A Mild Method for Encapsulation of Citral in Monodispersed Alginate Microcapsules

Abstract

Citral is a typical UV-irritation and acid-sensitive active and here we develop a mild method for the encapsulation of citral in calcium alginate microcapsules, in which UV irritation or acetic acid is avoided. Monodispersed oil-in-water-in-oil (O/W/O) emulsions are generated in a capillary microfluidic device as precursors. The middle aqueous phase of O/W/O emulsions contains sodium alginate, calcium-ethylenediaminetetraacetic acid (EDTA-Ca) complex as the calcium source, and D-(+)-Gluconic acid δ-lactone (GDL) as the acidifier. Hydrolysis of GDL will decrease the pH value of the middle aqueous solution, which will trigger the calcium ions released from the EDTA-Ca complex to cross-link with alginate molecules. After the gelling process, the O/W/O emulsions will convert to alginate microcapsules with a uniform structure and monodispersed size. The preparation conditions for alginate microcapsules are optimized, including the constituent concentration in the middle aqueous phase of O/W/O emulsions and the mixing manner of GDL with the alginate-contained aqueous solution. Citral-containing alginate microcapsules are successfully prepared by this mild method and the sustained-release characteristic of citral from alginate microcapsules is analyzed. Furthermore, a typical application of citral-containing alginate microcapsules to delay the oxidation of oil is also demonstrated. The mild gelling method provides us a chance to encapsulate sensitive hydrophobic actives with alginate, which takes many potential applications in pharmaceutical, food, and cosmetic areas.

pH/chitinase dual stimuli‐responsive essential oil‐delivery system based on mesoporous silica nanoparticles for control of rice blast

“…3.3 UV and storage stability of CT@HMS@CH/TA Owing to the poor photostability of CT, it is particularly important to develop pesticide formulations with UV resistance to minimize the decomposition and enhance the utilization efficiency of CT. [45][46][47][48] As shown in Figure 5(A) and Table 3, the CT decomposition rate rapidly reached 15.73% after 1 h of UV radiation treatment. Then, after 48 h, the CT decomposition rate in both CT@HMS and CT@HMS@CH/TA was less than that of CT alone, and that of CT@HMS was higher than that of CT@HMS@CH/TA, likely because CT was not encapsulated; consequently, there was more CT on the surface of HMS and the outward loss from the carrier was fast, whereas the CT protected in the carrier by the encapsulation of CH and TA was not damaged by UV light.…”

Revolutionizing targeting precision: microfluidics-enabled smart microcapsules for tailored delivery and controlled release

“…For instance, alginate microcapsules encapsulating the citral exhibited a release profile well described by the first-order model, enabling sustained release. 76 Biodegradable microcapsules with hydrophilic bioactives exhibited long-term release as the membranes degraded, fitted with a biexponential function. 244 However, owing to the complexity and susceptibility to relevant factors, no single equation is universally accepted to accurately describe release kinetics.…”

Encapsulation of Active Substances in Natural Polymer Coatings

“…Chelating agents are incorporated into the microgels to improve their functional performance. The chelating agent, ethylenediaminetetraacetic (EDTA), was used as a control agent for the formation of alginate beads under mild conditions [ 70 ]. The probiotic, Lactobacillus rhamnosus ATCC 53103, was encapsulated in a pH-responsive hydrogel based on an EDTA calcium alginate (EDTA-Ca-Alg) system.…”