Diffraction observation of responsive properties of hydrogel nanopillars

Federica Pirani, Nityanand Sharma, A. Cencerrado, Stefan Fossati, Christian Petri, Ulrich Jonas, Emiliano Descrovi, Jose Luis Toca-Herrera, Jakub Dostalek

    Research output: Contribution to journalArticlepeer-review


    Optical diffraction measurements are reported for in situ observation of swelling and collapsing of responsive hydrogel nanostructures. The optical signal is enhanced by probing the surface carrying periodic arrays of hydrogel nanostructures by resonantly excited optical waveguide modes. UV-nanoimprint lithography is employed for the preparation of the arrays of nanopillars from photo-crosslinked N-isopropylacrylamide (pNIPAAm)-based hydrogel that are covalently tethered to a gold surface. The thermo-responsive properties of such pNIPAAm nanopillars that swell in 3D are compared to those of a thin film prepared from the identical material and that is allowed to swell predominantly in 1D. The nanopillars with a diameter of ≈100 nm and aspect ratio of 2 swell by a factor of ≈6 as determined by optical measurements supported by simulations that are compared to morphological characteristics obtained from atomic force microscopy. Bending of nanopillars above the lower critical solution temperature (LCST), erasure of the topographic structure by drying at temperature below the LCST, and recovery by subsequent swelling below the LCST and drying at temperature above the LCST are observed.
    Original languageEnglish
    Pages (from-to)1600400
    Number of pages1
    JournalMacromolecular Chemistry and Physics
    Issue number218
    Publication statusPublished - 2017

    Research Field

    • Biosensor Technologies


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