The Impedimetric Human Papiloma Virous DNA Biosensor Fabrication Based on Gold Nanotubes

Shariati, Mohsen | 2019

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 52223 (48)
  4. University: Sharif University of Technology
  5. Department: Institute for Nanoscience and Nanotechnology
  6. Advisor(s): Ghorbani, Mohammad; Sasanpour, Pezhman
  7. Abstract:
  8. An impedimetric human papilloma virus (HPV) DNA biosensor based on gold nanotubes (AuNTs) in label free detection was materialized. The AuNTs decorated nanoporous polycarbonate (AuNTs-PC) template as biosensor electrode was fabricated by electrodeposition method. The single strand DNA (ss-DNA) probe was covalently immobilized onto the AuNTs-PC electrode. The hybridization of target sequences with the ss-DNA probe was observed by the electrochemical impedance spectroscopy (EIS). The biosensor showed high selectivity and could differentiate between the complementary, mismatch and non-complementary DNA sequences. The EIS measurements were matched to Randle's equivalent circuit. The negatively-charged HPV DNA oligonucleotides under external electric field were oriented in a preferred direction and the bio-sensing responses were intensified by controlling the immobilization and hybridization of the sequences on the AuNTs surface. The fabricated DNA biosensor under electric field amplification was stable up to six weeks and demonstrated 97% of its initial detection responses. The biosensor displayed the HPV DNA hybridization detection in very low concentrations in the linear response ranges of 0.01 pM to 1 μM and was able to acquire a limit of detection (LOD) of 1 fM. As a comparative biosensor, A DNA biosensor for detection of humanpapilloma virus (HPV) based on gold nanoparticles decorated nanoporous anodized aluminum oxide (AuNPs AAO) has been fabricated. The highly sensitive DNA biosensor was optimized under electric field amplification. The single strand DNA probe (ssDNA) was immobilized on the AuNPs decorated AAO electrode. The AuNPs AAO electrode detected the hybridization of complementary DNA in very low concentrations in label free mechanism. The electrochemical impedance spectra (EIS) measurements for DNA detection were conducted in the presence of the reduction–oxidation reaction. The EIS signals were amplified by AuNPs and electric field to achieve the detection limit (LOD) of 20 fM. The AuNPs decorated AAO biosensor could detect the DNA concentrations from 0.1 pM to 1 μM linearly in the calibration diagram. By applying the electric field, the DNA sequences were aligned in a preferred direction inside the nanopores. The sequences alignment was bettered the immobilization and hybridization processes and enhanced the signal to noise in the EIS responses. The biosensor showed high specifity and could distinguish the complementary target from the mismatch and non-complementary ones. The stability and repeatability of the AuNPs-AAO biosensor were investigated and the AuNPs-AAO biosensor demonstrated 91% of its initial responses after six weeks maintenance
  9. Keywords:
  10. Human Papilloma Virus ; Nanoporous Polycarbonate ; Gold Nanotubes ; Anodized Aluminum Oxide ; Impedance Spectroscopy ; Biosensor

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