Electrospray-assisted encapsulation of caffeine in alginate microhydrogels

Abstract

One of the major challenges with microencapsulation and delivery of low molecular weight bioactive compounds is their diffusional loss during storage and process conditions as well as under gastric conditions. In an attempt to slow down the release rate of core material, electrospray fabricated calcium alginate microhydrogels were coated with low molecular weight and high molecular weight chitosans. Caffeine as a hydrophilic model compound was used due to its several advantages on human behavior especially increasing consciousness. Mathematical modeling of the caffeine release by fitting the data with Korsmeyer-Peppas model showed that Fick's diffusion law could be the prevalent mechanism of the release. Electrostatic interaction between alginate and chitosan (particularly in the presence of 1% low molecular weight chitosan) provided an effective barrier against caffeine release and significantly reduced swelling of particles compared to control samples. The results of this study demonstrated that calcium alginate microhydrogels coated by chitosan could be used for encapsulation of low molecular compounds. However, more complementary research must be done in this field. In addition, electrospray, by producing monodisperse particles, would be as an alternative method for fabrication of microparticles based on natural polymers.

Fabrication of Polymeric Microparticles by Electrospray: The Impact of Experimental Parameters

“…In the ES process, there are several ways of collecting the MPs, such as on stainless steel plates [34], stainless steel plates coated with an aluminum foil [28], aluminum foils [40], an aluminum plate [63], beakers or Petri dishes containing different solvent such as MeOH or EtOH [39], Polysorbat 80 surfactant (Tween 80) [39], phosphate buffer or citrate buffer [35], solutions containing 2% (w/v) CaCl 2 , etc. [64]. In this context, Faramarzi et al investigated the production of MPs of PLGA in different collection baths [39].…”

Use of Plant Proteins as Microencapsulating Agents of Bioactive Compounds Extracted from Annatto Seeds (Bixa orellana L.)

“…The gelation phenomenon is triggered when calcium ions react with the free carboxyl moieties present in the alginate structure by ion crosslinking, forming hydrogels, and thus trapping the bioactive substances [7,9]. The extrusion method mostly produces capsules with diameters of several mm dominantly controlled by rheological properties of the polymer solution and the extrusion system tip diameter [10,11]. To fabricate capsules by ionic gelation in a more controllable manner, techniques such as the electrospraying (electrohydrodynamic atomization) method have gained great attention, but traditional extrusion techniques continue to be used to assess the gelation capacity of different coating materials.…”

Glucose oxidase release of stressed chia mucilage‐sodium alginate capsules prepared by electrospraying

“…These results also indicate that the structure of capsules must be different depending on the production method. In this regard, Nikoo et al (2018) reported for capsules prepared by EM that the electrostatic interaction between wall materials provides an effective barrier against, in this case, the release of caffeine, along with a decrement of the swelling of particles. In another study, the swelling behavior has been related to pH, solubilization, and degradation of wall materials (Bajpai & Sharma, 2004;Xie et al, 2016), where at higher pH a larger effect was observed, as a result of diffusion of calcium ions, which would lead to higher liberation of the capsule enclosed materials.…”

“…It is biocompatible, biodegradable, and hydrophilic (Dima et al., 2016) and has been used in the encapsulation of several enzymes (tyrosinase, urease). However, its network structure has open pores (Nikoo et al., 2018), which leads to an inefficient retention of smaller molecular compounds (Hao et al., 2020), including enzymes, and a rapid initial release in aqueous environments. Therefore, to control or delay the release rate, it is necessary to strengthen its structure using secondary biopolymers, thus emerging the need to combine it with other biopolymers.…”