Self-assembly of emulsion droplets through programmable folding.

In the realm of particle self-assembly, it is possible to reliably construct nearly arbitrary structures if all the pieces are distinct1-3, but systems with fewer flavours of building blocks have so far been limited to the assembly of exotic crystals4-6. Here we introduce a minimal model system of colloidal droplet chains7, with programmable DNA interactions that guide their downhill folding into specific geometries. Droplets are observed in real space and time, unravelling the rules of folding. Combining experiments, simulations and theory, we show that controlling the order in which interactions are switched on directs folding into unique structures, which we call colloidal foldamers8. The simplest alternating sequences (ABAB...) of up to 13 droplets yield 11 foldamers in two dimensions and one in three dimensions. Optimizing the droplet sequence and adding an extra flavour uniquely encodes more than half of the 619 possible two-dimensional geometries. Foldamers consisting of at least 13 droplets exhibit open structures with holes, offering porous design. Numerical simulations show that foldamers can further interact to make complex supracolloidal architectures, such as dimers, ribbons and mosaics. Our results are independent of the dynamics and therefore apply to polymeric materials with hierarchical interactions on all length scales, from organic molecules all the way to Rubik's Snakes. This toolbox enables the encoding of large-scale design into sequences of short polymers, placing folding at the forefront of materials self-assembly.

Ophthalmic Nanoemulsions: From Composition to Technological Processes and Quality Control.

Nanoemulsions are considered as the most promising solution to improve the delivery of ophthalmic drugs. The design of ophthalmic nanoemulsions requires an extensive understanding of pharmaceutical as well as technological aspects related to the selection of excipients and formulation processes. This Review aims at providing the readers with a comprehensive summary of possible compositions of nanoemulsions, methods for their formulation (both laboratory and industrial), and differences between technological approaches, along with an extensive outline of the research methods enabling the confirmation of in vitro properties, pharmaceutical performance, and biological activity of the obtained product. The composition of the formulation has a major influence on the properties of the final product obtained with low-energy emulsification methods. Increasing interest in high-energy emulsification methods is a consequence of their scalability important from the industrial perspective. Considering the high-energy emulsification methods, both the composition and conditions of the process (e.g., device power level, pressure, temperature, homogenization time, or number of cycles) are important for the properties and stability of nanoemulsions. It is advisible to determine the effect of each parameter on the quality of the product to establish the optimal process parameters' range which, in turn, results in a more reproducible and efficient production.

Experimental Study on the Raman Spectra of Imine Emulsification with Chemometrics.

In this study, we aimed to investigate imine emulsification using Raman spectroscopy with chemometrics. The imine emulsification samples were obtained by mixing aldehydes and amines in methanol and aqueous methanol. The Raman spectra of the samples were measured over time between 400 and 2300 cm-1 every 40 s using a Raman spectrometer. The obtained spectra were regarded as a dataset matrix. A multivariate curve resolution with alternating least squares was applied to the dataset. A multivariate analysis based on the Raman spectrum revealed that raw materials, emulsions, and products were decomposed when the water-rich samples were emulsified. Additionally, we evaluated the kinetics of the synthesis. The effect of water content on emulsification was investigated using Raman spectroscopy. The molecular dynamics of the co-solvent model were also investigated. The phase-layer construction was consistent with the phase transition in the water-methanol imine samples.

Development of a Spontaneous Emulsifying Technique Using Porous Microparticles with Water-soluble Polymers.

A novel spontaneous emulsification method using porous polymer particles was investigated for the facile preparation of emulsions without mechanical manipulation. Porous water-soluble polymer particles prepared by spray freeze-drying could absorb soybean oil via capillary action. When the particles were added to water, emulsification proceeded rapidly with the dissolution of the polymer. The importance of using a water-soluble polymer for particle formation for the formation of fine emulsions and maintenance of dispersibility was confirmed. This emulsification technology is expected to be applied to the development of formulations that improve the solubility and mucosal absorption of poorly water-soluble drugs.

Spatio-temporal control over destabilization of Pickering emulsions stabilized by light-sensitive dextran-based nanoparticles.

