Layer-by-layer concurrent encapsulation of probiotics and bioactive compounds with supplementation in intermediary layers: An establishing instrument for microbiome recharge, core safety, and targeted delivery

The human gut microbiota, especially probiotics, plays a crucial role in maintaining human health, which directed researchers to investigate various methods for recharging the gut microbiome with a sufficient number of probiotics (∼10⁶ CFU/mL). Among these methods, the layer-by-layer (LbL) encapsulation technique exhibits promising probiotic protection against harsh environmental conditions and preserving cell viability. The current review aims to examine the present state and prospects of using the LbL assembly technique for the concurrent delivery of both probiotics and bioactive compounds into the gastrointestinal system. In LbL assemblies, unigenric and polygenric wall material could be used to encapsulate a single or an aggregate of cells through direct or indirect encapsulation. It is established that during LbL assembly synthesis for encapsulation, polyelectrolytes with large molecular weights are used for layering, giving the opportunity to use these layers to carry bioactive compounds while keeping probiotics in the core. Several technologies, including extrusion, coacervation, emulsification, spray and freeze drying, and others, could be solely used or in combination to produce LbL assemblies of desired properties. The LbL assemblies can significantly reduce environmental damage to encapsulated cells and bioactive compounds and preserve their metabolic activity and function. Moreover, a wide array of compounds, such as prebiotics, omega-3 fatty acids, phytosterols, curcuminoids, carotenoids, anthocyanins, vitamins, and several other bioactive compounds of interest, could be supplemented in the layers of LbL assemblies, which are delivered to a precise location by systematic disintegration of layers in the gastrointestinal system. Therefore, the resultant LbL assemblies are excellent devices for core safety, microbiome recharge, and target delivery of probiotics and bioactive compounds simultaneously.