An easy-to-use wound dressing gelatin-bioactive nanoparticle gel and its preliminary in vivo study.

Beyond promoting hard tissue repairing, bioactive glasses (BGs) have also been proved to be beneficial for wound healing. Nano-scale BGs prepared by sol-gel method were found to have a better performance as they have a larger specific surface area. In this work, bioactive nanoparticles (nBPs) with mean diameter of 12 nm (BP-12) instead of conventional BGs were mixed with gelatin to form an easy-to-use hydrogel as a dressing for skin wound. It was found that the composite of BP-12 and gelatin could form a hydrogel (BP-12/Gel) under 25 °C, which showed pronounced thixotropy at a practically accessible shear rate, therefore become easy to be used for wound cover. In vitro, the composite hydrogel of BP-12 and gelatin had good biocompatibility with the fibroblast cells. In vivo, rapid cutaneous-tissue regeneration and tissue-structure formation within 7 days was observed in the wound-healing experiment performed in rats. This hydrogel is thus a promising easy-to-use wound dressing material.

Emission Characteristics and Health Risks of Volatile Organic Compounds (VOCs) Measured in a Typical Recycled Rubber Plant in China.

The continued development of the automotive industry has led to a rapid increase in the amount of waste rubber tires, the problem of "black pollution" has become more serious but is often ignored. In this study, the emission characteristics, health risks, and environmental effects of volatile organic compounds (VOCs) from a typical, recycled rubber plant were studied. A total of 15 samples were collected by summa canisters, and 100 VOC species were detected by the GC/MS-FID system. In this study, the total VOCs (TVOCs) concentration ranged from 1000 ± 99 to 19,700 ± 19,000 µg/m3, aromatics and alkanes were the predominant components, and m/p-xylene (14.63 ± 4.07%-48.87 ± 3.20%) could be possibly regarded as a VOCs emission marker. We also found that specific similarities and differences in VOCs emission characteristics in each process were affected by raw materials, production conditions, and process equipment. The assessment of health risks showed that devulcanizing and cooling had both non-carcinogenic and carcinogenic risks, yarding had carcinogenic risks, and open training and refining had potential carcinogenic risks. Moreover, m/p-xylene and benzene were the main non-carcinogenic species, while benzene, ethylbenzene, and carbon tetrachloride were the dominant risk compounds. In the evaluation results of LOH, m/p-xylene (25.26-67.87%) was identified as the most key individual species and should be prioritized for control. In conclusion, the research results will provide the necessary reference to standardize the measurement method of the VOCs source component spectrum and build a localized source component spectrum.

Conjoined-network rendered stiff and tough hydrogels from biogenic molecules.

Hydrogels from biological sources are expected as potential structural biomaterials, but most of them are either soft or fragile. Here, a new strategy was developed to construct hydrogels that were both stiff and tough via the formation of the conjoined-network, which was distinct from improving homogeneity or incorporating energy dissipation mechanisms (double-network) approaches. Conjoined-network hydrogels stand for a class of hydrogels consisting of two or more networks that are connected by sharing interconnection points to collaborate and featured as follows: (i) All the composed networks had a similar or equal energy dissipation mechanism, and (ii) these networks were intertwined to effectively distribute stress in the whole system. As a specific example, a biogenic conjoined-network hydrogel was prepared by electrostatically cross-linking the chitosan-gelatin composite with multivalent sodium phytate. The combination of high compressive modulus and toughness was realized at the same time in the chitosan-gelatin-phytate system. Moreover, these physical hydrogels exhibited extraordinary self-recovery and fatigue resistance ability. Our results provide a general strategy for the design of biocompatible stiff and tough conjoined-network hydrogels due to a variety of potential cross-linking mechanisms available (e.g., electrostatic attraction, host-guest interaction, and hydrogen bonding).

Biomineralizing Dental Resin Empowered by Bioactive Amphiphilic Composite Nanoparticles.

Adhesive failure due to resin contraction is one of the major reasons for dental restoration failure, which leads to the exposure of dentinal tubules, and remineralization in saliva would provide a great solution for the above problem. In this study, bioactive amphiphilic raspberry-like composite nanoparticles were used as fillers for resin composites, which have good compatibility with the resin matrix and dispersed well in the matrix. Thus, the resin composites showed improved mechanical property and resistance to water sorption and solubility. Furthermore, the incorporation of bioactive nanoparticles endued the resin composites with bioactivity, forming apatite on resin composites upon reacting with artificial saliva within seven days, inducing denser mineral precipitation on the dentin surface and stimulating human dental pulp cell attachment and proliferation. Therefore, this bioactive nanoparticle filled composite resin may offer great benefits for dental restoration.

Surface modification of bioactive glass nanoparticles and the mechanical and biological properties of poly(L-lactide) composites.

