Understanding the nanostructures of prolamin-based oral carrier to deliver functional compounds: A review

The high hydrophobicity of prolamin results in the mucoadhesive properties, enabling it suitable for oral delivery. Prolamin could self-assemble into nanospheres for a variety of hydrophobic and hydrophilic bioactive substances after the quality of solvent used to dissolve prolamin is reduced. Significant and emerging nanotechnologies tremendously contribute the preparation of prolamin-based nanomaterials with various microstructures and different characteristics, presenting the structure-activity relationship. Considering the structure-activity relationship, this review focuses on solid, hollow, solid/hollow core-shell, solid/hollow co-assembled, and layer-by-layer co-assembled/coated prolamin-based nanostructures for the encapsulation of bioactive molecules. The fabricated nanoparticles with various microstructures frequently affect the performances of prolamin-based nanoparticle. Moreover, due to the different microstructures resulted from various fabrication processes, bioactive substances with varied polarities are often entrapped into the different nanoparticle regions via polarity mediation, thus subsequently exhibiting diverse advantages and disadvantages. This review examined the nanostructures of prolamin-based particles achieved by different preparation technologies. The effects of different treatments such as acid, alkali, and heating on changing the microstructure, improving the physicochemical stability, and enhancing the biological activity of encapsulated particles are discussed, with the purpose to inspire the development of novel prolamin-based nanoparticles for improving the particle performances. By encapsulating functional compounds into the prolamin-based nanoparticles, their solubility/dissolution, gastrointestinal stability, retention in gastrointestinal tract and permeability are obviously enhanced, thereby improving oral bioavailability. Finally, trends of fabricating prolamin nanoparticles with improved performances are detailed in aid of the preparation of novel nanostructures.