Zuratul Ain Abdul Hamid

Epoxy-amine synthesised hydrogel scaffolds for soft-tissue engineering

Highly porous and biodegradable hydrogels based on poly(ethylene glycol) (PEG) and cystamine (Cys) were fabricated using epoxy-amine chemistry and investigated as scaffolds for soft-tissue engineering. Whereas the application of fused-salt templates provided a comprehensive interconnecting pore morphology, the incorporation of a specially designed poly(epsilon-caprolactone) (PCL) cross-linker provided enhanced mechanical function without adversely effecting the scaffolds positive biological interactions. The addition of only 1.2 wt% of the PCL cross-linker was sufficient to provide improvements in the ultimate stress of 30-40%. In vitro studies not only confirmed the non-cytotoxic nature of the scaffolds, but also their degradation products, which were isolated and characterised by nuclear magnetic resonance (NMR) and matrix-assisted laser desorption/ionisation time-of-flight mass spectroscopy (MALDI ToF MS). In vivo trials were conducted over a period of 8 weeks through implantation of the scaffolds into the dorsal region of rats. At both 2 and 8 week time points the explants revealed complete infiltration by the surrounding tissue and the development of a vascular network to support the newly generated tissue, without an excessive foreign-body response.

Surface Engineered Poly(lactic acid) (PLA) Microspheres by Chemical Treatment for Drug Delivery System

Poly (lactic acid) (PLA) is well known for their biodegradability and bioresorbable properties and these properties made them suitable in drug delivery system as drug carriers. PLA is relatively hydrophobic and lack of cell-recognition group to interact with biologically active molecules which reduce the surface compatibility of microspheres. In this project, alkaline hydrolysis was used to induce hydrophilic functional group on the microspheres surface. Alkaline solution at 0.01M and 0.1M was used to modify microspheres surfaces. The engineered surfaces were evaluated using Scanning Electron Microscopy and Water Contact Angle. 0.1M alkaline solution hydrolyzed microspheres at higher extends as compared to 0.01M, where partial microspheres disintegrated and porous structure was revealed. The water contact angle of PLA films shows decreased from 65 ̊ to range 42 47 ̊ after alkaline hydrolysis.

Comparison Effect of Mica and Talc as Filler in EPDM Composites on Curing, Tensile and Thermal Properties

In this work, the comparison effect of mica and talc as filler in EPDM composites on curing, tensile, thermal properties was studied. EPDM/mineral fillers composites were compounded using two roll mill at various filler loading (i.e., 100/0, 100/10, 100/15, 100/30, 100/50, 100/70) and curing characteristics were carried out at 160°C using a Monsanto Moving Die Rheometer. The tensile and thermal properties as well as fracture surfaces of composites were tested using Instron Universal Testing Machine, Thermal Gravimetric Analysis (TGA) and Emission Scanning Electron Microscope (SEM). The results indicated that the optimum cure time (t90), scorch time (ts2) decreased, while maximum torque (MH) increased for both composites with increasing filler loading. The tensile properties of EPDM/mica and EPDM/talc composites increased with increasing filler loading and the optimum tensile strength and tensile modulus for both mineral fillers occurred at 50 phr. EPDM/mica composites showed better tensile properties due to strong interfacial interaction between filler and matrix than EPDM/talc composites. In addition, thermal stability of both composites improved with increasing filler loading.

Effect of Synthesis Parameters on Size of the Biodegradable Poly (L-Lactide) (PLLA) Microspheres

In this work, PLLA microspheres were prepared via emulsion solvent evaporation technique. Several synthesis parameters were studied to evaluate their effect on the size of PLLA microspheres. PLLA pallets before emulsion and PLLA microspheres surface chemistry after emulsion were determined using Fourier Transform Infra-red (FTIR). Results showed that PLLA pallets and microspheres FTIR obtained an identical spectrum. Microspheres size and surface morphology were determined using Scanning Electron Microscopy (SEM). In conclusion, the parameters that significantly affect the size of PLLA microspheres were PLLA concentration, DCM to water volume ratio, PVA concentration and stirring speed. PVA molecular weight variation showed no significant change in microspheres size.

Effect of Silane Coupling Agent on the Curing, Tensile, Thermal, and Swelling Properties of EPDM/Mica Composites

In this work, the influence of silane (bis (3-triethoxysilylpropyl) tetrasulfide) or Si69 coupling agent on properties of EPDM/mica composites was studied. Both EPDM/mica composites with silane and without silane were compounded using two roll mill at various filler loading (i.e., 100/0, 100/10, 100/30, 100/50, 100/70). The tensile and thermal properties as well as fracture surfaces of composites were tested using Instron Universal Testing Machine, Thermal Gravimetric Analysis (TGA) and Emission Scanning Electron Microscope (SEM). The results indicated that the optimum cure (t90), scorch time (ts2) value was lower, while maximum torque (MH) value slightly higher for EPDM/mica composites with silane compared to EPDM/mica composites without silane. The tensile properties, M100 and M300 value increased for EPDM/mica composites in the presence of silane and the optimum filler loading for those properties occurred at 50 phr. In addition, thermal stability and swelling ratio for both composites improved with increasing filler loading. However, EPDM/mica composites with silane show better thermal stability and swelling ratio due to stronger linkage taking place at the rubberfiller boundary and it promotes filler dis-agglomeration.

