11 research outputs found
The effect of hydroxyapatite addition on biocompatibility of porous alumina microcarriers for vero cell culture
Incorporation of poly(Vinyl alcohol) for the improved properties of hydrothermal derived calcium phosphate cements
Calcium phosphate cement (CPC) has been synthesized via a straightforward hydrothermal route. Calcium
oxide and ammonium dihydrogen phosphate were used as calcium and phosphate precursors. The precursors were
refluxed in distilled water at 90โ100 ยฐC and dried overnight until the calcium phosphate powder was formed. CPC
was then produced by mixing the powder and distilled water at the powder-to-liquid (P/L) ratio of 1.5. Poly(vinyl
alcohol) (PVA) of 1 to 7% (w/w) was added and its effect on physical properties was investigated. It was proved that
PVA addition up to 7% (w/w) has shortened the setting time but decreased the injectability. The PVA free CPC has
the initial and final setting times of 71 and 187 min, respectively and the injectability of 99.92%. The compressive
strength also increased with the amount of PVA added in CPC. In addition, soaking CPC in Ringer's solution for 7,
14 and 21 days also gave remarkable effects on cohesion, microstructure and mechanical properties of the cement
Calcium phosphate /poly (ethylene glycol) bone cement: cell culture performance
Calcium phosphate cement (CPC) for injectable
bone cement application has been developed in this study. The
CPC was produced using a novel wet chemical precipitation
method derived hydroxyapatite (HA) powder. The calcium and
phosphorus precursors used to synthesize HA powder were
calcium hydroxide, Ca(OH)2
, and di-ammonium hydrogen
phosphate, (NH4
)2HPO4
. The HA powder was mixed with distilled
water at certain powder-to-liquid (P/L) ratios. In this study, the
P/L ratios were varied at 1.3 and 1.7. PEG was added into CPC
with the P/L ratio of 1.3, and it was adjusted at 1 and 5 wt%. The
results of this study revealed that higher P/L ratio contributed to
the decreased in porosity of CPC. Meanwhile, the addition of
PEG increased the porosity of CPC. This is significant for cells
adhesion and proliferation, such that cell proliferate faster and
better adhesion with the incorporation of PEG into CPC. The cell
culture on CPC has proven that the fabricated CPC shows no
toxic reaction and cells grow well
Characteristic features of plasma electrolytic treated layers in Na3PO4 solution
Plasma electrolytic oxidation (PEO) treatment of Ti6Al4V (Ti) using various concentrations of Na3PO4 (NAP) has been carried
out. Based on the PEO process, characteristics of the treated layers, such as structure, chemical composition, phases, roughness,
hardness and porosity level were investigated. Irregular micro-channel spots were found on all treated surfaces. Larger pores
were more evident on the PEO treated with NAP-7.5 g/L, and are considered to be related to the high intensity of micro-arc
discharges on Ti surface. XRD analyses revealed that the surfaces of treated layers are composed of Ti, TiO6 and anatase. The
Profilometry test depicted that the surface roughness of PEO treated layers is significantly higher than bare Ti. The thickness and
hardness of PEO-treated layers increased with increasing NAP concentration and found to be highest with sample processed with
NAP-10 g/L. Among all the NAP concentration used, 5 g/L showed the least level of porosity. Reflection on the results portends
that the PEO treated with 10 g/L concentrations could serve a potential candidate for clinical purposes
Recent development of calcium phosphate based coating on titanium alloy implants
Titanium alloy implants are widely employed in biomedical devices and components, especially as
hard tissue replacements as well as orthopaedic applications, owing to their favourable properties such as
high-strength to weight ratio, low density, low Youngโs modulus and biocompatibility. However, metallic
implants cannot meet all of the clinical requirements. Therefore, in order to increase their clinical success and
long term stability in the physiological environment, surface modification is often performed. This review
focuses on the latest achievements in the field of surface modification techniques including sol-gel, thermal
spray, magnetron sputtering, electrophoretic deposition and micro-arc oxidation of biocompatible calcium
phosphates (CaP) based ceramics coatings for metallic implants with emphasis on the structure, morphological
characterization, phase transformation and coating composition. A reflection on the results shows that
CaP coatings can be grown with the each type of techniques and a stronger fixation can be enhanced with CaP
fabrication on metallic implants. Advantages and limitations of the aforementioned techniques of CaP-based
coatings from the point of view of the process simplicity as well as the most important challenges of each coating
techniques are highlighted. Further, the most promising method for CaP deposition was identified and a
specific area for improvement was discussed
Synthesis of TiO2 nanosized powder photocatalyst via soft-gel method for bacteria inactivation application
