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Authors: A. Van Eeghem, S. Werquin, J.F.I.B Hoste, A. Goes, E. Vanderleyden, P. Dubruel, P. Bienstman
Title: Double positive effect of adding hexaethyelene glycol when optimizing the hybridization efficiency of a microring DNA detection assay
Format: International Journal
Publication date: 2/2017
Journal/Conference/Book: Applied Surface Science
Volume(Issue): p.321-328
Internal Reference: [N-2060]
Download: Download this Publication (1.7MB) (1.7MB)

Abstract

In this paper, a method for detection of DNA molecules using silicon-on-insulator (SOI) microring resonators
is described. The influence of temperature and the use of formamide on the hybridization
efficiency were studied. It was shown that 50 v/v% of formamide in the hybridization buffer can ensure
hybridization when working close to physiological temperature. Furthermore, the use of hexaethylene
glycol (HEG) as backfilling agent was studied in order to resolve issues of non-specific adsorption to the
surface. The results indicated that not only non-specific binding was reduced significantly but also that
HEG improves the orientation of the DNA probes on the surface. This led to a 4-fold increase in hybridization
efficiency and thus in an equal decrease in the detection limit, compared to hybridization without
the use of HEG. An improvement in robustness of the assay was also observed. This DNA reorientation
hypothesis was confirmed by studying the thickness and density of the layers by using dual polarization
microring sensing. Finally, the different steps in the sensing experiment were characterized in more detail
by static contact angle (SCA) and X-ray photoelectron spectroscopy (XPS) analysis. The results showed
quantitatively that the surface modifications were successful.

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