Biocompatible Emulsions Research Articles

Novel Pickering emulsion gels stabilized solely by phenylalanine amidated pectin: Characterization, stability and curcumin bioaccessibility

Pickering emulsion gels represent a novel class of non-toxic and biocompatible emulsions, offering extensive applications in the pharmaceutical and food additive sectors. This study delineates the synthesis of Pickering emulsion gels utilizing native and amidated pectin samples. Phenylalanine amidated pectin (AP) was procured via an ultra-low temperature enzyme method, while the control group (LP) adhered to an identical procedure without papain catalysis. Experimental outcomes revealed that the AP Pickering emulsion gel manifested superior stability compared to pectin emulsion samples (PE and LP). The Pickering emulsion gel from 5 % amidated pectin (5AP) retained stability throughout a 14-day emulsion stability assessment. Furthermore, all emulsion samples were evaluated for their capacity to deliver and sustain curcumin within an in vitro digestion simulation. Rheological properties and oil droplet size results indicated that the 5AP Pickering emulsion gel exhibited optimal cream index and emulsion stability, effectively inhibiting premature water-oil stratification within the emulsion and augmenting curcumin bioaccessibility. Within the in vitro digestion simulation, the 5AP Pickering emulsion gel demonstrated the highest curcumin bioaccessibility, measured at 17.96 %.

Amphiphilic O(Phe-r-Glu) oligopeptides randomly polymerized via papain exhibiting a pH-insensitive emulsification property

Natural amino acid polymers have been wide-used as bio-compatible emulsion stabilizers. In this study, Amphiphilic O(Phe-r-Glu)s were synthesized through the papain-catalyzed random polymerization of L-phenylalanine and L-glutamate with the major degree of polymerization value of 6–7. The polymerization yield was increased by more than 35 % using choline to reduce the energy barrier for the amino substrates to form the tetrahedral intermediate with the catalytic triad. The squalene/water emulsions stabilized by O(Phe-r-Glu) nanoparticles were pH-insensitive at pH 1–12. The investigation of mechanism found the combined effects of steric hindrance, electrostatic repulsion and the viscosity of the emulsion contributed to the stability of the emulsion droplets. Under acidic condition, the layers of O(Pho-r-Glu)s particle aggregates formed around the emulsion droplets and the higher viscosity of emulsion mainly contributed to the stability of emulsions. At basic condition, the strong electrostatic repulsion between emulsion droplets covered by the negatively charged O(Pho-r-Glu) particles and the steric hindrance contributed mainly to the prevention of the coalescence of emulsion droplets. The application of enzymatically synthesized amphiphilic peptides in emulsion, along with tunable performance through the polymerization of amino substrates, is in line with the sustainable development requirements in fields such as pharmaceuticals, food and cosmetics.

Formulation of Silk Fibroin Nanobrush-Stabilized Biocompatible Pickering Emulsions.

Silk fibroin is widely believed to be sustainable, biocompatible, and biodegradable, providing promising features such as carriers to deliver drugs and functional ingredients in food, personal care, and biomedical areas, which are consistent with emulsion characteristics; especially, green, all-natural biopolymer-based stabilizers are in great demand to stabilize Pickering emulsions and match the multifunctional needs for developing ideal materials. Herein, an unprecedented three-dimensional (3D) nanostructure, namely a brush-like silk nanobrush (SNB), is applied as the stabilizer to formulate and stabilize Pickering emulsions. The size and interfacial tension are compared among the SNB, a regenerated silk nanofiber, and a nanowhisker. Additionally, optimization processes are conducted to determine the ideal ultrasonication intensity and SNB concentration required to prepare Pickering emulsions by analyzing the morphology, creaming index, mean oil droplet size, and rheological behavior. The results indicate that an SNB with the characteristic structure and suitable size shows superior potential to form sophisticated and interconnected networks in oil-water interfaces, and is proved to be able to resist creaming at a wide range of concentrations and subsequently stabilize Pickering emulsions from liquid-like emulsions to gel-like emulsions. Additionally, SNB is proved to be biocompatible according to cell experiments, providing a promising alternative in designing all-natural, green, and biocompatible emulsions with the aim of efficiently delivering nutrients or drugs associated with health benefits.

