HK1191879A - Nanoemulsions - Google Patents

Description

Nano-emulsion

The divisional application is based on the original Chinese patent application with the application number of 200880124383.6, the application date of 2008, 11 and 18, and the name of the invention of nano emulsion.

Technical Field

The present invention relates to oil-in-water nanoemulsions, methods for their preparation and their use as delivery vehicles for active ingredients for ophthalmic, dermatological, food, cosmetic, pharmaceutical, agrochemical, textile, polymer, and chemical applications.

Background

Emulsions are colloidal systems that find application in many industrial products such as food, cosmetics, and pharmaceuticals. Oil-in-water emulsions consist of oil droplets dispersed in an aqueous continuous phase. One of the applications of emulsions in industry is to deliver active ingredients and components such as fragrances, pigments, vitamins, antioxidants, antimicrobials, pesticides, herbicides, cosmetics, nutritional supplements, phytochemicals and pharmaceuticals.

The active ingredients may be oil-soluble or water-soluble, but their solubility in these environments may vary from highly soluble to poorly soluble. Administration of water-insoluble active ingredients presents a challenge because it requires the use of an appropriate vehicle to bring an effective amount of the active ingredient into the desired site of action. Oil-in-water emulsions are commonly used to deliver water-insoluble active ingredients. The oil-soluble active ingredient is dissolved/dispersed within the oil phase of the emulsion. Active ingredients that are poorly soluble in both oil and water may be incorporated as part of the interfacial region of an oil-in-water emulsion.

Conventional emulsions for delivering active ingredients have a number of significant limitations and disadvantages. Emulsions are kinetically stable structures that destabilize by many mechanisms, ultimately leading to complete phase separation of the emulsion. The tendency of emulsions to physically change over time presents problems for their storage and handling. In addition, these physical degradations increase the likelihood of the preparation being in a non-optimal state when physically administered.

Conventional oil-in-water emulsions range in size (diameter) from a few hundred nanometers to a few micrometers. Because these particles are on the order of or larger than the wavelength of light, they have an opaque appearance. This creates the disadvantage of altering the optical clarity of any product in which the emulsion is incorporated, reducing visual appeal. In addition, emulsions of this size have a low interfacial area to volume ratio. This has a negative impact on the ability of the emulsion to solubilize poorly soluble biologically active substances (soluble at the interface). The amount of poorly soluble biologically active substance that can be dissolved at the interface is directly related to the relative amount of interfacial area.

Another disadvantage of using conventional oil-in-water triglyceride emulsions for the delivery of active ingredients is that upon oral ingestion, the release of the active ingredient depends on the rate and extent of lipolysis. Although such emulsions are capable of transporting the active ingredient through the aqueous environment of the gastrointestinal tract, the ultimate release of the emulsified active ingredient is dependent upon digestion of the emulsion. The rate of triglyceride emulsion digestion varies with a number of factors (pH, colipase/lipase concentration, bile salts and emulsion surface area). Of which the most important is the relative proportion of the interfacial area of the emulsion to its volume. Emulsions with a larger surface area to volume ratio will lipolyze more rapidly than emulsions with a smaller surface area to volume ratio.

At emulsion particle sizes below 100nm, the emulsion has additional benefits: becomes translucent or even transparent. The formation of very fine (less than 100nm) emulsions has the additional benefit of a significant increase in the relative amount of interfacial area. An increase in the relative amount of interfacial area may result in a greater ability to dissolve/disperse the poorly soluble active component at the interface. Furthermore, an increase in the relative amount of interfacial area can result in a faster rate of digestion by lipolysis compared to conventional oil-in-water emulsions. A faster rate of lipolysis can cause a faster release of the emulsified active ingredient.

The two types of emulsions that may have a particle size of less than 100nm are microemulsions or nanoemulsions. These two types of emulsions are completely different.

Microemulsions are emulsions that form spontaneously due to ultra-low interfacial tension and favorable energy of structure formation. Microemulsions are thermodynamically stable, with their particle size not changing over time. One disadvantage of microemulsions is that they are prone to become physically unstable if their composition changes, for example upon dilution, acidification or heating. The spontaneous formation of microemulsions results from the synergistic interaction of surfactants, co-surfactants and co-solvents to effectively "solubilize" the oil molecule. It is therefore well known that microemulsions have the disadvantage that they contain large amounts of surfactant (relative to the amount of oil). In the case of food products, many surfactants have a bitter taste. In addition, WHO and FDA have limitations on the daily intake of many of these surfactants.

Nanoemulsions are emulsions that do not form spontaneously, but are formed by applying shear to a mixture of oil, water and surfactant. Unlike microemulsions, nanoemulsions are kinetically stable and their particle size can increase over time by coalescence, flocculation and/or austenite ripening. The very small size of the nanoemulsions makes them particularly susceptible to grain size growth through austenite ripening. An increase in the particle size of the emulsion over time is disadvantageous, since the emulsion loses its transparency with a corresponding increase in the surface area.

Like microemulsions, nanoemulsions may have the advantage of appearing translucent/transparent due to their small size. Also, like microemulsions, nanoemulsions have the advantage of a large interfacial area to volume ratio, which facilitates the dissolution of poorly soluble bioactive substances and rapid digestion of the emulsion through a faster rate of lipolysis. Furthermore, unlike many microemulsions, nanoemulsions retain their structure (small size) upon dilution and/or acidification. This may have the additional advantage of facilitating adsorption of the active substance, as it is currently believed that emulsions below 100nm have a greater ability to penetrate epithelial layers such as skin and oral mucosa. Another advantage of nanoemulsions is that the production of nanoemulsions requires significantly lower amounts of surfactant than microemulsions. This gives the nanoemulsion the advantage of incorporating smaller amounts of surfactant when a certain amount of active/oil is added. This is advantageous in terms of toxicology, management and taste.

The nature of the oil contained in the nanoemulsion is also important. The use of triglycerides as oils is advantageous because triglycerides offer lower toxicological and/or irritation profiles than synthetic oils or hydrocarbon oils. Triglycerides are divided into three categories: short chain triglycerides (having less than 6 carbons in the fatty acid chain), medium chain triglycerides (having 6-12 carbons in the fatty acid chain) and long chain triglycerides (having more than 12 carbons in the fatty acid chain). It is advantageous if the triglyceride oil in the nanoemulsion is a long chain triglyceride, preferably with some degree of unsaturation, as these oils have been shown to provide positive nutritional benefits and are significantly more stable against austenitic ripening.

