BUKU ABSTRAK - Universiti Putra Malaysia

Science, Technology & Engineering
Electrochemical DNA Biosensor for the Detection of Specific Gene related to
Trichoderma harzianum Species
Assoc. Prof. Dr. Nor Azah Yusof
Shafiquzzaman Siddiquee, Abu Bakar Salleh, Soon Guan Tan, Fatimah Abu Bakar and Lee Yook Heng
Faculty of Science, University Putra Malaysia,
43400 UPM Serdang, Selangor, Malaysia.
+603-8946 6782; azah@science.upm.edu.my
An electrochemical DNA biosensor was successfully developed by depositing ZnO nanoparticles, ionic
liquid (e.g., 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([EMIM][Otf])) in chitosan (CHIT)
nanocomposite membrane at modified gold electrode (AuE). The properties of the ZnO/CHIT/[EMIM][Otf]/AuE
and the characteristics of the immobilisation and hybridisation of DNA were studied by cyclic voltammetry using
MB as the redox electrochemical indicator. ZnO/CHIT/[EMIM][Otf]/AuE dramatically enhanced the sensitivity
of DNA hybridization recognition. Under optimal conditions, the dynamic range of DNA concentrations for
detecting the sequence specific DNA of Trichoderma harzianum gene was 1.0×10-18 to 1.82x10-4 mol L-1, and
the detection limit was 1.0×10-19 mol L-1, suggesting that the ZnO/CHIT/[EMIM][Otf] nanocomposite held
great promises for the applications in electrochemical biosensor.
Keywords: DNA electrochemical biosensor, DNA hybridisation, ZnO nanoparticles, ionic liquid, chitosan
Effect of Nonuniform Temperature and Magnetic Field on Marangoni Convection
Assoc. Prof. Dr. Norihan Md. Arifin
Siti Suzilliana Putri Mohamed Isa, Roslinda Nazar and Mohd. Noor Saad
Institute of Mathematical Research, University Putra Malaysia,
43400 UPM Serdang, Selangor, Malaysia.
+603-8946 6850; norihan@math.upm.edu.my
Linear stability analysis is applied to investigate the effect of nonuniform temperature gradient and magnetic
field on Marangoni convection in a horizontal fluid layer heated from below and cooled from above with a
constant heat flux. The influence of various parameters on the onset of convection is analysed. Six nonuniform
basic temperature profiles are considered, and some general conclusions about their destabilising effects are
presented.
Keywords: Marangoni convection, nonuniform temperature, magnetic field
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