Papers by Author: Naruporn Monmaturapoj

Abstract: The objective of this study was to evaluate the antibacterial properties and pH changes of bioactive glasses and zinc oxide nanowire in different concentrations. Bioactive glasses (45S5 and 45S5F) were prepared in three concentrations of 10, 20, and 50 mg/ml and zinc oxide nanowire was prepared in 1 and 5 mg/ml concentrations. The materials were exposed to 500 ml brain heart infusion broth (BHI) with 1.5 x 10⁷ of S.mutans and S.sanguinis separately. Antibacterial properties were tested indirectly by collecting 100 ml of each sample and transferred into a 96 well-plate. The optical density (OD) was evaluated using spectrophotometry at 630 nm at 24h and 48h. The pH changes were recorded. The data were statistically analyzed by Kruskal-Wallis tests. The result showed that the pH changes were significantly different in the Bioactive glass samples, while zinc oxide nanowire showed stable pH. Antibacterial activity against S.mutans was significant lower for 45S5 at 50 mg/ml, 45S5F and zinc oxide nanowire in all concentrations at 24 h. While in 48 h, 45S5, 45S5F and zinc oxide nanowire showed significant antibacterial activity in all concentration except 45S5F at 10 mg/ml. Antibacterial activity against S.sanguinis was significant for 45S5 and 45S5F at 20 and 50 mg/ml and zinc oxide nanowire in all concentration at 48h. It can be concluded that Bioactive glasses (45S5 and 45S5F) exhibited antibacterial properties and pH changes depending on its concentration, while zinc oxide nanowire exhibited antibacterial properties at low concentrations with a constant pH value.

Abstract: This work proposes three different glass formula derived from the SiO₂-Li₂O-K₂O-Al₂O₃ system to investigate the effect of glass compositions on their crystal formation and mechanical properties. Glass LD_1 was SiO₂-Li₂O-K₂O-Al₂O₃ system with adding P₂O₅ and CaF₂ as nucleating agents. In Glass LD_2, a few amount of MgO was mixed to improve the viscosity of the glass. Finally, an important factor of Si:Li ratio was increased in Glass LD_3. Glass batches were melted at 1500°C and cast into a graphite mold which was annealed at 400-500°C before heat treatment at 700, 750, 800 and 850°C. XRD results can be indexed Li₂Si₂O₅, Li₂SiO₃, Ca₅(PO₄)₃F and SiO₂ as an early crystallization when heat treated at 700°C. After heat treatment at 750-850°C, the intensity of SiO₂ disappeared and the peaks associated to Li₃PO₄ appeared; meanwhile, Li₂Si₂O₅ increased in intensity. Adding MgO resulted in decreasing the viscosity of the glass with no significant effects on the formation of lithium disilicate. By increasing Si:Li ratio, the peak of SiO₂ more obviously observed. SEM results revealed the development of microstructure from plate-like to interlocking rod-shaped crystals in all glasses. The highest indentation fracture toughness and biaxial flexural strength found in all glass ceramics heat treatment at 800°C because the finest microstructure observed at this temperature, except LD_3 heat treated at 850°C, which obtained the finest microstructure. LD_1 heat treated at 850°C presented the best chemical solubility 59 μg/cm².

Abstract: This study aims to improve the strength of porous BCP samples by the addition of titanium dioxide (TiO₂), the well known biocompatible and strong ceramic. BCP powder with HA/TCP ratio of 70/30 (BCP7030) obtained by mixing a pure HA and β-TCP powder. TiO₂ powder with 2 (BCP_2Ti), 5 (BCP_5Ti) and 10 (BCP_10Ti) %wt were added into the BCP7030 powder, then ball milled in ethanol for 6 hrs. The porous samples were fabricated by the combination of the gel-casting and freeze drying techniques. All samples were sintered at 1100°C for 2 hrs. X-ray diffractometry (XRD) and scanning electron microscopy (SEM) were used to determine crystal structures and morphology of the sintered samples, respectively. Mechanical properties and porosity of samples were measured by using the universal testing machine and Archimedess principle, respectively. XRD results showed that the phases of the undoped sample can be indexed HA and β-TCP with the ratio of 70/30 as the major phases. In BCP_2Ti, CaTiO₃ was observed as a minor phase among the crystallization of HA and β-TCP with the proportion of 30:70. Meanwhile, in BCP_5Ti and BCP_10Ti, XRD patterns revealed a completely transformation of HA to β-TCP with minor phases of CaTiO₃ and TiO₂. The microstructure of sintered samples present highly porous structure which consisted of two-dimensional pore channels along the long axis and the short axis, which replicates the ice and pore orientation in the direction of freezing. Relatively, the porosity of the samples was increased with the amount of TiO₂. Surprisingly, an additions of the TiO₂ was not rather improved the mechanical strength of porous BCP7030 in this study. This might be a result of a high percentage of porosity (84%).

Abstract: Biphasic calcium phosphate (BCP) ceramic is commonly used in the biomedical applications particularly as a bone substitute due to its biocompatibility and directly bond to bones. However, the mechanical strength is quite poor. Therefore, well known biocompatible and strong ceramics such as SiO₂, ZrO₂ and TiO₂ were added to improve the strength of BCP. BCP powder with HA/TCP ratios of 70/30 (HAP7030) was obtained by controlling the calcining temperature of the mixture between a pure HA and TCP. SiO₂, ZrO₂ and TiO₂ powder with 2, 5 and 10 %wt were mixed with the HAP7030 powder by ball milling in ethanol. The mixtures were dried, pressed and sintered at 1100°C for 2 hrs. XRD and SEM were used to determine crystal structures and morphology of the sintered samples, respectively. Physical properties and flexural strength of samples were measured. Results showed that the bending strength of HAP7030 sample was rather improved by adding TiO₂ than the addition of SiO₂ or ZrO₂. With increasing TiO₂, HAP7030 strength was superior and HAP7030 with 10 %wt of TiO₂ obtained the optimum bending strength around 61 MPa. However, the addition of TiO₂ induced the thermal stability of HA/TCP, in which HA completely decomposed to β-TCP in this study.

Abstract: The biphasic calcium phosphate (BCP) concept was introduced to overcome disadvantages of single phase biomaterials. In this study, we prepared BCP from nanoHA and β-TCP that were synthesized via a solid state reaction. Three different ratios of pure BCP and collagen-based BCP scaffolds (%HA/%β-TCP; 30/70, 40/60 and 50/50) were produced using a polymeric sponge method. Physical and mechanical properties of all materials and scaffolds were investigated. XRD pattern proved the purity of each HA, β-TCP and BCP. SEM showed overall distribution of macropores (80-200 µm) with appropriate interconnected porosities. Total porosity of pure BCP (93% ± 2) was found to be higher than collagen-based BCP (85%± 3). It was observed that dimensional shrinkage of larger scaffold (39% ± 4) is lower than smaller one (42% ± 5) and scaffolds with higher HA (50%) ratio experienced greater shrinkage than those with higher β-TCP (70%) ratio (45% ±3 and 36% ±1 respectively). Mechanical properties of both groups tend to be very low and collagen coating had no influence on mechanical behavior. Further studies may improve the physical properties of these composite BCP.