Synthesis and Characterization of Thermally Responsive Pluronic F127-Chitosan Nanocapsules for Controlled Release and Intracellular Delivery of Small Molecules

In this study, we synthesized empty care-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 similar to 37 nm at 37 degrees C and expand to similar to 240 nm when cooled to a 4 degrees C in aqueous solutions, exhibiting > 200 times change in volume Moreover, the permeability of the nanocapsule wall is high at 4 degrees C (when the nanocapsules are swollen), allowing free diffusion of small molecules (ethidium bromide, MW= 394 3 Da) across the wall, while at 37 degrees C (when the nanocapsules are swollen), the wall permeability is so how 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 nancancerous (C3H10T1/2) mammalian cells The cancerous cells were found to take up the nanocapsules much faster than the noncancerous cells dunng 45 min incubation at 37 degrees 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 degrees C and hypothermic temperatures is naturally done