Fabrication and characterization of ZnO nanostructures for DNA detection
Zinc oxide (ZnO), a representative of group II-IV metal-oxide semiconductor material is widely studied in the current research community. ZnO with its wide direct band-gap (3.37eV) and high exciton binding energy (60meV) providing the advantages of their electrical and optical properties. Due to...
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| Format: | Thesis |
| Language: | English |
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| Online Access: | http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/31220/1/Page%201-24.pdf http://dspace.unimap.edu.my:80/xmlui/bitstream/123456789/31220/2/Full%20text.pdf |
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| Summary: | Zinc oxide (ZnO), a representative of group II-IV metal-oxide semiconductor
material is widely studied in the current research community. ZnO with its wide direct
band-gap (3.37eV) and high exciton binding energy (60meV) providing the advantages
of their electrical and optical properties. Due to these unique properties and easiness to
grow using bottom-up approach combines with high isoelectric point, toxic-free, high
surface-area-to-volume ratio, biosafe, and biocompatible, ZnO nanostructures have
great interest in the application of biosensor. The aim of this research work is to
synthesis, fabricate, and characterize ZnO nanostructures based sensor for DNA
immobilization and hybridization detection. Two types of ZnO nanostructures were
studied, namely thin films and nanorods (NRs). Highly transparent ZnO thin films were
successfully synthesized using ease and low-cost sol-gel spin-coating method. ZnO NRs
with nanoscale possessed high crystalline structure was further grown from the asprepared
thin films through low-temperature hydrothermal growth. In this thesis, we
studied the influence of different solvents on the structure, optical and electrical
properties of the ZnO nanostructures. Four types of solvents namely methanol, ethanol,
isopropanol, and 2-methoxyethanol had been chosen for ZnO seed solution preparation.
The observed results using FESEM indicated that the nanoparticles and nanorods with
the size less than 40 nanometer and 60 nanometer, respectively were successfully
synthesized. The investigation on optical properties using UV-Vis-NIR
spectrophotometer confirmed ZnO is classified as a wide band gap semiconductor
material. In order to fabricate a biosensor with high sensitivity and selectivity, a gold
nanoparticles (GNPs) were selected for the surface modification of ZnO nanostructures
which later formed gold-thiolate conjugation with thiol-modified ssDNA probes. Two
approaches were used for the immobilization and hybridization of DNA detection,
which were dielectric analysis and electrochemical analysis. DNA detection using
dielectric analyzer was done on interdigitated electrodes gold modified ZnO thin films.
The developed sensor clearly differentiated complementary and non-complementary of
target DNA through the measurement of capacitance, permittivity, and impedance.
DNA detection using electrochemical analysis with cyclic voltammetry confirmed
surface ZnO NRs modified with (3-Aminopropyl)triethoxysilane (APTES) and gold
nanoparticles provided better detection of target DNA in comparison with those only
contained gold nanoparticles. |
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