Microscale Delivery Systems for Hydrophilic Active Ingredients in Functional Consumer Goods

Abstract

Hydrophilic active ingredients play a crucial role in formulated consumer products, encompassing antioxidants, flavoring substances, and pharmaceuticals. Yet, their susceptibility to environmental factors, such as light, pH, temperature, and humidity, poses challenges to their stability and sustained release. Microencapsulation offers a promising avenue to address these challenges, facilitating stabilization, targeted delivery, and enhanced efficacy of hydrophilic actives. However, despite significant advancements in the field, microencapsulation of hydrophilic actives remains at the forefront of innovation. This is primarily due to the intrinsic characteristics of hydrophilic actives, including small molecular weight and thus high permeability through many microcarriers (e.g., shells), which often necessitate complex and costly technologies to be developed. Moreover, in light of escalating regulatory frameworks, the pursuit of biodegradable and other compliant materials suitable for the entrapment of hydrophilic ingredients is gaining momentum. These advancements aim to provide alternatives to currently used non-degradable synthetic polymer materials. Research is currently pushing towards meeting these regulatory constraints via cutting-edge technologies to engineer novel microscale delivery systems for hydrophilic active ingredients, including microcapsules, microspheres, microneedles, and micropatches. Although still in its infancy, this approach holds true potential for revolutionizing the future of formulated consumer goods.

Keywords: drug delivery; hydrophilic active ingredients; microcapsules; micromanipulation; microneedles; micropatches; microspheres; microsponges.

FIGURE 1

Schematic of the process for co‐encapsulating ascorbic acid (Vc) and GX‐50 (xanthoxylin) via double emulsification and complex coacervation of gum Arabic (GA) and carboxymethyl cellulose (NaCMC). Reproduced with permission from Wang et al. (2023). Copyright 2023 American Chemical Society.

FIGURE 2

(A) Schematic of the fabrication and study of vitamin B12 microcapsules via spray‐chilling. Reprinted from Chalella Mazzocato et al. (2019); (B) Fabrication scheme of the MF1‐OTS‐MF microcapsules via two in situ polymerization steps and one dropwise coating step. The insets display: (B1) MF1; (B2) MF1‐OTS; (B3) MF1‐OTS‐MF2 microcapsules Sui et al. (2021). Both reprinted with permission. Elsevier copyright (2019 and 2020).

FIGURE 3

(A) Schematic of W/O Pickering emulsion templated enzyme encapsulation process and mechanisms utilizing zein/casein and polydiisocyanate (PHDI); (B) structure of crosslinker, PHDI; (C) crosslinking mechanism between functional groups in protein and isocyanate groups in PHDI; (D) CSLM image; (E) enzyme activity. Reprinted with permission from Liu et al. (2023). Elsevier copyright (2023).

FIGURE 4

Illustration depicting the mechanisms of five distinct types of microneedles utilized for drug transdermal delivery: (A) Solid microneedles, (B) Coated microneedles, (C) Dissolvable microneedles, (D) Hollow microneedles, and (E) Hydrogel‐forming microneedles. Reprinted with permission from Larrañeta et al. (2016), CC BY 4.0.

FIGURE 5

SEM images of clindamycin‐loaded microsponge (A) C5 formulation, 500×, (B) C5 formulation, 3000×, (C) C6 formulation, 500×, (D) C6 formulation, 3000×. Reprinted with permission from Khattab and Nattouf (2021), CC BY 4.0.