Fabrication of device with poly(N-isopropylacrylamide)-b-ssDNA copolymer brush for resistivity study

Journal of Nanobiotechnology

Research

Yi-Zu Liu¹  Jem-Kun Chen¹  Shih-Hsun Chen²  Chih-Chia Cheng³  May-Show Chen⁴ 

[1] Department of Materials Science and Engineering, National Taiwan University of Science and Technology, 43, Sec 4, Keelung Rd, 106, Taipei, Taiwan, ROC;Department of Mechanical Engineering, National Taiwan University of Science and Technology, 43, Sec 4, Keelung Rd, 106, Taipei, Taiwan, ROC;Graduate Institute of Applied Science and Technology, National Taiwan University of Science and Technology, 10607, Taipei, Taiwan, ROC;School of Oral Hygiene, College of Oral Medicine, Taipei Medical University, 11031, Taipei, Taiwan, ROC;Department of Dentistry, Taipei Medical University Hospital, 11031, Taipei, Taiwan, ROC;

关键词: Block copolymer brush;    Supramolecular complex;    Resistivity;   

DOI  :  10.1186/s12951-017-0303-4

 received in 2017-03-28, accepted in 2017-09-23,  发布年份 2017

来源: Springer

【 摘 要 】

In this study, we grafted bromo-terminated poly(N-isopropylacrylamide) (PNIPAAm) brushes onto thin gold films deposited on silicon, and then reacted with NaN3 to produce azido-terminated PNIPAAm brushes. A probe sequence of single-stranded DNA (ssDNA) with a 4-pentynoic acid succinimidyl ester unit was grafted onto the azido-terminated PNIPAAm brushes through a click reaction, resulting in the formation of block copolymer brushes. The PNIPAAm-b-ssDNA copolymer brushes formed supramolecular complexes stabilized by bio-multiple hydrogen bonds (BMHBs), which enhanced the proton transfer and thereby decreased the resistivity of the structures. In addition, the optimal operation window for DNA detection ranges from 0 to 0.2 M of NaCl concentration. Therefore, the specimens were prepared in the PBS solution at 150 mM NaCl concentration for target hybridization. The supramolecular complex state of the PNIPAAm-b-ssDNA copolymer brushes transformed into the phase-separated state after the hybridization with 0.5 ng/µL of its target DNA sequence owing to the competition between BMHBs and complementary hydrogen bonds. This phase transformation of the PNIPAAm and probe segments inhibited the proton transfer and significantly increased the resistivity at 25 °C. Moreover, there were no significant changes in the resistivity of the copolymer brushes after hybridization with the target sequence at 45 °C. These results indicated that the phase-separated state of the PNIPAAm-b-ssDNA copolymer brushes, which was generally occurred above the LCST, can be substantially generated after hybridization with its target DNA sequence. By performing the controlled experiments, in the same manner, using another sequence with lengths similar to that of the target sequence without complementarity. In addition, the sequences featuring various degrees of complementarity were exploited to verify the phase separation behavior inside the PNIPAAm-b-ssDNA copolymer thin film.

【 授权许可】

CC BY   
© The Author(s) 2017

【 图 表 】

12951_2017_303_Article_IEq1.gif