Please use this identifier to cite or link to this item:
https://ptsldigital.ukm.my/jspui/handle/123456789/499628| Title: | Urea and DNA biosensors based on multiwall carbon nanotubes and fullerene |
| Authors: | Kasra Saeedfar (P43902) |
| Supervisor: | Lee Yook Heng, Prof. Dr. |
| Keywords: | Urea DNA biosensors Carbon nanotubes Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia |
| Issue Date: | 12-Mar-2015 |
| Description: | Multi-wall carbon nanotubes (MWCNT) and fullerene (C60) were modified for the purposes of designing new urea and DNA biosensors. Urease enzyme was anchored onto carboxylated MWCNT and fullerene by using 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide cross-linker to fabricate urea biosensors. Functionalized multi-wall carbon nanotubes were also attached with gold nanoparticles (~15 nm) (GNP-MWCNTCOOH) to construct DNA biosensors based on carbon-paste screen-printed electrode (C-SPE). These modified electrode biomaterials were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray (EDX), transmittance electron microscopy (TEM), attenuated total reflectance IR (ATIR) and UV-Vis spectroscopies. The modified fullerene-urease (C60-urease) and MWCNT-urease biomaterials have been confirmed to catalyze the hydrolysis of urea in solution to produce OH-. Therefore potentiometric urea biosensors were developed via silver-silver chloride screen-printed electrodes (Ag/AgCl SPE) containing a non-plasticized acrylate pH-selective membrane. The MWCNT-urease based urea biosensor showed linear response range of 5.0 × 10-5 to 1.0 × 10-2 M for urea with a Nernstian slope of 59.74 ± 0.72 mV/decade (R2=0.98, n=5). The lower detection limit of the biosensor was 5.0 × 10-5 M, whereas the reproducibility and repeatability were 2.09% and 1.19% relative standard deviation (RSD), respectively (n=5). Potentiometric urea biosensor designed from modified fullerene-urease, the linear response range was from 5×10-5 M to 1×10-3 M. The biosensor's sensitivity was 59.67 ± 0.91 mV/decade (R2=0.97, n=5). Common cations showed little interference to the performance of these urea biosensors. Amperometric DNA biosensors were constructed by the attachment of ss-DNA probes onto the GNP-MWCNTCOOH. The DNA hybridization redox indicator anthraquinone-2-sulfonic acid mono sodium salt (AQMS) was initially used but AQMS and MWCNT was found to interact which resulted in unspecific responses. Thus, other redox indicators were studied but only ruthenium(III) chloride hexaammoniate was found suitable as a hybridization indicator for MWCNT based DNA biosensor. The optimized biosensor responses were obtained at 0.05 M phosphate buffer, pH 7.0 and 90 min interaction time between ruthenium(III) chloride hexaammoniate hybridization labels. The linear response range for DNA determination was 10-15 to 10-3 μM complementary DNA. The advantages of MWCNTs and fullerene, such as high chemical stability, large surface area, favorable electrochemical properties, and good adhesion onto electrode surfaces contributed to the overall improvement in biosensor responses. In conclusion, MWCNT and fullerene can amplify the response of biosensors via an increase in the surface area of the electrodes, thus enhanced the sensitivity of biosensors.,Ph.D. |
| Pages: | 230 |
| Publisher: | UKM, Bangi |
| Appears in Collections: | Faculty of Science and Technology / Fakulti Sains dan Teknologi |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| ukmvital_80374+SOURCE1+SOURCE1.0.PDF Restricted Access | 443.91 kB | Adobe PDF |  View/Open |
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.