FIG. 4.

Supercritical ${\mathrm{CO}}_2$-assisted nanoparticle synthesis in microfluidics. (a) Supercritical ${\mathrm{CO}}_2$ enhances the mixing of ${\mathrm{H}}_2$ and toluene, thereby promoting nanocrystal formation; the schematic is adapted from Ref. 49. Reproduced with permission from Gendrineau et al., Angew. Chem. 124, 8653–8656 (2012). Copyright 2012 John Wiley and Sons. (b) Palladium nanocrystal synthesis assisted by sc ${\mathrm{CO}}_2$ in microfluidics as catalysts. The surface of palladium nanocrystals was functioned by different ligands.⁴⁹ Reproduced with permission from Gendrineau et al., Angew. Chem. 124, 8653–8656 (2012). Copyright 2012 John Wiley and Sons. (c) Schematic illustration of nanoparticle formation in co-axial flow microfluidics, where supercritical ${\mathrm{CO}}_2$ extracts the solvent and nanoparticles precipitate. (d) Sc ${\mathrm{CO}}_2$ assisted synthesis of poly(3-hexylthiophene) nanoparticles in microfluidics for OFET applications.⁵⁰ Reproduced with permission from Couto et al., Chem. Commun. 51, 1008–1011 (2015). Copyright 2015 Royal Society of Chemistry. (e) Nucleation and growth of organic nanoparticles synthesized with sc ${\mathrm{CO}}_2$ in microfluidics.⁸⁰ Reproduced with permission from Jaouhari et al., Chem. Eng. J. 397, 125333 (2020). Copyright 2020 Elsevier. (f) The process of supercritical fluid extraction of emulsion (SFEE) to fabricate polymeric nanoparticles of solid lipid nanoparticles for drug delivery applications. (g) Ibuprofen-loaded nanosuspension functioned by chitosan produced using sc ${\mathrm{CO}}_2$ in microfluidics.⁵² Reproduced with permission from Murakami and Shimoyama, J. Supercrit. Fluids 128, 121–127 (2017). Copyright 2017 Elsevier. (h) Solid lipid nanoparticles of stearic acid generated in microfluidic flow using sc ${\mathrm{CO}}_2$.⁸¹ Reproduced with permission from Wijakmatee et al., Ind. Eng. Chem. Res. 61, 9274–9282 (2022). Copyright 2022 American Chemical Society. (i) Synthesis of liposomes in microfluidics using supercritical ${\mathrm{CO}}_2$. (j) TEM images of liposomes produced using sc ${\mathrm{CO}}_2$ in a LipTube micro-mixing device.⁵⁴ Reproduced with permission from Murakami et al., Ind. Eng. Chem. Res. 61, 14598–14608 (2022). Copyright 2022 American Chemical Society.