CLIAMS:A stable colloidal nano-carrier for cosmetics and dermatological application comprising
a) oils in an amount ranging from 5% to 40% by weight;
b) emulsifier in an amount ranging from 0.1% to 5% by weight
c) lipid in an amount ranging from 0.02 to 5 % by weight; and
d) water
such that particle size of the colloidal nano-carrier ranges between 50-300 nm.
2. The stable colloidal nano-carrier for cosmetics and dermatological application as claimed in claim 1, wherein particle size of the colloidal nano-carrier ranges from 50 to 300 nm, more preferably 75-250 nm.
3. The stable colloidal nano-carrier for cosmetics and dermatological application as claimed in claim 1, wherein said oil are selected from synthetic and natural oils.
4. The stable colloidal nano-carrier for cosmetics and dermatological application as claimed in claim 3, wherein synthetic and natural oil selected from Helianthus Annuus (Sunflower) Seed Oil, Oryza Sativa (Rice) Bran Oil, Sesamum Indicum (Sesame) Seed Oil, Glycine Soja (Soybean) Oil, Olea Europaea (Olive) Oil, mineral oil, almond oil, jojoba oil wheat germ oil and their mixtures thereof.
5. The stable colloidal nano-carrier for cosmetics and dermatological application as claimed in claim 1, wherein said emulsifier is selected from esters of tribehenin PEG, cetyl alcohol, stearic acid, sorbitan laurate, sucrose cocoate, sorbitan olivate, cetearyl olivate, and mixture thereof.
6. The stable colloidal nano-carrier for cosmetics and dermatological application as claimed in claim 1, wherein said lipid is lecithin of natural or synthetic origin.
7. The stable colloidal nano-carrier for cosmetics and dermatological application as claimed in claim 1, wherein said oil is from 10% to 30% by weight.
8. The stable colloidal nano-carrier for cosmetics and dermatological application as claimed in claim 1, wherein said emulsifier is from 0.25% to 3% by weight.
9. The stable colloidal nano-carrier for cosmetics and dermatological application as claimed in claim 1, wherein said lipid is from 0.125% to 2.5% by weight.
10. A process for the preparation of stable colloid nano-carrier comprising steps of
a) weighing oil or mixture of oils and emulsifier in a container and melting it at a high temperature;
b) pouring the melted mixtures as obtained in (a), into water (cold or hot) while homogenizing it and continuing the process of homogenization for a specific time;
c) pouring the pre-homogenized mixture as obtained in (b) into a high pressure homogenizer and passing the same at a pressure for a specific number of cycles to get the colloidal dispersion; and
d) achieving particle size of 50-300 nm for the nano-colloidal dispersion.

11. A process for the preparation of stable colloid nano-carrier comprising steps of
a) weighing oil or mixture of oils and emulsifier in a container and melting it at a high temperature;
b) pouring water (cold or hot) into the melted mixtures as obtained in (a) while homogenizing it and continuing the process of homogenization for a specific time;
c) pouring the pre-homogenized mixture as obtained in (b) into a high pressure homogenizer and passing the same at a pressure for a specific number of cycles to get the colloidal dispersion; and
d) achieving particle size of 50-300 nm for the nano-colloidal dispersion.

12. The process as claimed in claims 10 or 11, wherein melting of oils and emulsifiers is carried out at temperature ranging from 45-80°C.
13. The process as claimed in claims 10 or 11, wherein oils and emulsifiers are homogenized at a speed of 5000-8000 rpm.
14. The process as claimed in claims 10 or 11, wherein oils and emulsifiers are homogenized for 10-40 minutes.
15. The process as claimed in claims 10 or 11, wherein the pressure of homogenizing ranges from 100-600 pressure (MPa).
16. The process as claimed in claims 10 or 11, wherein the specific number of cycles to get the colloidal dispersion is 20. ,TagSPECI:FIELD OF THE INVENTION
The invention relates to a stable colloidal nano-carrier and the process for preparing the same. More particularly it relates to a stable colloidal nano-carrier for cosmetics and dermatological application.
BACKGROUND AND PRIOR ART OF THE INVENTION
Skin is the largest organ of the human body, which safe guards the body from external environmental effects. Skin barrier function is essential for survival and is critical to preventing body from percutaneous entry of foreign mater into skin; trans epidermal water loss, microbial attack. Therefore the skin itself provides a natural barrier against particle penetration for topical delivery of active ingredients from cosmetic and pharmaceutical formulations. To overcome this barrier function of skin against the delivery of cosmetics ingredients into skin, prior art teaches us uses of emulsion, micro-emulsion, nano-emulsion, liposome and other lipid based and polymeric delivery systems.

