Skip Navigation LinksVolume : Volume 20 No.1 2011

  
  
  
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paper_9.pdfSYNTHESIS OF POLYAMIDOAMINE DENDRIMER-PEG-DRUG CONJUGATES
  
ABSTRACT:
Star polymers offer promising multifunctional nanomaterials as carriers for the drug delivery system due to their well-defined size and tailor ability. Polyamidoamine (PAMAM) dendrimer is the most suitable star polymers for biomedical applications. In the present study, the effect of alterations of the chemical structure of PAMAM dendrimer on the conjugation of methotrexate (MTX) was investigated. Monomethyl poly (ethylene) glycol (MPEG) was used as spacer to facilitate the conjugation and reduce the toxicity of dendrimer. Two methods were studied to produce PAMAM-PEG-MTX and PAMAM-MTX conjugates. Characterization of the conjugates has been determined by multiple analytical methods such as UV Visible spectroscopy (UV-Via). Fourier Transform Infra-red (FTIR), Nuclear Magnetic Resonance (NMR) and Differential Scanning Calorimetry (DSC). The conjugates efficiency of both methods was compared. 

KEYWORDS: PAMAM dendrimer, PEG, MTX, conjugate 

Author: Siti Noorzidah Mohd Sabri, Azreena Mastor, Norhidayah Abu, Kartini Noorsal
Year: 2011
paper_8.pdfPREPARATION AND CHARACTERIZATION OF ZEOLITE BETA SUPPORTED MONOMETALLIC AND BIMETALLIC CATALYSTS
  
ABSTRACT : 
It had been reported that the sonochemical reduction of Au (III) in the presence of an organic additive proceeds via the following reaction: (i) formation of radical H (*H) from sonolysis of water (ii) formation of *R and H2 from the abstraction reaction of organic additive with *OH or *H (iii) pyrolysis radicals and unstable products are formed by pyrolysis of organic additives and water (iv) the reduction of Au (III) proceeds by the reac-tion with various reducing species. In this work, stable suspension of gold nanoparticles were prepared using sonochemical synthesis by reduction of Au(III) in water without adding any reducing agent in the presence of a small amount of 2-propanol by using 20 KHz ul-trasonic probe. 2-propanol had been used as an accelerator for the reduction of Au (III) and polyvinyl pyrrolidone (PVP) had been used in the aqueous solution to prevent clustering of the formed gold nanoparticles. The effects of different concentration of PVP on the size and shape of gold nanoparticles had been studied. As a comparison, solution containing PVP and trisodium citrate had been reported here. The formation of gold nanoparticles had been confirmed by using UV-Visible Spectroscopy. The morphology and size of gold nanoparticles were analyzed by using a Transmission Electron Microscope. Our results suggested that when we increased the concentration of PVP, the size of gold nanoparticles will decrease. When we add citrate into the solution, the particle size of gold nanoparticles will actually become smaller comparing to the solution without citrate. 

KEYWORDS : Gold nanoparticles, sonochemical reduction, Transmission Electron Microscope

Author: N.M. Yusof , N.I Abd Azes, F. Mirkhalaf, A.K. Masrom
Year: 2011
paper_7.pdfPREPARATION OF STABLE SUSPENSION OF GOLD NANOPARTICLES IN WATER BY SONOCHEMISTRY METHOD
  
ABSTRACT : 
It had been reported that the sonochemical reduction of Au (III) in the presence of an organic additive proceeds via the following reaction: (i) formation of radical H (*H) from sonolysis of water (ii) formation of *R and H2 from the abstraction reaction of organic additive with *OH or *H (iii) pyrolysis radicals and unstable products are formed by pyrolysis of organic additives and water (iv) the reduction of Au (III) proceeds by the reac-tion with various reducing species. In this work, stable suspension of gold nanoparticles were prepared using sonochemical synthesis by reduction of Au(III) in water without adding any reducing agent in the presence of a small amount of 2-propanol by using 20 KHz ul-trasonic probe. 2-propanol had been used as an accelerator for the reduction of Au (III) and polyvinyl pyrrolidone (PVP) had been used in the aqueous solution to prevent clustering of the formed gold nanoparticles. The effects of different concentration of PVP on the size and shape of gold nanoparticles had been studied. As a comparison, solution containing PVP and trisodium citrate had been reported here. The formation of gold nanoparticles had been confirmed by using UV-Visible Spectroscopy. The morphology and size of gold nanoparticles were analyzed by using a Transmission Electron Microscope. Our results suggested that when we increased the concentration of PVP, the size of gold nanoparticles will decrease. When we add citrate into the solution, the particle size of gold nanoparticles will actually become smaller comparing to the solution without citrate. 

