Surface-Engineered Titanium with Nanoceria to Enhance Soft Tissue Integration Via Reactive Oxygen Species Modulation and Nanotopographical Sensing.

The design of implantable biomaterials involves precise tuning of surface features because the early cellular fate on such engineered surfaces is highly influenced by many physicochemical factors [roughness, hydrophilicity, reactive oxygen species (ROS) responsiveness, etc.]. Herein, to enhance soft tissue integration for successful implantation, Ti substrates decorated with uniform layers of nanoceria (Ce), called Ti@Ce, were optimally developed by a simple and cost-effective in situ immersion coating technique. The characterization of Ti@Ce shows a uniform Ce distribution with enhanced roughness (∼3-fold increase) and hydrophilicity (∼4-fold increase) and adopted ROS-scavenging capacity by nanoceria coating. When human gingival fibroblasts were seeded on Ti@Ce under oxidative stress conditions, Ti@Ce supported cellular adhesion, spreading, and survivability by its cellular ROS-scavenging capacity. Mechanistically, the unique nanocoating resulted in higher expression of amphiphysin (a nanotopology sensor), paxillin (a focal adhesion protein), and cell adhesive proteins (collagen-1 and fibronectin). Ti@Ce also led to global chromatin condensation by decreasing histone 3 acetylation as an early differentiation feature. Transcriptome analysis by RNA sequencing confirmed the chromatin remodeling, antiapoptosis, antioxidant, cell adhesion, and TGF-ß signaling-related gene signatures in Ti@Ce. As key fibroblast transcription (co)factors, Ti@Ce promotes serum response factor and MRTF-α nucleus localization. Considering all of this, it is proposed that the surface engineering approach using Ce could improve the biological properties of Ti implants, supporting their functioning at soft tissue interfaces and utilization as a bioactive implant for clinical conditions such as peri-implantitis.

Removal of lead ions in aqueous solution by hydroxyapatite/polyurethane composite foams.

We have prepared hydroxyapatite/polyurehthane (HAp/PU) composite foams with two different HAp contents of 20 and 50 wt.% and investigated their removal capability of Pb2+ ions from aqueous solutions with various initial Pb2+ ion concentrations and pH values of 2-6. HAp/PU composite foams synthesized exhibited well-developed open pore structures which provide paths for the aqueous solution and adsorption sites for Pb2+ ions. With increasing the HAp content in the composites, the removal capability of Pb2+ ions by the composite foams increases owing to the higher adsorption capacity, whereas the removal rate is slower due to the less uniform dispersity of HAp in composite foams. The removal rate of Pb2+ ions is also slower with increasing the initial Pb2+ ion concentration in aqueous solutions. The removal mechanism of Pb2+ ion by the composites is varied, depending on the pH value of aqueous solution: the dissolution of HAp and precipitation of hydroypyromorphite is dominant at lower pH 2-3, the adsorption of Pb2+ ions on the HAp/PU composite surface and ion exchange reaction between Ca2+ of HAp and Pb2+ in aqueous solution is dominant at higher pH 5-6, and two removal mechanisms compete at pH 4. The equilibrium removal process of Pb2+ ions by the HAp/PU composite foam at pH 5 was described well with the Langmuir isotherm model, resulting in the maximum adsorption capacity of 150 mg/g for the composite foam with 50 wt.% HAp content.

Preparation and lead ion removal property of hydroxyapatite/polyacrylamide composite hydrogels.