The implementation of light-sensitive Pickering emulsions with spatio-temporal responsiveness in advanced applications like drug-delivery, colloidal or reaction engineering would open new avenues. However, curiously, light-sensitive Pickering emulsions are barely studied in the literature and their biocompatibility and/or degradability scarcely addressed. Thus, their development remains a major challenge. As an original strategy, we synthesized light-sensitive nanoparticles based on biocompatible Poly(NitroBenzylAcrylate) grafted dextran (Dex-g-PNBA) to stabilize O/W Pickering emulsions. The produced emulsions were stable in time and could undergo time and space-controlled destabilization under light stimulus. Irradiation time and alkaline pH-control of the aqueous phase were proved to be the actual key drivers of destabilization. As the nanoparticles themselves were photolyzed under light stimulus, possible harmful effects linked to accumulation of nanomaterials should be avoided. In addition to UV light (365 nm), visible light (405 nm) was successfully used for the spatio-temporal destabilization of the emulsions, offering perspectives for life science applications.

Preparation of double-layer nanoemulsions with controlled release of glucose as prevention of hypoglycemia in diabetic patients.

Encapsulation systems promote targeted delivery to the gastrointestinal tract. An oil-in-water (O/W) nanoemulsion was covered using new delivery system composition based on zein and sodium alginate. The impact of aqueous phase (distilled water and cooked pumpkin puree), pH (2-4), and zein-alginate concentration solution (0.05-0.20% w/v) was investigated on particle size, zeta potential, incorporation efficiency (IE), stability, viscosity, and glucose release from single-layer (SLN) and double-layer nanoemulsion (DLN). DLNs showed a larger droplet size and zeta potential. The slow gradual release of glucose proved effective application of zein/alginate as delivery system for nanoemulsion. Moreover, cooked pumpkin and 0.12% of zein exhibited more delayed release of glucose than distilled water as an aqueous phase of DLN and as a delivery system respectively. Up-to-49% IE, up-to-50% stability in a period of 7-day storage, and controlled-release glucose for 240 min under in vitro gastrointestinal conditions were obtained in DLN. The results of the current study revealed that SLN covered by zein at 0.12% of concentration can be an ideal delivery system composition for patients with hypoglycemia and clinical problems.

Highly Active, Entirely Biobased Antimicrobial Pickering Emulsions.

We present the development of surfactant-free, silica-free and fully biobased oil-in-water antimicrobial Pickering emulsions, based on the self-assembly of ß-cyclodextrin and phytoantimicrobial oils (terpinen-4-ol or carvacrol). Undecylenic acid (UA), derived from castor oil, can be used as bio-based drug to treat fungal infection, but is less effective than petroleum-based drugs as azole derivatives. To maximize its antifungal potential, we have incorporated UA in fully biobased Pickering emulsions. These emulsions are effective against fungi, Gram-positive and Gram-negative bacteria. The carvacrol emulsion charged with UA is +390 % and +165 % more potent against methicillin-resistant S. aureus (MRSA), compared to UA and azole-based commercial formulations. Moreover, this emulsion is up to +480 % more efficient that UA ointment against C. albicans. Finally, remarkable eradication of E. coli and MRSA biofilms was obtained with this environmental-friendly emulsion.

One-Step Generation of Multisomes from Lipid-Stabilized Double Emulsions.

Multisomes are multicompartmental structures formed by a lipid-stabilized network of aqueous droplets, which are contained by an outer oil phase. These biomimetic structures are emerging as a versatile platform for soft matter and synthetic biology applications. While several methods for producing multisomes have been described, including microfluidic techniques, approaches for generating biocompatible, monodisperse multisomes in a reproducible manner remain challenging to implement due to low throughput and complex device fabrication. Here, we report on a robust method for the dynamically controlled generation of multisomes with controllable sizes and high monodispersity from lipid-based double emulsions. The described microfluidic approach entails the use of three different phases forming a water/oil/water (W/O/W) double emulsion stabilized by lipid layers. We employ a gradient of glycerol concentration between the inner core and outer phase to drive the directed osmosis, allowing the swelling of lamellar lipid layers resulting in the formation of small aqueous daughter droplets at the interface of the inner aqueous core. By adding increasing concentrations of glycerol to the outer aqueous phase and subsequently varying the osmotic gradient, we show that key structural parameters, including the size of the internal droplets, can be specifically controlled. Finally, we show that this approach can be used to generate multisomes encapsulating small-molecule cargo, with potential applications in synthetic biology, drug delivery, and as carriers for active materials in the food and cosmetics industries.

