Now showing 1 - 2 of 2
  • Publication
    Gold nanoparticles enhanced DNA biosensor based on Silica interdigitated electrodes for detection of Human Papillomavirus
    The increment in cervical cancer cases caused by the genital Human Papillomavirus (HPV) is a major worldwide problem for the women healthcare. In Malaysia, more than 5,000 cervical cancer patients, die from the delay in detecting cancer cells that are spreading to the final stage in 2015. The National Cancer Society of Malaysia (NCSM) reports that more than 11,000 women have been diagnosed with cervical cancer every year, especially young women in the late 30s. Rapid detection methods for the prevention and identification are required to solve the health and safety problems related to this pathogenic virus. Current detection methods require extensive specimen sample preparation and prolonged assay procedures. Thus, this research has focused on developing rapid detection methods, which are capable of sensing these viruses at a higher sensitivity. HPV 16 was used as the standard reference strain for the development of rapid methods. Nanoscaled interdigitated electrodes (IDEs) has been developed for the identification and miniaturizing the size of sensor but have higher performance for the biomedical engineering usage by detecting deoxyribonucleic acid (DNA) of HPV caused cervical cancer. With the conventional lithography (CL) for device fabrication, an electrical biosensor based on gold nanoparticle (GNP) IDE wasconstructed before the addition of 3-aminopropyltriethoxysilane (APTES). The optimized IDE was then employed for the detection of HPV DNA by the introduced two-steps mechanism after the surface modification by APTES. APTES is linking the modified HPV DNA probe with carboxyl group (-COOH) immobilization by covalent binding via amine (-NH2) coupling APTES on the sensing surface based IDE, and DNA hybridization. Surface structure analysis with scanning electron microscopy (SEM) was used to characterize the changes in the surface appearance. Fourier transform infrared (FTIR) spectroscopy analysis was used to assess the attachment procedures. The detection principle works by detecting the changes in the electrical current of IDE, which bridges the source and drain terminal to sense the immobilization of HPV DNA probe and hybridization with target DNA. It was found that the sensor showed the selectivity for HPV DNA target in a linear range with the concentrations ranges from 1 pM to 1 µM. With this analysis, the sensitivity limit of detection (LOD) was approximately 1 pM and it is comparable with the currently available sensors.In addition, the developed biosensor device was able to discriminate among complementary synthetic target, single mismatch, and non-complementary DNA sequences. A commercial, HCII Hybrid capture based Enzyme-Linked Immunosorbent Assay (ELISA) method for 13 types of high-risk HPV including HPV 16 and 18 wasused as a validation technique for confirming the effectiveness of GNP based IDE electrical biosensor in real samples. The advantage of this sensor is fast detection without labeling application and is useful in identifying the strength of HPV DNA probe binding to HPV target. This electrical biosensor system will be useful for the development of devices with on-site analysis.
  • Publication
    Dielectric properties and microwave absorbing properties of silicon carbide nanoparticles and silicon carbide nanowhiskers
    Silicon carbide (SiC) is well known for their outstanding microwave absorbing properties. SiC nanomaterials (SiCNMs) are expected to have better microwave absorption performance due to their high specific surface area. To date, no study was reported to compare the dielectric properties and microwave absorbing properties of different type of SiCNMs. Therefore, the objective of this paper is to compare the dielectric properties and microwave absorption properties of different types of SiCNMs. In this paper, SiC nanoparticles (SiCNPs) and SiC nanowhiskers (SiCNWs) were characterised using SEM and XRD. In addition, their dielectric properties and microwave absorbing properties were measured using network analyser and transmission line theory. It was found that SiCNWs achieved higher dielectric constant and loss factor which are and εr’ =17.94 and εr″ = 2.64 compared to SiCNPs that only achieved εr’ = 2.83 and εr″ = 0.71. For microwave absorbing properties, SiCNWs and SiCNPs attained minimum reflection loss of -10.41 dB and -6.83 dB at 5.68 GHz and 17.68 GHz, respectively. The minimum reflection loss of SiCNPs and SiCNWs obtained in this study is much lower than the nanometer-SiC reported previously. These results suggested that SiCNWs can be an ideal candidate of microwave susceptors for various microwave applications