Nanocapsules, i.e. core-shell nanoparticles with a liquid core, can be also electrospun. In this case, the encapsulated payload is protected by the organic or inorganic shell of the nanocapsules and by the fiber´s matrix. We have shown that this configuration is of high interest for materials for photon upconversion, i.e. the emission of light at shorter wavelength than the excitation wavelength. For nanocapsules containing upconverting dyes, the nanocapsules-in-nanofibers system was found to be more stable against oxygen than the sole nanocapsules thanks to the use of a fiber´s matrix with excellent oxygen barrier properties [8]. The fibers matrix can be additionally used to control the release of encapsulated payloads in nanocontainers [9]. This means that the release profile is then controlled by the stimuli-responsive properties of the nanocontainers and the ones of the fibers matrix [10] (Figure 2).


We are also interested in developing non-wovens for biomedical applications. We are currently applying the nanocontainers-in-nanofibers to produce unique wound dressing containing several antibacterial agents of opposite polarities. These antibacterial agents are showing a synergetic effect when encapsulated in the same construct. Such concept can be employed for combined therapy and to produce membranes for water purification.




Figure 2. Scheme showing redox-responsive silica nanocontainers embedded in pH-responsive crosslinked nanofibers (polyacrylic acid PAA). The hierarchical construct could be used to release selectively corrosion inhibitors. From reference 10.