Synthesis of Temperature/pH Dual-Stimuli-Response Multicompartmental Microcapsules via Pickering Emulsion for Preprogrammable Payload Release

Abstract

Stimuli-responsive microcapsules, which can release the encapsulated payload under various environmental stimuli, have attracted great interests of the food, pharmaceutical, cosmetics, and agricultural fields in recent years. However, most reported responsive microcapsules normally have a single storage area and thus load/release only one type of payload under one stimulus. In this work, we fabricated a novel kind of multicompartmental intelligent microcapsule with two storage areas and independently controlled (preprogrammable) releasing behavior under different stimuli via rapid photopolymerization of Pickering emulsions. In our strategy, a temperature-sensitive polymeric (Nisopropyl acrylamide, pNIPAM) particle was prepared and loaded with Nile Red (NR), which was then employed as a Pickering emulsifier to stabilize oil-in-water droplets. The oil was composed of pH-responsive monomers and oil-soluble fluorescent green (OG). Upon exposure to photoirradiation, pH-responsive monomers were polymerized along the interior of the droplets and converted into microcapsules. With NR in the temperature-sensitive pNIPAM@NR particles and OG in the interior of the microcapsules, the as-prepared microcapsules possess dual-carrier capability with two payloads encapsulated dependently in two different compartments. In addition, the microcapsules could respond to two different external stimuli (temperature and pH) and realize the selective and independent release of encapsulated molecules (NR and OG) from the shell and core without any mutual interference. More importantly, the release of NR and OG can be programmed by preprogramming the order of the stimulus responses, which can be altered. Our work develops a simple and effective strategy to fabricate responsive multicompartment microcapsules with preprogrammable release of different molecules.

Smart Nanomaterials for Biomedical Applications—A Review

“…Temperature and pH stimuli-responsive microcapsules for controlled drug release applications were obtained by Chen et al [133]. Dual stimuli-responsive pNIPAM particles were obtained and loaded with oil-soluble fluorescent green (OG) and Nile red (NR).…”

Stimuli-Responsive Nanomaterials for Application in Antitumor Therapy and Drug Delivery

“…Chen et al prepared dual-stimuli-responsive microcapsules with drug loading and controlled release behaviors [ 87 ]. In their study, temperature-sensitive polymer particles (pNIPAM particles) were synthesized and loaded with Nile Red (NR) and oil-soluble fluorescent green (OG).…”

“…Therefore, the pH stimulus only triggered the release of OG molecules but did not have any influence on the NR molecules inside the particles. When the microcapsules were exposed to increasing temperatures, the NR molecules inside the particles were released because the microcapsules collapsed, but the OG molecules were unaffected [ 87 ].…”

Edible CaCO3 nanoparticles stabilized Pickering emulsion as calcium‐fortified formulation

“…Pickering emulsions, a type of emulsion stabilized by solid particles rather than molecular surfactants, have received growing attention in the food, cosmetic, and biomedical industries due to their stability, which ranges from months to years, high internal payload capacity and added functionality derived from the stabilizing particles themselves [1][2][3][4]. In the field of drug oral delivery and release, Pickering emulsions enable the delivery of cargo to sites of interest (e.g., small intestine and colon) through passive diffusion-controlled or actuated release manners [1], relying on the combination of emulsifier properties and external triggers [5,6]. When ingested, the stabilizing particles generally experience complex physicochemical changes as they are sequentially exposed to the human gastrointestinal (GI) tract, which encompasses the mouth, stomach, and small intestine [7][8][9].…”