Stable incorporation of gold nanorods into N-isopropylacrylamide hydrogels and their rapid shrinkage induced by near-infrared laser irradiation

Atsushi Shiotani, Takeshi Mori, Takuro Niidome, Yasuro Niidome, Yoshiki Katayama

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In this study, we prepared gold nanorod (NR)-embedded N-isopropylacrylamide (NIPAM) hydrogels and studied their volume phase transition behavior induced by near-infrared (near-IR) laser irradiation utilizing the photothermal conversion characteristics of the NRs. When poly(ethylene glycol)-modified NRs were used for the preparation of composite gels, the NRs showed marked dispersion stability in the gel. Near-IR laser irradiation of the gel (cylindrical shape, diameter = 140 μm) under the following conditions, NR concentrations in the gel ≥ 100 μM and laser irradiation power ≥490 mW, resulted in shrinkage of the gel in the following manner: (1) waist formation around the irradiation spot and (2) growth of the waist along the axial directions of the gel. The gel shrinking induced by near-IR irradiation occurred much more rapidly than that afforded by a temperature jump, because the former was not accompanied by the skin layer formation, which disturbs the rapid shrinking of the gels. When a composite gel containing the model drug (rhodamine-labeled dextran) was irradiated with a near-IR laser, the rapid release of the drug was observed. Taking advantage of the high spatial resolution of the irradiation point, we further achieved the irradiation-point-specific release of the drug from one such gel.

Original languageEnglish
Pages (from-to)4012-4018
Number of pages7
Issue number7
Publication statusPublished - Mar 27 2007


All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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