It is known to use medium chain triglycerides (in particular miglyol812) to produce nanoemulsions and/or nanodispersions. Medium chain triglycerides are used because they have a smaller molecular volume and a higher solubility in water contributes to their ability to form nanoemulsions and/or nanodispersions. In contrast, it is well known that the large molecular volume of long chain triglycerides prevents them from easily forming clear microemulsions or nanoemulsions.

It remains a challenge to produce nanoemulsions in which the oil phase comprises long chain triglycerides, wherein the emulsion has an average particle size value of less than 100nm, high stability against austenite ripening and relatively low amounts of surfactants. The production of such a nanoemulsion is advantageous because it increases the stability and clarity of the product, improves the solubility of some poorly soluble actives and improves the organoleptic properties.

Disclosure of Invention

In a first aspect, there is provided an oil-in-water nanoemulsion comprising

Up to 40% by volume of an oil phase comprising at least 50% by volume of triglycerides with fatty acid chain lengths of 12 or more carbon atoms;

a hydrophilic nonionic surfactant having a hydrophilic-lipophilic balance (HLB) of greater than 7; and

the water phase of the mixture is water phase,

wherein the oil droplets of the nanoemulsion have an average particle size value of less than 100nm and the surfactant to oil ratio is less than 1:1, more preferably between 0.2 and 0.8: 1.

In a second aspect, there is provided a method of preparing an oil-in-water nanoemulsion comprising

Subjecting up to 40% by volume of an oil phase comprising at least 50% by volume of triglycerides with fatty acid chain lengths of 12 or more carbon atoms, a hydrophilic nonionic surfactant with a hydrophilic-lipophilic balance (HLB) of greater than 7 and an aqueous phase to homogenisation, sonication, or membrane emulsification to produce a nanoemulsion in which the average particle size (intensity average size) of the oil droplets is less than 100nm and the surfactant to oil ratio is less than 1:1 (more preferably 0.2-0.8: 1).

In a third aspect, there is provided the use of a nanoemulsion as defined above as a delivery vehicle for an active ingredient.

The active components include ingredients and components for food, beverages, cosmetics, pharmaceuticals, ophthalmic pharmaceuticals, skin products, agrochemicals, textiles, polymers and chemical applications.

Also provided is a delivery vehicle for an active ingredient comprising a nanoemulsion as defined above.

In a fourth aspect, there is provided a formulation comprising a nanoemulsion as defined above and an active ingredient.

In a fifth aspect, there is provided a method of preparing a formulation as defined above, comprising mixing a nanoemulsion as defined above with the active ingredient.

In a sixth aspect, there is provided a process for the preparation of a formulation as defined above, comprising

Subjecting an active ingredient, up to 40% by volume of an oil phase comprising at least 50% by volume of triglycerides with fatty acid chain lengths of 12 or more carbon atoms, a hydrophilic nonionic surfactant with a hydrophilic-lipophilic balance (HLB) of greater than 7 and an aqueous phase to homogenization, sonication, or membrane emulsification to produce a nanoemulsion in which the average particle size value of the oil particles is less than 100nm and the ratio of surfactant to oil is less than 1:1, more preferably 0.2-0.8: 1.

Detailed Description

The present invention relates to oil-in-water nanoemulsions, methods of preparing nanoemulsions and uses of the nanoemulsions for delivering active ingredients.

The oil-in-water type nano-emulsion comprises

Up to 40% by volume of an oil phase comprising at least 50% by volume of a triglyceride having a fatty acid chain length of 12 or more carbon atoms and a hydrophilic nonionic surfactant having a hydrophilic-lipophilic balance (HLB) of greater than 7; and

the water phase of the mixture is water phase,

wherein the oil droplets have an average particle size value of less than 100nm and the surfactant to oil ratio is less than 1:1, more preferably 0.2 to 0.8: 1.

In a preferred embodiment, the oil-in-water nanoemulsion comprises up to 40% by volume of an oil phase comprising at least 50% by volume of a triglyceride having a fatty acid chain length of 12 or more carbon atoms, a hydrophilic nonionic surfactant having a hydrophilic-lipophilic balance (HLB) of greater than 7, and a co-solvent and an aqueous phase.

The nanoemulsion may also comprise a co-surfactant, which preferably interacts synergistically with the non-ionic surfactant to reduce emulsion particle size.

For food, cosmetic, pharmaceutical, ophthalmic pharmaceutical and dermatological applications, it is preferred that the components are food grade or pharmaceutical grade, resulting in edible nanoemulsions.

The nanoemulsions have high clarity, are physically stable against austenite ripening due to the use of long chain triglycerides, and have good formulation stability since they can be easily infinitely diluted. The lower surfactant to oil ratio also means that the nanoemulsion should be organoleptically appealing, since surfactants are generally bitter. Preferably, the nanoemulsion is food grade or pharmaceutical grade, and the lower surfactant to oil ratio allows for a greater amount of nanoemulsion to be incorporated into food products without violating WHO and FDA determined regulatory levels of synthetic surfactants in food products.

Nano-emulsion

The term "nanoemulsion" refers to oil-in-water emulsions in which the oil droplets are ultra-small, having a diameter of 100nm or less, preferably 80nm or less, more preferably 75nm or less, and most preferably 60nm or less. The droplet size is the Z-average particle size or an intensity weighted average particle size as measured by dynamic light scattering (also known as photon correlation spectroscopy).

Oil phase

The oil phase comprises at least 50% by volume of triglycerides having a fatty acid chain length of 12 carbon atoms or more. The triglyceride may be a liquid or solid fat of animal, vegetable, marine or synthetic origin, preferably a food grade triglyceride of the general formula:

wherein R is₁、R₂And R₃Independently selected from saturated and unsaturated fatty acid residues (unbranched and branched) having a chain length C₁₂Or greater, preferably C₁₂-C₂₄More preferably C₁₆-C₂₂I.e. long chain triglycerides.