Novel bioactive glass (BG) nanoparticles/poly(L-lactide) (PLLA) composites were prepared as promising bone-repairing materials. The BG nanoparticles (Si:P:Ca=29:13:58 weight ratio) of about 40nm diameter were prepared via the sol-gel method. In order to improve the phase compatibility between the polymer and the inorganic phase, PLLA (M(n)=9700Da) was linked to the surface of the BG particles by diisocyanate. The grafting ratio of PLLA was in the vicinity of 20 wt.%. The grafting modification could improve the tensile strength, tensile modulus and impact energy of the composites by increasing the phase compatibility. When the filler loading reached around 4 wt.%, the tensile strength of the composite increased from 56.7 to 69.2MPa for the pure PLLA, and the impact strength energy increased from 15.8 to 18.0 kJ m(-2). The morphology of the tensile fracture surface of the composite showed surface-grafted bioactive glass particles (g-BG) to be dispersed homogeneously in the PLLA matrix. An in vitro bioactivity test showed that, compared to pure PLLA scaffold, the BG/PLLA nanocomposite demonstrated a greater capability to induce the formation of an apatite layer on the scaffold surface. The results of marrow stromal cell culture revealed that the composites containing either BG or g-BG particles have much better biocompatibility compared to pure PLLA material.

Amphiphilic Bioactive Filler for Acrylic Bone Cement to Enhance Its Cell Adhesion.

Bioactive amphiphilic raspberry particles (BRPs) were proposed to addressing the challenge in cement-bone interface non-integration that was often taking place when poly(methyl methacrylate) (PMMA) bone cements are used. BRPs were designed to have surface patches with different functions, some of which are bioactive to promote bonding to bone and the rest are hydrophobic to promote well compatibility with PMMA matrix. With Pickering emulsion polymerization plus post-modification on surface, such functional particles have been successfully prepared and the composite cements (BRP-PMMA composite cements) were indeed found to promote bone related cell adhesion, while not to sacrifice any of the virtues of the conventional PMMA bone cements.

Molecular imaging and depth profiling of biomaterials interfaces by femtosecond laser desorption postionization mass spectrometry.

Mass spectrometry (MS) imaging is increasingly being applied to probe the interfaces of biomaterials with invasive microbial biofilms, human tissue, or other biological materials. Laser desorption vacuum ultraviolet postionization with ∼75 fs, 800 nm laser pulses (fs-LDPI-MS) was used to collect MS images of a yeast-Escherichia coli co-culture biofilm. The method was also used to depth profile a three-dimensionally structured, multispecies biofilm. Finally, fs-LDPI-MS analyses of yeast biofilms grown under different conditions were compared with LDPI-MS using ultraviolet, nanosecond pulse length laser desorption as well as with fs laser desorption ionization without postionization. Preliminary implications for the use of fs-LDPI-MS for the analysis of biomaterials interfaces are discussed and contrasted with established methods in MS imaging.

The nanocomposite scaffold of poly(lactide-co-glycolide) and hydroxyapatite surface-grafted with L-lactic acid oligomer for bone repair.

Nanohydroxyapatite (op-HA) surface-modified with l-lactic acid oligomer (LAc oligomer) was prepared by LAc oligomer grafted onto the hydroxyapatite (HA) surface. The nanocomposite of op-HA/PLGA with different op-HA contents of 5, 10, 20 and 40wt.% in the composite was fabricated into three-dimensional scaffolds by the melt-molding and particulate leaching methods. PLGA and the nanocomposite of HA/PLGA with 10wt.% of ungrafted hydroxyapatite were used as the controls. The scaffolds were highly porous with evenly distributed and interconnected pore structures, and the porosity wasaround 90%. Besides the macropores of 100-300microm created by the leaching of NaCl particles, the micropores (1-50microm) in the pore walls increased with increasing content of op-HA in the composites of op-HA/PLGA. The op-HA particles could disperse more uniformly than those of pure HA in PLGA matrix. The 20wt.% op-HA/PLGA sample exhibited the maximum mechanical strength, including bending strength (4.14MPa) and compressive strength (2.31MPa). The cell viability and the areas of the attached osteoblasts on the films of 10wt.% op-HA/PLGA and 20wt.% op-HA/PLGA were evidently higher than those on the other composites. For the animal test, there was rapid healing in the defects treated with 10 and 20wt.% op-HA/PLGA, where bridging by a large bony callus was observed at 24weeks post-surgery. There was non-union of radius defects implanted with PLGA and in the untreated group. This was verified by the Masson's trichrome staining photomicrographs of histological analysis. All the data extrapolated that the composite with 10 and 20wt.% op-HA exhibited better comprehensive properties and were the optimal composites for bone repairing.