Highly reactive zinc metal was prepared by electrolysis of a N,N-dimethylformamide (DMF) solution containing naphthalene and a supporting electrolyte in a one-compartment cell fitted with a platinum cathode and a zinc anode. This highly reactive electrogenerated zinc (EGZn/Naph) was used for transformation of ethyl 2-bromoacrylate into the corresponding organozinc compound, which can not be achieved by the use of usual zinc metals. Reaction of the organozinc compounds thus prepared with various aryl halides in the presence of 5 mol% of palladium catalyst gave the corresponding cross-coupling products in high yields. These cross-coupling reactions were successfully applied to a synthesis of the precursor of anti-inflammatory agents such as ibuprofen, naproxen, cicloprofen and suprofen.
Neem, Azadirachta indica, is a plant from the family Meliaceae, known as "Pokok Semambu" in Malay community. It has been extensively used in India as traditional Ayurvedic and folklore minedicine for the treatment of various diseases. This study aimed to determine the distribution of selenium in the liver of rats during hepatocarcinogenesis when neem aqueous extract and dietary selenium was supplemented.
In this study the surface properties of two particulate coral and polyhydroxybutrate (PHB) were studied in order to characterize them prior to use in composite production. Coral powder and PHB particle were evaluated using scanning electron microscopy and confocal laser scanning microscopy, to measure surface porosity and pores size. The results showed that coral powder has multiple pleomorphic micropores cross each others give appearance of micro-interconnectivity. Some pore reached to 18 microm with an average porosity of 70%. PHB revealed multiple different size pores extended to the depth, with an average some times reach 25 microm and porosity 45%. These findings demonstrate that both coral and PHB have excellent pores size and porosity that facilitate bone in growth, vascular invasion and bone development. We believe that incorporation of coral powder into PHB will make an excellent composite scaffold for tissue engineering.
In the present study, natural coral of porites species was used as scaffold combined with in vitro expanded bone marrow stem cell derived osteoblasts (BMSC-DO), to develop a tissue-engineered bone graft in a rat model. Coral was molded into the shape of rat mandible seeded with 5x10(6) /ml BMSC-DO subsequently implanted subcutaneously in the back of 5 week Sprague dawely rats for 3 months. Coral alone was implanted as a control. The implants were harvest and processed for gross inspection and histological observations. The results showed that newly bone grafts were successfully formed coral seeded with cells group showed smooth highly vascularized like bone tissue. Histological sections revealed mature bone formation and lots of blood vessel, the bone formation occurred in the manner resemble intramembraneous bone formation. This study demonstrates that coral can be use as a suitable scaffold material for delivering bone marrow mesenchymal stem cells in tissue engineering.
We have previously formulated an optimized human chondrocytes growth medium based on 2% fetal bovine serum supplementation. For clinical usage, the animal serum must be replaced by patient own serum. We investigated the effects of human serum concentration for human nasal septum chondrocytes monolayer culture and cartilage reconstruction. Human serum demonstrated a dose dependent manner in promoting chondrocytes growth and cartilage engineering.
To date there is no optimal approach to reconstruct an external ear. However, advances in tissue engineering technologies have indicated that in vitro autologous elastic cartilage might be of great importance in the future treatment of these patients. The aim of this study was to observe monolayer expansion of auricular cartilage and to evaluate engineered cartilage using standard histochemical study.
The study was carried out to evaluate macroscopically the ability of coral to repair a large size bone defect. A total 12 adult, male sheep were used in the study. The large bone defect (2.5cm x 0.5cm x 0.5cm) was created surgically on the left proximal femur and replaced by a block of coral (Porites sp.). Radiographs were obtained immediately after surgery and at 2, 4, 8 and 12 weeks post-implantation. Ultrasonographic examinations were carried out every 2 weeks after implantation up to 12 weeks using ultrasound machine (TOSHIBA Capasee II) connected with 7MHz frequency transducer. The sheep were euthanased at 2, 4, 8, and 12 weeks post-implantation and the bone examined grossly. Both ultrasonographs and radiographs taken at 8 and 12 weeks showed that the implants had been resorbed and left the space that much reduced in size. There was no sign of implant rejection observed in all animals. The results showed that processed coral has potential to become bone substitute for reconstructive bone surgery.
Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) evaluation were carried out in the in vivo skin construct using fibrin as biomaterial. To investigate its progressive remodeling, nude mice were grafted and the Extracellular Matrix (ECM) components were studied at four and eight weeks post-grafting. It was discovered that by 4 weeks of remodeling the skin construct acquired its native structure.
Hydroxyapatite powder was mechanochemically synthesized from calcium pyrophosphate (Ca2P2O7) and calcium carbonate (CaCO3) using a solid-state reaction. The two powders were mixed in distilled water, milled for 8 hours, dried and calcined at 1100 degrees C for 1 hour. The phase(s) formed was analyzed by x-ray diffraction (XRD). It was found that hydroxyapatite was not the only one formed. This result will be used as the starting point to produce a single-phase hydroxyapatite in terms of excess hydroxyl group in a mechanochemical reaction.
The present paper reports on the influence of sintering temperature on the porosity and strength of porous hydroxyapatite (HA). HA powder was first prepared by the sol-gel precipitation method using calcium hydroxide and ortho-phosporic acid. The fine HA powder, measuring <50 microm was then mixed into a slurry with the addition of binder agent, being a mixture of sago and PVA. A small amount of sodium dodecyl sulphate was also used as a foaming agent. Porous HA samples were then prepared via slip casting technique. The surface morphology of the sintered samples was observed under scanning electron microscopy at 20 kV and the compositions were determined via SEM-EDX. A universal testing machine was used to determine the compaction strength of the sintered samples.
A mixture with different compositions of HA and TCP were synthesize in this work by precipitation method using Ca(NO3)2 4H2 and (NH4)2HPO4 as the starting materials. A mixture with HA and TCP phases in different ratios were produced. The powders were sintered from 1000 degrees C to 1250 degrees C. The phase compositions of the mixtures were then studied via XRD. This work shows that the pH value determines the different phase compositions of the HA-TCP mixture. Chemical analyses were carried out by FTIR. The microstructure was observed under SEM.
Biomaterials intended for end-use application as bone-graft substitutes have to undergo safety evaluation. In this study, we investigated the in vitro cytotoxic effects especially to determine the mode of death of two hydroxyapatite compounds (HA2, HA3) which were synthesized locally. The methods used for cytotoxicity was the standard MTT assay whereas AO/PI staining was performed to determine the mode of cell death in HA treated L929 fibroblasts. Our results demonstrated that both HA2 and HA3 were not significantly cytotoxic as more than 75% cells after 72 hours treatment were viable. Furthermore, we found that the major mode of cell death in HA treated cells was apoptosis. In conclusion, our results demonstrated that these hydroxyapatite compounds are not cytotoxic where the mode of death was primarily via apoptosis.
The aim of this study was to evaluate the in vitro cytotoxicity of biomaterials; Hydroxyapatite (HA), Natural coral (NC) and Polyhydroxybutarate (PHB). Three different materials used in this study; HA (Ca10(PO4)6(OH)2), NC (CaCO3) and PHB (Polymer) were locally produced by the groups of researcher from Universiti Sains Malaysia. The materials were separately extracted in the complete culture medium (100mg/ml) for 72h and introduced to the osteoblast cells CRL-1543. The viability of osteoblast CRL-1543 cultivated with these extraction materials after 72h incubation period was compared to negative control with neutral red assay by using spectrophotometer at 540nm. The results showed the non-cytotoxicity of the materials. After 72h of incubation period, HA showed 123% viable cells, NC was 99.43% and PHB was 176.75%. In this study, cytotoxicity test dealt mainly with the substances that leached out from the biomaterial. The results obtained showed that the materials were not toxic and also promoted cells growth in the sense of biofunctionality.
Hybrid organic-inorganic membranes were fabricated using sol-gel technique using PMMA and TEOS with 80/20 (w/w) ratio at various solvents. The thin membrane films were then characterized using DSC and TGA. From DSC analysis, the Tg value of the PMMA moieties in hybrids membranes was in the order H-15-Toluene < Pure PMMA < H-15-THF < H-15-DMF. Furthermore, from TGA analysis it was found that the hybrid membranes have higher thermal stability compared to pure PMMA, and the type of solvents used play an important role in their degradation behavior.