It has been shown that long chain triglycerides (preferably with some degree of unsaturation) provide positive nutritional benefits and are significantly more stable against austenitic ripening. Figure 1 depicts the physical stability of a nanoemulsion made using mineral/paraffin oil (hexadecane), medium chain triglyceride (miglyol812) or long chain triglyceride (peanut oil). From this figure, the stability of long chain triglycerides is evident.

Examples of long chain triglycerides include those of animal origin, such as fish oil, cod liver oil, whale oil, lard, tallow, chicken oil, and milk fat; those of vegetable origin, such as canola oil (canola oil), castor oil, cocoa butter, coconut oil, coffee seed oil, corn oil, cottonseed oil, evening primrose oil, grape seed oil, linseed oil, menhaden oil, mustard oil, olive oil, palm kernel oil, peanut oil, poppy seed oil, rapeseed oil, rice bran oil, safflower oil, sesame oil, soybean oil, sunflower oil, palm kernel oil, hazelnut oil, sesame oil and wheat germ oil; those of seaweed origin, such as vegetable oils. Also included are synthetic triglycerides, rectified triglycerides, modified triglycerides, hydrogenated triglycerides or mixtures of partially hydrogenated triglycerides and triglycerides.

The nanoemulsion may comprise one or more additional oils, such as short chain triglycerides, for example glycerol triacetate, glycerol tributyrate, glycerol trihexanoate and miglyol; mineral oils, for example paraffinic oils such as decane, tetradecane, hexadecane and octadecane; and flavor oils such as limonene, mandarin oil, orange oil, lemon oil, lime oil or other citrus oils, peppermint oil, peach oil, vanilla flavor oil, and vanillin; and aromatic oils (aromatic oils) such as peppermint, tea tree oil, eucalyptus oil, wild mint (mentha arvensis), cedar wood oil, spearmint, orange oil, lemin oil and clove.

The ratio between triglyceride and further oil is preferably 1:0 to 1: 1.

The total amount of oil in the nanoemulsion, including the long chain triglycerides and the additional oil (if present), may be 0.01-70 wt%, preferably 0.01-50 wt%, more preferably 0.01-40 wt%.

Hydrophilic nonionic surfactant

The hydrophilic nonionic surfactant has a hydrophilic-lipophilic balance (HLB) of greater than 7 and is preferably a food-grade or pharmaceutical-grade hydrophilic surfactant, such as polysorbates (polyethylene glycol sorbitan fatty acid esters), polyethylene glycol alkyl ethers, sugar esters, polyethoxylated fatty acids, polyoxyethylene-polyoxypropylene block copolymers (Pluronics), polyethylene glycol alkylphenol surfactants, citric acid esters of monoglycerides, polyglycerol esters, polyethoxylated fatty acid diesters, PEG-fatty acid monoesters and diesters, polyethylene glycol glycerol fatty acid esters and alcohol oil transesterifiers (alcohol oil transesters), or mixtures thereof.

Suitable nonionic surfactants include:

polysorbates such as polyethoxylated sorbitan monoesters including polyoxyethylene sorbitan monolaurate (Tween20), polyoxyethylene sorbitan monopalmitate (Tween40), polyoxyethylene sorbitan monostearate (Tween60), polyoxyethylene sorbitan tristearate (Tween65), and polyoxyethylene sorbitan monooleate (Tween 80);

sugar surfactants such as sucrose monopalmitate, sucrose monolaurate, sucrose distearate 3Crodesta F-10, sucrose distearate, monostearate Crodesta F-110, sucrose dipalmitate, sucrose monostearate F-160, sucrose monopalmitate, sucrose (sucrose) monolaurate and sucrose (saccharose) monolaurate;

polyoxyethylene-polyoxypropylene block copolymers, available under different trade names, include the Synperonic PE series (ICI), Pluronic. RTM. series (BASF), Emkalyx, Lutrol (BASF), supranic, Monolan, Pluracane and Plurodac.

Polyoxyethylene-polyoxypropylene block copolymers, also known as polyoxamers, have the general formula:

HO(C₂H₄O)_A(C₃H₆O)_B(C₂H₄O)_AH

wherein A and B represent the number of polyoxyethylene and polyoxypropylene units, respectively.

Polyoxamers wherein A is 1-100 and B is 1-100 and compositions thereof are suitable for use in the nanoemulsion of the present invention.

The amount of the hydrophilic surfactant in the nanoemulsion may be 0.1-15 wt%, preferably 1-10 wt%, more preferably 3-7 wt%.

Cosurfactant

The nanoemulsion may also comprise a co-surfactant, preferably a surfactant that works synergistically with the hydrophilic non-ionic surfactant to change the curvature of the interface. This reduces the interfacial tension, allowing the emulsion to form more easily.

Preferably, the co-surfactant is food grade or pharmaceutical grade.

Suitable food grade co-surfactants include:

sorbitan fatty acid esters such as sorbitan monolaurate (Span20), sorbitan monopalmitate (Span40), sorbitan tristearate (Span65), sorbitan monostearate (Span60), sorbitan monooleate (Span80) and sorbitan trioleate (Span 85);

phospholipids such as lecithin/soya lecithin, e.g. epikuron, topcirin, leciprime, lecisoy, emulfluid, emulpur, metarin, emultop, lecigran, lecimuthn, ovothin lyso lecithin/soya lecithin, hydroxylated lecithin lysolecithin, cardiolipin, sphingomyelin, phosphatidylcholine, phosphatidylethanolamine, phosphatidic acid, phosphatidylglycerol, phosphatidylserine, and mixtures of phospholipids with other surfactants; and

ionic surfactants such as sodium stearoyl lactylate (sodium stearoyl lactylate) and calcium stearoyl lactylate (calcium stearoyl lactylate).

The amount of co-surfactant in the nanoemulsion may be 0.1-15% by weight. Preferably, the co-surfactant is present in a ratio of from 0:1 to 2:1, more preferably from 0:1 to 1.3:1, and most preferably from 0.5:1 to 1.3:1, relative to the hydrophilic nonionic surfactant.

Aqueous phase

The aqueous phase may be purified or ultrapure water, saline, or buffered saline.

