Surface interactions of a W-DLC-coated biomedical AISI 316L stainless steel in physiological solution.

The corrosion stability of a W-DLC coated surgical AISI 316L stainless steel in Hanks' solution has been evaluated. Particle induced X-ray emission (PIXE) measurements were performed to evaluate the incorporation of potentially bioactive elements from the physiological solution. The film structure was analyzed by X-ray diffractometry and micro-Raman spectroscopy. The wear behavior was assessed using the sphere-on-disc geometry. The in vitro biocompatibility of the W-DLC film was evaluated by cytotoxicity tests. The corrosion resistance of the stainless steel substrate decreased in the presence of the PVD layer. EIS measurements suggest that this behavior was closely related to the corrosion attack through the coating pores. PIXE measurements revealed the presence of Ca and P in the W-DLC film after immersion in Hanks' solution. This result shows that the PIXE technique can be applied to identify and evaluate the incorporation of bioactive elements by W-DLC films. The film showed good wear resistance and biocompatibility.

Lanthanide-based ß-Tricalcium Phosphate Upconversion Nanoparticles as an Effective Theranostic Nonviral Vectors for Image-Guided Gene Therapy.

Lanthanide-based beta-tricalcium phosphate (ß-TCP) upconversion nanoparticles are exploited as a non-viral vector for imaging guided-gene therapy by virtue of their unique optical properties and multi-modality imaging ability, high transfection efficiency, high biocompatibility, dispersibility, simplicity of synthesis and surface modification. Ytterbium and thulium-doped ß-TCP nanoparticles (ßTCPYbTm) are synthesized via co-precipitation method, coated with polyethylenimine (PEI) and functionalized with a nuclear-targeting peptide (TAT). Further, in vitro studies revealed that the nanotheranostic carriers are able to transfect cells with the plasmid eGFP at a high efficiency, with approximately 60% of total cells producing the fluorescent green protein. The optimized protocol developed comprises the most efficient ßTCPYbTm/PEI configuration, the amount and the order of assembly of ßTCPYbTm:PEI, TAT, plasmid DNA and the culturing conditions. With having excellent dispersibility and high chemical affinity toward nucleic acid, calcium ions released from ßTCPYbTm:PEI nanoparticles can participate in delivering nucleic acids and other therapeutic molecules, overcoming the nuclear barriers and improving the transfection efficacy. Equally important, the feasibility of the upconversion multifunctional nanovector to serve as an effective contrast agent for imaging modality, capable of converting low-energy light to higher-energy photons via a multi-photons mechanism, endowing greater unique luminescent properties, was successfully demonstrated.

Pseudoboehmite as a drug delivery system for acyclovir.

Herpes simplex virus is among the most prevalent sexually transmitted infections. Acyclovir is a potent, selective inhibitor of herpes viruses and it is indicated for the treatment and management of recurrent cold sores on the lips and face, genital herpes, among other diseases. The problem of the oral bioavailability of acyclovir is limited because of the low permeability across the gastrointestinal membrane. The use of nanoparticles of pseudoboehmite as a drug delivery system in vitro assays is a promising approach to further the permeability of acyclovir release. Here we report the synthesis of high purity pseudoboehmite from aluminium nitrate and ammonium hydroxide containing nanoparticles, using the sol-gel method, as a drug delivery system to improve the systemic bioavailability of acyclovir. The presence of pseudoboehmite nanoparticles were verified by infrared spectroscopy, transmission electron microscopy, and X-ray diffraction techniques. In vivo tests were performed with Wistar rats to compare the release of acyclovir, with and without the addition of pseudoboehmite. The administration of acyclovir with the addition of pseudoboehmite increased the drug content by 4.6 times in the plasma of Wistar rats after 4 h administration. We determined that the toxicity of pseudoboehmite is low up to 10 mg/mL, in gel and the dried pseudoboehmite nanoparticles.

Novel fluoride and stannous -functionalized ß-tricalcium phosphate nanoparticles for the management of dental erosion.

