No abstract

The development of responsive antibacterial implants is highly significant for the treatment of implant-associated infection. In this study, one self-adaptive antibacterial porous implant with sustainable responses is flexibly designed and constructed for infected bone defect therapy. Porous hydroxyapatite (HA) implants derived from nature bones, one typical implant, are first functionalized via low-cytotoxic ethanediamine-functionalized poly(glycidyl methacrylate) brushes, and gentamicin sulfate (GS, a kind of aminoglycoside antibiotic in clinic) is subsequently conjugated by an acid-responsive bond to produce smart antibacterial HA implants (HA-GS). The release of GS can be triggered by the acidic environment induced by the metabolism of bacteria for self-adaptive antibacterial response. Due to the good drug loading capacity and chemical stability of HA-GS in neutral condition, the sustainable antibacterial ability is readily achieved for long-term applications. The highly effective in vivo anti-infection therapy with HA-GS is demonstrated in one infected bone defect rabbit model. The implantassociated infection is completely inhibited by HA-GS at the early stage and the defected bones exhibit superior recovery at the late stage. This design strategy of sustainable self-adaptive antibacterial implants will provide a promising concept for the prevention and therapy of implant-associated infections.

Tissue engineering has become a rapidly developing field of research because of the increased demand from regenerative medicine, and hydrogels are a promising tissue engineering scaffold because of their three-dimensional structures. In this study, we constructed novel hydrogels of gelatin methacrylate (GelMA) hydrogels modified with histidine and Zn (GelMA-His-Zn(II)), which possessed fascinating antibacterial properties and tunable mechanical properties because of the formation of a functionalized dual network of covalent crosslinking and metal coordination bonds. The introduction of metal coordination bonds not only improves the strength of the GelMA hydrogels with covalent crosslinking but also makes their mechanical properties tunable via adjustments to the concentration of Zn. The synergistic effect of Zn and the imidazole groups gives the GelMA-His-Zn(II) hydrogels fascinating antibacterial properties (up to 100% inhibition). Counting the colony forming units and compression tests confirmed the fascinating antibacterial abilities and tunable mechanical properties, respectively, of the GelMA-His-Zn(II) hydrogels. In addition, Cell Counting Kit-8 assays, cytoskeletal staining assays, and live/dead assays confirmed the excellent cytocompatibility of the GelMA-His-Zn(II) hydrogels. Therefore, the GelMA-His-Zn(II) hydrogels are promising for applications in tissue engineering.

Treatment of bone defects remains a challenge in the clinic. Artificial bone grafts are the most promising alternative to autologous bone grafting. However, one of the limiting factors of artificial bone grafts is the limited means of regulating stem cell differentiation during bone regeneration. As a weight-bearing organ, bone is in a continuous mechanical environment. External mechanical force, a type of biophysical stimulation, plays an essential role in bone regeneration. It is generally accepted that osteocytes are mechanosensitive cells in bone. However, recent studies have shown that mesenchymal stem cells (MSCs) can also respond to mechanical signals. This article reviews the mechanotransduction mechanisms of MSCs, the regulation of mechanical stimulation on microenvironments surrounding MSCs by modulating the immune response, angiogenesis and osteogenesis, and the application of mechanical stimulation of MSCs in bone regeneration. The review provides a deep and extensive understanding of mechanical stimulation mechanisms, and prospects feasible designs of biomaterials for bone regeneration and the potential clinical applications of mechanical stimulation.

Technically, this is achieved by increasing the particle density through changing the drop's surface area and, in the case of a liquid marble, the approach mainly includes droplet/marble impingement on a powder, [23,31] marble coalescence, [28,32] evaporation from the marble, [25][26][27] and artificial liquid extraction. [33] Given that marble shapes can be well controlled, such structured marbles could serve as smart containers allowing complex manipulations of the internal substances and, hence, a wider variety of results can be expected, compared with applying only spherical or puddle-shaped liquid marbles. However, nearly all the above works addressed liquid marble deformations mainly as phenomenon discussions, instead of being concerned with controllability or application feasibility. Obviously, although random shape is not hard to obtain, the nature of liquid destines the difficulty in transforming a spherical droplet into a designed shape despite particle coverage. For this, an addition strategy which joined units of simply deformed liquid marbles was proposed recently, demonstrating a fair designability of liquid shape, and the resulting shaped liquids were so coined the term "liquid plasticine." [34] However, the defects of this down-top shape design are significant. The main problem is that droplet movement during the joining process is difficult to control, such that the shape of the final liquid plasticine is not accurate in detail, particularly when constructing a large, complex structure.Here we show that the fine control of liquid shape could be realized using a top-down design with a subtraction strategy, in which a coated liquid pancake, with a large surface area, is segmented into a liquid plasticine with a precise structure. The process is well controlled and a clear advantage is achieved in the form of timesaving. A sol-gel superhydrophobic coating with weak binding force, and a container accommodating liquid of milliliter order, are key factors in this method. This work may provide opportunities for real and practical applications of structured/shaped liquids as smart containers.A Petri dish was coated on all surfaces by immersing it into an alkylated SiO 2 collosol, which was then withdrawn and air dried for 2 min. The resulting xerogel-coated Petri dish displayed a colorful appearance because of its nonuniform coating thickness that induced inhomogeneous light interference (Figure 1a). The coating was composed of about a dozen layers of hydrophobic SiO 2 nanoparticles (NPs) of ≈20 nm in diameter (Figure 1b), and a water drop on such a coating had a contact Liquid marbles with quasi-spherical shapes have great application potential as miniature containers. Recently, their shape modification is investigated, revealing great possibilities in broadening the uses for such containers. Current methods have demonstrated shape designability, but fine control of the final shape, important in applications, has remained a problem. Here, a facile method, based on a gravity-induced liquid pancake coated...

No abstract

Due to its good properties such as low cytotoxicity, degradability, and biocompatibility, poly(aspartic acid) (PAsp) is a good candidate for the development of new drug delivery systems. In this work, a series of new PAsp-based degradable supramolecular assemblies were prepared for effective gene therapy via the host-guest interactions between the cyclodextrin (CD)-cored PAsp-based polycations and the pendant benzene group-containing PAsp backbones. Such supramolecular assemblies exhibited good degradability, enhanced pDNA condensation ability, and low cytotoxicity. More importantly, the gene transfection efficiencies of supramolecular assemblies were much higher than those of CD-cored PAsp-based counterparts at various N/P ratios. In addition, the effective antitumor ability of assemblies was demonstrated with a suicide gene therapy system. The present study would provide a new means to produce degradable supramolecular drug delivery systems.

No abstract