Advanced Materials Research Vols. 93-94

Abstract: Poly(L)lactide (PLLA), aliphatic polyester, and poly(LLA-co-DLLA) copolymers consisting of 2.5, 7.5, 50% of DLLA content were also synthesized. PLLA was successfully electrospun by using 15wt% solution in (1DMF:3CHCl3) mixed solvent. 2.5, 7.5, 50% P(LLA-co-DLLA) copolymers were then spun at 8, 10, and 15wt% concentration in a single chloroform solvent, respective. The lactide-based polymeric nanofibers were characterized by Scanning Electron Microscope (SEM). Smooth surface morphology was observed in nanofibers produced from PLLA and 50% P(LLA-co-DLLA) copolymer. However, surface porosity was observed in the corresponding fibers from 2.5 and 7.5% P(LLA-co-DLLA) copolymers. These nanofibers have high potential for wide range of applications such as filter media, nano-sensor, drug delivery and tissue scaffold, especially, those derived from 2.5 and 7.5% P(LLA-co-DLLA) copolymers which contain high degree of porosity.

Abstract: Solid polymer electrolytes comprising of various weight ratios of poly(ethyl methacrylate) (PEMA) and lithium perchlorate (LiClO4) salt were prepared via solution casting technique using N,N-Dimethylformamide (DMF) as the solvent. The conductivity values of the electrolytes were determined utilizing Solatron 1260. The highest conductivity obtained is in the order of 10-6 S cm-1. Structural properties of the electrolytes were investigated by X-ray diffraction and the results show that the highest conducting film is the most amorphous.

Abstract: Sericin, one of the two main proteins of silk cocoon besides fibroin, has been wildly used as ingredient in cosmetic products and nutrition supplements; however there are considerable controversial reports on its toxicity to cells and its advantages. This work aimed to investigate cell biocompatibility of sericin both in the systems of blended silk fibroin/sericin and pure sericin films using L929 mouse fibroblasts. The effect of concentration of commercial heat extracted sericin on cell viability was first investigated in the system of silk fibroin/sericin (F/S) films using 2 types of silk fibroin, Bombyx mori Nangnoi Srisaket 1 and Bombyx mori Jul 1/1. For both types of silk fibroin, it was found the lower cell number attached and proliferated on the blended F/S films at all sericin concentrations, compared to that on glass and pure fibroin. However, proliferation rate of cells cultured on the blended F/S films was similar to that of cells cultured on glass and pure fibroin films, as confirmed by population doubling time (PDT). Cytotoxicity of sericin extracted from 4 different methods including heat, acid, alkali and urea treatments was further studied in this work in the system of pure sericin films. It could be seen that acid and urea extracted sericin films showed high percentage of cell attachment at 92% and 88%, respectively. However, number of cells proliferated on all sericin films after 48 h culture was not significantly different. This indicated that L929 cells had different proliferation rate when cultured on different types of sericin films. Among 4 extraction methods, the PDT of cells proliferated on urea extracted sericin film was lowest (27 h) and also lower than that of the blended F/S films. This study suggested that sericin extracted by urea treatment could enhance proliferation rate of L929 mouse fibroblasts.

Abstract: The purpose of this study was to develop matrix-type transdermal systems containing Centella asiatica extract for treatment of varicose veins by using various polymers such as ethylcellulose (EC), methylcellulose (MC), hydroxypropylmethylcellulose (HPMC), polyvinylpyrolidone (PVP) and hydroxyproply cellulose (HPC-H, HPC-M and HPC-L grades) at various concentrations (0.75%, 1.00%, 1.25%, 1.50%, 1.75% and 2.00%) and using 30% of propylene glycol (PG), diethyl phathalate (DEP), dibutyl phathalate (DBP), glycerine, polyethylene glycol (PEG) 400 as plasticizers. Centella asiatica extract at 7% of solid content of the formulation was added to the matrix formulation prior to pouring on backing layer which was prepared by using either EC as polymer and DBP as plasticizer or polyethylene wrap. It was found that the use of polyethylene wrap as backing layer, PG as plasticizer and HPC as matrix layer showed better appearance, flexibility and compatibility. It was also found that HPC-H and HPC-M showed high adhesion and stickiness. It was concluded that HPC at concentration of 1.75% and 2.00% could be formulated as satisfactory transdermal matrix-type patch for Centella asiatica extract.

