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Title:	Carrageenan membrane materials for new urea and DNA biosensors
Authors:	Chakavak Esmaeili (P54497)
Supervisor:	Lee Yook Heng, Prof. Dr.
Keywords:	Biosensors DNA Urea Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	1-Jan-2016
Description:	In this work, kappa-carrageenan (KC) was studied with the aim of designing new biosensor membranes for urea and DNA determinations. KC and a composite material from kappa-carrageenan-polypyrrole-gold nanoparticles (KC-PPy-AuNPs) were investigated. Immobilization of urease (Urs) enzyme and DNA molecule in the KC and KC-PPy-AuNPs matrix surface was able to minimize the loss of the biomolecular activity. New potentiometric and reflectometric urea biosensors based on KC matrix was designed. The urea biosensors was based on the concept of enzymatic reaction of urea to cause a change in pH, which was detected by a hydrogen ionophore entrapped in poly (n- butyl acrylate) membrane (for potentiometric biosensor) or Nile Blue chromoionophore ETH5294 (for reflectometric biosensor). The response of potentiometric urea biosensor was linear and exhibited a near Nernstian response for urea in the range 3.1×10-3 to 1.3×10-4 M (R2=0.982) with lower detection limit (LOD) of 1.0×10-4 M and for reflectometric urea biosensor, the response range was 1 ×10-6 to 1×10-1 M (R2=0.950) and LOD = 1 ×10-6 M. No obvious interferences from cations such as Na+, K+, Mg2+ and NH4 was observed and the biosensors demonstrated long term stability. For the development of a DNA biosensor, the KC-PPy-AuNPs nanocomposite material was prepared by chemical polymerization and characterized by various methods. This composite material was observed to show enhance conductivity and mechanical properties compared with the original unmodified KC polymer. Thus, the material was useful for constructing a DNA biosensor with the immobilization of thiolated DNA recognition probe onto the AuNPs in the KC-PPy-AuNPs nanocomposite. The DNA biosensor showed discrimination between complementary target and non-complementary DNA or base-pair mismatched DNA. The dynamic range of the DNA detected was 5.0×10-12 to 5.0 ×10-18 M (R2= 0.968) with LOD of 5.0 ×10-18 M. The studies proved the usefulness of carrageenan and its new nano-composite KC-PPy as materials for the immobilization of enzyme and DNA to develop new membrane materials for biosensors.,Ph.D.
Pages:	193
Call Number:	R857.B54E846 2016 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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