Preparation, characterization and in vitro digestive behaviors of emulsions synergistically stabilized by γ-cyclodextrin/sodium caseinate/alginate

Developing natural, safe, and biocompatible emulsion stabilizers for highly stable emulsions remains a difficult challenge. In this study, stable nano-scale emulsions were prepared using γ-cyclodextrin (γ-CD), sodium caseinate (SC), and alginate (Alg) as emulsifiers. The synergistic stabilization of γ-CD/SC/Alg enabled the emulsions to remain stable even under high-acidic (pH 3.0), high-alkaline (pH 11.0) and high temperature (90 °C) conditions. The improved stability at acidic conditions was attributed to the positive impact of Alg. Additionally, the rheological measurements showed that the emulsions exhibited elastic gel networks and a more stable emulsion structure was formed with the increasing addition of γ-CD. Finally, the gastrointestinal behavior of the emulsions was studied using a standardized INFOGEST method. Results showed that most of the oil were digested and absorbed in the small intestine, and the bioaccessibility of curcumin was high. This work provided a new solution to prepare stable emulsions which could be used as dairy products or desirable food delivery systems for hydrophobic bioactive agents.

Pickering emulsion as template for porous bioceramics in the perspective of bone regeneration

Calcium phosphate (CaP) based bioceramics are widely used as bone substitutes. The most encountered CaP ceramics are obtained from high temperature phases. However, their bioactivity and their association with biomolecules are limited, as well as their bioresorption in-vivo. The aim of this work is to develop biomimetic low temperature apatites ceramics with tunable porosity via biocompatible high internal phase Pickering emulsions. The biocompatible emulsions developed were stabilized by stoichiometric hydroxyapatite (HA) particles. Several parameters (mass of HA particles, oil/water weight ratio, electrolytes concentration in the aqueous phase) were investigated to define the optimized formulation conditions leading to a kinetically stable monodisperse emulsion with a minimum drop diameter of 200 µm and drops enough percolated to induce interconnected porosity. Two types of porous bioceramics were produced by low temperature processes with controlled composition and porosity, evidenced by X-ray microtomography: calcium phosphate monoliths from an apatitic gel, and silica-HA monoliths via a sol-gel process. These low temperature processes should provide bioceramics able to perform bioactivity and bio-resorption in-vivo, and could prefigure a drug or other therapeutic ions-delivery disposals for filling bone defects in maxillofacial or orthopedic surgery.

Microfluidic Generation of All-Aqueous Double and Triple Emulsions.

Higher order emulsions are used in a variety of different applications in biomedicine, biological studies, cosmetics, and the food industry. Conventional droplet generation platforms for making higher order emulsions use organic solvents as the continuous phase, which is not biocompatible and as a result, further washing steps are required to remove the toxic continuous phase. Recently, droplet generation based on aqueous two-phase systems (ATPS) has emerged in the field of droplet microfluidics due to their intrinsic biocompatibility. Here, a platform to generate all-aqueous double and triple emulsions by introducing pressure-driven flows inside a microfluidic hybrid device is presented. This system uses a conventional microfluidic flow-focusing geometry coupled with a coaxial microneedle and a glass capillary embedded in flow-focusing junctions. The configuration of the hybrid device enables the focusing of two coaxial two-phase streams, which helps to avoid commonly observed channel-wetting problems. It is shown that this approach achieves the fabrication of higher-order emulsions in a poly(dimethylsiloxane)-based microfluidic device, and controls the structure of the all-aqueous emulsions. This hybrid microfluidic approach allows for facile higher-order biocompatible emulsion formation, and it is anticipated that this platform will find utility for generating biocompatible materials for various biotechnological applications.

Montmorillonite and alginate co-stabilized biocompatible Pickering emulsions with multiple-stimulus tunable rheology

A biocompatible oil-in-water emulsion containing no surfactant or other organic modifier was prepared using two negatively charged, naturally derived materials: alginate and montmorillonite (MMT), and it was found that the stable emulsion has good storage stability and coalescence stability. The dispersing and suspending effects of alginate to MMT were observed, and the interaction between alginate and MMT was confirmed by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and Zeta potential. The distribution of particles at the oil-water interface and in the aqueous phase of the emulsion was observed by confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM). A unique mechanism of the stable Pickering emulsion was then proposed. It is demonstrated that alginate not only thicken the continuous phase, create a gel-like environment around the droplets, but also could modify the MMT surface, synergistically enhance the electrostatic force of droplets due to the same charge property with MMT. Moreover, the rheological properties of the emulsion co-stabilized by MMT/Alginate can be well adjusted using various stimuli including pH and salt. In general, this work presents a highly stable, tunable and biocompatible emulsion for potential applications in food and cosmetic products.

