No abstract

Methacrylated gelatin films with in situ-generated TiO 2 nanoparticles containing varying weight percentages of gelatin (0 %, 0.5 %, 1 %, 2 % and 4 %) were successfully prepared as novel biomaterials. 1 H-NMR spectroscopy confirmed their methacrylation with a 79 % degree of substitution. TiO 2 nanoparticles were uniformly distributed in the films with the average particle size increasing from 85 to 130 nm in proportion to an increase in TiO 2 concentration from 0.5 to 4 wt%. The water absorption of various gelatin methacrylamide/TiO 2 films was in the range of 471-758 %, which was enough to prevent wound beds from exudates accumulation. And in vitro degradation test in PBS showed that the three-dimensional structure of all samples basically remained unchanged although more than or nearly half the mass of specimens decreased after 4 weeks' degradation, and the pH levels of all sample solutions were maintained in an adequate range of 6.5-7.4 for cell and tissue growth during the whole process. The antibacterial activities of the films against E. coli and S. aureus were measured via a shake flask test and demonstrated good performance after the importation of TiO 2 nanoparticles. Cytotoxicity testing revealed that all films had no cytotoxicity and showed favorable adherence in the presence of L929 cells. The results suggest that hybrid hydrogel films hold potential for antibacterial wound dressing and tissue engineering scaffold applications.

Repair and reconstruction of large bone defect were often difficult, and bone substitute materials, including autogenous bone, allogenic bone and artificial bone, were common treatment strategies. The key to elucidate the clinical effect of these bone repair materials was to study their osteogenic capacity and immunotoxicological compatibility. In this paper, the mechanical properties, micro-CT imaging analysis, digital image analysis and histological slice analysis of the three bone grafts were investigated and compared after different time points of implantation in rat femur defect model. Autogenous bone and biphasic calcium phosphate particular artificial bone containing 61.4% HA and 38.6% β-tricalcium phosphate with 61.64% porosity and 0.8617 ± 0.0068 g/cm3 density (d ≤ 2 mm) had similar and strong bone repair ability, but autogenous bone implant materials caused greater secondary damage to experimental animals; allogenic bone exhibited poor bone defect repair ability. At the early stage of implantation, the immunological indexes such as Immunoglobulin G, Immunoglobulin M concentration and CD4 cells’ population of allogenic bone significantly increased in compared with those of autologous bone and artificial bone. Although the repair process of artificial bone was relatively inefficient than autologous bone graft, the low immunotoxicological indexes and acceptable therapeutic effects endowed it as an excellent alternative material to solve the problems with insufficient source and secondary trauma of autogenous bone.

Polarization properties of apertureless-type scanning near-field optical microscopy (a-SNOM) were measured experimentally and were also analyzed using a finite-difference time-domain (FDTD) simulation. Our study reveals that the polarization properties in the a-SNOM are maintained and the a-SNOM works as a wave plate expressed by a Jones matrix. The measured signals obtained by the lock-in detection technique could be decomposed into signals scattered from near-field region and background signals reflected by tip and sample. Polarization images measured by a-SNOM with an angle resolution of 1° are shown. FDTD analysis also reveals the polarization properties of light in the area between a tip and a sample are p-polarization in most of cases.

Polarization properties in aperture-less scanning near-field optical microscopy (SNOM) were investigated using the 3D finite-difference time-domain (FDTD) method. We found that scattered light became elliptically polarized with linear or circular-polarized light illumination, and the polarization state of scattered light was preserved. In addition, Jones matrices that express the relationship between incident light and scattered light in terms of the polarization states were successfully obtained. We succeeded in calculating the polarization state of scattered light with arbitrary polarized light illumination by using the Jones matrix method.