Abstract: Dense pure biphasic calcium phosphate (BCP) and Mn-doped BCP ceramics were fabricated via uniaxial pressing using the sol-gel derived powders. The compacted discs were sintered in air atmosphere with temperatures ranging from 1000 °C to 1400 °C. All powders have been proved to show HA and β-TCP phases only. Manganese doping improves the densification in the BCP structure as the relative density increased with Mn doping and also sintering temperature. Considerable grain growth has been observed at 1300 °C for Mn-doped BCP samples compared to the pure BCP. 15 mol% Mn showed the maximum hardness value of 6.66 GPa at 1400 °C compared to pure BCP of only 2.89 GPa. Similarly, the Mn-doped BCP has superior fracture toughness where it attained maximum values of 1.05 MPam1/2 at 1400 °C compared to 0.72 MPam1/2 at 1300 °C of pure BCP. In a nutshell, Mn doping has successfully brought improvement in the mechanical properties of the BCP.

Abstract: The porous alumina ceramics were fabricated through protein foaming-consolidation method using egg yolk as pore creating agent. The influence of stirring time and drying temperature on the physical properties of the porous bodies was investigated. The porosity of the 3 h stirring time’s sample was 42% and it increased to 71% at 24 h stirring time. As the drying temperature increased, the pores became interconnected with less dense and thinner pore and were found in the range of 100-650 µm. The density of 180°C drying temperature’s sample was 1.5 g/cm3 and it increased to1.9 g.cm-3 when dried at 100°C. An alumina-to-yolk ratio of 1.4 in weight was found to be optimum composition to give porous bodies with higher compressive strength. The compressive strength of the porous bodies increased from 3.7 MPa at 61.1% porosity to 7.7 MPa at 42.5% porosity, showing that the compressive strength is strongly dependent on porosity.

Abstract: In this study, strontium doped hydroxyapatite (SrHA) nanopowder was synthesized through a sol-gel method. Strontium concentration was varied from 0 to 15 mol%. The obtained gel was then dried and subsequently subjected to 900 °C calcination. SrHA porous bodies were fabricated by using polymeric sponge method with different chemical compositions (0, 2 and 10 mol% SrHA). To prepare the porous samples, the synthesized SrHA powders was mixed with distilled water and appropriate amount of dispersing agent followed by drying in the ambient air for 72 hours. The dried impregnated sponges were then sintered at 1300°C for 3 hours. The XRD patterns showed high crystallinity of HA phase only for all porous samples. Morphological evaluation by FESEM measurement revealed that the SrHA scaffolds were characterized by a uniform distribution of interconnected pores (200-800 µm). Compression test on the porous scaffolds revealed that doping 10 mol% of strontium in HA has increased the compressive strength compared to the undoped HA.

Abstract: Hydroxyapatite of calcium phosphate materials, one of the most frequently used ceramic material in biomedical application, has been produced via chemical reaction involves both calcium and phosphorus precursors. Effect of suspension concentration on available phases was investigated using a basis of 2 mole % excess of calcium oxide. The synthesis was performed at 90°C until paste was obtained. To improve crystallinity, hydroxyapatite was calcined at 900°C. However, β-TCP appeared as trace which varied in fraction with suspension concentration. Varying concentration is then one approaching method in designing phase composition through which a functional material could be attained.

Abstract: Hydrophobic lignin’s character is used as the base of lignin usage as the binder in the urea fertilizer tablet. Lignin was isolated from black liquor of pulp and paper with palm empty bunch materials. Sulfonation of lignin isolate produced lignin sulfonate. Acetylation of lignin isolate produced lignin acetate. Lignin, lignin sulfonate and lignin acetate analyzed its solubility showed that lignin has no solubility in water. Therefore, urea fertilizer need to be modified by lignin. Nitrogen concentration of tablet lignin – urea with variation of lignin percentage 1,2,3,4 and 5 % examined with Kjehdahl method, produced nitrogen concentration in average 43%. Binding lignin isolate with percentage of 1 – 5 % to commercial urea fertilizer formed lignin – urea tablet. Its solubility test showed that lignin – urea formation will dissolve in 96 ; 137 ; 435 ; 759 ; 625 seconds, respectively. As control was commercial urea fertilizer with solubility’s time is 142 seconds.

Abstract: A compact dc magnetron sputtering system capable of silver thin films depositions was designed and constructed. The novel small footprint sputtering head with target diameter of 52 mm was constructed utilizing powerful neodymium alloy magnet. Silver metal was sputter-deposited under various powers. Plasma parameters were analyzed by using the sweeping-bias single langmuir probe. The electron temperatures of the plasma glow were constant at approximately 2 eV even with the increasing of input power whereas plasma density increases with the increasing of the input power. The X-ray diffraction analysis (XRD) and scanning electron microscope (SEM) were used to study the crystalline structure and the surface morphology of the obtained silver thin films. Crystalline orientations of (111) and (200) in the silver films deposited on slide glass substrates were revealed from XRD pattern. The highest degrees of (111) and (200) orientations was obtained at the sputtering power between 0.228 and 0.265 Wcm-2. Sub-micron crystalline silver grain structure were observed using SEM micrographs. Facetted grain size and deposition rate of silver thin films increases as the sputtering power increases.