We report the synthesis of hydroxyapatite/polyacrylamide (HAp/PAAm) composite hydrogels with various HAp contents by free radical polymerization and their removal capability of Pb(2+) ions in aqueous solutions with controlled initial Pb(2+) ion concentrations and pH values of 2-5. The swelling ratio of the composite gels in aqueous solutions decreases with increasing the HAp content in the gels. The composite gel with higher HAp content exhibits the higher removal capacity of Pb(2+) ions owing to the higher adsorption sites for Pb(2+) ions, but shows the slower removal rate of Pb(2+) ions due to the lower degree of swelling. The removal mechanism of Pb(2+) ion is very sensitive to the pH value in aqueous solution, although the removed amount of Pb(2+) ion is nearly same, regardless of pH values of 2-5. The removal mechanism, the dissolution of HAp in the composite gel and subsequent precipitation of hydroxypyromorphite (HPy), is dominant at lower pH 2-3, whereas the mechanism, the adsorption of Pb(2+) ions on the composite gel and following cation exchange reaction between Pb(2+) ions adsorbed and Ca(2+) of HAp, is dominant at higher pH 4-5. The equilibrium removal process of Pb(2+) ions by the composite gels at pH 5 is described well with the Langmuir isotherm model. The equilibrium removal capacities of the composite gels with 30, 50, and 70 wt.% HAp contents are evaluated to be 123, 178, and 209 mg/g, respectively.

Enhanced bone regeneration in beagle dogs with bovine bone mineral coated with a synthetic oligopeptide.

BACKGROUND: Recombinant human bone morphogenic protein-2 stimulates bone augmentation in animal models. The aim of this study was to evaluate the capacity of bovine bone mineral coated with synthetic oligopeptides to enhance guided bone regeneration in the beagle 3-wall defect model and the clinical implications. METHODS: The second and fourth mandibular premolars of four adult beagle dogs were extracted bilaterally, and the extraction sites were allowed to heal for 2 months. An L-shaped defect was prepared at the central part of the extraction site with a round bur on a low-speed motor. Peptide-coated bone mineral was implanted on one side, and uncoated bone mineral was implanted on the other side. The membrane was tucked underneath the mobilized lingual flap. New bone formation at the test and control sites was determined at 4 weeks. RESULTS: No specimen revealed any evidence of infection or foreign body reaction, and all wounds showed a good healing response. Sites augmented with peptide-coated bone mineral and uncoated mineral exhibited excellent maintenance of the ridge contour. There was more new bone at sites with peptide-coated bone mineral than at control sites. The new bone in sites with peptide-coated bone mineral was deposited evenly around the graft material, and bone mineral was integrated fully into the new bone. CONCLUSION: Deproteinized cancellous bovine bone coated with synthetic oligopeptides enhanced new bone formation, and it seemed to be a better material for guided bone regeneration in the beagle L-shaped defect model.

Osteopromotion with synthetic oligopeptide-coated bovine bone mineral in vivo.

BACKGROUND: Recombinant human bone morphogenetic protein (rhBMP)-2 has been shown to stimulate significant regeneration of alveolar bone and cementum in periodontal defects clinically. The aim of this study was to evaluate the osteopromotive effect of oligopeptide domain-coated bovine bone mineral granules in a rabbit calvarial defect model. METHODS: The peptide-coated bovine bone was fabricated by incubating the graft material in a solution of oligopeptide domain. The cell attachment and proliferation were measured in vitro. Peptide-coated (test group) or uncoated (control group) bone minerals were implanted into 10-mm calvarial defects in rabbits, and the animals were sacrificed at 1, 2, or 4 weeks post-surgery. RESULTS: The cells grown with peptide-coated bone showed significantly higher proliferation activity at all times compared to cells grown with peptide-uncoated bone mineral. At 2 weeks post-surgery, the control wounds showed a limited amount of osteoid formation in a centripetal pattern around the grafted bone, but the oligopeptide domain-coated grafted bone had formed new bone around the grafted area. At 4 weeks post-surgery, the control sites showed increased new bone formation, but they still showed a significant difference from the peptide-coated bone-implanted sites. CONCLUSIONS: At 2 and 4 weeks, accelerated new bone formation was observed within the experimental sites compared to control groups. The use of deproteinized bovine bone combined with a synthetic oligopeptide seems to be a more beneficial material for bone regeneration in the early healing period.

Comparative Study of rhPDGF-BB Plus Equine-Derived Bone Matrix Versus rhPDGF-BB Plus ß-TCP in the Treatment of Periodontal Defects.

