Synthesis and characterization of thermally responsive pluronic F127-chitosan nanocapsules for controlled release and intracellular delivery of small molecules

Wujie Zhang, Kyle Gilstrap, Laying Wu, K. C. Remant Bahadur, Melissa A. Moss, Qian Wang, Xiongbin Lu, Xiaoming He

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In this study, we synthesized empty core-shell structured nanocapsules of Pluronic F127 and chitosan and characterized the thermal responsiveness of the nanocapsules in size and wall-permeability. Moreover, we determined the feasibility of using the nanocapsules to encapsulate small molecules for temperature-controlled release and intracellular delivery. The nanocapsules are ∼37 nm at 37 °C and expand to ∼240 nm when cooled to 4 °C in aqueous solutions, exhibiting >200 times change in volume. Moreover, the permeability of the nanocapsule wall is high at 4 °C (when the nanocapsules are swollen), allowing free diffusion of small molecules (ethidium bromide, MW = 394.3 Da) across the wall, while at 37 °C (when the nanocapsules are swollen), the wall-permeability is so low that the small molecules can be effectively withheld in the nanocapsule for hours. As a result of their thermal responsiveness in size and wall-permeability, the nanocapsules are capable of encapsulating the small molecules for temperature-controlled release and intracellular delivery into the cytosol of both cancerous (MCF-7) and noncancerous (C3H10T1/2) mammalian cells. The cancerous cells were found to take up the nanocapsules much faster than the noncancerous cells during 45 min incubation at 37 °C. Moreover, toxicity of the nanocapsules as a delivery vehicle was found to be negligible. The Pluronic F127-chitosan nanocapsules should be very useful for encapsulating small therapeutic agents to treat diseases particularly when it is combined with cryotherapy where the process of cooling and heating between 37 °C and hypothermic temperatures is naturally done.

Original languageEnglish
Pages (from-to)6747-6759
Number of pages13
JournalACS Nano
Issue number11
StatePublished - 23 Nov 2010



  • Chitosan
  • Controlled release
  • Intracellular delivery
  • Nanocapsule
  • Pluronic F127
  • Thermal responsiveness
  • Wall-permeability

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