The aim of this work was to study radiation and the effects of temperature on conductivity properties of polyvinyl alcohol (PVA)-based potassium hydroxide (KOH) and propylene carbonate (PC), where the ionic conduction preferentially occurs in the amorphous phase by free radicals ions through gamma-irradiation. Alkaline composite polymer electrolyte (ACPE) consisting of PVA, KOH and PC of different concentration ratios were prepared by solvent-casting technique. The ACPE were irradiated with different doses from 5 kGy up to 200 kGy. The conductivity properties of the electrolyte films were measured at different frequencies in the range 20 Hz to 1 MHz using LCR meter. The results showed that the conductivity properties were dependent on the radiation dose, temperature and the concentration of the polymer blends.
The aim of this study was to evaluate the morphological and biological properties of a locally produced "Bovine Bone Sponge" for use in dentistry. Bovine bone sponge was prepared from local calf bone. Endotoxin level and surface properties were investigated. The pore size and water uptake ability were measured and results were compared with the commercial haemostatic agent. The material was tested for its haemostatic property and its inhibition of alveolar bone resorption in a sheep model following dental extraction. Results revealed a significant difference in haemostatic effect, and a shorter bleeding time and a lower rate of alveolar bone resorption in bovine bone sponge compare to a commercial haemostatic agent.
The aim of this study was to evaluate the mechanical properties and glass transition temperature (Tg) of a denture base material prepared from high molecular weight poly methyl methacrylate (PMMA) and alumina (Al2O3). The glass transition temperature was studied by using differential scanning calorimetry (DSC). The effect of powder-to-liquid ratio was investigated. The result showed that the tensile properties and the Tg were slightly effected by the powder-to-liquid ratio. The ratio of 2.2:1 by weight of powder to liquid was found to be the best ratio for mixing the material to give the best result in this formulation.
Hydroxyapatite is the main component of the bone which is a potential biomaterial substance that can be applied in orthopaedics. In this study, the biocompatibility of this biomaterial was assessed using an in vitro technique. The cytotoxicity and genotoxicity effect of HA2 and HA3 against L929 fibroblast cell was evaluated using the MTT Assay and Alkaline Comet Assay respectively. Both HA2 and HA3 compound showed low cytotoxicity effect as determined using MTT Assay. Cells viability following 72 hours incubation at maximum concentration of both HA2 and HA3 (200 mg/ml) were 75.3 +/- 8.8% and 86.7 +/- 13.1% respectively. However, the cytotoxicity effect of ZnSO4.7H2O as a positive control showed an IC50 values of 46 mg/ml (160 microM). On the other hand, both HA2 and HA3 compound showed a slight genotoxicity effect as determined using the Alkaline Comet Assay following incubation at the concentration 200 mg/ml for 72 hours. This assay has been widely used in genetic toxicology to detect DNA strand breaks and alkali-labile site. The percentage of the cells with DNA damage for both substance was 27.7 +/- 1.3% and 15.6 +/- 1.0% for HA2 and HA3 respectively. Incubation of the cells for 24 hours with 38 microg/ml (IC25) of positive control showed an increase in percentage of cells with DNA damage (67.5 +/- 0.7%). In conclusion, our study indicated that both hydroxyapatite compounds showed a good biocompatibility in fibroblast cells.
Metal implants such as titanium, stainless steel and Co-Cr-Mo are used for load bearing purposes such as hip joint prostheses, fixing plates and dental root implants. For practical application, plasma-sprayed coatings of hydroxyapatite (HA) on metal implants are applied to promote early formation of strong bonds between metal implant and living bone. Plasma spray coating involves heating of HA material to a semi-molten or molten state and then propels its to a metal substrate. The plasma flame temperature is in the range of 6,000 degrees C to 16,000 degrees C but the surface temperature of the substrate rarely exceeds 150 degrees C. The HA materials are feed into the spray gun in the form of powders. Furthermore, this paper will discuss the processes of plasma-sprayed coating of HA on various types of metal implants.