Mechanical resistant bioactive materials are of high interest for biomedical applications. In this work, we address the improvement in mechanical properties of HA coatings by the addition of a cheap and widely available secondary phase material, the talc from soapstone. The composites hydroxyapatite/talc (HA/talc) were successfully obtained by pulsed electrodeposition and characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectroscopy, corrosion and wear resistance and biocompatibility tests. We found that the addition of talc greatly improves the mechanical properties of coatings (i. e., wear track and friction coefficient in wear tests were significantly diminished) without diminishing corrosion resistance and biocompatibility. Alamar Blue® tests, alkaline phosphatase activity, and collagen production indicate that the biocomposites are biocompatible and talc itself induce bone maturation.
We employed PBE and BLYP semi-local functionals and the van der Waals density functional of Dion et al. (2004) (vdW-DF) to investigate structural properties of liquid acetonitrile and methanol. Among those functionals the vdW-DF is the only one that correctly predicts energy minima in inter-molecular interactions between acetonitrile molecules. We found that van der Waals interactions have a negligible effect on H-bonds in methanol chains. However, it significantly increases chain packing resulting in a more dense liquid in comparison to the other two functionals. The overall trend is that the vdW-DF tends to overestimate density and bulk modulus, meanwhile the semi-local functionals tend to underestimate density. Thus, van der Waals interactions play an important role in the properties of liquids in which much stronger dipole-dipole interactions are present.
Optical microscopy has been one of the most important tools for visualizing biological samples since the seventeenth century. Recently, with the advances in femtosecond laser technology, all the nonlinear optical processes have now been included as optical microscopy methods, and second harmonic generation (SHG) microscopy has emerged as a powerful new optical imaging tool with applications in medicine and biology. Here we use SHG microscopy to obtain images of 76 prostate biopsies on histological slides. Multiple samples from the excised prostates of patients who underwent a radical prostatectomy were evaluated. The samples were collected from prostate positions as in needle biopsy procedures. The results show the collagen fiber architecture among malignant acini, and analysis of the fiber orientation in the images reveals that the collagen fibers become more aligned at higher malignancy grades. Furthermore, we find that the degree of fiber alignment correlates directly with the Gleason patterns.
Optical microscopy is one of the most important tool for understanding biology processes. Recently with the advance of femtosecond laser all the nonlinear optical processes have been included into optical microscopy methods and Second Harmonic Generation (SHG) microscopy has emerged as a powerful new optical imaging tool with applications in disease diagnostics \[1-2\]. The ``gold standard'' in cancer diagnostics is still the traditional histology analysis where accuracy depends on the experience and interpretation skill of the pathologist. A major development would be to use the SHG microscopy as a quantitative tool to cancer diagnosis. Here we show SHG imaging results of the collagen fibers in prostate cancer tissue that can be directly correlated with the cancer malignancy diagnostic \[3\]. We performed SHG imaging in a back-scattering geometry on the histological slides from the same biopsies that were analyzed by the pathologist. We studied prostate from patients treated at the the Urology Center of UFMG Hospital, Belo Horizonte. A 1 mm diameter punch biopsy was extracted from multiple peripheral zone of the prostate showing normal tissue and cancer tissue with Gleason scores ranging from 3 to 5. The study was approved by the UFMG Institutional Review Board and the Brazilian National Health Committee on the use of humans as experimental subjects. Written informed consent was obtained from all participants before their biopsy procedures. Figure 1 shows SHG images for normal and cancer tissue. The SHG images show major differences on the collagen fiber alignment that changes with cancer progression. The average direction of the fibers in the image was calculated and we obtained a value for the fiber anisotropy \[4\]. The statistical analysis is presented in the boxplot in figure 1. Note that both the average values (crosses) and the median lines (black center lines) are well separated for the normal and cancer tissue.