Physicochemical properties of nanostructured lipid carriers as colloidal carrier system stabilized with polysorbate 20 and polysorbate 80, African Journal of Biotechnology Vol. 10(9), pp. 1684-1689, 28 February, 2011. Chee Wun How, Rasedee Abdullah, Roghayeh Abbasalipourkabir. In this document How et.al discloses nanostructured lipid carriers (NLC), a colloidal carrier system which offer many advantages as drug carrier. The document further discloses that incorporation of liquid lipid can improve the loading capacity of drugs in the NLCs. The NLC20 and NLC80 were produced by high-pressure homogenization technique, stabilized with emulsifiers such as polysorbate 20 and polysorbate 80, respectively. Page 1685, first column of this document discloses preparation of NLC where the lipid matrices are composed of hydrogenated palm oil, Lipoid S100 and olive oil at the ratio of 7:3:3. The mixtures were heated to approximately 10°C above the melting point of the lipid matrices to avoid lipid memory effect. After stirring with a teflon-coated magnet, a yellowish-milky solution was obtained. Thereafter Sorbitol, surfactant and thimerosal of 4.75, 1.0 and 0.005%, respectively, were dissolved in bi-distilled water. Subsequently, this aqueous surfactant was heated to the same temperature as that of the lipid matrices. Nanostructured lipid nanoparticles containing 5% of lipid matrices were then dispersed into aqueous surfactant mixture with high-speed stirring in Ultra-Turrax® at 13000 rpm for 10 min to produce a hot pre-emulsion. The hot pre-emulsions were then homogenized in a high-pressure homogenizer EmulsiFlex® at 1000 bar for 20 cycles using an optimized protocol. The emulsions were allowed to re-crystallize at room temperature to form NLC.
How et al., describes nano-structured lipid carriers (NLC) wherein the NLC having lipid matrix is prepared by combination of lipid and oil, melting them and making a dispersion of the same. The lipid matrix thus formed is not a stable system and hence the matrix is stabilized using an aqueous surfactant mixture.
Physico-chemical characterization of nano-emulsions in cosmetic matrix enriched on omega-3, Tin-hinan Kabri, Elmira Arab-Tehrany, Nabila Belhaj and Michel Linder, J Nanobiotechnology. 2011; 9: 41, Published online 2011 September 21. doi: 10.1186/1477-3155-9-41 (Kabri et. al). Kabri et. al discloses nano-emulsions are oil-in-water (O/W) or water-in-oil (W/O), transparent or translucent, colloidal dispersions, usually in the 20-500 nm size range. It discloses mixing the three oils (miglyol, rapeseed and salmon) in different proportions. The glycerol (3%) and tween 80 were separately mixed with water (55%) at 50°C and under vortex. The oil phase was added into aqueous phase and then the mixture was sonicated at 40 kHz to achieve a homogeneous solution. This solution is further subjected to high-pressure valve homogenizer Emulsiflex-C3 at 22,000 psi. It discloses the proportions of the various components in the emulsions as (wt):
• 30% of oily phase
• 12% of emulsifiants
• 3% glycerol
• 55% aqueous phase (water)