Preparation of porous polymers based on high internal phase emulsion for enrichment of estrogens in urine.

In this work, graphene oxide-hybridized high internal emulsion polymers with crosslinking and open-cell structure was prepared and applied for separation and enrichment of estrogens. The prepared graphene oxide-hybridized high internal emulsion polymer monoliths had hydrophobicity, porosity and stability, which were just obtained by one step in-situ emulsion polymerization of 2-ethylhexyl acrylate, glycidyl methacrylate, and divinylbenzene after doping with graphene oxide. Benefit from the advantages of its unique character, the graphene oxide-hybridized high internal emulsion polymers monolith with low background pressure (85 kPa) and high mechanical strength could be applied for efficient separation for trace estrogens in urine. Under the optimized condition, trace estrogens, including estrone, estradiol, and diethylstilbestrol in urine, were detected by high-performance liquid chromatography, all the sample preparation process were carried out in 15 min, the recovery rate was ranged from 85.0 to 106.0% and the relative standard deviation was less than 4.

Functionalized PLGA nanoparticles prepared by nano-emulsion templating interact selectively with proteins involved in the transport through the blood-brain barrier.

During the last few decades, extensive efforts has been made to design nanocarriers to transport drugs into the central nervous system (CNS). However, its efficacy is limited due to the presence of the Blood-Brain Barrier (BBB) which greatly reduces drug penetration making Drug Delivery Systems (DDS) necessary. Polymeric nanoparticles (NPs) have been reported to be appropriate for this purpose and in particular, poly(lactic-co-glycolic acid) (PLGA) has been used for its ability to entrap small molecule drugs with great efficiency and the ease with which it functionalizes NPs. Despite the fact that their synthetic identity has been studied in depth, the biological identity of such manufactured polymers still remains unknown as does their biodistribution and in vivo fate. This biological identity is a result of their interaction with blood proteins, the so-called "protein corona" which tends to alter the behavior of polymeric nanoparticles in the body. The aim of the present research is to identify the proteins bounded to polymeric nanoparticles designed to selectively interact with the BBB. For this purpose, four different PLGA NPs were prepared and analyzed: (i) "PLGA@Drug," in which a model drug was encapsulated in its core; (ii) "8D3-PLGA" NPs where the PLGA surface was functionalized with a monoclonal anti-transferrin receptor antibody (8D3 mAb) in order to specifically target the BBB; (iii) "8D3-PLGA@Drug" in which the PLGA@Drug surface was functionalized using the same antibody described above and (iv) bare PLGA NPs which were used as a control. Once the anticipated protein corona NPs were obtained, proteins decorating both bare and functionalized PLGA NPs were isolated and analyzed. Apart from the indistinct interaction with PLGA NPs with the most abundant serum proteins, specific proteins could also be identified in the case of functionalized PLGA NPs. These findings may provide valuable insight into designing novel vehicles based on PLGA NPs for crossing the BBB.

Application of Nanoemulsions (W/O) of Extract of Opuntia oligacantha C.F. Först and Orange Oil in Gelatine Films.