The purpose of this study was to evaluate the efficacy and safety of equine-derived bone matrix as a carrier for recombinant human platelet-derived growth factor BB (rhPDGF-BB) versus beta-tricalcium phosphate (ß-TCP) for the treatment of intraosseous periodontal defects in adult patients. This study was performed on 32 adults with advanced periodontal disease. Eligible subjects were randomized in 1:1 ratio into a test (rhPDGF-BB-coated equine-derived bone matrix) or control group (rhPDGF-BB-coated ß-TCP). Probing pocket depth (PD), clinical attachment level (CAL), gingival recession (GR), and defect depth on radiographs were measured at 2 weeks before surgery, on the day of surgery (DOS), and 6 months postsurgery (6MPS). The clinical and radiographic data were analyzed over the test period. Statistically significant PD reductions and CAL gain between baseline and 6MPS and between ODS and 6MPS were seen in both groups (P < .01). No statistically significant differences in PD reduction were found between groups. However, the test group showed significant CAL gain between DOS and 6MPS. The radiographic bone level change was statistically significant compared to baseline (P < .01) in both groups. The results suggested that equine-derived bone matrix is a viable, effective, and safe carrier scaffold for rhPDGF in periodontal defects.

Enhanced osteogenic promotion around dental implants with synthetic binding motif mimicking bone morphogenetic protein (BMP)-2.

Synthetic receptor binding motif mimicking bone morphogenetic protein-2 (BMP-2) was covalently linked to titanium (Ti) surfaces through a chemical conjugation process. The composition and properties of surface-modified Ti were investigated by XPS as well as by measuring surface radioactivity. In vitro tests were conducted with osteoblast-like MC3T3-E1 cells to assess cell attachment, morphology, and expression of osteogenic marker in the cells grown on modified Ti surfaces. In addition, in vivo experiments involved implants in mandibular bone defects of beagles to evaluate the effect of surface modification on bone regeneration. Results of XPS measurements showed a complete and homogeneous peptide overlayer on the Ti surfaces; the content was further measured by gamma counting. Biological evaluations showed that the biochemically modified Ti samples were active in terms of cell attachment behavior. The MC3T3-E1 cell growth rate, marker protein expression, and alkaline phosphatase production of the peptide-modified surfaces were all higher than those of control Ti. Importantly, the implants in the canine mandibles showed significant increase of bone growth when modified with bioactive peptide, thereby confirming that biochemical modifications of Ti surfaces can enhance the rate of bone healing as compared with untreated Ti surfaces.

Removal of acetic acid from simulated hemicellulosic hydrolysates by emulsion liquid membrane with organophosphorus extractants.

Selective removal of acetic acid from simulated hemicellulosic hydrolysates containing xylose and sulfuric acid was attempted in a batch emulsion liquid membrane (ELM) system with organophosphorus extractants. Various experimental variables were used to develop a more energy-efficient ELM process. Total operation time of an ELM run with a very small quantity of trioctylphosphine oxide as the extractant was reduced to about a third of those required to attain almost the same extraction efficiency as obtained in previous ELM works without any extractant. Under specific conditions, acetic acid was selectively separated with a high degree of extraction and insignificant loss of xylose, and its purity and enrichment ratio in the stripping phase were higher than 92% and 6, respectively. Also, reused organic membrane solutions exhibited the extraction efficiency as high as fresh organic solutions did. These results showed that the current ELM process would be quite practical.

Purification of xylose in simulated hemicellulosic hydrolysates using a two-step emulsion liquid membrane process.

Purification of xylose in simulated hemicellulosic hydrolysates was attempted using a two-step emulsion liquid membrane (ELM) process. The effects of various experimental variables on extraction of each component in the hydrolysates were investigated in the ELM steps. In the first ELM step, acetic acid could be selectively removed from the hydrolysates and highly enriched in the stripping phase, and loss of xylose was insignificant. In the second ELM step, sulfuric acid could be selectively removed from simulated acetic acid-free hemicellulosic hydrolysates and somewhat enriched in the stripping phase. There was just small loss of xylose, and the final pH of the feed phase approached a pH level suitable for ethanol fermentation. Also, concentration of xylose in the feed phase was attained as an incidental outcome during each ELM run. Conclusively, the two-step ELM process was found to be a promising futuristic technology for purification of sugars in real hemicellulosic hydrolysates.