Synthesis of High Specific Surface Area Macroporous Pectin Particles by Template-Assisted Spray Drying

Many types of porous particles containing inorganic and organic substances, such as carbon, metals, metal oxides, inorganic-organic hybrids, and polymers, have been developed. However, natural polymer-derived particles are relatively rare. To our knowledge, this report describes the first synthetic method for obtaining meso-/macroporous particles made from pectin, which is a natural polymer with a wide range of biological activities suitable for active substance support applications. These porous particles were prepared using a template-assisted spray-drying method, followed by a chemical etching process. An organic template [i.e., poly(methyl methacrylate) (PMMA)] or an inorganic template [i.e., calcium carbonate (CaCO₃)] was used to evaluate the resulting formation of macroporous structures in the pectin particles. Furthermore, the concentration of the templates in the precursor solution was varied to better understand the mechanism of porous pectin particle formation. The results showed that the final porous particles maintained the characteristic properties of pectin. The differences between the two templates resulted in two distinct types of porous particles that differed in their particle morphologies (i.e., spherical or wrinkled), particle sizes (ranging from 3 to 8 μm), pore sizes (ranging from 80 to 350 nm), and pore volume (ranging from 0.024 to 1.40 cm³ g^-1). Especially, the porous pectin particles using the CaCO₃ template have a significantly high specific surface area of 171.2 m² g^-1, which is 114 times higher than that of nonporous pectin particles. These data demonstrated the potential for using PMMA and CaCO₃ templates to control and design desired porous materials.