Seed's morphology-induced core-shell composite particles by seeded emulsion polymerization for drug delivery

Preparation of Monodisperse Poly(Methyl Methacrylate)/Polystyrene Composite Particles by Seeded Emulsion Polymerization Using a Sequential Flow Process

We develop a sequential flow process for the production of monodisperse poly (methyl methacrylate) (PMMA)/polystyrene (PS) composite particles through a soap-free emulsion polymerization of methyl methacrylate (MMA) using the first water-in-oil (W/O) slug flow and a subsequent seeded emulsion polymerization of styrene (St) using the second W/O slug flow. In this process, monodisperse PMMA seed particles are first formed in the dispersed aqueous phase of the first W/O slug flow. Subsequently, removal of the oil phase from the slug flow is achieved through a porous hydrophobic tubing, resulting in a single flow of the aqueous phase containing the seed particles. The aqueous phase is then mixed with an oil phase containing St monomer to form the second W/O slug flow. Finally, monodisperse PMMA/PS composite particles are obtained by a seeded emulsion polymerization of St using the second W/O slug flow. We compared the reaction performance between the slug flow and the batch processes in terms of particle diameter, monomer conversion, particle size distribution, and the number of particles in the system. We found that internal circulation flow within the slugs can enhance mass transfer efficiency between them during polymerization, which results in monodisperse PMMA/PS composite particles with a large particle diameter and a high monomer conversion in a short reaction time, compared to those prepared using the batch process. We believe that this sequential microflow process can be a versatile strategy to continuously produce monodisperse composite particles or core-shell particles in a short reaction time.

Phospholipid/zein hybrid nanoparticles as promising carriers for the protection and delivery of all-trans retinoic acid

A totally biodegradable mixed system made up of phospholipids and zein was developed in order to effectively improve the photostability of all-trans retinoic acid (ATRA) preserving its pharmacological properties. Photon correlation spectroscopy showed that the formulation obtained using phospholipon 85G and zein at a ratio of 7:3 w/w was characterized by an average diameter of less than 200 nm, a narrow size distribution and a significant time- and temperature-dependent stability. The use of specific cryoprotectants such as mannose and glucose favoured the long-term storage of the nanocarriers after the freeze-drying procedure. The nanoparticles increased the stability of the ATRA against photochemical degradation with respect to the free drug and its antitumor effect was preserved as a consequence of the cell uptake of the colloidal systems. The results demonstrate the potential of the proposed hybrid nanosystems to provide a high level of stabilization for sensitive and labile antitumor compounds.

Drug-zein@lipid hybrid nanoparticles: Electrospraying preparation and drug extended release application

The reasonable selection and elaborate conversion of raw materials into desired functional products represent a main topic in modern material engineering. In this study, zein (a plant protein) and lipids (extracted from egg yolk) are converted into a new type of drug-polymer@lipid hybrid nanoparticles (HNPs) via modified coaxial electrospraying. Tamoxifen citrate (TC) is used as a model anticancer drug to prepare TC-zein monolithic nanocomposites (MNCs) via traditional blended electrospraying; these MNCs are then used for comparison. Modified coaxial electrospraying is a continuous and robust process for the preparation of solid particles because of the action of unsolidifiable shell lipid solutions. HNPs have a round morphology with clear core-shell nanostructures, whereas MNCs have an indented flat morphology. Although both hold the drug in an amorphous state because of the fine compatibility of TC and zein, HNPs demonstrate a better sustained release of TC compared with MNCs in terms of retarding initial burst release (6.7 %±2.9 % vs. 37.2 %±4.3 %) and prolonged linear release period (20.47 h vs. 4.97 h for releasing 90 % of the loaded drug). Mechanisms by which the shell's lipid layer adjusts the release behavior of TC molecules are proposed. The present protocol based on coaxial electrospraying shows a new strategy of combining edible protein and lipids to fabricate advanced functional nanomaterials.