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A detailed study of the production of polysaccharide aerogel (bio-aerogel) particles from lab to pilot scale is surveyed in this article. An introduction to various droplets techniques available in the market is given and compared with the lab scale production of droplets using pipettes and syringes. An overview of the mechanisms of gelation of polysaccharide solutions together with non-solvent induced phase separation option is then discussed in the view of making wet particles. The main steps of particle recovery and solvent exchange are briefly described in order to pass through the final drying process. Various drying processes are overviewed and the importance of supercritical drying is highlighted. In addition, we present the characterization techniques to analyse the morphology and properties of the aerogels. The case studies of bio-aerogel (agar, alginate, cellulose, chitin, κ-carrageenan, pectin and starch) particles are reviewed. Potential applications of polysaccharide aerogel particles are briefly given. Finally, the conclusions summarize the prospects of the potential scale-up methods for producing bio-aerogel particles.

Polysaccharide-based aerogels in the form of microspheres were investigated as carriers of poorly water soluble drugs for oral administration. These bio-based carriers may combine the biocompatibility of polysaccharides and the enhanced drug loading capacity of dry aerogels. Aerogel microspheres from starch, pectin and alginate were loaded with ketoprofen (anti-inflammatory drug) and benzoic acid (used in the management of urea cycle disorders) via supercritical CO2-assisted adsorption. Amount of drug loaded depended on the aerogel matrix structure and composition and reached values up to 1.0×10-3 and 1.7×10-3 g/m2 for ketoprofen and benzoic acid in starch microspheres. After impregnation, drugs were in the amorphous state in the aerogel microspheres. Release behavior was evaluated in different pH media (pH 1.2 and 6.8). Controlled drug release from pectin and alginate aerogel microspheres fitted Gallagher-Corrigan release model (R2>0.99 in both cases), with different relative contribution of erosion and diffusion mechanisms depending on the matrix composition. Release from starch aerogel microspheres was driven by dissolution, fitting the first-order kinetics due to the rigid starch aerogel structure, and showed different release rate constant (k1) depending on the drug (0.075 and 0.160 min-1 for ketoprofen and benzoic acid, respectively). Overall, the results point out the possibilities of tuning drug loading and release by carefully choosing the polysaccharide used to prepare the aerogels. HIGHLIGHTS-Polysaccharide aerogel microspheres are investigated as carriers of drugs for oral administration -Aerogels were loaded with ketoprofen and benzoic acid, poorly water soluble model drugs -Starch, with the lowest specific surface area, was more prone to adsorb drug molecules -Release of ketoprofen from alginate and pectin aerogel particles was sensitive to pH of the medium -Results point out the possibilities of polysaccharide aerogels of tuning drug loading and release Polysaccharide-based aerogels in the form of microspheres were investigated as carriers of poorly 19 water soluble drugs for oral administration. These bio-based carriers may combine the 20 biocompatibility of polysaccharides and the enhanced drug loading capacity of dry aerogels. Aerogel 21 microspheres from starch, pectin and alginate were loaded with ketoprofen (anti-inflammatory drug) 22and benzoic acid (used in the management of urea cycle disorders) via supercritical CO 2 -assisted 23 adsorption. Amount of drug loaded depended on the aerogel matrix structure and composition and 24 reached values up to 1.0×10 -3 and 1.7×10 -3 g/m 2 for ketoprofen and benzoic acid in starch 25 microspheres. After impregnation, drugs were in the amorphous state in the aerogel microspheres. 26Release behavior was evaluated in different pH media (pH 1.2 and 6.8). Controlled drug release from 27 pectin and alginate aerogel microspheres fitted Gallagher-Corrigan release model (R 2 >0.99 in both 28 cases), with different relative contribution of erosion and...

a b s t r a c tThis paper presents a novel approach toward the production of hybrid alginate-lignin aerogels. The key idea of the approach is to employ pressurized carbon dioxide for gelation. Exposure of alginate and lignin aqueous alkali solution containing calcium carbonate to CO 2 at 4.5 MPa resulted in a hydrogel formation. Various lignin and CaCO 3 concentrations were studied. Stable hydrogels could be formed up to 2:1 (w/w) alginate-to-lignin ratio (1.5 wt% overall biopolymer concentration). Upon substitution of water with ethanol, gels were dried in supercritical CO 2 to produce aerogels. Aerogels with bulk density in the range 0.03-0.07 g/cm 3 , surface area up to 564 m 2 /g and pore volume up to 7.2 cm 3 /g were obtained. To introduce macroporosity, the CO 2 induced gelation was supplemented with rapid depressurization (foaming process). Macroporosity up to 31.3 ± 1.9% with interconnectivity up to 33.2 ± 8.3% could be achieved at depressurization rate of 3 MPa/min as assessed by micro-CT. Young's modulus of alginate-lignin aerogels was measured in both dry and wet states. Cell studies revealed that alginate-lignin aerogels are non-cytotoxic and feature good cell adhesion making them attractive candidates for a wide range of applications including tissue engineering and regenerative medicine.