Abstract:In this paper, a low-cost yet effective method of irreversible bonding between two elastomeric polydimethylsiloxane (PDMS) interfaces using Piranha solution is investigated. Piranha solutions at a weight ratio of 3:1 using different acids and hydrogen peroxide were attempted. The average tensile strengths of the device bonded with concentrated sulfuric acid-based piranha solution and nitric acid-based piranha solution were found to be 200 ± 20 kPa and 100 ± 15 kPa respectively. A PDMS surface treated with Piranha Solution demonstrated an increase in hydrophilicity. In addition, relatively straightforward swelling studies of PDMS using a weight loss method with common organic solvents were also investigated. Experimental results show that hexane, toluene, ethyl acetate, n-propyl alcohol and acetone swell PDMS significantly over a duration of up to 1 h and above; PDMS samples reached a steady state of swelling only after 5 min of immersion in other solvents. This will enable researchers to develop devices for the future according to the interaction between the material and the solvents in contact.

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The highly pathogenic avian influenza (HPAI) virus subtype H5N1 has been found to be the most virulent and deadliest virus strain, with capability of interspecies transmission to human infection. Most human HPAI H5N1 cases were diagnosed late in their illnesses for medical care, resulting in severe complications that led to death. In this study, a novel graphene-enhanced electrochemical DNA biosensor had been fabricated for the detection of polymerase chain reaction (PCR) amplicon derived from the haemagglutinin (H5) gene of the HPAI. The graphene-enhanced DNA biosensor showed excellent linear correlation between PCR amplicon concentration and amperometric signal with a correlation coefficient, r2 of 0.9987. The amperometric response of the proposed biosensor was compared with conventional gel electrophoresis while the feasibility of the proposed sandwich sensing platform was verified via dot blot assay. The results obtained indicate that the electrochemical DNA biosensing assay is significantly more sensitive (P < 0.05) and time efficient. This work serves as a proof of concept in hopes for further development of the graphene enhanced electrochemical DNA biosensor into a portable, on-site screening platform for point-of-care detection of various pathogens.