Preparation of biodegradable and biocompatible emulsion templated scaffolds for tissue engineering by thiol-acrylate polymerization of polycaprolactone macromers

Preparation of biodegradable and biocompatible emulsion templated scaffolds for tissue engineering by thiol-acrylate polymerization of polycaprolactone macromers

Stable emulsions prepared by self-assembly of hyaluronic acid and chitosan for papain loading.

A simple, green and effective process is developed to fabricate hyaluronic acid (HA)/chitosan (CS) complex colloidal particles through electrostatic interactions. The obtained complexes can be used as biocompatible emulsifiers and novel potential carriers for papain loading. An HA/CS mass ratio of 2 is the optimal condition leading to the smallest Dh (420.9 nm). The complexes with eight different mass ratios are used to stabilize white oil/water emulsions. The structure of the complexes at the oil-water interface varies in response to the mass ratio and can be classified into two typical structures, similar to typical polymeric surfactants and solid particulate emulsifiers. Furthermore, papain is introduced into the complex systems. Formation of the papain/HA/CS complexes in a compact form can protect the enzyme. Here, a novel strategy is introduced to fabricate a biocompatible emulsion from the HA/CS complexes and demonstrate that the stable complex is a suitable enzyme delivery system.

Fully biodegradable and biocompatible emulsion templated polymer scaffolds by thiol-acrylate polymerization of polycaprolactone macromonomers

Polycaprolactone triacrylate is used to make fully biodegradable and biocompatible tissue engineering scaffolds by emulsion templating and thiol-acrylate photopolymerisation.

PEG 400/Paraffin oil non‐aqueous emulsions stabilized by PBut‐Block‐P2VP block copolymers

ABSTRACTFor the preparation of PEG 400 in paraffin oil non‐aqueous biocompatible emulsions, the stabilization efficiency was compared for two well‐defined poly(butadiene)‐block‐poly(2‐vinylpyridine) (PBut‐block‐P2VP) block copolymers, with similar molecular weights but different compositions. The PBut128‐block‐P2VP50 and PBut189‐block‐P2VP37 samples, designated as copolymer A and B, respectively, are self‐organized in paraffin oil as micelles with a P2VP core and a PBut corona. The PEG 400/paraffin oil emulsion characteristics were determined as a function of the copolymers concentrations and phase ratios. Higher static and shear stabilities were obtained for emulsions stabilized by copolymer B than for those obtained in the presence of copolymer A. A further difference concerns the droplet size, relative viscosity, and loss modulus values obtained at a given dispersed phase volume fraction. At constant copolymer concentrations, it appeared that copolymer B, with a longer PBut sequence, is a more efficient emulsifier and stabilizer than copolymer A. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41390.

Stabilization of non-aqueous emulsions by poly(2-vinylpyridine)-b-poly(butadiene) block copolymers

Non-aqueous sub-micron biocompatible emulsions, which are of interest for biomedical and cosmetic formulations, were developed for the system polyethylene glycol (PEG 400) dispersed in a typical liquid glycerine ester (Miglyol 812). These emulsions were stabilized by poly(2-vinylpyridine)-b-poly(butadiene) (P2VP-b-PBut) copolymers, each of these sequences being well adapted to the solubility parameters of the two liquid phases. A comparative study of the emulsifying and stabilization efficiency was performed for two copolymers with quasi-identical molecular weights but of different compositions, such as P2VP50-b-PBut128 (A) and P2VP37-b-PBut189 (B). These block copolymers form in Miglyol 812 star-like micelles having a P2VP core and a PBut corona. The PEG 400/Miglyol 812 emulsion characteristics were determined as a function of the dispersed phase volume fractions and of the copolymer concentrations. At constant concentrations, copolymer B, with longer Miglyol 812 soluble PBut chains, appeared to be more efficient as emulsifier and stabilizer than copolymer A. By combination of the two block copolymer, a synergetic emulsifying and stabilizing effect could be achieved.

