Advanced Materials Research Vol. 506

Abstract: Rutile TiO₂ films are normally used as biomaterial that synthesized on unheated stainless steel type 316L and glass slide substrates by dual cathode DC unbalanced magnetron sputtering. The influence of the substrate bias voltages (V_sb), from 0 V to-150V, on the structure of the as-deposited films was investigated. The crystal structure was characterized by grazing-incidence X-ray diffraction (GIXRD) technique, the films thickness and surface morphology was evaluated by atomic force microscopy (AFM) technique, respectively. The results show that the as-deposited films were transparent and have high transmittance in visible regions. The crystal structure of as-deposited films show the XRD patterns of rutile (110) with V_sb at 0V and shifted to rutile (101) with increasing V_sb. The films roughness (R_rms) and the thickness were 3.0 nm to 5.7 nm and 420 nm to 442 nm, respectively.

Abstract: Nanocrystalline β-TCP was successfully synthesized by simple precipitation method using calcium nitrate obtained eggshell as the calcium source, ammonium phosphate as the phosphate source and ammonia solution as agents for pH adjustment via our synthesis condition. Also, the effect of calcination temperature in range of 200-1200°C on phase transformation was investigated. The synthesized powders were characterized by X-Ray Diffraction (XRD), Rietveld refinements and Fourier transform infrared (FT-IR) techniques. The results indicate that β-TCP was observed at the calcination temperature of 700 °C and above. Furthermore, their crystallinity and crystalline size increase with increasing temperature. The a/c ratio of lattice parameter at temperature of 700-1200°C is similar to the standard phase of β-TCP. The chemical structure confirmed via FT-IR showed the band positions and functional groups, which are similar to that of stoichiometric β-TCP. Finally, eggshells are the potential material for synthesizing nanostructured BCP and may be possible in a low-cost production.

Abstract: Human teeth (HT) are natural composites which consist of nanohydroxyapatite (HAp) arranged in lamellae and bound to collagen. In present study, prepared HT powders with different ages were characterized by X-Ray Diffraction (XRD), Fourier transform infrared (FT-IR) and thermogravimetric anlysis (TGA) techniques. HT at age ranges of 1-10, 11-20, 21-30, 31-40, 41-50 and 51-60 years old were selected for tests. To prepare samples, human teeth were washed in boiling water for 1 h and left in 1 M KOH solution for 6 h to remove any organic material. After HT samples were cleaned with ultrasonic in ethanol, they were then finely grounded using agate mortar. The results from XRD indicate that the major diffraction peaks of all samples with different ages were very closely identified to that of stoichiometric HAp. All HT powders were found to be nanocrystalline structure. Furthermore, it was found that the decrease in HAp crystallinity seem to increase with higher age of 31-40 years old. To investigate chemical structure confirmed by FT-IR, All HT powders showed the band positions and function groups, which are similar to that of HAp. group found in chemical structure indicates the structure of carbonated apatite. TGA results were found that the increase of weight loss seem to increase with higher age.

Abstract: Zn₃(PO₄)₂.4H₂O, which is an important component of biomedical zinc phosphate cement, was synthesized from an aqueous solution of zinc oxide and orthophosphoric acid by the sonochemical method. This synthesis method yielded best results with respect to high purity and crystallinity. Structural characteristics of the compound were investigated by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM). FT-IR spectra indicated the presences of different crystallographic PO₄³ ion and H₂O molecules for the Zn₃(PO₄)₂.4H₂O and Zn₃(PO₄)₂ structures. The resulting XRD patterns showed the purity phases of orthorhombic Zn₃(PO₄)₂.4H₂O and the monoclinic for its final decomposed Zn₃(PO₄)₂ product. The thermal stability, crystallite size, and plate-like microparticles of Zn₃(PO₄)₂.4H₂O and Zn₃(PO₄)₂ are different in this work from those in previous reports, which may be caused by the starting reagents and reaction condition for the sonochemical method.

Abstract: In this study, the optimization of esterification from the mixture of palm fatty acid distillate (PFAD) and palm stearin (PS) oil followed by transesterification reaction has been investigated. The free fatty acid (FFA) content of raw oil mixture was ca. 50%. Response surface methodology (RSM) and 3-level-3-factor Box-Behnken design were employed to predict the conversion of FFA as a function of reaction temperature, wt.% of catalyst (based on FFA in the mixture) and molar ratio of methanol to FFA. Experiments were performed under varied conditions with three fixed parameters; 3:1 molar ratio of methanol to triglycerides in oil mixture, 60 °C reaction temperature and 500 rpm stirring rate. From the statistical investigation, it was found that the molar ratio of methanol to FFA was the most important factor on reducing FFA content in esterification step.

