Browsing by Author "Phan Thi Kim Loan"

Now showing 1 - 3 of 3

Graphene/MoS2 Heterostructures for Ultrasensitive Detection of DNA Hybridisation
(2014-07-23)
Phan Thi Kim Loan
;
Zhang, Wenjing
;
Lin, Cheng-Te
;
Wei, Kung-Hwa
;
Li, Lain-Jong
The photoluminescence signals of a graphene/MoS2 heterostructural stacking film are sensitive to environmental charges, which allows the single-base sequence-selective detection of DNA hybridization with sensitivity to the level of aM. [GRAPHICS] .
Label-free detection of DNA hybridization using transistors based on CVD grown graphene
(2013-03-15)
Chen, Tzu-Yin
;
Phan Thi Kim Loan
;
Hsu, Chang-Lung
;
Lee, Yi-Hsien
;
Wang, Jacob Tse-Wei
The high transconductance and low noise of graphene-based field-effect transistors based on large-area monolayer graphene produced by chemical vapor deposition are used for label-free electrical detection of DNA hybridization. The gate materials, buffer concentration and surface condition of graphene have been optimized to achieve the DNA detection sensitivity as low as 1 pM (10(-12) M), which is more sensitive than the existing report based on few-layer graphene. The graphene films obtained using conventional PMMA-assisted transfer technique exhibits PMMA residues, which degrade the sensing performance of graphene. We have demonstrated that the sensing performance of the graphene samples prepared by gold-transfer is largely enhanced (by 125%). (C) 2012 Elsevier B.V. All rights reserved.
Label-Free Electrical Detection of DNA Hybridization on Graphene using Hall Effect Measurements: Revisiting the Sensing Mechanism
(2013-05-13)
Lin, Cheng-Te
;
Phan Thi Kim Loan
;
Chen, Tzu-Yin
;
Liu, Keng-Ku
;
Chen, Chang-Hsiao
There is broad interest in using graphene or graphene oxide sheets as a transducer for label-free and selective electrical detection of biomolecules such as DNA. However, it is still not well explored how the DNA molecules interact with and influence the properties of graphene during the detection. Here, Hall effect measurements based on the Van der Pauw method are used to perform single-base sequence selective detection of DNA on graphene sheets, which are prepared by chemical vapor deposition. The sheet resistance increases and the mobility decreases with the addition of either complementary or one-base mismatched DNA to the graphene device. The hole carrier concentration of the graphene devices increases significantly with the addition of complementary DNA but it is less affected by the one-base mismatched DNA. It is concluded that the increase in hole carrier density, indicating p-doping to graphene, is better correlated with the DNA hybridization compared to the commonly used parameters such as conductivity change. The different electrical observations of p-doping from Hall effect measurements and n-doping from electrolyte-gated transistors can be explained by the characteristic morphology of partially hybridized DNA on graphene and the mismatch between DNA chain length and Debye length in electrolytes.