Temperature-controlled uptake and release in PNIPAM-modified porous silica nanoparticles

Ye Zi You, Kennedy K. Kalebaila, Stephanie L. Brock, David Oupický

Research output: Contribution to journalArticlepeer-review

339 Scopus citations


Temperature-dependent uptake and release of small molecules within porous silica nanoparticles has been achieved by treatment of preformed, thiol-functionalized micro-to-mesoporous silica nanoparticles (MSN) with pyridyl disulfide-terminated poly(N-isopropylacrylamide) (PNIPAM-S-S-Py). The resulting nanoparticle - polymer composites show uptake and release of fluorescein at room temperature (below the lower critical solution temperature, LCST, of the polymer) and a low level of leakage at 38 °C (above LCST, <2% after 2 h). The data are consistent with a mode of action in which fluorescein diffusion occurs readily when the polymer is in the random coil conformation but is significantly retarded when the polymer adopts the globule conformation. This mode of action is opposite to that observed for systems in which the PNIPAM is grown from the porous silica surface or co-condensed with silica and is accompanied by a greater than 10improvement in fluorescein retention in the "pore-closed" conformation.

Original languageEnglish (US)
Pages (from-to)3354-3359
Number of pages6
JournalChemistry of Materials
Issue number10
StatePublished - May 27 2008
Externally publishedYes

ASJC Scopus subject areas

  • General Chemistry
  • General Chemical Engineering
  • Materials Chemistry


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