Surface Modification of Poly(Lactic Acid) Microspheres via Gamma Irradiation

Irradiation technique is one of methods used in modification of polymer surface although it has been used in sterilization for decades. It allows establishing simple and compact technique, non-contaminated with residues of toxic initiators, crossing agents or other additives. This study is to evaluate the effects of different gamma (γ) irradiation doses on poly (lactic acid) (PLA) microsphere surface grafted with maleic anhydride (MAH). Source of γ-irradiation used is 60Co and dose irradiation used in this study is10, 30, 50, 70, 90 and 110 kGy. Characterization was performed on samples before and after irradiation by FTIR, SEM and DSC. Results of FTIR suggest maleic anhydride successfully grafted onto PLA microsphere. Data from DSC shows thermal property of PLA changed after irradiation where the crystallization is increased compared to neat PLA. SEM images showed the difference of the PLA microspheres before and after γ irradiation. Neat PLA microspheres had a smooth surface, while after irradiation, the surface become rough. Degradation of microspheres observed by SEM as in suggest that PLA microspheres is degrade by bulk degradation. Gamma irradiation not only modified the surface of PLA microspheres by successfully grafting the maleic anhydride and increase surface roughness, it also affected the bulk properties of PLA microspheres.

Surface Morphology and Hydrophilicity Evaluation of PLA Microspheres Treated with Boronhydride (NaBH 4 ) at Different Concentrations

In drug delivery system, a controlled drug delivery carrier is favorable to ensure the delivery of drug at suitable and required rate and dosage to the targeted area. Microsphere is one of the approaches used to deliver drug in a controlled manner. A biodegradable poly (lactic) acid (PLA) has been used widely for drug delivery due to the fact that the polymer was non-toxic with a biodegradable property. Therefore, PLA microspheres were utilized in this research works. On the other hand, the major drawback of PLA is its extremely hydrophobic properties which limit its application in drug delivery system. In order to overcome this problem, surface modification via alkaline hydrolysis has been made on PLA. This research investigated the effect of surface modification with sodium boronhydride (NaBH4) at different concentrations and temperatures on the properties of PLA microspheres. The enhancement of hydrophilicity of PLA microspheres has been evaluated using FTIR and SEM. From these evaluations, it was found that the hydrophilicity of PLA microspheres had increased as the concentration of NaBH4 and temperature increased.

Fabrication of Carbonate Apatite Based on Hydrothermal Reaction Using Freeze-Casted β-TCP Precursor

Carbonate apatite (CO3Ap) has similarity to biological bone in composition which is expected to induce excellent tissue response and osteoconductivity. CO3Ap with lower crystallinity also promotes more apatite absorption in vivo. This study aims to fabricate low crystallinity of carbonate apatite from β-TCP scaffold as precursor using hydrothermal treatment at 200oC. An interconnected structure of β-TCP scaffolds were fabricated by freeze casting method which immersed in 5 mol/L of disodium carbonate (Na2CO3) solution for hydrothermal with various days of treatment; 3, 5 and 7 days. The morphology of apatite transformed was investigated by scanning electron microscopy (SEM) while the crystallinity was measured by X-ray diffraction (XRD). The carbonate content and Ca/P ratio after hydrothermal were obtained by CHN analyzer and X-ray fluorescence (XRF), respectively. The results show that carbonate content higher than 11 wt% was obtained which is important for both cell adhesion and proliferation. The apatite structure in the form of needle-like crystal is also observed.

Thermal properties of silica-filled high density polyethylene composites compatibilized with glut palmitate

A study of thermal properties resulting from the utilization of Glut Palmitate (GP) on the silica filled high density polyethylene (HDPE) composites was carried out. The composites with the incorporation of GP at 0.5, 1.0, 2.0 and 3.0 phr were prepared by using an internal mixer at the temperature 180 °C and the rotor speed of 50 rpm. The thermal behaviours of the composites were then investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It was found that the crystallinity and the thermal stability of the composites increased with the incorporation of GP. The highest crystallinity contents and decomposition temperatures were observed at the 1 phr GP loading.

Synthesis and Functionalization of Silicone Hydride Copolymer with Allyl Methacrylate via Hydrosilylation Method

Silicone hydride copolymer was functionalized with allyl methacrylate under the platinum catalyzed hydrosilylation reaction to yield comb-like poldimethylsiloxane grafted with methacrylate. The reaction was monitored via attenuated total reflectance Fourier transform infrared spectroscopy. Silicone hydride copolymer was synthesized in advance under cationic equilibrium ring opening polymerization. From the results, silicone hydride copolymer was synthesized based on cationic equilibrium ring opening polymerization mechanism under acidic condition. The peaks obtained from attenuated total reflectance Fourier transform infrared spectrum and nuclear magnetic resonance spectra corresponded to silicone hydride copolymer structure and ascertained that the silicone hydride copolymer synthesis was completed after 72 hrs of reaction. Functionalization process of silicone hydride copolymer had proceeded according to the Chalk-Harrod mechanism. The disappearance of Si-H peak at 2157 cm-1 had been observed in the attenuated total reflectance Fourier transform infrared spectra had indicated that the functionalization process was completed after 48 hrs of reaction.