OBJECTIVE: To evaluate the anti-erosive effect of solutions containing ß-tricalcium phosphate (ß-TCP) nanoparticles functionalized with fluoride or with fluoride plus stannous on enamel and dentin. METHODS: ß-TCP nanoparticles were synthesized and characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Sixty enamel and dentin specimens were randomly allocated into the groups (n = 10): Control (water); F (NaF, 225 ppm F-); F + Sn (NaF + SnCl2, 800 ppm Sn2+); F+ß-TCP (F+40 ppm ß-TCP); F + Sn+ß-TCP (F + Sn+40 ppm ß-TCP); F + Sn+100ß-TCP (F + Sn+100 ppm ß-TCP). Specimens underwent erosion-remineralization cycling (5 min immersion into 1 % citric acid solution and 60 min exposure to artificial saliva, 4×/day, 5 days). Immersion in the test solutions was performed for 2 min, 2×/day. Surface loss (SL, in µm) was determined by optical profilometry at the end of cycling. Data were analyzed using one way-ANOVA and Tukey's tests (α = 0.05). RESULTS: XRD confirmed the ß-TCP phase. TEM micrographs showed differences between the bare nanoparticle and the ß-TCP functionalized with F and Sn. All enamel groups presented lower SL than the control, with F + Sn, F + Sn+ß-TCP, and F + Sn+100ß-TCP showing the lowest values. For dentin, all the groups had lower SL than the control. F+ß-TCP presented the lowest SL, significantly differing from all the other groups. CONCLUSION: ß-TCP nanoparticles functionalized with fluoride showed improved anti-erosive effect compared to the fluoride solution on dentin. There was no significant effect of the ß-TCP nanoparticles functionalized with fluoride plus stannous in both substrates. CLINICAL RELEVANCE: ß-TCP nanoparticles are a promising agent to be added to oral health products to improve the protective effect of fluoride against dentin erosion.

Effect of ozone therapy on wound healing in the buccal mucosa of rats.

OBJECTIVE: The objective of this study was to evaluate the effects of ozone therapy on wound healing formed experimentally in the oral cavity of rats. DESIGN: Two surgical wounds were generated on the cheeks of 24 Wistar rats, bilaterally. Half of the animals were submitted to ozone therapy on both wounds (experimental group) and the other half received no treatment (control group). In the experimental group, wounds were exposed to ozone gas 1, 2 or 3 (60 µg/mL) times. Evaluation of wound healing of the buccal mucosa was followed for 1, 3 and 7 days. The distribution of neutrophils, fibroplasia and angiogenesis were analyzed. Samples were classified in a healing numerical scale according to the inflammatory intensity. Data were submitted to Mann-Whitney and Kruskal-Wallis tests (α = 0.05). RESULTS: On day 1, wounds were similar in both groups, lesions were open and bloody with slightly minor bleeding in the ozone therapy group. On day 3, the group with ozone therapy was almost all refurbished and with higher angiogenesis, while the control group still had more bloody points and lower blood vessels. On day 7, both wounds were remodeled, with higher fibroplasia in the group that received ozone therapy. CONCLUSION: It can be concluded that ozone therapy was effective in improving angiogenesis and fibroblasts count in the buccal mucosa of rats.

Effect of titania addition and sintering temperature on the microstructure, optical, mechanical and biological properties of the Y-TZP/TiO2 composite.

OBJECTIVE: The aims of this study were: 1) to evaluate the effect of sintering temperature on microstructure, density and flexural strength of a 3Y-TZP/TiO2 composite containing 12.5 wt% of TiO2 compared to 3Y-TZP specimens (control); 2) to compare 3Y-TZP with the experimental 3Y-TZP/TiO2 composite, both sintered at 1400 °C, with respect to the following parameters: optical properties, characteristic strength, Weibull modulus, fatigue behavior, induction of osteoblasts proliferation and differentiation (mineralization nodules formation). METHODS: The 3Y-TZP and 3Y-TZP/TiO2 powders were uniaxially pressed and sintered at 1200 °C, 1300 °C, 1400 °C or 1500 °C for one hour in a furnace. The microstructural analysis consisted of X-ray diffraction and scanning electron microscopy. The density was measured by the Archimedes' principle and the flexural strength was obtained by the biaxial flexure test. The optical properties were measured using a spectrophotometer operating in the visible light wavelength range. The step-stress accelerated life testing was performed by the pneumatic mechanical cycler and the biological behavior achieved by using osteoblast-like cells (Osteo-1 cell line). RESULTS: Tetragonal zirconia was identified in all groups and cubic zirconia was identified only at 3Y-TZP group. The addition of TiO2 decreased the values of density and flexural strength of the composite 3Y-TZP/TiO2 in relation to 3Y-TZP regardless of the sintering temperature. The color difference between the two materials was not significant regarding L*a*b* parameters. The composite showed higher probability of failure, and induced higher proliferation and differentiation than control. SIGNIFICANCE: The composite developed have good aesthetic and biologics properties. However, its microstructure and mechanical properties need to be improved for future dental implant applications.