Kabri et. al describes transparent or translucent colloidal dispersions which is nano-emulsions (oil-in-water (O/W) or water-in-oil (W/O) type) usually in the 20-500 nm size range wherein the oil phase is added into aqueous phase and then the mixture is sonicated at 40 kHz to achieve a homogeneous solution. Kabri et. al describes preparation of nanoemulsion and it is well known state of the art that most of the nanoemulsion systems are unstable.
Despite having many advantages, the main limitation for developing application of nano-emulsions is their stability. Although it is generally accepted that these systems could remain stable even by years, however, due to the small droplet size, it has been reported that the Oswald ripening could damage nano-emulsions, causing their application to be limited.
The major limitation of adapting nano-emulsion is its limited stability. Stability of nano-emulsion is quite unacceptable and creates a big problem during the storage of formulation for the longer time period. Ostwald ripening is the main factor associated with unacceptability of nano-emulsion formulations. This is due to the high rate of curvature of small droplet show greater solubility as compared to large drop with a low radius of curvature.
The instability of nano-emulsion is due to some main factors including creaming flocculation, coalescence and Ostwald ripening [41]. Among them ostwald ripening is the main mechanism of nano-emulsion instability because rest of the problem are minimized by the small size of nano-emulsion and use of nonionic type of surfactant.
Lifshitz IM, Slezov VV. J, The kinetics of precipitation from supersaturated solid solutions, Phys Chem Solids, 1961; 19-35.
The only problem of instability of nano-emulsion can arise by the ostwald ripening. In ostwald ripening small droplets with high radius of curvature converted into large droplets with low radius of curvature .Two droplets diffuse and become one large droplet. Thus, after the storage for a long time period, droplets size distribution shifted to large sizes and the transparency of nano-emulsion become turbid. It is also identified that ostwald ripening create a problem dur­ing the delivery of formulations. Several theories have been suggested for the demonstration of ostwald ripening, among them LSW theory properly justified the factors affecting the ostwald ripening. Tadros et al demonstrated the addition of a small amount of insoluble oil (squalane) can reduce the diffusion of the smaller oil droplets from the small to the large droplet. Another method to prevent the effect of ost­wald ripening is addition of polymeric surfactant on the interface which increase the elasticity of droplets and fur­ther reduce the effect of ostwald ripening
Nano-emulsions obtained from the spontaneous nano-emulsification process are not thermodynamically stable, although they might have high kinetic energy and long-term colloidal stability.
A nano-emulsion is an emulsion which does not form spontaneously, but is instead formed by the application of shear to a mixture of oil, water and surfactant. Unlike micro-emulsions, nano-emulsions are kinetically stable and their particle size may increase over time via coalescence, flocculation and/or Ostwald ripening. The very small size of nano-emulsions makes them particularly prone to particle size growth by Ostwald ripening. An increase in emulsion particle size over time is disadvantageous as the emulsion will lose its clarity accompanied with a corresponding increase surface area.
The stability of nano-emulsions is quite unacceptable and produces a big problem during the storage of formulation for the longer time. Ostwald ripening is the main problem associated with unacceptability of nano-emulsions formulations. Ostwald ripening is due to the high rate of curvature of small droplet show greater solubility as compared to large drop with a low radius of curvature 49-50.
Lipid-based colloidal carriers for peptide and protein delivery – liposomes versus lipid nanoparticles, Susana Martins, Bruno Sarmento, Domingos C Ferreira and Eliana B Souto ; International Journal of Nanomedicine 2007:2(4) 595–607 (Martins et. al).
Martins et. al disclose that nanoparticles based on solid lipids (Solid Lipid Nanoparticle, Nanostructured Lipid Carrier) which have been proposed as an alternative colloidal drug delivery system to polymeric nano-particles, emulsions and liposomes. They are composed of solid lipids stabilized with an emulsifying layer in an aqueous dispersion, i.e., they resemble the nanoemulsions by replacing the inner liquid lipid with a solid lipid.
US 2006/0083781 A1 relates to functionalized solid lipid nanoparticles comprising a neutral lipid and a first functionalized polymer comprising at least one ionic or ionizable moiety and methods for providing same. [para 003] discloses that SLN prepared by conventional means generally require the use of surfactants or emulsifiers, typically fail to achieve stable aqueous suspensions, and/or fail to provide satisfactory surface functionalization. Therefore, there remains a need for methods and compositions that overcome these deficiencies and that effectively provide functionalized solid lipid nano-particles.
US 2006/0222716 A1: provides a drug carrier that includes a solid lipid nanoparticle (SLN), wherein the SLN includes tocopherol or a derivative thereof. [para 007] discloses that liposomes have poor stability properties. A prolonged release from liposomes is possible only to a limited extent, because identical redistribution processes of the active ingredient, and the metabolization of the phospholipids of the liposomes, limit the release time. The preparation of liposomes is also typically based on the use of toxic organic solvents, such as chloroform, and it may be difficult to eliminate the solvent completely. Further [para 013] discloses that SLNs built from waxes and/or glycerides have a high tendency for gelation during storage. Additionally, the solubility of many drugs in waxes and glycerides, particularly high-melting non-polar waxes and glycerides, is low. Initially-dissolved active components often separate from the lipid phase during storage, due to crystallization of either the lipid or the active components themselves. This is one of the main reasons for the physical instability of drug-loaded SLNs and nanoparticulate lipid conjugates (NLC).
Kumar, Sacheen et. al, (High melting lipid based approach for drug delivery: Solid lipid nanoparticles. Materials Science and Engineering: C, In Press, Corrected Proof, Jan 2013 doi:10.1016/j.msec.2013.01.037); teaches solid lipid nanoparticles production, stability, and characterization, differentiation based on route, preservation and storage.
Lipid technology- a promising drug delivery system for poorly water soluble drugs solid lipid nanoparticles, International Journal of Pharma Research and Development, Devesh Ashvin Bhatt and A. M. Pethe. Online, Publication Ref No.: IJPRD/ 2010/ PUB/ ARTI/ VOV-2/ ISSUE-7/SEP/002, ISSN 0974 – 9446, teaches various lipid systems.
Bhatt and Pethe et. al, discloses Solid Lipid Nanoparticles, its advantages and method of preparation. Accordingly to this publication SLN are prepared from solid lipids. They are submicron colloidal carriers (50-1000nm) which are composed generally of lipid dispersed in water or in an aqueous surfactant solution. The advantages of SLNs are:
• Their small size and relatively narrow size distribution permits size specific drug delivery.
• Controlled and sustained release of active drug can be achieved.
• The incorporated drug is protected from the onslaughts of biochemical degradation.
• Can be lyophilized.
• Relatively cheap and stable