KEYWORDS : Gold nanoparticles, sonochemical reduction, Transmission Electron Microscope

Author: N.M. Yusof , N.I Abd Azes, F. Mirkhalaf, A.K. Masrom
Year: 2011
paper_5.pdfGROWTH OF VERTICALLY ALIGNED SINGLE-WALLED CARBON NANOTUBES USING ALCOHOL CATALYTIC CVD METHOD
  
ABSTRACT:
A massive growth of vertically aligned single-walled carbon nanotubes (SWCNTs) from Al203-supported Co catalyst was performed using Alcohol Catalytic Chemical Vapor Deposition (ACCVD) method. Carpets of SWCNTs with an almost submillimeter height were grown on the Si/Si02 substrates via this technique. Growth temperature dependence analysis had been carried out in the first place to elucidate parametric study in determining optimum growth conditions, in which the CVD time was fixed at t = 10 min and CVD reactor internal pressure at 3 kPa. The analysis confirmed the maximum height of SWCNTs films grown on the substrate to be Tc,,E, = 750 ° C. Structural properties of as-grown SWCNTs have been measured by Raman spectroscopy with various laser excitations where we confirmed a relatively high quality and pure SWCNTs: determined from Raman intensities, IdID ratio. Morphology observation of the very high SWCNTs yield was performed by Scanning Electron Microscope (SEM).       KEYWORDS: Vertically aligned SWCNTs, ACCVD, CVD temperature dependence, Raman spectra analysis 

Author: Mohd Asyadi Azam, M.A. Mohamed, E. Shikoh, Fujiwara
Year: 2011
paper_3.pdfOPTIMIZATION OF CARBON NANOTUBES SYNTHESIS VIA METHANE DECOMPOSITION OVER ALUMINA-BASED CATALYST
  
ABSTRACT :
Carbon nanotubes (CNTs) were synthesized from alumina-based catalyst via decomposition of methane in a horizontal reactor system. By using a statistical design of experiments (DoE), six factors (reaction temperature, reaction duration, metal loading of catalyst, amount of catalyst, flow rate of methane and flow rate of nitrogen) were optimized for the synthesis of carbon nanotubes. The response of the process towards the factors was assessed using two quantitative signifiers, which are the yield of carbonaceous material and the /A ratio from Raman spectrum. The parameter space for significant factors that influence the response was first screened using a Resolution Ill fractional factorial design. A response surface which is defined by the most significant parameters was then incurred from Box-Behnken design and finally optimal conditions were found. The morphology of the as-produced CNTs from the selected samples was observed using a Transmission Electron Microscope (TEM).     

KEYWORDS: Carbon Nanotubes, Chemical Vapor Deposition, Raman Spectroscopy, Transmission Electron Microscopy, process optimization 

Author: Kim-Yang Lee, Wei-Ming Yeohl, Siang-Piao Chal, Jul Rahman Mohamedi
Year: 2011
paper_2.pdfSURFACE MODIFICATION OF MIXED SELF-ASSEMBLED MONOLAYER BY CUM-CATALYZED CYCLOADDITION AND ESTER HYDROLYSIS
  
ABSTRACT:
Organic reactions in small dimension of space in mixed self-assembled monolayer have been performed and characterized by contact angle measurement and XPS. Mixed self-assembled monolayers, containing both azido and acetylene terminal groups homogeneously distributed across the surface, were prepared by dipping Au substrates into mixed solutions of azido disulfide and acetylene disulfide at equal concentrations. The mean value of water contact angle measurement on the surface compared to mono-functional azido and acetylene monolayers suggesting the gold substrate was homogenously covered by mixture of azido and acetylene terminal groups at the desired ratio. The surface was further treated with Cu(I) catalyst solution followed by alkaline solution. Water contact angle measurement of mixed monolayer dropped significantly after the treatments shows the surface has been modified from hydrophobic into hydrophilic surface character. The result is consistent with XPS analysis at narrow scan of C and N elements i.e. the presence of a signal at 289 eV for carbonyl group and disappearance of azido signal at about 400 eV. This experiment was reflecting sequential intramolecular organic reactions of cycloaddition and hydrolysis of ester in mild condition on single layer of activated functional groups of organized ultra thin film.   