Over the past decade, consumers have demanded natural, completely biodegradable active packaging serving as food containers. Bioactive plant compounds can be added to biopolymer-based films to improve their functionality, as they not only act as barriers against oxidation, microbiological, and physical damage, they also offer functionality to the food they contain. A water-in-oil (W/O) nanoemulsion was produced by applying ultrasound to xoconostle extract and orange oil, and was incorporated into gelatine films in different proportions 1:0 (control), 1:0.10, 1:0.25, 1:0.50, 1:0.75, and 1:1 (gelatine:nanoemulsion). The nanoemulsions had an average size of 118.80 ± 5.50 nm with a Z-potential of -69.9 ± 9.93 mV. The presence of bioactive compounds such as phenols, flavonoids, and betalains in the films was evaluated. The 1:1 treatment showed the highest presence of bioactive compounds, 41.31 ± 3.71 mg of gallic acid equivalent per 100 g (GAE)/100g for phenols, 28.03 ± 3.25 mg of quercetin equivalent per 100 g (EQ)/100g flavonoids and 0.014 mg/g betalains. Radical inhibition reached 72.13% for 2,20-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS), and 82.23% for 1,1-diphenyl-2-picrylhydrazyl (DPPH). The color of the films was influenced by the incorporation of nanoemulsions, showing that it was significantly different (p < 0.05) to the control. Mechanical properties, such as tensile strength, Young's modulus, and percentage elongation, were affected by the incorporation of nanoemulsified bioactive compounds into gelatine films. The obtained films presented changes in strength and flexibility. These characteristics could be favorable as packaging material.

Preparedness against pandemic influenza: Production of an oil-in-water emulsion adjuvant in Brazil.

Increasing pandemic influenza vaccine manufacturing capacity is considered strategic by WHO. Adjuvant use is key in this strategy in order to spare the vaccine doses and by increasing immune protection. We describe here the production and stability studies of a squalene based oil-in-water emulsion, adjuvant IB160, and the immune response of the H7N9 vaccine combined with IB160. To qualify the production of IB160 we produced 10 consistency lots of IB160 and the average results were: pH 6.4±0.05; squalene 48.8±.0.03 mg/ml; osmolality 47.6±6.9 mmol/kg; Z-average 157±2 nm, with polydispersity index (PDI) of 0.085±0.024 and endotoxin levels <0.5 EU/mL. The emulsion particle size was stable for at least six months at 25°C and 24 months at 4-8°C. Two doses of H7N9 vaccine formulated at 7.5 µg/dose or 15 µg/dose with adjuvant IB160 showed a significant increase of hemagglutination inhibition (HAI) titers in sera of immunized BALB/c mice when compared to control sera from animals immunized with the H7N9 antigens without adjuvant. Thus the antigen-sparing capacity of IB160 can potentially increase the production of the H7N9 pandemic vaccine and represents an important achievement for preparedness against pandemic influenza and a successful North (IDRI) to South (Butantan Institute) technology transfer for the production of the adjuvant emulsion IB160.

Engineered macroporous hydrogel scaffolds via pickering emulsions stabilized by MgO nanoparticles promote bone regeneration.

Hydrogels are appealing biomaterials for regenerative medicine since biomimetic modifications of their polymeric network can provide unique physical properties and emulate the native extracellular matrix (ECM). Meanwhile, therapeutic metal ions, such as magnesium ions (Mg2+), not only regulate cellular behaviours but also stimulate local bone formation and healing. However, the absence of a meaningful macroporous structure and the uncompromising mechanical strength are still challenges. Herein, we designed a macroporous composite hydrogel based on mild and fast thiol-ene click reactions. The Pickering emulsion method was adopted to form a macroporous structure and introduce MgO nanoparticles (NPs). The results show that the composite hydrogel possesses good mechanical strength and an evenly distributed macroporous structure. MgO NPs stabilized at the oil/water interface not only function as effective emulsion stabilizers, but also enhance the mechanical properties of hydrogels and mediate the sustained release of Mg2+. In vitro cell experiments demonstrated that the composite hydrogel displays good biocompatibility. More importantly, the release of Mg2+ ions from hydrogels can effectively promote the osteogenic differentiation of BMSCs. Furthermore, an in vivo study showed that macroporous hydrogels can provide a good extracellular matrix microenvironment for in situ osteogenesis and accelerate bone tissue regeneration.

Production of lipophilic nanogels by spontaneous emulsification.