The lipid nanoparticles were prepared by first melting the lipid and it was dispersed in a hot aqueous surfactant by stirring or ultrasonic treatment. Micro emulsion technique was used for the preparation of solid lipid nanoparticles. The hot micro emulsion containing the lipid was poured in to cold water leading to solidification of nanoparticles. SLNs facilitate prolonged drug release and possess lower cytotoxicity.
Similarly SLNs are known from SOLID LIPID NANOPARTICLES: A REVIEW, P. Ekambaram, A. Abdul Hasan Sathali and K.Priyanka, Sci. Revs. Chem. Commun.: 2(1), 2012, 80-102, ISSN 2277-2669, which discloses colloid nano particle carrier using lipids, oils, emulsifiers and water and possessing advantageous effect of stability, improved delivery of active.
Bhatt and Pethe et. al and P. Ekambaram et al., discloses Solid Lipid Nanoparticles, its advantages and method of preparation. However Solid Lipid Nanoparticles is highly unstable and there are various ways by which the Solid Lipid Nanoparticles are stabilized as detailed in the state of the art like: (a) lyophilization of the Solid Lipid Nanoparticles, (b) spray drying in the solid powder form, (c) coating the Solid Lipid Nanoparticles with polymers such as PEG derivatives, (d) altering surface characteristics using hydrophilic molecules that increases surface stability. Moreover the lipid matrix of nanostructured lipid carriers is also not a stable system and hence the matrix is stabilized using an aqueous surfactant mixture.
US2012/0201862 (US’862) discloses process for the preparation of colloidal systems, such as nanocapsules and nanoparticles, which incorporates a homogenization step for reducing particle size. The process for the preparation of colloidal systems of a size less than 1 µm comprises: a) providing a lipophilic phase comprising: a.1) at least, a phospholipid component; and a.2) an oil; and a.3) a biologically active lipophilic molecule; in the presence or in the absence of an organic solvent, b) providing an aqueous phase which comprises: b.1) chitosan or a derivative thereof; and b.2) a polyoxyalkylenated compound; c) mixing said lipophilic and aqueous phases so as to form an emulsion; d) subjecting said emulsion to a homogenization process to form nanocapsules having an average effective particle size of less than 1 µm; or alternatively, e) providing an aqueous solution comprising chitosan or a derivative thereof and, optionally a polymer selected from glucomannan, hyaluronic acid, a polyoxyalkylenated compound and derivatives thereof, f) providing an aqueous solution comprising a crosslinking agent and a biologically active molecule; g) mixing said both aqueous solutions so as to form an agglomerate; and h) subjecting said agglomerate to a homogenization process to form particles having an average effective particle size of less than 1 µm. US’862 use an organic solvent and chitosan to stabilize the colloidal system. It was found that the colloidal nano-carrier of the present invention possesses long-term stability and the most probable reason for its exceptional stability may due to unique combination of oils and emulsifier/s.
The major disadvantages of using conventional delivery systems are
Micro-emulsion
· Use of high surfactant level that limits the application of the same in cosmetics formulation
· Due to the presence of high surfactant concentration, the product perceived to be harsh
Nano-emulsion
· High temperature (Phase inversion PIT) that leads to limitation in incorporating temperature sensitive active ingredients in nano-emulsion
· Specialized surfactant
· Unstable system
Liposome
· Unstable system
Hence there is an utmost need for production of a stable delivery system that overcomes the disadvantages of the prior art.
OBJECTS OF THE INVENTION
The primary object of the present invention is to overcome the drawbacks of the prior art.
Another object of the present invention is to provide a stable colloidal nano-carrier for cosmetics and dermatological application.
Yet another object of the present invention is to provide a process for preparation of the sable colloidal nano-carrier.
SUMMARY OF THE PRESENT INVENTION
According to one aspect of the present invention, there is provided a composition of colloidal nano-carrier for cosmetics and dermatological application comprising
a) oils in an amount ranging from 5% to 40% by weight;
b) emulsifier in an amount ranging from 0.1% to 5% by weight
c) lipid in an amount ranging from 0.02 to 5% by weight; and
d) water
such that particle size of the colloidal nano-carrier ranges between 50-300 nm.
According to another aspect of the present invention, there is provided a process for the preparation of colloid nano-carrier comprising steps of
a) weighing oil or mixture of oils and emulsifier in a container and melting it at a high temperature;
b) pouring the melted mixtures as obtained in (a), into water (cold or hot) while homogenizing it and continuing the process of homogenization for a specific time;
c) pouring the pre-homogenized mixture as obtained in (b) into a high pressure homogenizer and passing the same at a pressure for a specific number of cycles to get the colloidal dispersion; and
d) achieving a particle size of 50-300 nm for the nano-colloidal dispersion.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 illustrates particle Size distribution of the colloidal dispersion.
Figure 2 illustrates the stability of the colloidal nano-carrier towards dilution (the particle size of the diluted samples was monitored during one to two week).
Figure 3 illustrates the kinetic stability of the colloidal nano-carrier towards storage at longer time (11 months).
Figure 4 illustrates delivery of actives ascorbic acid from Colloidal delivery system.
Figure 5 illustrates delivery of actives vitamin E from Colloidal delivery system.
Figure 6 illustrates time dependent particle size measurement of nano-emulsion of sample 2.
Figure 7 illustrates time dependent particle size measurement of nano-emulsion of Sample 3.
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a stable nano-carrier for cosmetic and dermatological application. The particle size of the colloidal nano-carrier of the present invention ranges between 50-300 nm, preferably from 75-250 nm.
The term “colloidal nano-carrier” as used herein means a particulate dispersion of oil and emulsifier/s in aqueous medium having size ranges between 50-300 nm (figure 1).
The colloidal nano-carrier of present invention comprises of oils, emulsifier, lipid and water.
Suitable oils are selected from but not limited to synthetic, natural oils and essential oil like Helianthus Annuus (Sunflower) Seed Oil, Oryza Sativa (Rice) Bran Oil, Sesamum Indicum (Sesame) Seed Oil, Glycine Soja (Soybean) Oil, Olea Europaea (Olive) Oil, mineral oil, coconut oil, apricot oil, cucumber seed oil, Macadamia nut oil, castor oil, grape seed oil, walnut oil, hazelnut oil, pomegranate seed oil, kiwi seed oil, Bisabolol oil, Raspberry Seed Oil, Cranberry Seed Oil, almond oil, jojoba oil, wheat germ oil and their mixtures thereof. Essential oils like Basil oil, Cedarwood oil, Chamomile German oil, Chamomile Roman oil, Cinnamon Leaf oil, Citronella oil, Clary Sage oil , Clove Leaf oil , Eucalyptus oil , Frankincense oil, Lemon oil, Lemon Grass oil, Mandarin oil, Orange oil (sweet), Patchouli oil, Peppermint oil, Rose oil, , Sandal oil, , Thyme oil, , Wintergreen oil, Ylang Ylang oil, Geranium oil, Ginger oil, Grape Fruit oil, Jasmine oil, Lavender oil, Rosemary oil, Tea Tree oil, Vetiver oil.