Titanium dioxide (TiO2) is the most widely used photocatalyst and has been applied for water and air purification and disinfection of microorganism. Anatase structured TiO2 is a wide bandgap (3.2 eV) semiconductor which, under UV light, is able to degrade chemicals and cell components of microorganisms. In this study, TiO2 nanopowder photocatalyst was synthesized by sol-gel process using a titanium chelate compound, titanium (di-isopropoxide) bis(acetylacetonate) (PTP) as the precursor. The precursor was hydrolyzed under an acidic catalyst condition, followed by reflux for 15 minutes and 1 hour. The precipitate powder obtained after filtration was calcined at 400ยฐC. XRD analysis confirmed that the TiO2 powders A (15 minutes reflux) and B (1 hour reflux) have strongest peak at 25ยฐ which indicates anatase crystal structure. The particle size of powder A was smaller than the Powder B as proved by calculation using Scherrerโs equation. The crystallization temperature of TiO2 powder A was higher due to its smaller particles that needed more heat to crystallize than powder B as confirmed by TG/DTA. FESEM analysis showed powder A have homogenous spherical shape, contrast to powder B showing inhomogenous spherical shape and connected particle. The TiO2 photocatalyst activity in killing bacteria was investigated for 5 hours by varying the concentration of TiO2 and UV light intensity
Miscibility, morphology and mechanical properties of compatibilized polylactic acid/thermoplastic polyurethane blends
Polylactic acid (PLA) is a biodegradable polymer and has an excellent strength, however its inherent brittleness and
low impact resistance has limited its application. One of the potential alternatives for enhancing the weakness of
PLA is by blending it with thermoplastic polyurethane (TPU) which possesses several attractive properties such as
high toughness, durability and flexibility. Nevertheless, few works have been reported on the effect of
compatibilizer on physical properties of PLA/TPU blends. In this work, the effect of ethylene-methyl acrylateglycidyl methacrylate (EMA-GMA) compatibilizer addition in various blend compositions on miscibility,
morphological development and mechanical properties of PLA/TPU blends was analysed. The blends were prepared
through melt blending technique and analysis of miscibility and morphological development were conducted using
dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM), while evaluation of mechanical
properties were performed through tensile and impact tests. Inclusion of EMA-GMA improved miscibility of
PLA/TPU blends by reducing the size of the droplets and uniformly dispersed the droplets throughout the matrix.
Addition of EMA-GMA further improved mechanical properties of PLA which is showed by significant increment
of elongation at break and impact strength of PLA/TPU blends with some composition exhibited non-break
behaviour
Effects of sintering time and temperature to the characteristics of FeCrAl powder compacts formed at elevated temperature
This paper presents the outcomes of an experimental investigation on the effect of
sintering schedule, i.e., holding time and temperature to the final properties of FeCrAl powder
compacts prepared through uniaxial die compaction process at above room temperature. The
feedstock was prepared by mechanically mixing iron powder ASC 100.29 with chromium (22
wt%) and aluminium (11 wt%) for 30 min at room temperature. A cylindrical shape die was
filled with the powder mass and heated for one hour for uniform heating of the die assembly
together with the powder mass. Once the temperature reached to the setup temperature, i.e.,
150ยบC, the powder mass was formed by applying an axial pressure of 425 MPa simultaneously
from upward and downward directions. The as-pressed green compacts were then cooled to
room temperature and subsequently sintered in argon gas fired furnace at a rate of 5ยบC/min for
three different holding times, i.e., 30, 60, and 90 min at three different sintering temperatures,
i.e., 800, 900, and 1000ยบC. The sintered samples were characterized for their density, electrical
resistivity, bending strength, and microstructure. The results revealed that the sample sintered
at 1000ยบC for 90 min achieved the better characteristics
Physicochemical characteristics of magnesium hydroxyapatite (MgHA) derived via wet precipitation method
Hydroxyapatite (HA) has been known for so many decades as an implant material for medical applications due to its chemical composition that is very similar to the inorganic component of human bone. However, synthetic HA possesses relatively low mechanical strength characteristic, making it less suitable to be used in load bearing applications. Thus, the presence of metal ion like magnesium (Mg) is expected to improve the properties of synthetic HA as biomedical devices. The main objective of this research is to develop and characterize the magnesium hydroxyapatite (MgHA) nanopowders derived from the wet precipitation method. The amount of Mg, which acts as a metallic dopant in HA were varied at 0, 5 and 10% and calcined at 700C for imperative comparison. The resultant nanopowders were then characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) to examine their physicochemical properties. Morphological evaluation by FESEM showed that the particle size of 10% MgHA powders was larger and spherical in shape but still highly agglomerated at calcination temperature of 700C. This result coincides with the data obtained from the XRD analysis, which revealed that the particle size of pure HA, 5 and 10% MgHA after calcination was 87 nm, 98 nm and 116 nm, respectively. These results demonstrate that doping Mg into HA has caused an increase in the particle size, proving that Mg acts as a sintering additive during the calcination process