Application of 19F magnetic resonance to study the efficacy of fluorine labeled drugs in the three-dimensional cultured breast cancer cells

The cellular monitoring of tumor response to treatments is important for drug discovery and drug development in cancer therapy. We studied efficacy of Herceptin, a common breast cancer drug conjugated with a fluorine organic compound, perfluoro-15-crown-5-ether (PFCE) which easily forms biocompatible emulsions. Three new pharmaceutical forms of Herceptin, Herceptin/PFCE, Herceptin/PFCE/Lipoplex and Herceptin/PFCE/HydraLink were synthesized for the ex vivo study of their efficacy in breast cancer treatment. The emulsions were administered to 10(9)cells mL(-1) of HER-2 positive human adenocarcinoma (MCF-7) cells and the same amount of human mammary epithelial cells (HMEC) cultured in three-dimensional (3D) geometry using hollow fiber bioreactor (HFB) device. Following drugs administration ex vivo, fluorine-19 magnetic resonance imaging ((19)F MRI) was applied for cells imaging to measure their viability and to study drug efficacy over 72h. To ensure optimum drug tracking, HydraLink was used to provide stable binding affinity of emulsified Herceptin to receptor while cationic lipid (Lipofectamine) was used to enhance lipophilicity of the emulsions. After 72h of treatment with Herceptin, Herceptin/PFCE, Herceptin/PFCE/Lipoplex and Herceptin/PFCE/HydraLink the viability of cells was 54+/-2%, 49+/-3%, 43+/-5% and 42+/-1%, respectively, as compared with control 93+/-2%. The efficacy (EC(50)) of Herceptin conjugated with emulsions was found to be 970+/-13 microg mL(-1) for Herceptin/PFCE, 645+/-11 microg mL(-1) for Herceptin/PFCE/Lipoplex, 678+/-7 microg mL(-1) for Herceptin/PFCE/HydraLink and 1000+/-3 microg mL(-1) for Herceptin. The results show that fluorine emulsions improved the efficacy of Herceptin and (19)F signal intensity changes validated drug efficiency. The significant correlations between duration of treatments and MCF-7 cells viability were observed. While we studied breast cancer cells, the fluorine emulsions could be applied for treatment of other cancer cells overexpressing HER-2.

Vers une deuxième génération d'émulsions de fluorocarbures. Méthodologies : synthèse des fluorocarbures, formulation préparation et contrôle des émulsions

The fluorocarbons to be used as intravascular gas carriers may be prepared: by fluorination of hydrocarbons, by means of gaseous fluorine or of metallic fluorides or by electrolysis in anhydrous hydrogen fluoride; by selective synthesis from small fluorinated molecules. Selective synthesis seems preferable because of the high purity of the compounds thus obtained, allowing fairly simple purification and detoxification procedures. The adequacy of fluorocarbons for intravascular use (limited by the values of some of their crucial physicochemical properties such as vapour pressure, gas dissolving power, viscosity) was found dependent of their molecular weight range, preferably between 460 and 540 dalton. Ionic balance, osmolarity, viscosity, mean particle size and particle size distribution are among the most important criteria to be respected in the preparation of biocompatible emulsions. Several physicochemical methods were developed for selecting the best ingredients and the best emulsification procedures and for evaluating the stability of the emulsions to storage and to thermal stress. The combination of these physicochemical measurements may be used as a methodology for the optimisation and control of fluorocarbon emulsions as well as a way of evaluating new ingredients and formulations.

Biological and physicochemical demands to perfluorochemicals (PFC) used as component of biocompatable emulsions

The main requirements to PFC in manufacturing biocompatible emulsions is their ability to give stable emulsions and their rapid elimination from animal tissues. The stability of emulsions depends on the types of PFC. The order of PFC stability is the following: perfluoroamines, perfluoroetheres and perfluorocarbons. Those requiring extremely high energy for emulgation can not be widly used in practice. The PFC making stable emulsions were found to be kept in organisms longer and vici versa. The choice of PFC depends on the aim of the further practical use of emulsions. Biocompatibility of PFC emulsions can largely be accounted for by toxical impurities of PFC and surfactants, low level of free fluorid ions, range of particle size and reological properties of emulsions an important criterion of PFC is their biological activity mainly related to membranotropic properties. The membrane activity of PFC reveals itself in membrane hydrophobic phase modification and should be taken into account in practical usage (cardioplegia, organ conservation, blood substitution, treatment of toxical states).