The preferable oil is rice bran oil, sun flower oil, olive oil and their mixture thereof.

The amount of oil ranges from 5% to 40% by weight, more preferably from 10% to 30% by weight, and most preferably is 20% by weight.

Suitable emulsifiers are selected but are not limited to esters of tribehenin PEG, cetyl alcohol, stearic acid, sorbitan laurate, sucrose cocoate, sorbitan olivate, cetearyl olivate, and their mixture thereof.
The amount of emulsifiers ranges from 0.1% to 5% by weight, more preferably from 0.25% to 3% by weight, and most preferably is 2% by weight.
The preferable emulsifiers are tribehenin ester of polyethylene glycol, sorbital oliviate, straric acid, cetyl alcohol and their mixture thereof.
The lipid which is suitably used in the present invention is lecithins having natural or synthetic origin.
The amount of lipid ranges from 0.02 to 5 % by weight, more preferably from 0.125% to 2.5% by weight, and most preferably is 1% by weight.
The process disclosed in the present invention provides stability to the colloidal nano-carrier and solves the disadvantages of having unstable delivery system as disclosed in figure 2 and 3.
The stable colloidal nano-carrier of the present invention finds its use in cosmetic and dermatological applications particularly in the care of skin, hair, area around eye and face etc.
Compositions in Skin Care:
· moisturizing cream or gel
· Anti-ageing cream or gel
· moisturizing face masks
· under eye cream or gel
· hand moisturizing cream or gel
· foot cream or gel
· moisturizing and nourishing mist
· component in face wash
Compositions in Hair Care:
· Conditioning hair gel or cream
· hair and scalp nourishing serum
· hair spray
In another embodiment of present invention the present invention discloses a process for the preparation of the colloidal nano-carrier comprising steps of:
· Making of lamellar gel structure by pouring water (cold or hot) into melted oil, emulsifier and lipid mixture under stirring conditions.

· Passing the lamellar gel through high pressure homogenizer (10-20 pass) to get a particle size ranging from 50 nm to 300 nm.