Nanosized gel particles, so-called nanogels, have attracted substantial interest in different application fields, thanks to their controllable and three-dimensional physical structure, good mechanical properties and potential biocompatibility. Literature reports many technologies for their preparation and design, however a recurrent limitation remains in their broad size distributions as well as in the poor size control. Therefore, the monodisperse and size-controlled nanogels preparation by simple process -like emulsification- is a real challenge still in abeyance to date. In this study we propose an original low energy emulsification approach for the production of monodisperse nanogels, for which the size can be finely controlled in the range 30 to 200 nm. The principle lies in the fabrication of a direct nano-emulsion containing both oil (medium chain triglycerides) and a bi-functional acrylate monomer. The nanogels are thus formed in situ upon UV irradiation of the droplet suspension. Advantage of such modification of the oil nano-carriers are the potential modulation of the release of encapsulated drugs, as a function of the density and/or properties of the polymer chain network entrapped in the oil nano-droplets. This hypothesis was confirmed using a model of hydrophobic drug -ketoprofen- entrapped into the nanogels particles, along with the study of the release profile, carried out in function of the nature of the monomers, density of polymer chains, and different formulation parameters.

Preparation, Physicochemical Characterisation and DoE Optimisation of a Spray-Dried Dry Emulsion Platform for Delivery of a Poorly Soluble Drug, Simvastatin.

In the presented study, insight into the development and optimisation of the dry emulsion formulation and spray drying process is provided. The aim was to facilitate the dissolution of the poorly soluble, highly lipophilic drug, simvastatin, by forming spray-dried dry emulsion particles having adequate powder flow properties, while assuring sufficient drug content. Simvastatin and a mixture of caprylic, capric triglyceride and 1-oleoyl-rac-glycerol were employed as a model drug and solubilising oils, respectively. A matrix of the dry emulsions was composed at a fixed ratio mixture of mannitol and HPMC. Tween 20 was used in low amounts as the primary emulsion stabiliser. To facilitate process optimisation, a DoE surface response design was used to study the influence of formulation and process parameters on the particle size distribution, powder bulk properties, emulsion reconstitution ability, drug stability and process yield of spray-dried products. Two-fluid nozzle geometry was identified, studied and confirmed to be important for most product critical quality attributes. Models obtained after the study showed acceptable coefficients of determination and provided good insight in the relationship governing the process and product characteristics. Five model optimised products showed adequate process yield, suitable particle size distribution, good reconstitution ability and improved dissolution profile, when compared to a non-lipid-based tablet and the pure drug. However, the obtained dry emulsion powders exhibited poor flow character according to the Carr index. The optimised product was further analysed with NMR during lipolysis to gain insight into the species formed during digestion and the kinetics of their formation.

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

Cross-liked poly(2-hydroxyethyl methacrylate-co-methacrylic acid) seeds with different morphologies such as cauliflower-like, lobed spherical, and spherical were used in seeded emulsion polymerization (SEP) of 2-(dimethylamino)ethyl methacrylate (DMAEMA), 2-hydroxyethyl methacrylate (HEMA), and methacrylic acid (MAA). The morphological structure of produced composite particles was observed using field emission scanning electron microscopy (FE-SEM). The origin of the formation of different morphologies was discussed using various thermodynamic parameters such as solubility parameters and intermolecular forces between polymeric components involved. Also, the effect of the morphology of seed particles on the resultant structures was investigated. Results showed that morphology of fabricated composite particles is induced from morphology of seed particles with larger sizes. Finally, the fabricated composite particles were utilized in the controlled release of DOX. The effect of morphological changes of synthesized composite particles on the cumulative release behavior at acidic environment indicated the pH-sensitive nature of drug release through carriers. The particles with PDMAEMA shell showed the highest release of DOX at pH = 7.4 whereas PMAA shells displayed the least cumulative release. Inversely, the lowest cumulative release at pH = 1.2 was shown by PDMAEMA-coated carriers. Moreover, particles with spherical morphology had better drug release than cauliflower-like ones originated from smart nature of carriers.

Effects of zein stabilized clove essential oil Pickering emulsion on the structure and properties of chitosan-based edible films.

