Use of supercritical fluid technology for the production of tailor-made aerogel particles for delivery systems

• Starch aerogel microspheres were assessed as delivery carriers for active compounds.
• Starch source and concentration and stirring rate changed final aerogel properties.
• Aerogel micronization led to faster solvent extraction by supercritical drying.
• Long supercritical drying times were detrimental to the textural properties.
• Ketoprofen release from starch aerogels correlated well with Korsmeyer–Peppas model.

Supercritical and compressed fluid technology provides a powerful tool for particle design and engineering. On the other hand, aerogels are nanoporous materials holding many world-class properties. However, the morphology of the end product can be the limiting factor for aerogels in some applications. The integration of different technologies for the production of particles can lead to a breakthrough in aerogel production. In this work, the combination of the emulsion–gelation process with supercritical fluid extraction was tested as a versatile technology for the production of microspherical aerogel particles. Novel natural product-based nanoporous materials (aerogels) based on starch were obtained using this method and were specifically targeted to chemical carriers for life science applications (e.g. pharmaceutics, tissue engineering, cosmetics, food, biotechnology, and agriculture). Aerogels in the form of cylinders and microspheres (400–800 μm) with the intrinsic outstanding textural aerogel properties (high surface area – Sa = 100–240 m2/g, low density – ρ = 0.10–0.25 g/cm3, large porosity – ɛ = 85–90%) were produced. The effect of micronization on the kinetics of the supercritical drying of the wet gel (in ethanol) was also studied. Thus the obtained aerogels were then tested for their use as active agent carriers regarding loading capacity using ketoprofen as model compound as well as the release behavior of the loaded active compound in aqueous media simulating physiological pHs.

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