Carrier design based on zein: From the perspectives of multi-molecule encapsulation, probiotic encapsulation, and application standards

Abstract

Zein is an excellent carrier material for active substances. Previous reviews have mainly focused on the encapsulation of single active molecules, while this review is for the first time to comprehensively review the design of multi-molecules and probiotics carriers, and summarize its application standards. For multi-molecule encapsulation, zein nanoparticles with core-shell structure are widely used. Based on the difference in fabrication methods and physicochemical properties of active molecules, zein nanoparticles were categorized into mixed/isolated encapsulation. Besides, zein microparticles and Pickering emulsions (with two-compartment structures for different active molecules) stabilized by zein nanoparticles as multi-molecule delivery platforms are also discussed. For carrier design of probiotics, the methods include layer-by-layer self-assembly/complex coacervation based on zein nanoparticles, microcapsules, emulsion, and probiotic biofilm formation based on zein fibers. Importantly, zein has different criteria in the food/pharmaceutical industry, which is a prerequisite for practical application. Although zein-based multi-molecule carriers have been studied extensively, most of the current work focuses on characterizing properties instead of mechanism investigation of complex systems. In the future, designing carriers with superior structures to control the release rate of different molecules and targeted colonic delivery of probiotics are the main challenges for expanding zein applications. This review is expected to guide the rapid and scientific progress of zein-based carrier design for multi-molecules and probiotics.

Keywords: Carrier; Multi-molecules; Probiotics; Zein.

Graphical abstract

Fig. 1

Schematic diagrams of mixed multi-molecule encapsulation based on zein nanoparticles. A, Coenzyme Q10/piperine-loaded zein nanoparticles coated by K⁺ cross-linked κ-carrageenan (Chen et al., 2020d); B, pH regulates the particle size of particles with core-shell structure (Ma et al., 2023); C, Curcumin/diosmetin-loaded zein nanoparticles coated by soy protein isolate (Yu et al., 2023). SPI is soy protein isolate. NPs are nanoparticles.

Fig. 2

Schematic diagrams of multi-molecule encapsulation based on zein microparticles (A) (Tchuenbou-Magaia et al., 2022), (B) Pickering emulsion (Wei et al., 2022), and (C) emulsion gel (Yan et al., 2021). TG is transglutaminase. SA is sodium alginate.

Fig. 3

Schematic diagrams of encapsulation of probiotics based on zein nanoparticles. A, layer-by-layer assembly using zein nanoparticles and pectin (Liu et al., 2023); B, layer-by-layer assembly using chitosan and zein/tween-80/fucoidan nanoparticles (Lei et al., 2024), CHI is chitosan, LGG is Lacticaseibacillus rhamnosus GG, ZTFD is zein/tween-80/fucoidan nanoparticles; C, bilayer microencapsulation based on complex coacervation reaction of zein and chitosan (Ma et al., 2024), CS is chitosan, ZNPs are zein nanoparticles, ZCSC are zein-chitosan complex coacervates.

Fig. 4

SEM images of biofilms formed in zein nanofibrous scaffolds: (a) S. thermophilus, (b) Bifidobacterium, (c) L. paracasei, (d) S. cerevisiae N85, and (e) S. cerevisiae 321 (Hu et al., 2023). The time is culture time of probiotics.