Clove essential oil (CLO) Pickering emulsions were prepared with zein colloid particles as stabilizer, and the effects of CLO Pickering emulsion incorporation on the structure, mechanical, barrier and antimicrobial properties of chitosan-based edible films were explored. CLO Pickering emulsions with 3% w/v zein and 50% v/v CLO had smaller particle size and more even distribution. Incorporation of CLO Pickering emulsion in the films decreased the water vapor permeability and tensile strength, but the elongation at break firstly increased then decreased with the maximum value of 19.2% when the content of emulsion was 0.4%. Scanning electron microscopy revealed the formation of microstructure-sized holes in the films by the addition of CLO Pickering emulsion. The emulsified oil droplets were uniformly distributed, due to the good compatibility between oil phase and chitosan matrix. The antimicrobial properties of the films were strengthened by CLO Pickering emulsion incorporation and mainly depended on its concentration.

Formulation, production, in vitro release and in vivo pharmacokinetics of cinnamaldehyde sub-micron emulsions.

Objective: The purpose of this study was to study the effects of formulation of cinnamaldehyde submicron emulsion (CA-SME) and optimize the preparation process parameters of CA-SME, characterize CA-SME and study on in vitro release kinetics and in vivo pharmacokinetics.Methods: Single factor methodology was used to screen the formulation of CA-SME. Response surface methodology combined with Box-Behnken design (BBD) was used to optimize the process variables of CA-SME. The dynamic dialysis method was used to investigate the in vitro release of CA from CA-SME. The blood concentrations of CA in rats were measured after oral administration of CA-SME, with CA solution as reference.Results: The optimal formulation of CA-SME was as follows: 2.5% CA + 1.5% Tween-80 and Span-80 (1:1)+1.5% medium chain triglyceride (MCT)+1.5% Poloxamer-188 + 1.5% lecithin + 91.5% ultrapure water. With the entrapment efficiency (EE/%) of CA-SME as index, BBD experiments indicated that the optimum emulsification temperature, homogenization pressure and cycles were 56 °C, 52 MPa, and two cycles, respectively. The mean particle size and EE of optimum CA-SME were 257.23 ± 3.74 nm and 80.31 ± 0.68%, respectively. The in vitro release study exhibited that the release kinetics of CA-SME was first-order model. Pharmacokinetic parameters of CA-SME in rats were Tmax 60 min, Cmax 1063.41 mg/L, AUC0-∞ 113102.61 mg/L*min, respectively. Tmax, Cmax, and AUC0-∞ of CA-SME were 3, 3.5, and 2.3 times higher than that of CA solution, respectively. The pharmacokinetic parameters of CA-SME in rats were significantly higher than those of CA solution. Submicron emulsion shows great potential as delivery strategy for this volatile herbal oil in oral administration.

Fluorinated cryptophane-A and porphyrin-based theranostics for multimodal imaging-guided photodynamic therapy.

Herein, we developed fluorinated nanoemulsions with significantly enhanced in vitro and in vivo129Xe hyper-CEST MRI, 19F MRI and fluorescence imaging signals for selective and sensitive tumor detection and NIR-activated photodynamic therapy.

Fabrication of Oleogels via a Facile Method by Oil Absorption in the Aerogel Templates of Protein-Polysaccharide Conjugates.

In this study, a novel and facile method was developed to fabricate oleogels. The alginate/soy protein conjugates with excellent emulsifying activity and emulsion stability were prepared via Maillard reaction and freeze-dried to form the aerogel templates, which were then immersed in corn oil within 6 h to induce the oleogels. Compared with the alginate and soy protein solutions, the viscosity and elastic modulus G' of the conjugate solutions increased, indicating the formation of a new macromolecule and strengthened gel network from Maillard reaction. The conjugate aerogels presented the morphology of serious aggregation and conglutination but the higher elastic modulus and better thermal stability, due to the increasing covalent interactions. These aerogel templates showed a good oil absorption of up to 10.89 g/g aerogel and holding capacity of 40%. The resulting oleogels loaded with thymol showed excellent antimicrobial activities against Staphylococcus aureus and Escherichia coli. This work suggests that the fabrication of oleogels is not limited to the choice of existing oleogelators but from a wide variety of protein-polysaccharide conjugates to form the aerogel templates for oil absorption.