Photolithographic modification of polyethylene glycol silane monolayer for development of label-free dengue biosensor
Dengue disease becomes critical global health issue after millions were infected worldwide every year, which lead to fatality due to late detection. Hence, a new technique has been explored to improve the performance of the detection in term of time, price, sensitivity and selectivity. In orde...
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| Format: | Thesis |
| Language: | English |
| Published: |
2015
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/71171/1/FS%202015%2063%20IR.pdf |
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| Summary: | Dengue disease becomes critical global health issue after millions were infected
worldwide every year, which lead to fatality due to late detection. Hence, a new
technique has been explored to improve the performance of the detection in term of
time, price, sensitivity and selectivity. In order to develop the diagnostic devices,
electron beam (e-beam) or ultra-violet (UV) lithography were used to fabricate smallsized
patterns to provide surfaces with high sensitivity and selectivity to biomolecules.
For this particular project, polyethylene glycol (PEG)-silane monolayer, which was the
best-known antifouling polymer was used as a lithographic template due to its nonpolar,
non-toxic and non-immunogenic properties of the surface. The monolayer
formed was thoroughly characterized with contact angle, atomic force microscopy
(AFM), and X-ray photoelectron spectroscopy (XPS). The AFM and contact angle data
showed a uniform surface and hydrophilic properties of PEG-silane monolayer
obtained which confirmed by the XPS. The e-beam and UV irradiations were
subsequently performed, which generated the aldehyde functional groups. These offers
conjugation sites for the immobilization of DNA dengue. Further studies were done to
verify the presence of aldehyde functionality by testing with reducing agent and 2-
amino-1,1,1-trifluoroethane (TFEA). The TFEA test showed an increased value of
contact angle from 42° to approximately 74°, suggesting the hydrophobicity of surface
that corresponds to the bonding of carbon atom to three fluorine atoms was formed.
The reduction test studied the reduction aldehyde to alcohols which resulted in the
decrease of contact angle values. The properties of gold nanoparticles (AuNPs) on
particles sizes, shape, morphology and elemental composition were investigated which
was utilized as a colorimetric probe for the determination dengue-DNA. For the DNA
hybridization, target DNA was attached directly to probe DNA that had been
immobilized on irradiated modified surfaces in which an amine-terminus (or Nterminus)
from the DNA bound with aldehyde on modified surfaces. Gold
enhancement process was introduced for naked eye detection after inducing
electrostatic interaction between positively charged AuNPs and negatively charged
target DNA to probe DNA. Control experiments were performed with mismatch DNA
sequences to confirm the selectivity of the sensor. The effect of target DNA
concentration was studied in the hybridization of DNA. The results obtained indicate
an efficient and selective device have been successfully developed for label-free
dengue detection. |
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