Composite Fiber Spun Mat Synthesis and In Vitro Biocompatibility for Guide Tissue Engineering.

Composite scaffolds are commonly used strategies and materials employed to achieve similar analogs of bone tissue. This study aims to fabricate 10% wt polylactic acid (PLA) composite fiber scaffolds by the air-jet spinning technique (AJS) doped with 0.5 or 0.1 g of zirconium oxide nanoparticles (ZrO2) for guide bone tissue engineering. ZrO2 nanoparticles were obtained by the hydrothermal method and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). SEM and fourier-transform infrared spectroscopy (FTIR) analyzed the synthesized PLA/ZrO2 fiber scaffolds. The in vitro biocompatibility and bioactivity of the PLA/ZrO2 were studied using human fetal osteoblast cells. Our results showed that the hydrothermal technique allowed ZrO2 nanoparticles to be obtained. SEM analysis showed that PLA/ZrO2 composite has a fiber diameter of 395 nm, and the FITR spectra confirmed that the scaffolds' chemical characteristics are not affected by the synthesized technique. In vitro studies demonstrated that PLA/ZrO2 scaffolds increased cell adhesion, cellular proliferation, and biomineralization of osteoblasts. In conclusion, the PLA/ZrO2 scaffolds are bioactive, improve osteoblasts behavior, and can be used in tissue bone engineering applications.

In vitro and in vivo biological characterization of poly(lactic acid) fiber scaffolds synthesized by air jet spinning.

Poly(lactic acid) (PLA) is one of the most promising renewable and biodegradable polymers for mimic extracellular matrix for tissue engineering applications. In this work, PLA spun membrane scaffold were successfully prepared by air jet spinning technology. Morphology, mechanical properties, in vitro biocompatibility, and in vitro and in vivo degradation of PLA fibrous scaffold were characterized by X-ray diffraction, Fourier Transform Infrared, and scanning electron microscope (SEM). Morphological results assessed by SEM analyses indicated that PLA scaffolds possessed an average fiber diameter of approximately 0.558 ± 0.141 µm for 7% w/v of PLA and approximately 0.647 ± 0.137 µm for 10% w/v. Interestingly, our results showed that the nanofiber size of PLA scaffold allow structural stability after 100 days of in vitro degradation in Ringer solution where the average fiber diameter were of approximately 0.633 ± 0.147 µm for 7% w/v and approximately 0.645 ± 0.140 µm for 10% w/v of PLA. Mechanical properties of PLA fibers scaffold after in vitro degradation showed decrease in terms of flexibility elongation, and less energy was needed to achieve maximal elastic deformation. The fiber size exerts an influence on the biological response of human Bone Marrow Mesenchymal Stromal Cells as confirmed by MTT assay after 9 days of cell culture and the in vivo degradation assay of 7% w/v and 10% w/v of PLA scaffold, did not demonstrate evidence of toxicity with a mild inflammatory respond. In conclusion, airbrushing technology promises to be a viable and attractive alternative technique for producing a biocompatible PLA nanofiber scaffold that could be considered for tissue engineering regeneration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2435-2446, 2018.

Influence of diameter of fiber membrane scaffolds on the biocompatibility of hPDL mesenchymal stromal cells.

This study evaluated the influence in the biocompatibility of human periodontal ligament (hPDL) mesenchymal stromal cell onto poly lactic-acid (PLA) films and PLA fiber membrane. Fiber scaffold was prepared via air jet spinning (AJS) from PLA solutions (6, 7, and 10%) and analyzed using SEM, AFM and FTIR. Biocompatibility was evaluated by adhesion, proliferation and cell-material interaction. PLA film exhibited a smooth and homogenously surface topography in comparison with random orientation of PLA fiber with roughness structure where diameter size depends on PLA solution. Moreover, cell adhesion; proliferation and cell-material interaction has the best respond on random orientation nanofiber of 10, followed by 7, and 6% of PLA in comparison with PLA films. It could be concluded that AJS is an attractive alternative technique for manufacture fiber scaffolds with a tunable random orientation geometry of fibers that allow to produce interconnected porous formed by nanometric fiber diameter structures that could be a potential scaffold for periodontal tissue engineering applications.

Synthesis and characterization of RuS2 nanostructures.

