase-Mimetic Artificial Biocatalysts with Ru Catalytic Centers for ROS Elimination and Stem-Cell Protection.

Exploring high-efficiency reactive oxygen species (ROS)-elimination materials is of great importance for combating oxidative stress in diverse diseases, especially stem-cell-based biotherapeutics. By mimicking the FeN active centers of natural catalase, here, an innovative concept to design ROS-elimination artificial biocatalysts with Ru catalytic centers for stem-cell protection is reported. The experimental studies and theoretical calculations have systematically disclosed the activity merits and structure diversities of different Ru sites when serving as ROS-elimination artificial biocatalysts. Benefiting from the metallic electronic structures and synergetic effects of multiple sites, the artificial biocatalysts with Ru cluster centers present exceptional ROS-elimination activity; notably, it shows much higher catalytic efficiency per Ru atom on decomposing H2 O2 when compared to the isolated single-atom Ru sites, which is more efficient than that of the natural antioxidants and recently reported state-of-the-art ROS-scavenging biocatalysts. The systematic stem-cell protection studies reveal that the catalase-like artificial biocatalysts can provide efficient rescue ability for survival, adhesion, and differentiation functions of human mesenchymal stem cells in high ROS level conditions. It is suggested that applying these artificial biocatalysts with Ru cluster centers will offer a new pathway for engineering high-performance ROS-scavenging materials in stem-cell-based therapeutics and many other ROS-related diseases.

Hydrogels for Exosome Delivery in Biomedical Applications.

Hydrogels, which are hydrophilic polymer networks, have attracted great attention, and significant advances in their biological and biomedical applications, such as for drug delivery, tissue engineering, and models for medical studies, have been made. Due to their similarity in physiological structure, hydrogels are highly compatible with extracellular matrices and biological tissues and can be used as both carriers and matrices to encapsulate cellular secretions. As small extracellular vesicles secreted by nearly all mammalian cells to mediate cell-cell interactions, exosomes play very important roles in therapeutic approaches and disease diagnosis. To maintain their biological activity and achieve controlled release, a strategy that embeds exosomes in hydrogels as a composite system has been focused on in recent studies. Therefore, this review aims to provide a thorough overview of the use of composite hydrogels for embedding exosomes in medical applications, including the resources for making hydrogels and the properties of hydrogels, and strategies for their combination with exosomes.

A hierarchical bilayer architecture for complex tissue regeneration.

Engineering a complete, physiologically functional, periodontal complex structure remains a great clinical challenge due to the highly hierarchical architecture of the periodontium and coordinated regulation of multiple growth factors required to induce stem cell multilineage differentiation. Using biomimetic self-assembly and microstamping techniques, we construct a hierarchical bilayer architecture consisting of intrafibrillarly mineralized collagen resembling bone and cementum, and unmineralized parallel-aligned fibrils mimicking periodontal ligament. The prepared biphasic scaffold possesses unique micro/nano structure, differential mechanical properties, and growth factor-rich microenvironment between the two phases, realizing a perfect simulation of natural periodontal hard/soft tissue interface. The interconnected porous hard compartment with a Young's modulus of 1409.00 ± 160.83 MPa could induce cross-arrangement and osteogenic differentiation of stem cells in vitro, whereas the micropatterned soft compartment with a Young's modulus of 42.62 ± 4.58 MPa containing abundant endogenous growth factors, could guide parallel arrangement and fibrogenic differentiation of stem cells in vitro. After implantation in critical-sized complete periodontal tissue defect, the biomimetic bilayer architecture potently reconstructs native periodontium with the insertion of periodontal ligament fibers into newly formed cementum and alveolar bone by recruiting host mesenchymal stem cells and activating the transforming growth factor beta 1/Smad3 signaling pathway. Taken together, integration of self-assembly and microstamping strategies could successfully fabricate a hierarchical bilayer architecture, which exhibits great potential for recruiting and regulating host stem cells to promote synergistic regeneration of hard/soft tissues.

Roles and mechanisms of YAP/TAZ in orthodontic tooth movement.

Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are transcriptional coactivators encoded by paratactic homologous genes, shuttle-crossing between cytoplasm and nucleus to regulate the gene expression and cell behavior and standing at the center place of the sophisticated regulatory networking of mechanotransduction. Orthodontic tooth movement (OTM) is a process in which extracellular mechanical stimuli are transformed into intracellular biochemical signals to regulate cellular responses and tissue remodeling. Literature studies have confirmed that YAP/TAZ plays an important role not only in embryonic development, homeostasis and tumorigenesis, but also in mechanical-biochemical signal transduction of periodontal tissues under the mediation of various signal molecules in its upstream and downstream. Herein, we review the advances in the roles and mechanisms of YAP/TAZ in OTM to provide insights for better understanding and further study of the OTM and possible targeted clinical intervention in orthodontic treatment.

Assessment of available sites for palatal orthodontic mini-implants through cone-beam computed tomography.

OBJECTIVE: To measure the palatal thickness of both hard and soft tissues and to determine safe regions for the placement of mini-implants. The influences of sex and age on palatal thickness were also examined. MATERIALS AND METHODS: Cone-beam computed tomography images of 30 patients (12 males, 18 females), including 15 adults and 15 adolescents, were used in this study. The thicknesses of palatal hard tissue, soft tissue, and hard+soft tissues were measured at the coronal planes of first premolars, second premolars, first molars, and second molars (P1, P2, M1, and M2 planes, respectively). RESULTS: The hard tissue was thickest at the P1 plane, followed by at the P2, M1, and M2 planes, while the thickness of soft tissue was similar among the four planes. The trends in the changes of palatal thickness from midline to the lateral sides (V-pattern) were similar for the four planes. Palatal thickness was influenced by sex, age, and their interaction. Mapping of recommended and optimal sites for palatal mini-implants was accomplished. CONCLUSIONS: Sex and age factors could influence palatal thickness. Therefore, the findings might be helpful for clinicians in guiding them to choose the optimal sites for palatal mini-implants.

[Research progress of scaffold materials for tissue engineered meniscus].

OBJECTIVE: To summarize and analyze the research progress of scaffold materials used in tissue engineered meniscus. METHODS: The classification and bionics design of scaffold materials were summarized by consulting domestic and foreign literature related to the research of tissue engineered meniscus in recent years. RESULTS: Tissue engineered meniscus scaffolds can be roughly classified into synthetic polymers, hydrogels, extracellular matrix components, and tissue derived materials. These different materials have different characteristics, so the use of a single material has its unique disadvantages, and the use of a variety of materials composite scaffolds can learn from each other, which is a hot research area at present. In addition to material selection, material processing methods are also the focus of research. At the same time, according to the morphological structure and mechanical characteristics of the meniscus, the bionic design of tissue engineered meniscus scaffolds has great potential. CONCLUSION: At present, there are many kinds of scaffold materials for tissue engineered meniscus. However, there is no material that can completely simulate the natural meniscus, and further research of scaffold materials is still needed.