The balance of water after the nanoemulsion comprises all other formulation components may be 50-100 wt%, preferably 40-99.99 wt%, more preferably 30-99.90 wt%.

Co-solvent

In a preferred embodiment, the nanoemulsion further comprises a co-solvent. The co-solvent reduces the interfacial tension of the aqueous phase, allowing the formation of smaller emulsion droplets.

Suitable co-solvents include C₁-C₁₀Alcohols such as methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, and decanol; polyols such as glycerol, 1, 2-propanediol, 1, 3-propanediol, polyethylene glycol and polypropylene glycol; and long chain fatty alcohols. Preferably, the solvent is C₁-C₄The alcohol is more preferably ethanol.

The amount of solvent in the nanoemulsion may be 0-70 wt%, preferably 0-50 wt%, more preferably 15-45 wt%.

Active component

The active ingredient is an oil or any ingredient that is oil soluble, spaced apart from the oil phase, poorly soluble in oil and water, or soluble or dispersible at the interface, and imparts color, flavor, antimicrobial action, aesthetic action, health promoting action, disease prevention action or technique, or disease treatment action to the nanoemulsion.

The active ingredient may be a food or beverage ingredient such as food supplements, food additives, aromas, aromatic oils, colors, flavors, and sweeteners; a cosmetic; drugs, such as pharmaceuticals, peptides, proteins, and carbohydrates; a nutritional supplement food; a phytochemical; a vitamin; essential polyunsaturated fatty acids; a plant extract; agrochemicals, such as insecticides and herbicides; a fabric; a polymer; and chemicals.

Suitable active ingredients include:

phytochemicals such as polyphenols (e.g., catechin, epicatechin gallate, quercitrin (quercitrin), and resveratrol), carotenoids (e.g., lycopene, lutein esters, beta-carotene, retinyl palmitate, and zeaxanthin), ubiquinone (CoQ10), and phytosterols;

vitamins such as vitamin A (e.g., retinol and retinol palmitate), vitamin D (e.g., vitamin D2), vitamin E (e.g., vitamin E acetate, and vitamin E palmitate), vitamin K (e.g., K₁Phylloquinone and K₂-menaquinone)

Essential polyunsaturated fatty acids such as linoleic acid, alpha-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid;

flavoring agents, such as natural flavoring oils, e.g., citrus oil, limonene, mandarin oil, orange oil, lemon oil, lime oil, peppermint oil, peach oil, vanilla flavor oil, and vanillin, or synthetic flavoring substances, e.g., hexanol, ethyl laurate, apple flavor oil, strawberry flavor oil, benzaldehyde, cinnamaldehyde, chili flavor oil, citronellyl butyrate, phenylethyl acetate, ethyl propionate, ethyl decanoate, ethyl butyrate, ethyl hexanoate, brandy flavor oil, hexyl aldehyde, blackberry flavor oil, phellandrene (phellanene), blueberry flavor oil, honey flavor, oil, nerol, licorice flavor oil, maple flavor oil, ethyl octanoate, and watermelon flavor oil; and

aromatic oils such as peppermint, tea tree oil, eucalyptus oil, peppermint, cedar wood oil, spearmint, orange oil, lemin oil, and clove.

The amount of active ingredient in the nanoemulsion may be 0.01-50 wt%, preferably 0.01-10 wt%.

Additive agent

The nanoemulsion may comprise additives such as stabilizers, antioxidants, preservatives, buffers, charge inducers, weighting agent polymers and proteins. The stabilizer may be a pH adjuster, a grease inhibitor or an antifoaming agent or an agent that imparts stability to the nanoemulsion. Examples of stabilizers include sodium oleate, glycerin, xylitol, sorbitol, ascorbic acid, citric acid, and sodium edetate. Antioxidants include carotenoids such as alpha-tocopherol or its derivatives (which are members of the vitamin E family), beta-carotene, lutein, lycopene, ascorbic acid, trolox, beta-carotene, polyphenols such as catechin, epicatechin gallate, quercetin, resveratrol, ascorbyl palmitate, and Butylated Hydroxytoluene (BHT). Buffering agents include sodium phosphate, citric acid, formic acid and ascorbic acid. Examples of the charge inducing agent include sodium deoxycholate, sodium lauryl sulfate, deoxycholic acid, octadecylamine, oleylamine, chitosan, and cetyltriethylammonium bromide. The weighting agent comprises brominated vegetable oil. Examples of polymers and proteins include hydrocolloids such as guar gum, pectin, xanthan gum (xanthan), and alginates.

The amount of the additive in the nanoemulsion may be 0-50 wt%, preferably 0-25 wt%, more preferably 0-10 wt%.

Method of producing a composite material

The process for preparing the nanoemulsion in its broadest sense comprises subjecting the oil phase comprising triglycerides, the hydrophilic surfactant, the aqueous phase and the co-solvent and/or co-surfactant (when present) to homogenization, sonication or membrane emulsification, preferably high shear homogenization. The interaction between the hydrophilic surfactant and the co-solvent and/or co-surfactant (when present) reduces the interfacial tension of the emulsion, which results in better homogenization and smaller nanoemulsion particle size. Homogenization may be carried out at a pressure such as 1000 bar using any suitable known homogenization device such as a microfluidizer (such as Microfluidics M-110YMicrofluidiser from MFIC Corporation), a high pressure homogenizer (such as those produced by Gauline, Avestin or NiroSoavi, etc.), or a probe sonicator. Examples of devices that can be used for sonication include a Hielscher ultrasonic homogenizer, a Branson ultrasonic homogenizer, a Cole-Palmer ultrasonic homogenizer, or an Omni Ruptor4000 ultrasonic homogenizer. Membrane emulsification can be performed using, for example, a Polytron PT3100 membrane homogenizer or a LiposoFast membrane homogenizer (Avestin, Canada). The number of passes through the homogenization apparatus may vary depending on the desired nanoemulsion particle size, and typically 5 passes are sufficient.