In an embodiment of the present invention colloidal nano-carrier is prepared by the addition of melted mixture in water. Oils or mixtures of oils are weighed and mixed with emulsifier in a container and then melted at high temperature. The molten mixture of oil and emulsifier is then mixed with water. The water can be hot or cold. The mixture is then homogenized for some time. This pre-homogenized mixture is then poured into a high pressure homogenizer. The colloidal dispersion obtained from the pre-homogenized mixture is by high pressure homogenization and passing the same at a pressure for a specific number of cycles.
In another embodiment of the present invention colloidal nano-carrier is prepared by the addition of water into the melted mixture. Oils or mixtures of oils are weighed and mixed with emulsifier in a container and then melted at high temperature. Water is then mixed with the molten mixture of oil and emulsifier. The water can be hot or cold. The mixture is then homogenized for some time. This pre-homogenized mixture is then poured into a high pressure homogenizer. The colloidal dispersion obtained from the pre-homogenized mixture is by high pressure homogenization and passing the same at a pressure for a specific number of cycles.

The temperature ranges from 45-75°C. The preferable range of temperature is from 50 to 60°C.
The process of homogenization takes place at a speed of 5000-8000 rpm. The preferable speed for the process of homogenization ranges from 5000 to 7000 rpm.
The time for which the process of homogenization takes place is from 10-40 minutes.
The process of high pressure homogenization takes place at 100-600 pressure, preferably at a pressure of 200 to 450.

The number of cycles required for obtaining colloidal dispersion is 20 which results in the particle size of the colloidal nano-carrier to range from 50-300 nm, preferably from 75-250 nm.

The process provided in the present invention as mentioned above in both the embodiments provides the same end product which is the colloidal nano-carrier. The two embodiments disclosed above exhibit that both oil (melted) and water can be mixed vice-versa. The two processes are alternative procedures. There is no critical difference in the process step of "pouring water on molten mixture" and "pouring molten mixture into water". These two steps can be used interchangeably.

Further in accordance to the present invention there is provided process steps for the incorporation of an active ingredient into the colloidal nano-carrier. Oils or mixtures of oils are weighed and mixed with emulsifier in a container and then melted at high temperature. The active ingredient and water are weighed in a container. Water is then mixed with the molten mixture of oil and emulsifier or vice-versa. The water can be hot or cold. The mixture is then homogenized for some time. This pre-homogenized mixture is then poured into a high pressure homogenizer. The colloidal dispersion obtained from the pre-homogenized mixture is by high pressure homogenization and passing the same at a pressure for a specific number of cycles.

The present invention is now illustrated by way of non limiting examples.

Example 1: Process for the preparation of colloidal nano-carrier where melted mixture is added to water:

Step 1: Weigh 10 gm oil/s (Rice bran oil, sunflower oil, olive oil or their mixture) in a container
Step 2: Weigh 1 gm each of PEG-20 ester of tribehenic acid and lecithin and add them in the oil mixture as obtained in step 1and melt them at 45-80°C.
Step 3: Weigh water (QS to 100) in a container and pour the melted mixtures as obtained in 2, into it (either cold or hot) while homogenizing at 5000-8000 rpm. Continue homogenization for 10-40 mins
Step 3: Pour the pre-homogenized mixture as obtained in 3 into a high pressure homogenizer and pass the same at 100-600 pressure (MPa) for 20 cycles to get the colloidal nano-carrier
Step 4: The particle size of the final colloidal dispersion was determined to be 50-300 nm

Example 2: Process for the preparation of colloidal nano-carrier where water is added to molted mixture:

Step 1: Weigh 10 gm oil/s (Rice bran oil, sunflower oil, olive oil or their mixture) in a container
Step 2: Weigh 1 gm each of PEG-20 ester of tribehenic acid and lecithin and add them in the oil mixture as obtained in step 1 and melt them at 45-80°C.
Step 3: Weigh water (QS to 100) in a container and pour the water in the melted mixtures as obtained in 2, into it (either cold or hot) while homogenizing at 5000-8000 rpm. Continue homogenization for 10-40 mins
Step 3: Pour the pre-homogenized mixture as obtained in 3 into a high pressure homogenizer and pass the same at 100-600 pressure (MPa) for 20 cycles to get the colloidal nano-carrier
Step 4: The particle size of the final colloidal dispersion was determined to be 50-300 nm

Example 3: Incorporation of active ingredients (Vitamin C) into nano carrier:

Step 1: Weigh 10 gm oil/s (Rice bran oil, sunflower oil, olive oil or their mixture) in a container
Step 2: Weigh 1 gm each of PEG-20 ester of tribehenic acid and lecithin and add them in the oil mixture as obtained in step 1 and melt them at 45-80°C.
Step 3: Weigh water (QS to 100) in a container
Step 4. Weigh vitamin C and add in the water as mentioned in step 3
Step 5. Pour the water and active mixture as obtained in step 4 in the melted mixtures as obtained in 2, while homogenizing at 5000-8000 rpm. Continue homogenization for 10-40 mins
Step 6: Pour the pre-homogenized mixture as obtained in 3 into a high pressure homogenizer and pass the same at 100-600 pressure for 20 cycles to get the colloidal nano-carrier
Step 7: The particle size of the final colloidal dispersion was determined to be 50-300 nm

