Natural rubber latex membranes incorporated with three different types of propolis: Physical-chemistry and antimicrobial behaviours.

Natural Rubber Latex (NRL) is a biocompatible material with demonstrated capacity to induce vascularisation and tissue regeneration. Propolis is a complex resinous product prepared by Apis mellifera with the aim of protecting beehives against infectious microorganisms. It is flora-dependent and its antimicrobial activity can vary according to its geographical origin. This study compares the incorporation of three different types of propolis into an NRL membrane aiming at optimal controlled release of propolis potential antimicrobial compounds towards Candida albicans whilst keeping NRL mechanical characteristics desirable for wound healing bandage purposes. The propolis samples were classified as red, green and poplar propolis according to their chemical composition determined by ultra-high performance liquid chromatography coupled in series with both UV spectrophotometry and high-resolution mass spectrometry. The Minimum Inhibitory Concentrations (MIC) towards C. albicans were determined before their incorporation into NRL membranes. The release of NRL-propolis components in Simulated Body Fluid (SBF) was monitored by UV-Vis spectroscopy. The antimicrobial activity and the effects of the materials released on mouse fibroblasts were assessed. FTIR analyses were carried out in order to verify the formation of new chemical bonds that might prevent the release of propolis components from the NRL membrane. The mechanical characteristics of the NRL membranes remained adequate after the incorporation of the three types of propolis investigated whilst allowing the release of the red, and poplar propolis most active compounds against C. albicans. At 30 and 50% the released materials (eluates) from the NRL membranes incorporated with red and poplar propolis types were not toxic to fibroblast cells. These results suggest that red and poplar propolis can be incorporated into NRL membranes for the preparation of wound healing dressing.

Defective Multilayer Carbon Nanotubes Increase Alkaline Phosphatase Activity and Bone-Like Nodules in Osteoblast Cultures.

Carbon nanotubes (CNT) is one of the most studied biomaterials, and issues about its cytotoxicity remain. The objective of our study was to investigate the in vitro influence of defective CNT on culture growth and on the formation of mineralized matrix nodules by primary osteoblastic cells grown in plastic or titanium (Ti) surfaces. Cellular viability, alkaline phosphatase activity and formation of mineral nodules were evaluated, besides the CNT characterization tests. The CNT studies showed better cell viability for osteoblasts incubated at stationary phase of culture in the presence of Ti (about 70%), but for the other phases, the cells suffered a significant reduction in viability. A peak of maximum alkaline phosphatase activity in the intermediate stage of growth (14 days of culture), which is characteristic for osteoblasts, was not affected, regardless of the presence of Ti or combination of CNT and Ti. Mineralized matrix nodules grew much more when the cells were incubated with CNT in the last 2 phases than when incubated in the first week, mainly when the cultures were grown on Ti discs. This study provides information for the application of CNT associated or not with Ti in processes of mineralization biostimulation.

The effect of photosensitizer drugs and light stimulation on osteoblast growth.

OBJECTIVE: A promising new treatment in dentistry involves the photodynamic process, which utilizes a combination of two therapeutic agents, namely a photosensitizer drug and a low dose of visible light. We investigated the in vitro effect of low intensity laser irradiation (visible light irradiation at 670 nm) using doses ranging between 0.5 and 3 J/cm(2), combined with nanoemulsion (NE) of the photosensitizer drug aluminum phthalocyanine chloride (AlClPc), ranging from 0.5 to 5 µmol/L, on the growth and differentiation of osteoblastic cells isolated from rat bone marrow. BACKGROUND DATA: Treatments using laser radiation of low intensity in dentistry are of great interest, especially in bucco-maxillofacial surgery and dental implantology, where this approach is currently employed to stimulate osteogenesis. In the presence of oxygen, the combination of these agents could induce cellular biostimulation, via an efficient noninvasive method. METHODS: We have done the colorimetric MTT assay, collagen content, total protein content, ALP activity and bone-like nodule formation. RESULTS: We observed that an increased number of viable cells was evident upon application of a laser dosage equal to 0.5 J/cm(2) when combined with 0.5 µmol/L of AlClPc/NE, suggesting cellular biostimulation. CONCLUSIONS: It was possible to demonstrate that low intensity laser irradiation can play an important role in promoting biostimulation of osteoblast cell cultures. Therefore, whether biostimulation of osteoblastic cell cultures by photodynamic therapy or the cytotoxic effect of this therapy occurs only depends upon the light dose, and the results can be completely reversed.