In one embodiment, the nanoemulsion may be prepared by adding a hydrophilic surfactant and a co-surfactant to an oil phase comprising triglycerides and additional oil (if present). Preferably, the triglyceride oil and the further oil are pre-mixed. The oil/surfactant composition is then mixed with the solution comprising the aqueous phase and the co-solvent using any suitable known mixing device, such as a Silverson rotor stator mixer, at 12,000rpm for about 2 minutes to form a pre-emulsion (pre-emulsion). The pre-emulsion is then subjected to homogenization.

The formulation may be prepared by mixing the nanoemulsion with the active ingredient, preferably by stirring at room temperature for a suitable period of time (such as 12 hours at room temperature) or at elevated temperature, e.g. 60 ℃, for several hours. In another embodiment, the formulation may be prepared by mixing the active ingredient with the components of the emulsion and then homogenizing the resulting mixture. The final formulation is usually clear, indicating that the nanoemulsion dissolved/incorporated the active component.

Preparation

The nanoemulsion may act as a delivery vehicle for the active ingredient, which may be dissolved in the oil, spaced apart from the oil phase, or poorly soluble in both oil and water. The active ingredient may be entrapped in the nanoemulsion and incorporated into a formulation that maintains stability.

It will be appreciated by those skilled in the art that it is most preferred to prepare the nanoemulsion in the form of a concentrate, preferably containing from 15 to 40% by volume oil. The same nanoemulsion can also be prepared with much lower oil contents, e.g. 0.1-10 vol%. Although it is preferred that the nanoemulsion is prepared as a concentrate, it is also preferred that the nanoemulsion is added to food in a diluted form of 0.01-30 vol%.

Brief Description of Drawings

Figure 1 compares the nanoemulsion particle size over time for two triglyceride nanoemulsions made using i) medium chain triglyceride (miglyol812) and ii) long chain triglyceride (peanut oil).

Fig. 2 depicts typical particle size distributions of the nanoemulsions described in examples 2-6, i) intensity weighted particle size distribution, ii) volume weighted particle size distribution, as measured by dynamic light scattering.

Figure 3 shows typical physical stability (mean particle size over time during storage at 24 ℃) of the nanoemulsions described in examples 2-6.

Fig. 4 compares the ability of emulsions of canola oil (canola oil) of different sizes to solubilize phytosterols. The emulsion was i) a conventional canola oil emulsion (600nm diameter, 0.5 wt% polysorbate 80), ii) a high shear homogenized canola oil emulsion (160nm diameter, 5.6 wt% polysorbate 80), iii) a microfluidized canola oil emulsion (130nm diameter, 5.6 wt% polysorbate 80), iv) a canola oil nanoemulsion (50nm diameter) as described in example 5.

Figure 5 compares the solubility of resveratrol in i) water, ii) long chain triglycerides, iii) a conventional long chain triglyceride emulsion (0.6 μm diameter, 0.5 wt% polysorbate 80), and iv) the edible nanoemulsion described in example 11.

Examples

The invention is described below with reference to the following non-limiting examples.

Processing conditions

The triglyceride oil nanoemulsion was prepared as follows, using a silverson rotor stator mixer at 12,000rpm for 2 minutes to produce a pre-emulsion of a mixture of the ingredients described in the examples below. Nanoemulsions were prepared from the pre-emulsion using a Microfluidics M-110Y microfluidizer (MFIC Corporation, Newton, MA, USA) with an F20Y75 μ M interaction chamber and an H30Z200 μ M auxiliary chamber in series. Clear nanoemulsions were prepared by subjecting the pre-emulsion to 5 passes at 1000 bar (unless otherwise stated).

Formulation examples

The formulation examples described below have several factors that contribute to the small emulsion size. The interaction between the oil (or oil mixture), hydrophilic surfactant, co-solvent and co-surfactant results in an advantageously low interfacial tension which allows the emulsion particle size to be reduced to about 50-60 nm. The main formulations are triglyceride oils with side chain lengths equal to or greater than 12 carbons, polyoxyethylene sorbitan monoesters (Tween) as hydrophilic surfactant and ethanol as co-solvent. Different types of nanoemulsions are produced due to the different cosurfactants used, including: various lecithins, sorbitan monoester surfactants (Span) and sodium stearoyl lactylate (sodium stearoyl lactylate) and many similar co-surfactants.

It has been found that all formulation examples using any triglyceride oil work equally well.

Example 1: peanut oil nano emulsion-Tween/ethanol

A peanut oil-in-water nanoemulsion was prepared by adding 12 grams of polyoxyethylene sorbitan monooleate (Tween80) to 23 grams of peanut oil and then mixing this oil/surfactant mixture into 120 grams of a 3:2 water: ethanol solution using a Silverson rotor stator mixer for 2 minutes at 12,000rpm to form a pre-emulsion. Then the pre-emulsion is treated with a microfluidizer^TMHomogenization was performed at 1000 bar and 5 passes. The obtained nanoemulsion has a particle size of 45nm and high optical clarity. If diluted with water (10-99% dilution), the nanoemulsionShowing no change in size over a 100 day storage period.

Oil content: this formulation is effective at oil contents of up to 25-30% if the Tween80: oil ratio is kept constant.

This formulation works equally well when the following substitutions are made:

polyoxyethylene surfactant: tween40 and Tween 60. The Tween content is from 6g to more than 30 g.

Ethanol content: the content of water phase ethanol is 20-50%.

Fat/oil: lard, milk fat, canola oil, rapeseed oil, fish oil, sunflower oil, linseed oil, safflower oil, palm oil, coconut oil, soybean oil, olive oil, corn oil, or any other triglyceride oil or combination thereof.

Example 2: linseed oil nanoemulsion-Tween/ethanol/Emultop IP

The linseed oil nanoemulsion was prepared by adding 8 g of polyoxyethylene sorbitan monooleate (Tween80) and 5g of Emultop IP (lysolecithin) to 22.5 g of linseed oil. This oil/surfactant mixture was then mixed into 120g of a 3:1 aqueous: ethanol solution using a Silverson rotor stator mixer and mixed for 2 minutes at 12,000rpm to form a pre-emulsion. The pre-emulsion was then homogenized with a microfluidizer at 1000 bar and 5 passes. The obtained nano-emulsion has a particle size of 45nm, high optical clarity, and no change in particle size or optical clarity during 100-day storage.

Oil content: this formulation is effective at oil contents of up to 25-30% if the Tween80 and co-surfactant to oil ratio are kept constant.