KEYWORDS: Self-assembled monolayer, cycloaddition, hydrolysis, intramonolayer 

Author: Hairul A. Tajuddinl and Nicholas H. Williams
Year: 2011
paper_11.pdfHYDROXYAPATITE COATING ON TITANIUM SUBSTRATE BY ELECTROPHORETIC DEPOSITION
  
ABSTRACT:
Several methods have been used to coat Hydroxyapatite (HA) on metal substrates such as plasma spraying,dip coating,vacuum coating and electrophoretic deposition (EPD). In this work,EPD method has been used to coat HA on titanium substrates. The deposition was conducted under applied voltages of 10,20,30,40 and 50V in colloidal suspension containing 2.5 and 5.0 wt.% HA in ethanol. Deposition at higher voltage produced higher volume mass of the coating. Coating consisting of bigger particles size was deposited at higher deposition voltage.After deposition,the coating was dried at room temperature followed by sintering at 900 of in argon atmosphere to improve adhesion and densityof the coating. The phase purity and morphology of the as-deposited and sintered coatings were analyzed by XRD and SEM It was found that EPD method is capable of coating HA on titanium substrates and HA coating on titanium substrate retained itsphase after sintering at 900of.   

KEYWORDS: Hydroxyapatite, electrophoretic deposition, sintering, deposition potential

Author: Sit! Zaharah Abd Mutalib, Abdul Hakim Hashim*, Sit! Mariam Mohamed, Mohd Zakuan
Year: 2011
paper_10.pdfREINFORCEMENT OF EPOXIDISED NATURAL RUBBER BY PRECIITATED SILICA NANOFILLER: STUDIES ON CURE CHARACTERISTICS AND RUBBER -FILLER INTERACTION
  
ABSTRACT :
Epoxidised natural rubber, which is produced via modification of natural rubber enhanced the polarity of natural rubber. In this work, the rubber - filler interaction of epoxidised natural rubber (ENR) and precipitated silica nanofiller was investigated. The surfaces of silica are polar and hydrophilic, which normally required a coupling agent to make it more compatible with hydrocarbon polymer. The use of ENR in precipitated silica nanofiller compound eliminates the use of silane coupling agent in the compound formulation since ENR has boner compatibility with silica nanofiller. This study presents the rheological behaviour and cure characteristics of silica nanofiller - ENR compounds with different silica contents. For this purpose two different types of silica nanofiller have been compounded with ENR. The rubber-filler via bound rubber measurement shows a high rubber-filler interaction in ENR-silica nanofiller compound. Lower Payne effect was observed resulting from the reduction in filler-filler interaction. This indicates that there is a strong reinforcement mechanism exhibited by silica nanofiller in epoxidised natural rubber compound. The improved mixing enhanced the filler-rubber interaction and increased the nanofiller dispersion as well as reduced the filler-filler interaction.     

KEYWORDS : Precipitated silica, nanofiller, epoxidised natural rubber, Payne effect, rubber- filler interaction 

Author: Sit! Salina Sarkawi and Che Sn Mt Saad
Year: 2011
paper_1.pdfEFFECTS OF HOMOGENISATION AND ULTRASONICATION ON CURCUMIN-CHITOSAN NANOPARTICLES
  
ABSTRACT :
Homogenisation and ultrasonication are widely used techniques to produce nanoparticles. In the present study, we compared the phyaico| characteristics of curcumin-chitosan nanoparticles produced by these two processes and the combination of both. Parameters studied included homogenisation and ultrasonication speed and amplitude respectively, as well as duration in each instance. The decrease in mean particle size from homogenisation alone to the combination of both methods were calculated to be 29.6 % and 18.6 % for 5 minutes homogenisation and 10 minutes homogenisation respectively. On the other hand, the decrease in mean particle size from ultrasonication alone to the combination method were 30.47 % and 31.40 % for 5 minutes homogenisation and 10 minutes homogenisation respectively. Increase in zeta potential was also observed with the combination method. Hence it may be concluded that the combination method of homogenisation and ultrasonication produces better curcumin-chitosan nanoparticles with superior physical characteristics in terms of size and zeta potential compared to either method alone. 

KEYWORDS :  Curcumin, nanoparticles, ultrasonication, homogenisation 

Author: L.H. Chuah N Bill M. Svakuma
Year: 2011