Example 4: Protocol for the delivery of actives into skin from Colloidal Delivery System (CDS): Measurement of Antioxidant Activity in different depth from skin surface:
Colooidal delivery systems (CDS) containing 1 wt% ascorbic acid (AsA) (Figure 4) and 1 wt% vitamin E (Vit E) (figure 5) were prepared following the process disclosed in the present invention and penetration of the actives into skin were assessed from the measurement of antioxidant activity using DPPH assay. The skin samples were collected post use of the CDS using tape-stripping method. The protocol for the same is given below:
· Four regions of 2´2 cm2 were marked on volar fore arm.
· 20 µg of each CDS formulations containing either AsA or Vit E were applied on the respective site & massaged 20 times clock wise and 20 times anti clock wise (using finger).
· After 15-20 min post application of CDS formulations, the sample applied sites were washed with distilled water (10 times clock wise & 10 times anti-clock wise using finger).
· 4 consecutive samples were collected from each site using four different adhesive tape of 2´2 cm2 (tape stripping).
· The tape containing skin sample was kept in eppendorf tubes with 0.5 ml Phosphate buffer having pH 7.2. For Vitamin E, the tape containing skin samples was inserted into methanol.
· The tapes were vortexed to extract the water and oil soluble components in tape strip skin sample and analyzed for anti-oxidant activity using DPPH assay.
· The anti-oxidant activity that comes from Ascorbic acid and Vitamin E that has been penetrated in skin was quantified through free radical scavenging activity (DPPH assay by measuring the absorbance at 520nm).

Observation: The results obtained are shown in Figure 3 showing delivery of actives (ascorbic acid and Vitamin E) from colloidal delivery system. It is evident that formulations of current invention provided superior delivery of antioxidants in the dipper layer of skin.
Example 5: Process of preparation of skin moisturizing gel:
Prepare the colloidal nano carrier following process as mentioned in example 2. The skin moisturizing gel was prepared using the following process

Step 1: Weigh 50gm water in a container and warm it to 50-60 C and add Xanthan gum to it with continuous stirring till until whole powder gets dispersed to gel.
Step 2: Weigh 32 gm of water in a container and add 3 mg of glycerin, 2mg of sorbitol, 0.5 mg of b-panthenol, 0.2 mg of sodium hyaluronate, 0.1 mg of Alpha-arbutin, 1mg of Ascorbyl glucoside and mix well under stirring.
Step 3: Weigh the colloidal nano carrier as prepared in example 2 and add it into the mixture as obtained in step 2.
Step 4: Add Xanthan gum mixture of step 1 to the mixture obtained in step 3 and homogenized around 5000 to 10,000 rpm to get a gel structure.

Example 6: Skin moisturizing gel composition:
Table: 1
S No Ingredients Weight (gm)
1 Colloidal nano-carrier system* 10
2 Glycerol 3
3 Sorbitol 2
4 Sodium hyaluronate 0.2
5 b-Panthenol 0.5
6 Xanthan gum 0.6
7 Alpha-arbutin 0.1
8 Ascorbyl glucoside 1
9 Water qs to 100

*Colloidal nano-carrier system

Table: 2
S No Ingredients Weight (gm)
1 PEG-20 ester of tribehenic acid 0.2
2 lipid 0.2
3 Rice bran oil 1
4 Sunflower oil 1
5 Water qs to 100

Example 7: The stability of the colloidal nano-carrier towards dilution (the particle size of the diluted samples were monitored during one to two week)
Dilution Stress:
A colloidal suspension of 2% Tribehenin PEG ester, 2% Lecithin, 10 % Sunflower oil and 10% rice bran oil was prepared. To check the dilution stress of the suspension, various dilutions of the suspension was prepared as given in table and the physical observation as well as size was measured. For the size measurement, 1% solution was prepared and taken for the analysis.
Table: 3
S.No Dilution Physical Observation (After 7 days at RT) Size (nm)
1 As such Homogenous; No phase separation 245
2 2 times Homogenous; No phase separation 198
3 4 times Homogenous; No phase separation 216
4 6 times Homogenous; No phase separation 193
5 8 times Homogenous; No phase separation 176
6 10 times Homogenous; No phase separation 211

Observation: Variation of the size of colloidal nano-carrier was found to be constant within the limits of ±10% as evident from figure 2. System remains as it is without showing any sign of phase separation.

