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  • Written by Sharifah Noor Sahila Syed Jamal
  • Category: PENYELIDIKAN SLIDER

Studies of Geopolymerization Route For Metakaolin Geopolymeric Materials


Studies of Geopolymerization Route For Metakaolin Geopolymeric Materials

 

 

 


 

 

 

 

 

 


 
Investigation on production of metakaolin geopolymeric powder was aimed to increase the productivity and application of geopolymer products. Geopolymerization process was applied in the manufacturing of metakaolin geopolymeric powder to be used in geopolymer synthesis. Geopolymer slurry was made by alkaline activation of metakaolin in alkali activator solution (a mixture of NaOH and sodium silicate solutions). The geopolymer slurry was heated in an oven to produce pre-cured paste and then pulverized to get uniform particle size geopolymeric powder. By adopting the concept of “just add water”, the metakaolin geopolymeric powder was mixed with water and then oven-cured to produce resulting geopolymer pastes. The results showed that the optimum conditions for producing highest strength resulting paste are by using 8M of NaOH solution, solids/liquid ratio of 0.80, an activator ratio of 0.20, pre-curing of 80°C for 4 hours, 22% of mixing water and curing regime of 60°C for 72 hours. The resulting geopolymer pastes have low bulk density and were potential for a lightweight material. Upon the mixing of water with geopolymeric powder, densification of the structure occurred with the formation of compact geopolymer gels. The geopolymeric powder and resulting pastes showed the combination of amorphous and crystalline phases as analyzed by XRD. After ageing, the intensities of zeolites crystalline phases increased and this emphasized the benefit of zeolites in strength development of resulting pastes. This study clearly demonstrates that the production of metakaolin geopolymeric powder was able to be used in manufacturing geopolymer pastes.

Keywords: Geopolymer, powder, activator solution, geopolymerization, water
  • Written by Syed Abu Bakar Syed Ahmad
  • Category: PENYELIDIKAN SLIDER

Surface Functionalization of Carbon-Based Transistor For Aptamer Immobilization In Protein Sensor Application

 


Surface Functionalization Of Carbon-Based Transistor For Aptamer Immobilization In Protein Sensor Application
 

 

 

 

 

 


Carbon-based material including carbon nanotubes (CNTs), diamond and graphene are central materials in nanoscience. Their unique electrical, physical, mechanical and chemical properties are widely studied so as to develop biosensor devices. The current trend of biosensing is moving towards the realization of point-of-care diagnostic systems, which involve the integration of all the analytical stages on a single chip. In this study, a combination of aptamer modified multiwalled carbon nanotube integrated with field effect transistor (MWCNT-FET) were demonstrated for human immunodeficiency virus-1 (HIV-1) Tat protein detection. The effect of surface functionalization of multiwalled carbon nanotube (MWCNT) is investigated by introducing carboxyl functional group through chemical surface treatment.

The functional group on CNTs surface were characterized by using Fourier transform infra red (FTIR), Scanning electron microscope (SEM), Thermo gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). RNA aptamer were immobilized on the CNT functionalized surface by covalent binding. Aptamer act as molecular recognition element for HIV-1 Tat protein. The current-voltage measurements were studied before and after aptamer immobilization. A series of analyte concentration were measured to determine the limit of detection for CNTs-FET biosensor. The specificity of the aptamer probe and the stability of the device detection has been investigated. The device will be validate on the usage of the real sample from human bodily fluid to evaluate the effectiveness of detection. The performance of the biosensor were demonstrated not only by current-voltage measurement but also cyclic voltammetry. There were also supporting test on colorimetric study conducted to confirmed the reaction between the aptamer and protein.

Keywords: MWCNT, RNA Aptamer, HIV-1 Tat Protein, Surface Functionalization.