ABSTRACT
Pickering double oil-in-water-in-oil emulsions O/W/O were stabilized using solely cellulose nanocrystals (CNCs), which were modified by introducing surface brominated functions. The emulsions were formulated using only bio-friendly components, among which isopropyl myristate as oil phase, hydroxyl oligoethylene glycol methacrylate (OEGMA) as macromonomer, tetraethylene glycol diacrylate (TEGDA) as cross-linker, and CNCs as stabilizing particles. Formulation parameters could be tuned easily to modulate the fraction of inner emulsion droplets within the double emulsion drops or change the monomer(s) composition within the aqueous phase. The latter was further polymerized to synthesize matrix capsules. The obtained objects showed good resistance to the vacuum and were efficiently used as promising encapsulation vessels. Both hydrophobic and hydrophilic model dyes were encapsulated, with an encapsulation efficiency of about 90%.
Subject(s)
Cellulose/chemistry , Nanoparticles/chemistry , Acrylates/chemistry , Capsules , Coloring Agents/chemistry , Emulsions , Hydrophobic and Hydrophilic Interactions , Methacrylates/chemistry , Myristates/chemistry , Polyethylene Glycols/chemistry , PolymerizationABSTRACT
Pickering inverse emulsions of hydroxyl oligoethylene glycol methacrylate were stabilized in isopropyl myristate, a biofriendly oil, using surface-modified cellulose nanocrystals (CNCs) as stabilizing particles. The emulsions were further polymerized by free or controlled radical polymerization (ATRP), taking advantage of the bromoisobutyrate functions grafted on the CNC surface. Suspension polymerization of the emulsion led to full bead or empty capsule morphologies, depending on the initiation locus. The thickness of the CNC shell surrounding the polymerized emulsions could be tuned by modulating the aggregation state of the CNCs after their surface modification. An increase from 6 to 40 CNC layers helped improve the compression moduli of the beads from a dozen to hundreds of kPa.
Subject(s)
Cellulose , Nanoparticles , Capsules , Emulsions , PolymerizationABSTRACT
Cytotoxic drugs tend to have substantial side effects on healthy tissues leading to systemic toxicity, limited tolerated doses and reduced drug efficacy. A prominent research area focuses on encapsulating cytotoxic drugs for targeted delivery to cancer tissues. However, existing carriers suffer from low drug loading levels and high drug leaching both when circulating systemically and when accumulating in non-target organs. These challenges mean that only few encapsulation technologies for delivery of cytotoxic drugs have been adopted for clinical use. Recently, we have demonstrated efficient manufacture of impermeable metal-shell/liquid core microcapsules that permit localised delivery by triggering release with ultrasound. This method has the potential to improve on existing methods for localised drug delivery because it:We demonstrate here the further miniaturization of both the emulsion droplet template and the thickness of the surrounding metal shell to the nanoscale in an attempt to take advantage of the EPR effect and the excretion of nanoparticles by the hepatobiliary system.
