Hollow Particles Obtained by Prilling and Supercritical Drying as a Potential Conformable Dressing for Chronic Wounds

Abstract

The production of aerogels for different applications has been widely known, but the use of polysaccharide-based aerogels for pharmaceutical applications, specifically as drug carriers for wound healing, is being recently explored. The main focus of this work is the production and characterization of drug-loaded aerogel capsules through prilling in tandem with supercritical extraction. In particular, drug-loaded particles were produced by a recently developed inverse gelation method through prilling in a coaxial configuration. Particles were loaded with ketoprofen lysinate, which was used as a model drug. The core-shell particles manufactured by prilling were subjected to a supercritical drying process with CO₂ that led to capsules formed by a wide hollow cavity and a tunable thin aerogel layer (40 μm) made of alginate, which presented good textural properties in terms of porosity (89.9% and 95.3%) and a surface area up to 417.0 m²/g. Such properties allowed the hollow aerogel particles to absorb a high amount of wound fluid moving very quickly (less than 30 s) into a conformable hydrogel in the wound cavity, prolonging drug release (till 72 h) due to the in situ formed hydrogel that acted as a barrier to drug diffusion.

Keywords: aerogel capsules; ketoprofen lysine; prilling; supercritical drying; wound dressing.

Figure 1

FM images of core-shell microparticles obtained with different conditions: (a) non-spherical and non-homogeneous, alginate coated oily particle (Table 1: # 19,20); (b) multi-core capsule obtained by non-optimized parameters (Table 1: # 11, 12, 13); (c,d) homogeneous capsule in terms of sphericity and coaxiality (Table 1: # from 26 to 51).

Figure 2

SEM pictures of aerogels following SC-CO₂ drying (1) exhibit the following characteristics: (a) an individual bead, (b) the internal section of a bead, and (c) ketoprofen lysinate crystals within the inner region.

Figure 3

SEM images of F_1.75-10_2 (a–c) and F_1.75-20_2 (d–f) aerogels obtained after sc-CO₂ drying (2) at different magnifications: (a,d) single bead; (b,e) shell layer; (c,f) porous structure of the matrix.

Figure 4

The fluid uptake behavior of the F_1.75-20_ 2 formulation undergoes a transition from aerogel to hydrogel when it comes into contact with a single droplet of simulated wound fluid. This transition is visually depicted through photographs taken at two time intervals: 0 s and 6 s.

Figure 5

FTIR-ATR spectra of the alginate, the pure ketoprofen, and the loaded-aerogel; (a) alginate, (b) F_1.75-20_2 aerogel formulation, and (c) ketoprofen lysinate.

Figure 6

Release profiles of ketoprofen-loaded aerogel capsules with different polymer amounts and ketoprofen load: All samples, except the ketoprofen lysinate indicated by the empty circle, are the formulations (F) obtained with sc-CO₂ drying (2). In particular, 10 and 20 are the % (w/w) concentrations of ketoprofen lysinate and 1.75 and 2.25 are the % (w/v) concentrations of alginate.