Abstract: We propose the use of molecular buffers and networks for blood circulation in Haversian and Volkmanns canals to deliver the nutrient, drug and other essential substances in the regeneration process of bone and soft tissue. By using the dynamic optical tweezers generated within a PANDA ring resonator, the required molecules can be trapped and transported within the designed neural networks, in which the required substances can perform within the required region before reaching the required destinations. The advantage of the proposed system is that system, which can perform within the tiny system (thin film device). The system can be used to enhance the medical treatments, which can reduce the period of convalescence, i.e. operation, which means the in situ surgery can be realized. Furthermore, the transportation of the trapped molecule by light in the networks is described, the theoretical background is reviewed.

Abstract: Apatite wollastonite glass ceramic (AW-GC) (34.2% SiO₂, 44.9% CaO, 16.3%P₂O₅, 4.6% MgO, 0.5% CaF₂) was added into a brushite bone cement, which composed of β-tricalcium phosphate (β-Ca₃(PO₄)₂, β-TCP) and monocalcium phosphate monohydrate (Ca (H₂PO₄)2H₂O, MCPM) in powder phases. Cement was prepared using a 3 β-TCP:2 MCPM in weight ratio. To evaluate the effect of AW-GC on the mechanical strength and degradability of brushite bone cement, the powder phases and 1 wt.% of chitosan dissolved in 5 wt.% of citric acid solution were mixed and soaked in simulated body fluid solution at 37 ^°C for 1, 3, 5,7 and 14 days, respectively. The compressive strength and setting time of AW-GC added in brushite bone cement were studied and compared with pure brushite cement. The pH values increased with addition of AW-GC. Additionally, the obtained brushite bone cements were characterized by XRD, SEM techniques.

Abstract: The aim of this study was to fabricate 75:25 poly(DL-lactide-co-e-caprolactone), poly(DLL-co-CL) membranes for used in guided tissue regeneration (GTR). The copolymer was synthesized by ring-opening polymerization (ROP) in bulk. The 3-dimensional fiber networks with built-in microporosity membranes were prepared by electrospinning. The pore size was varied between 5-30 μm and the porosity of membrane was 69%. After immersing in phosphate buffered saline (PBS), the membranes were degradable with time, as indicated by molecular weight loss, mass weight loss, reduction of pH of the media and changes in the surface topography and shape of the membranes. However, the in vitro hydrolytic degradation of the membranes was too fast for use as periodontal GTR. The membranes maintained their original shape for the first 4 weeks and the porous structure disappeared within 2 weeks. Results from agar diffusion test suggest the membranes to be non-cytotoxic. In conclusion, the electrospun membrane was non-cytotoxic but the degradation rate was too fast to be used as GTR membrane in periodontal treatment.

Abstract: 75:25 poly (DL-lactide-co-ε-caprolactone) electrospun resorbable membranes were prepared by electrospinning and film casting techniques. Primary cultures of human periodontal ligament (HPDL) fibroblasts cells were seeded on the electrospun membranes, film-cast membranes, and control glass cover slips. The number of cell attached was determined at 1, 3, 24 and 72 h after cell seeding. Cell proliferation on the membranes was determined by MTT assay at 1.5 h and 1, 3, 5 and 7 days after cell seeding. The morphology of cells was also determined by SEM. The results indicated that the cell attached number and cell proliferation on the electrospun membranes were significantly higher than that of the film-cast membranes at every time point. From an SEM study, HPDL cells could healthy attach on both, the electrospun membranes and the film-cast membranes. HPDL cells were firmly attached to the membrane matrix in the electrospun membrane group. In the film-cast group, HPDL were loosely attached to the membrane surfaces. In conclusion, an electrospun membrane had better ability to promote HPDL cell attachment and proliferation than did film-cast membranes.

Abstract: Electrospinning of chitosan (CS) has been interested due to the excellent properties of CS such as biocompatibility, biodegradability, antibacterial and non toxic. In this study, chitosan-thiamine pyrophosphate (CS-TPP)/polyvinyl alcohol (PVA) blend nanofibers were prepared using electrospinning techniques without acidic and organic solvent. CS was dissolved with TPP aqueous solution and then blended with PVA solution at various weight ratios. Physicochemical properties of CS-TPP/PVA solution such as viscosity, conductivity and surface tension were evaluated. The morphology and diameter of the electrospun fiber mats were investigated by using scanning electron microscopy (SEM). The chemical structure was characterized by Fourier Transform Infrared (FT-IR) spectroscopy and Differential Scanning Calorimetry (DSC). The morphology and diameter of the nanofibers were mainly affected by the weight ratio of the blend polymers. Nanofibers were obtained when the CS-TPP content was less than 50 % wt. The average diameter of the nanofibers was 99.91-216.42 nm, and the fiber diameter decreased with increasing CS-TPP content. Cytotoxicity tests in human fibroblast cells showed that the fibers had low toxic to the cells. In conclusion, these CS electrospun nanofiber mats can be applied for the wound dressing or transdermal drug delivery systems.