This formulation works equally well when the following substitutions are made:

polyoxyethylene surfactant: tween40 and Tween 60. The Tween content is from 6g to a maximum of 30 g.

Ethanol content: the content of water phase ethanol is 20-50%.

Fat/oil: lard, milk fat, canola oil, rapeseed oil, fish oil, sunflower oil, peanut oil, safflower oil, palm oil, coconut oil, soybean oil, olive oil, corn oil, or any other triglyceride oil or combination thereof.

Example 3: tuna oil nanoemulsion-Tween/ethanol/Centromix E

Tuna oil nanoemulsion was prepared by adding 8 grams of polyoxyethylene sorbitan monooleate (Tween80) and 8 grams of Centromix E (lysolecithin) to 22.5 grams of tuna oil. This oil/surfactant mixture was then mixed into 120g of a 3:1 aqueous: ethanol solution using a Silverson rotor stator mixer and mixed for 2 minutes at 12,000rpm to form a pre-emulsion. The pre-emulsion was then homogenized with a microfluidizer at 1000 bar and 5 passes. The obtained nano-emulsion has a particle size of 45nm, high optical clarity, and no change in particle size or optical clarity during 100-day storage.

Oil content: this formulation is effective at oil contents of up to 25-30% if the Tween80 and co-surfactant to oil ratio are kept constant.

This formulation works equally well when the following substitutions are made:

polyoxyethylene surfactant: tween40 and Tween 60. The Tween content is from 6g to a maximum of 30 g.

Ethanol content: the content of water phase ethanol is 20-50%.

Oil: canola oil, rapeseed oil, fish oil, sunflower oil, peanut oil, and linseed oil.

Example 4: peanut oil nanoemulsion-Tween/ethanol/Span 80

The peanut oil nanoemulsion was prepared by adding 8 grams of polyoxyethylene sorbitan monooleate (Tween80) and 6 grams of sorbitan monooleate (Span80) to 22.5 grams of peanut oil. This oil/surfactant mixture was then mixed into 120g of a 3:1 aqueous: ethanol solution using a Silverson rotor stator mixer and mixed for 2 minutes at 12,000rpm to form a pre-emulsion. The pre-emulsion was then homogenized with a microfluidizer at 1000 bar and 5 passes. The obtained nano-emulsion has a particle size of 45nm, high optical clarity, and no change in particle size or optical clarity during 100-day storage.

Oil content: this formulation is effective at oil contents of up to 25-30% if the Tween80 and co-surfactant to oil ratio are kept constant.

This formulation works equally well when the following substitutions are made:

polyoxyethylene surfactant: tween40 and Tween 60. The Tween content is from 6g to a maximum of 30 g.

Ethanol content: the content of water phase ethanol is 20-50%.

Oil: canola oil, rapeseed oil, fish oil, sunflower oil, and linseed oil.

Example 5: canola oil nanoemulsion Tween/ethanol/Sodium stearoyl lactylate (Sodium steryl lactylate)

Canola oil nanoemulsion was prepared by adding 8 grams of polyoxyethylene sorbitan monooleate (Tween80) and 5 grams of Sodium Stearoyl Lactylate (SSL) to 22.5 grams of canola oil. This oil/surfactant mixture was then mixed into 120g of a 3:1 aqueous: ethanol solution using a Silverson rotor stator mixer and mixed for 2 minutes at 12,000rpm to form a pre-emulsion. The pre-emulsion was then homogenized with a microfluidizer at 1000 bar and 5 passes. The obtained nano-emulsion has a particle size of 45nm, high optical clarity, and no change in particle size or optical clarity during 100-day storage.

Oil content: this formulation is effective at oil contents of up to 25-30% if the Tween80 and co-surfactant to oil ratio are kept constant.

This formulation works equally well when the following substitutions are made:

polyoxyethylene surfactant: tween40, Tween60 and Tween 80. The Tween content is from 6g to a maximum of 30 g.

Ethanol content: the content of water phase ethanol is 20-50%.

Oil: rapeseed oil, fish oil, sunflower oil, peanut oil and linseed oil.

Example 6: mixed oil nanoemulsion-Tween/ethanol/lecithin

Mixed triglyceride oil nanoemulsion was prepared by adding 8 g of polyoxyethylene sorbitan monooleate (Tween80) and 8 g of Centromix E (lysolecithin) to 22g of a 50:50 mixture of peanut oil and miglyol which had been well premixed. This oil/surfactant mixture was then mixed into 120g of a 3:1 aqueous: ethanol solution using a Silverson rotor stator mixer and mixed for 2 minutes at 12,000rpm to form a pre-emulsion. The pre-emulsion was then homogenized with a microfluidizer at 1000 bar and 5 passes. The obtained nano-emulsion has a particle size of 45nm, high optical clarity, and no change in particle size or optical clarity during 100-day storage.

This formulation works equally well when the following substitutions are made:

polyoxyethylene surfactant: tween40, Tween60 and Tween 80.

Oil: canola oil, rapeseed oil, fish oil, sunflower oil, and linseed oil.

Ethanol content: the content of water phase ethanol is 20-50%.

And (3) replacing: the additional oil, miglyol, may be replaced by any mutually miscible oil including tributyrin, tricaprylin, triacetin, limonene, orange oil, lemon oil, decane, tetradecane and hexadecane.

Example 7: flavor oil nanoemulsion examples

Clear orange oil flavor concentrate

The orange flavor oil nanoemulsion was prepared as follows: first, 9g of orange oil was thoroughly mixed with 11.5 g of peanut oil. To this mixture of orange oil/peanut oil 8 grams of polyoxyethylene sorbitan monooleate (Tween80) and 5 grams of Emultop IP (lysolecithin) were added. This oil/emulsifier mixture was then mixed into 120g of a 3:1 aqueous: ethanol solution using a Silverson rotor stator mixer and mixed for 2 minutes at 12,000rpm to form a pre-emulsion. The pre-emulsion was then homogenized with a microfluidizer at 1000 bar and 5 passes. The obtained orange flavor nanoemulsion has a particle size of 45nm and high optical clarity. This orange flavor oil nanoemulsion was added to soda at 0.01 wt% to produce orange flavored soda.

