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DNA Hybridization in Thermoresponsive Polymer Nanoparticles

Authors

  • Leila M. Moura,

    1. Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, 1049-001 Lisboa (Portugal), Fax: (+351) 218464455
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  • Jose M. G. Martinho Prof.,

    1. Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, 1049-001 Lisboa (Portugal), Fax: (+351) 218464455
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  • Jose Paulo S. Farinha Prof.

    1. Centro de Química-Física Molecular and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, 1049-001 Lisboa (Portugal), Fax: (+351) 218464455
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Abstract

We achieve very high hybridization efficiencies by using a new method to immobilize DNA strands on the surface of thermoresponsive polymer nanoparticles. Hybridization efficiencies of about 70 % are obtained between the DNA immobilized in the particles and a complementary strand in solution, even at very low ionic strengths (1 mM). The polymer nanoparticles have a glassy poly(methylmethacrylate) (PMMA) core and a thermoresponsive shell of poly(N-isopropylacrylamide) (PNIPAM) containing positive charges. After a DNA strand labeled with a fluorescence probe is loaded onto the particles at room temperature, the temperature is increased above the volume phase transition temperature of the PNIPAM shell, TVPT ≈28 °C. The collapse of the particle shell immobilizes the DNA while maintaining its availability for hybridization with a complementary strand. Förster resonance energy transfer (FRET) is used to detect the hybridization with a complementary DNA strand labeled with a FRET acceptor probe.

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