Process for the preparation of colloidal nano-carrier:

Step 1: Weigh 10 gm oil/s (Rice bran oil, sunflower oil, olive oil or their mixture) in a container
Step 2: Weigh 1 gm each of PEG-20 ester of tribehenic acid and lecithin and add them in the oil mixture as obtained in step 1and melt them at 70-80°C.
Step 3: Weigh water (QS to 100) in a container and pour the melted mixtures as obtained in 2, into it (either cold or hot) while homogenizing at 5000-8000 rpm. Continue homogenization for 10-40 mins
Step 3: Pour the pre-homogenized mixture as obtained in 3 into a high pressure homogenizer and pass the same at 100-600 pressure for 20 cycles to get the colloidal nano carrier
Step 4: The particle size of the final colloidal dispersion was determined to be 50-300 nm

The process disclosed above provides the stable colloidal nano-carrier.

Example 8: The kinetic stability of the colloidal nano-carrier towards storage at longer time (11 months)
Table: 4
Time (Months) Size (nm)
0 167
4 179
11 169

Observation: Variation of the size of colloidal nano-carrier was found to be constant within the limits of ±10% as clear from figure 3. System remains as it is without showing any sign of phase separation.

Process for the preparation of colloidal nano-carrier:

Step 1: Weigh 10 gm oil/s (Rice bran oil, sunflower oil, olive oil or their mixture) in a container
Step 2: Weigh 1 gm each of PEG-20 ester of tribehenic acid and lecithin and add them in the oil mixture as obtained in step 1and melt them at 70-80C.
Step 3: Weigh water (QS to 100) in a container and pour the melted mixtures as obtained in 2, into it (either cold or hot) while homogenizing at 5000-8000 rpm. Continue homogenization for 10-40 mins
Step 3: Pour the pre-homogenized mixture as obtained in 3 into a high pressure homogenizer and pass the same at 100-600 pressure (MPa) for 20 cycles to get the colloidal nano-carrier
Step 4: The particle size of the final colloidal dispersion was determined to be 50-300 nm

The process disclosed above provides the stable colloidal nano-carrier.

Example 9: Comparative data demonstrating the advantageous features of the present invention in view of the prior Art- “Transdermal delivery of anticancer drug caffeine from water-in-oil nano-emulsions”, Colloids and Surfaces B: Biointerfaces Vol 74 (2010) 356-362.

Table 5:

Sample no. Oil (Isopropyl Myristate) Surfactant (Tween 20) Polyol (Sorbitol) Water Observations Initial Particle Size (nm) Remarks
1 1 20 20 59 Transparent solution with 98.5% transparency (1-3) -Remains transparent under storage condition at RT and elevated temperature (60°C)
2 7 20 20 53 Unstable emulsion formation >1000 -Average particle size was found to > 1000 nm.-Phase separated immediately at RT.
3 3 20 20 57 Nanoemulsion formation (200-350) -Particle size increase with time and after 120 minutes become polydispersed while stored at RT.-After 48 hours the average particle size increased to 1500-2500 nm while stored at RT.-Samples were phase separated, within, when stored at 60°C.
4 5 20 20 55

5. Oil (Rice bran oil, Sunflower oil)20 Surfactant (PEG-20 ester of tribehenic acid)0.2 Lipid0.2 qs to 100 Nano-carrier of the present invention 200 Free flowing milky system that remains stable under storage condition at RT and elevated temperature (60°C)

Process of preparation of the conventional nano-emulsion:
Step 1: Weight the required amount of surfactant (Tween-20) in a container
Step 2: Weigh required amount of polyol (sorbitol) and add it the container mentioned in step 1 and mix it for 5-20 minutes with a stirrer at 100-500 rpm
Step 3: Weigh the required amount of oil (isopropyl myristate) and add it to the mixture obtained from step 2 under stirring condition. Mix the whole mixture thorough until a homogeneous mixture is obtained.
Step 4: Weigh the required amount of water and add it to the mixture obtained from step 3 and mix it for 10-30 minutes to obtain the nanoemulsion
Step 5: Collect the sample and measure the particle size in the Zeta Trac from Metrom.

Observation: The nano-emusion obtained was very unstable under storage condition. The particle size of the nano-emulsion changed from 350 nm to 1637 nm and the system become turbid (white in color) and finally phase separated as disclosed in figure 6 and 7.

Example 10: Criticality of the particle size range:
Table 6:
Particle size range (nm) 50-300 (nm) Less than 50 (nm) More than 300 (nm)
Ingredients % w/w % w/w % w/w
PEG-20 ester of tribehenic acid 0.2 6 6
lipid 0.2 6 8
Rice bran oil 10 2 24
Sunflower oil 10 2 24
Water qs to 100 qs to 100 qs to 100
Observation A Stable free flowing milky white system formed An unstable system formed A viscous system formed whose particle size >300 nm