Perfluorodecalin nanocapsule as an oxygen carrier and contrast agent for ultrasound imaging
The preparation of a perfluorodecalin (PFD) encapsulated silica nanocapsules via a one-pot synthesis method using Pluronic F68 (PF68) stabilised PFD in water nanoemulsion as a template is demonstrated herein. The method described here simplifies previous multi-step procedures that required pre-fabrication of silica hollow spheres and post-loading of the perfluorocarbon. The size of the PFD nanoemulsion template can be varied easily by changing the concentration of PF68. Successful incorporation of PFD (78% wt) into the silica nanocapsule core and the mechanical stability of the structure were evident from 19F nuclear magnetic resonance analysis; these properties were conferred by the silica-PF68 surface structure. This significant improvement in PFD encapsulation results in higher oxygen carrying capacity compared to encapsulation without PFD as observed from oxygen solubility measurements. The nanocapsules did not show cytotoxicity against HepG2 and 3T3 cells after 24 h exposure at a concentration below 0.8 g L−1 and 0.08 g L−1, respectively. Ultrasound imaging of silica nanocapsules in agarose gel showed a greater than two-fold increment in echogenicity as compared to the PFD nanoemulsion at a similar concentration.