Preparation and Characterization of Polymeric Nanocapsules Produced by in Situ Polymerization From Nanoemulsions Produced by Direct Emulsification

Polymeric nanoparticles constitute an important drug delivery system with controlled release profile. This article describes a new way to produce polymeric nanocapsules using a vegetable oil nanoemulsion as template. The process occurs in two steps: First, a nanoemulsion was obtained with a low-energy method based on phase inversion emulsification, using 2-ethylhexyl acrylate as lipophilic monomer. The in situ polymerization of the nanoemulsion droplets is induced by the addition of polymerization catalyzers. The mean size of the polymeric nanoparticles was evaluated by photon correlation spectroscopy and atomic force microscopy. Both techniques showed the formation of polymeric nanocapsules with a mean particle size less than 300 nm.     

Thermo- and pH-Responsiveness of Emulsions Stabilized with Acidic Thermosentive Polymers

A temperature- and pH-responsive polymeric surfactant was prepared by copolymerizing N-isopropylacrylamide, methacrylic acid, and octadecylacrylate. Poly(N-isopropylacrylamide-co-methacrylic acid-co-octadecylacrylate) (P(NIPAM-MAA-ODA) was used as an emulsifier for the preparation of water-in-oil emulsions. The mean droplet size at room temperature was almost constant for 50 hours at pH 5.0, 7.0, and 9.0. However, the size markedly increased for 50 hours at pH 3.0, possibly because of the low hydrophilicity of the copolymer and the small interfacial area one molecule of the copolymer can stabilize at a low pH value. The droplet size markedly decreased from 4.7 to 1.8 µm, when the pH of medium increased from 5.0 to 9.0 with the temperature kept constant. This may be ascribed to that the hydrophilicity of the copolymer and the interfacial area one molecule of copolymer can stabilize will be higher at a higher pH value. When the temperature increased over 35°C with the pH kept constant, the droplet size significantly increased probably because the NIPAM segment of the copolymer becomes hydrophobic with increasing the temperature so the copolymer would poorly act as an emulsifier.     

Photogeneration of Silver Nanoparticle Facilitated by Pluronic F127 Surfactant in Ethanolic Solution

In the present study, the photo-generation of silver nanoparticles in ethanolic solution and in the presence of F127 block copolymer using UV irradiation have been investigated. The aim of the present study is preparing the green, facile and much faster method than previous studies. The kinetics of silver nanoparticles formation has been investigated by using UV-vis spectroscopy. The two-dimensioanl map technique has been used to estimate the switching time between the nucleation and growth of Ag nanoparticles. The results show that the dispersed Ag nanoparticle in ethanol can be formed by high intensity ultraviolet exposure within few minutes.     

Development of Ciprofloxacin HCl-Based Solid Lipid Nanoparticles Using Ouzo Effect: An Experimental Optimization and Comparative Study

This study was performed to develop solid lipid nanoparticles of water soluble drug ciprofloxacin HCl using quick solvent diffusion evaporation technique (ouzo effect). A statistical central composite rotatable design was used to study the effect of independent variables. In the subsequent step, optimized SLN were further compared with nanostructured lipid carriers and nanoemulsion for particle size, zeta potential, drug entrapment, drug release, and stability. Comparative study revealed that the drug encapsulation efficiencies were enhanced by adding the Capmul MCM C8 into the solid lipid nanoparticles. The in vitro drug release study of all three formulations showed rapid release for nanoemulsion while controlled release for SLN. Stability study of all the formulation proved that nanostructured lipid carrier and SLN could prevent the drug expulsion during the storage period. Results of the study suggested that the SLN and nanostructured lipid carriers produced by the principle of ouzo effect could potentially be exploited for better drug entrapment efficiency and controlled drug release of water soluble actives.     

Pickering Emulsion Stabilized by Self-Assembled Micelles of Amphiphilic Random Copolymer P(St-co-DM)

Self-assembled polymeric micelles can be used as efficient particulate emulsifiers. Styrene (St) and dimethylaminoethyl methacrylate (DM) were used to synthesize the amphiphilic random copolymer P(St-co-DM). This copolymer self-assembles into spherical polymeric micelles. The polymeric micelles show surface activity and pH sensitivity for producing Pickering emulsion. The experiment shows that the stability of the emulsion increases with the micelle concentration. The emulsion can only be formed when the salt concentration is below a certain limiting value. Using the white oil as the oil phase, polymeric micelles have emulsification in a large pH range. The emulsifying performance of the polymeric micelles could be enhanced by raising the water/oil volume ratio.      

Synthesis of AA-MMA Block Copolymer by RAFT Polymerization and Used as Emulsifier cum Macroinitiator and Its Influence on the Film Properties

Blocked copolymer of acrylic acid-methyl methacrylate with controlled molecular architecture were prepared by reversible addition chain fragmentation polymerization and were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (¹H NMR), and gel permeation chromatography (GPC) for structural evaluation. The neutralized copolymers were evaluated for the critical micelle concentration (CMC), hydrophilic lipophilic balance (HLB) and were utilized as polymeric emulsifier cum macro RAFT initiator for the synthesis of acrylic binder. The structure properties of the emulsifier were evaluated correlating with the film properties.     

A Comparison Investigation of Coix Seed Oil Liposomes Prepared by Five Different Methods

The physicochemical properties of coix seed oil (CSO) liposomes prepared by five different methods were evaluated for morphology, encapsulating efficiency, particle size, storage stability, and in vitro release. The different preparation methods resulted in several types of vesicles with different properties. The type of vesicles was closely related to leakage pattern, which affected the storage stability and in vitro release profiles. Ethanol injection method was the best choice for preparing safe and stable liposomes with controlled release. The release mechanisms might account for the diffusion of CSO, and Higuchi was the most suitable model for liposomes stored at high temperature or released in simulated intestinal fluid (SIF).     

Formation of Vesicles from Amphiphilic Random Copolymers in Solution: A Dissipative Particle Dynamics Simulation Study

Five coarse-grained models were built for amphiphilic random copolymers. The self-assembly of amphiphilic random copolymers in selective solvent was investigated via dissipative particle dynamics simulations. The simulation results showed that the content of hydrophilic particles and the repulsive parameter between solvent and copolymer particles were two key factors of the vesicle formation. We report herein on how to control the self-assembled morphology evolution. The two mechanisms of vesicle formation from amphiphilic random copolymers are found through investigating the dynamic processes of vesicle formation, which is in accordance with the experiment and simulation results of amphiphilic block copolymer reported in the literature.