Comparative example

Table 1: summary of particle size, clarity and physical stability of the dispersion formulations using medium chain triglyceride miglyol architecture

Comparative example 8: oil-in-water type nano dispersion of medium chain triglyceride

Preparation:

part a — nanodispersion: mix Miglyol812 and polysorbate 80. Soy lecithin was dissolved in ethanol and added to this mixture with stirring in a magnetic stir hood. The resulting solution was a clear homogeneous liquid indicating the formation of a nanodispersion.

Part B-dilution with water: this solution was diluted with water at 50 ℃ to 10% oil content to form a cloudy white dispersion with an average particle size of 2 microns, indicating that a regular size emulsion was formed.

Comparative example 9: medium chain triglyceride nanoemulsion

Medium chain triglyceride nanoemulsions were prepared by adding 8 grams of polyoxyethylene sorbitan monoester (Tween80) and 8 grams of CentromixE (lysolecithin) to 22 grams of miglyol812, which had been well premixed. This oil/surfactant mixture was then mixed into 120g of a 3:1 aqueous: ethanol solution using a Silverson rotor stator mixer and mixed for 2 minutes at 12,000rpm to form a pre-emulsion. Then the pre-emulsion is treated with a microfluidizer^TMHomogenization was performed at 1000 bar and 5 passes. The resulting nanoemulsion had a primary particle size of 45nm and initially had high optical clarity. However, this nanoemulsion is not stable to austenite ripening and its particle size increases to the point where the nanoemulsion loses clarity within a few weeks, see fig. 1.

Comparative example 10: medium chain triglyceride nanoemulsion Using Tween80

Medium chain triglyceride nanoemulsion was prepared as follows: 24 g of polyoxyethylene sorbitan monoester (Tween80) was added to 23.5g of miglyol 812. This oil/surfactant mixture was then mixed into 120g of water with a silverson rotor stator mixer and mixed for 2 minutes at 12,000rpm to form a pre-emulsion. Then the pre-emulsion is treated with a microfluidizer^TMHomogenization was performed at 1000 bar and 5 passes. The resulting dispersion had a clear bluish color and a particle size of 60nm, indicating the formation of high clarity nanoemulsion of medium chain triglycerides. However, this nanoemulsion is not stable to austenite ripening and its particle size increases over several weeks to the point where the nanoemulsion loses clarity over four weeks.

Bioactive substance delivery examples

Example 11: resveratrol nanoemulsion

A nutritional supplement is prepared by mixing powdered resveratrol with a clarified triglyceride nanoemulsion. Briefly, 300mg of high purity resveratrol was mixed with 100ml of the nanoemulsion formulated according to any of examples 1-3 by stirring at room temperature for 4 hours. The resulting solution was clear with no evidence of insoluble resveratrol particles, indicating that the nanoemulsion dissolved resveratrol.

This formulation works equally well when the following substitutions are made:

resveratrol is added as a solid powder to the emulsion ingredient mixture or dissolved/dispersed in one of the ingredients before pre-emulsion formation or immediately before microfluidization treatment.

Example 12: plant sterol nano emulsion

The nutritional supplement was prepared as follows: powdered plant sterol was dispersed and heated above 100 ℃ with the oil phase ingredients (triglyceride oil, surfactant and/or co-surfactant) of examples 1-7. This solution of phytosterols, oil and surfactant was then mixed into 120g of a 3:1 aqueous: ethanol solution using a Silverson rotor stator mixer and mixed for 2 minutes at 12,000rpm to form a pre-emulsion. Then the pre-emulsion is treated with a microfluidizer^TMHomogenization was performed at 1000 bar and 5 passes. The obtained nanoemulsion had a primary particle size of 45nm and high optical clarity. HPLC analysis showed that the so prepared nanoemulsion has a much greater capacity to solubilize than the oil, or emulsion of normal size, fig. 3.

Example 13: beta-carotene nanoemulsion

Nutritional supplements or natural colorants are prepared by nanoemulsification of beta-carotene dissolved/dispersed in triglyceride oils. 23g of beta-carotene loaded oil (e.g., olive oil containing Betatene 30%) was mixed well with 8 g of polyoxyethylene sorbitan monooleate (Tween80) and 8 g of Centromix E (lysolecithin). This oil/surfactant mixture was then mixed into 120g of a 3:1 aqueous: ethanol solution using a Silverson rotor stator mixer, mixing at 12,000rpmFor 2 minutes to form a pre-emulsion. Then the pre-emulsion is treated with a microfluidizer^TMHomogenization was performed at 1000 bar and 5 passes. The obtained nano-emulsion has a particle size of 50nm, high optical clarity, natural deep red color, and no change in particle size within 30 days of storage.

Example 14: lutein nano-emulsion

A nutritional supplement or natural colorant is prepared by nanoemulsifying a mixture of lutein and lutein esters dissolved/dispersed in triglyceride oil. 23g of lutein/lutein ester loaded oil (e.g., olive oil with Xangold15%, from Cognis) was mixed well with 8 g of polyoxyethylene sorbitan monooleate (Tween80) and 8 g of Centromix E (lysolecithin). This oil/surfactant mixture was then mixed into 120g of a 3:1 aqueous: ethanol solution using a Silverson rotor stator mixer and mixed for 2 minutes at 12,000rpm to form a pre-emulsion. Then the pre-emulsion is treated with a microfluidizer^TMHomogenization was performed at 1000 bar and 5 passes. The obtained nano-emulsion has a particle size of 50nm, high optical clarity, natural deep orange yellow color, and no change in particle size within 30 days of storage.

Example 15: nano emulsion of retinyl palmitate

Nutritional supplements, natural colorants, or cosmetic ingredients are prepared by nanoemulsifying a 1:1 mixture of a retinyl palmitate-containing oil and a vegetable oil. Briefly, 12G of retinyl palmitate loaded sunflower oil (e.g., vitamin a-palmitate 1.0Mio IU/G, BASF) and 12G of sunflower oil were mixed well with 8G of polyoxyethylene sorbitan monooleate (Tween80) and 8G of Centromix E (lysolecithin). This oil/surfactant mixture was then mixed into 120g of a 3:1 aqueous: ethanol solution using a Silverson rotor stator mixer and mixed for 2 minutes at 12,000rpm to form a pre-emulsion. Then the pre-emulsion is treated with a microfluidizer^TMHomogenization was performed at 1000 bar and 5 passes. The obtained nanoemulsion has a particle size of 50nm, high optical clarity, natural yellow color, and shelf life of 100 daysThe inner particle size was not changed.

