Publication: Development of a leakage-free printed circuit board (pcb) based biosensor for dna sensing
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Date
2023-10-01
Authors
Norshah Rizal Bin Ali @ Hasim
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Abstract
This research has developed a leakage-free and disposable deoxyribonucleic
acid (DNA) fingerprinting biochip, utilising amperometric detection on copper-clad
electrodes of FR-4 printed circuit board (PCB), with polydimethylsiloxane (PDMS) as
the separation microchannel. Fluid leakage is a significant challenge when building a
Lab-on-PCB (LOP) microfluidic device. Copper-clad electrodes simplify fabrication
and make it disposable. Nevertheless, a non-inert copper requires stable biological
buffers to stabilise the DNA. Redox properties investigation of nucleotides and
nucleobases as the target detection molecules are vital for improving biochip
transduction and detection resolution. Hence, the research objectives have been set up
to solve the leakage issue, the investigation of biological buffers, and the analysis of
target detection molecules in DNA. A preventative layer from photocurable diacrylate
bisphenol-A polymer (DABA) provided irreversible bonding between PDMS and the
PCB substrates. It was the first DABA application which has never been tested in
dentistry or biomedical applications. Tensile tests on PCB-DABA-PDMS revealed
bond breakages at the DABA-PCB interface, with an average tensile strength of 287.36
kPa and a standard deviation of 23.79 kPa. Meanwhile, the leakage test indicated that
the microchannel could resist more than 189 kPa pressures, which is acceptable for
this application. Cyclic voltammetry (CV) experiments on the copper electrode with
ethylenediaminetetraacetic acid (EDTA) and 2-(N-morpholino)ethanesulfonic acid
(MES) buffers showed that deoxyguanosine triphosphate (dGTP) molecules undergo
irreversible oxidation potentials at 0.9 and 1.245 V, respectively. The experiments also confirm that the dGTP was stable inside the buffers and sensitive to the obtained
potentials. DNA analysis experiments on single-band DNA (PCR amplicon) and
multiple-band (1kbp DNA ladders) revealed that the proposed design could accurately
separate and detect DNA fragments at an electric field strength of 20V/cm with low
background noise. The first findings show that DABA is biocompatible and
biologically inert to DNA samples, where the new technique efficiently closes the
device, preventing liquid leakage from the sensor’s grid. Secondly, DNA stability with
copper electrodes could also be achieved electrochemically within EDTA and MES
buffers. Finally, the detecting target molecule employing guanine nucleotides offers a
good current detection even with a small DNA sample. The discoveries paved the way
for the development of completely disposable biosensing devices.