Small naked ruthenium sulfide nanoparticles (NPs) with narrow size distribution (2.5 +/- 0.4 nm of diameter) were synthesized in DMSO colloidal dispersions, under mild reaction conditions and using commercial RuCl3 as precursor. To test the chemical reactivity with soft and hard bases, fresh presynthesized RuS2 colloids were mixed with triethylamine (N(Et)3) and ammonium tetrathiomolybdate ((NH4)2MoS4) dimethyl sulfoxide solutions. Naked N(Et)3 and [MoS4](2-)-capped RuS2 nanoparticle colloids were characterized using UV-visible electronic absorption and emission spectroscopies and high-resolution transmission electron microscopy (HR-TEM). It has also been shown that capped RuS2-[MoS4]2- nanoparticles yield MoO3 crystalline matrix by means of HR-TEM experiments. The emission spectra of RuS2 and N(Et)3-RuS2 dispersions show that both nanosized materials have strong fluorescence. The existence of the ruthenium precursor species in solution was established by cyclic voltammetry. Moreover, naked RuS2 NPs were mixed with a chemical mixture with composition similar to gasoline (dibenzothiophene (Bz2S, 400 ppm), hexane, and toluene (55:45% v/v)). The reaction mixture consisted of two phases; in the polar phase, we found evidences of a strong interaction of Bz2S and toluene with the naked RuS2 NPs. We have also obtained self-organized thin films of capped N(Et)3- and RuS2-[MoS4]2- nanoparticles. In both cases, the shape and thickness of the resulting thin films were controlled by a dynamic vacuum procedure. The thin films have been characterized by atomic force microscopy, scanning electron microscopy, HR-TEM, energy dispersion spectroscopy, X-ray diffraction, and absorbance and fluorescence spectroscopies.

X-ray microanalysis of human cementum.

An energy dispersive x-ray microanalysis study was performed throughout the total length of cementum on five impacted human teeth. Mineral content of calcium, phosphorous, and magnesium were determined with an electron probe from the cemento-enamel junction to the root apex on the external surface of the cementum. The concentration profiles for calcium, phosphorous, and magnesium were compared by using Ca/P and Mg/Ca atomic percent ratio. Our findings demonstrated that the Ca/P ratio at the cemento-enamel junction showed the highest values (1.8-2.2). However, the area corresponding to the acellular extrinsic fiber cementum (AEFC) usually located on the coronal one-third of the root surface showed a Ca/P media value of 1.65. Nevertheless, on the area representing the fulcrum of the root there is an abrupt change in the Ca/P ratio, which decreases to 1.3. Our results revealed that Mg(2+) distribution throughout the length of human cementum reached its maximum Mg/Ca ratio value of 1.3-1.4 at.% around the fulcrum of the root and an average value of 0.03%. A remarkable finding was that the Mg/Ca ratio pattern distribution showed that in the region where the Ca/P ratio showed a decreasing tendency, the Mg/Ca ratio reached its maximum value, showing a negative correlation. In conclusion, this study has established that clear compositional differences exist between AEFC and cellular mixed stratified cementum varieties and adds new knowledge about Mg(2+) distribution and suggests its provocative role regulating human cementum metabolism.

Anti-cementoblastoma-derived protein antibody partially inhibits mineralization on a cementoblastic cell line.

The effect of human anti-cementoblastoma-derived protein antibody during cementogenesis in vitro was investigated by using human cementoblastoma-derived cells. Cultures treated with 5 microg/ml of CP antibody from day 1 to day 15 revealed a significant decrease in alkaline phosphatase activity (ALP) 40% (p < 0.005), 44% (p < 0.001), 49% (p < 0.1), and 45% (p < 0.02) at 9, 11, 13, and 15 days, respectively. Immunoexpression of osteopontin revealed that in cultures treated with anti-CP antibody, the positive number of cementoblastoma cells was reduced by 87, 83, 69, and 52% at 5, 7, 9, and 11 days, respectively. Bone sialoprotein immunoexpression showed a decrease in positive cells of 82, 51, 60, 80, 83, and 87% at 5, 7, 9, 11, 13, and 15 days, respectively, as compared to controls. The Ca/P ratio of the mineral-like tissue deposited in vitro by cementoblastoma cells revealed that control cultures had a Ca/P ratio of 1.45 and 1.61 at 5 and 15 days, whereas experimental cultures revealed a Ca/P ratio of 0.50 and 0.79 at 5 and 15 days, respectively. Electron diffraction patterns showed inner double rings representing D-spacing that were consistent with those of hydroxyapatite in both control and experimental cultures. Examination of the crystallinity with high resolution transmission electron microscopy showed homogeneous and preferential spatial arrangement of hydroxyapatite crystallites in control and experimental cultures at 15 days. Atomic force microscopy images of control cultures at 5 and 15 days revealed small granular particles and grain agglomeration that favored the formation of crystalline plaques with a lamellar-like pattern of the mineral-like tissue. Experimental cultures at 5 and 15 days showed tiny and homogeneous granular morphology. The agglomerates maintained spherical morphology without organization of needle-like crystals to form plaque-like structures. Based on these findings, it is hypothesized that cementoblastoma-derived protein may be associated to crystal growth, compositional and morphological features during the mineralization process of cementum in vitro.