The tuna oil embodiment described above can also be used as a bioactive substance embodiment, since tuna oil is a bioactive substance.

In this specification, unless the context requires otherwise, due to implication of express language, the word "comprise", or variations such as "comprises" or "comprising", is used in an inclusive sense, i.e. to specify the presence of the stated features in various embodiments of the invention but not to preclude the presence or addition of further features.

It will be appreciated by those skilled in the art that variations may be constructed without departing from the spirit and scope of the invention.

Claims (29)

1. A method of preparing an oil-in-water nanoemulsion, comprising:

(i) adding a hydrophilic nonionic surfactant having a hydrophilic-lipophilic balance HLB of greater than 7 to up to 40% by volume of an oil phase comprising at least 50% by volume of triglycerides with fatty acid chain lengths of 12 or more carbon atoms;

(ii) (ii) mixing the product of step (i) with water to form a pre-emulsion; and

(iii) (iii) subjecting the pre-emulsion of step (ii) to homogenization to produce a nanoemulsion having an average particle size value of oil droplets of less than 100nm and a surfactant to oil ratio of less than 1: 1.

2. The process of claim 1, wherein step (ii) is carried out using a Silverson rotor-stator mixer.

3. The process of claim 2, wherein the Silverson rotor-stator mixer is operated at 12,000rpm for 2 minutes.

4. The process of claim 1, wherein the homogenization of step (iii) is a high shear homogenization.

5. The method of claim 1, wherein the homogenization of step (iii) is performed in a microfluidizer or a high pressure homogenizer.

6. The method of claim 5, wherein the microfluidizer is a Microfluidics M-110Y microfluidizer manufactured by MFIC Corporation.

7. The method of claim 5, wherein the high pressure homogenizer is produced by Gauline, Avestin, or Niro Soavi.

8. The process of claim 1, wherein the homogenization of step (iii) is carried out at a pressure of 1000 bar.

9. The process of claim 8, wherein the homogenizing of step (iii) comprises 5 passes through a homogenizing device.

10. The method of claim 1, wherein the oil droplets of the nanoemulsion have a diameter of 80nm or less, 75nm or less, or 60nm or less.

11. The method of claim 1, wherein the triglyceride is of chain length C_12-24Long chain triglycerides of (4).

12. The method of claim 11, wherein the long chain triglycerides are fish oil, cod liver oil, whale oil, lard, tallow, chicken oil, and milk fat; of vegetable origin, such as canola oil, castor oil, cocoa butter, coconut oil, coffee seed oil, corn oil, cottonseed oil, evening primrose oil, grape seed oil, linseed oil, menhaden oil, mustard oil, olive oil, palm kernel oil, peanut oil, poppy seed oil, rapeseed oil, rice bran oil, safflower oil, sesame oil, soybean oil, sunflower oil, palm kernel oil, hazelnut oil, sesame oil, wheat germ oil, vegetable oils, synthetic triglycerides, fractionated triglycerides, modified triglycerides, hydrogenated triglycerides, partially hydrogenated triglycerides or mixtures thereof.

13. The process of claim 1, wherein the oil phase of step (i) comprises one or more additional oils.

14. The method of claim 13, wherein the additional oil is a short chain triglyceride, a mineral oil, or a fragrance oil.

15. The method of claim 13, wherein the ratio of triglyceride to additional oil is 1:0 to 1: 1.

16. The method of claim 1, wherein the total amount of oil, including triglycerides and additional oil if present, in the nanoemulsion is 0.01-70 wt.%, 0.01-50 wt.%, or 0.01-40 wt.%.

17. The method of claim 1, wherein the hydrophilic nonionic surfactant is selected from the group consisting of polysorbates, polyethylene glycol alkyl ethers, sugar esters, polyethoxylated fatty acids, polyoxyethylene-polyoxypropylene block copolymers, polyethylene glycol alkylphenol surfactants, citric acid esters of monoglycerides, polyglycerol esters, polyethoxylated fatty acid diesters, PEG-fatty acid mono-and diesters, polyethylene glycol glycerol fatty acid esters, and alcohol oil transesterification products, or mixtures thereof.

18. The method of claim 1, wherein the amount of hydrophilic surfactant is 0.1-15 wt%, 1-10 wt%, or 3-7 wt%.

19. The process of claim 1, wherein the aqueous phase of step (ii) further comprises a co-solvent.

20. The method of claim 19, wherein the co-solvent is C₁-C₁₀Alcohols or long chain fatty alcohols.

21. The method of claim 20, wherein said C₁-C₁₀The alcohol is ethanol.

22. The method of claim 19, wherein the amount of co-solvent is 0-70 wt%, 0-50 wt%, or 15-45 wt%.

23. The method of claim 1, wherein a co-surfactant is also added to step (ii).

24. The method of claim 23, wherein the amount of co-surfactant is 0.1 to 15 wt%.

25. The method of claim 23, wherein the co-surfactant is present in a ratio of 0:1 to 2:1, 0:1 to 1.3:1, or 0.5:1 to 1.3:1 relative to the hydrophilic nonionic surfactant.

26. The process of claim 1, wherein the balance of water in the aqueous phase of step (ii) is 50-100 wt.%, 40-99.99 wt.%, or 30-99.90 wt.%.

27. The method of claim 1, wherein the components of the nanoemulsion are food-grade or pharmaceutical-grade.

28. The method of claim 1, wherein an active ingredient is also added to step (i).

29. The method of claim 28, wherein the active ingredient is selected from the group consisting of food supplements, food additives, fragrances, essential oils, pigments, flavors, sweeteners, cosmetics, pharmaceuticals, nutraceuticals, phytochemicals, vitamins, essential polyunsaturated fatty acids, plant extracts, agrochemicals, textiles, polymers, and chemicals.