This article is an adaptation and translation of our previously published article in Summer 2019 edition of Industria Cosmetica Magazine. Find original article here.
Introduction
The cosmetics and personal care business, like everything in this life, is under continuous change, and what attracted the consumer yesterday, might be getting old today, and tomorrow lose its value. We cannot sit and chill (without it affecting the health of our business).
We can all agree that among the aspects that concern cosmetic brands the most, stability, efficacy and safety of their formulas are at the top of the pyramid. As expected, these 3 aspects are closely linked to the active ingredients in these formulas, since in most cases the active ingredients must be stable at the time of storage, in order to ensure their efficacy and safety In the consumer. We have all ever happened to buy a product that has a changing smell over time (not in a good way), has separated in different phases or darkens over time. Ok, it's true, we all like to think that the purchased product from the shelf of our favorite shop or our favorite e-commerce is going to comply with what their "reviews" say and it's going to take away, for example, those little extra aging wrinkles. Unfortunately, many of the active ingredients that serve the brands as a commercial claim, will lose part of their properties during the production and storage of the cosmetic formula, due among other reasons, to its destabilization and probable degradation (and this you know if you work actively in this business). When an active ingredient degrades, creates a residue that 1) is inert (useless, ineffective) or 2) has an unknown biological activity (which can be benign, toxic or irritating).
Let's get to the point. Yes, encapsulation. In this article we would like to present problems with which many cosmetic professionals find theirselves and explain how to solve them through the use of encapsulation technologies. Unfortunately, it is against us the fact that encapsulation is still a fairly unknown concept for many people in the cosmetics business [but it is our mission to change this :)] and we believe that as experts, it is worthy investing some time in creating a document that, above all, informs.
Let's start from scratch:
What is an encapsulate or a cosmetic encapsulation?
It is the physical-chemical technique or process by which a cosmetic ingredient is protected and surrounded by a liposome or polymeric wall that isolates it from its environment. It also allows the controlled and sustained release of the active ingredient depending on external factors. Thus giving new sensory and physico-chemical properties to the active ingredient.
This article is addressed from two points of view, first of all, the encapsulator/manufacturer of encapsulates and second that of the cosmetic formulator, CMO or cosmetic brand.
The Encapsulator
Among the key aspects that a producer should take into account to launch a microencapsulate or nanoencapsulate into the mass market are:
- Reproducibility: It is key that the encapsulation is repeatable and reproducible both in the laboratory and during scale up in order to certify its quality and ensure its long-term presence in the market. Some encapsulation technologies or methodologies might present variability between batches such as particle size distribution, ionic charge, pH, etc. which need to be optimized prior to getting the products out in our potential customers cosmetic formulations.
- Compatibility: Before using an encapsulation it is necessary to ensure its compatibility with the cosmetic formula where it will be added. Otherwise, we might encounter problems of phase separation over time. In the same way we shall take into account that standard formulation and industrial processes must be checked and adapted to encapsulation technologies to ensure their compatibility. For example, when working with microencapsulates it is important to not use homogenizing and very high shear mixing techniques (aka ultraturrax and cowles agitation) as these could damage the microcapsules during formulation. If on the contrary we use nanoencapsulates, most likely these will resist homogenization techniques such as ultraturrax and/or cowles.
VIDEO 1. Mixing process of proprietary retinyl propionate capsules (CapsuretinolTM RP) into Cetaphil Moisturizing Lotion shows the immediate redispersion of the product at room temperature with low speed agitation into an o/w lotion.
- Stability: One of the main reasons for the use of encapsulation systems, both mili, micro and nano, is to increase the stability of active ingredients that 1) are easily degraded by the action of heat, light, moisture 2) evaporate easily, as fragrances or essential oils 3) are easily oxidized, as antioxidants (e.g. retinol, tocopherol) 4) precipitate/flocculate in contact with other ingredients. These phenomena of degradation can occur both during the storage and in the production process of the cosmetic formulation.
- Release: The protection of cosmetic active ingredients through encapsulation would make little sense if we were not able to release the active at the right time and at the right place to carry out its function. So it is crucial that our controlled release system carries out its function in a premeditated and humanly possible way. That is to say to release its content by friction, drying, enzymatic degradation, etc.
"There are a number of properties and concepts that must be understood in order to be able to choose wisely the encapsulate to be added in a cosmetic formula, which will bring along those unique properties"
- Skin penetration: It is well known that penetrating the epidermis, the outer layer of the skin, is not easy. The space between corneocytes (stratum corneum main skin cells) is made of fatty molecules, highly lipophilic, and not bigger than 75 nm in healthy skin. Therefore, most of hydrophilic actives and mini/microemulsions won't be able to penetrate to deeper layers. Nanoencapsulation of active ingredients can help improve the skin penetration of key active ingredients that would otherwise stay on the surface of the skin.
- Safety: Recently, with the advent of nanotechnologies, there has been a general euphoria and depression in equal parts. The promises and benefits of nanoencapsulation are often marred by fear of possible bioaccumulation toxicity. The best way to open up to new trends and overcome the fears of the unknown is the study, documentation and testing with toxicological studies in humans, both in vitro and in vivo. In this way both producers and buyers will be able to work in a more profitable and safe way. Nature is full of microencapsulates (cells, bacteria, natural emulsions) and nanoencapsulates (cellular organelles, viruses, ocean spray), so, why not create them ourselves responsibly to improve our daily beauty routine?
- Regulatory: In order to be able to commercially exploit an encapsulation, we will have to ensure that the ingredients that configure it are already introduced in the market where it is going to be marketed. It is important to be transparent in terms of not only the main ingredients but also the traces of monomers, catalysts, etc. used during the production process. Depending on their percentages the FDA, REACH, IECIC or the regulatory agency in question shall dictate how to declare them on a cosmetic label. For example, recently, formaldehyde and formaldehyde-releasing ingredients such as preservatives and polymers have been banned in the EU, Canada and Japan, among others, due to some studies showing potential skin carcinogenicity.
- Sustainability: This is an aspect that was often overlooked when it came to bringing an encapsulation to the market, but it is nowadays a key factor in producing a positive change on our planet. It is important to be aware of the biodegradability of the encapsulation system, the amount of inert molecules that will inevitably end up in the sea, as well as if solvents are used during the production process and whether they are reused later or not. All these aspects should be taken into account by producers and also by cosmetic companies before acquiring one or another encapsulate. For example, ECHA (European Chemicals Agency) has submitted a proposal of restriction of non-biodegradable microplastics that might affect the cosmetics, textiles and detergence industries, among others. As it has been found that microplastics accumulate in living organisms.
- Production costs: One cannot forget that although the cosmetic sector is in full growth, especially in emerging markets, the costs of new encapsulated ingredients can never be more expensive than a cosmetic company is willing to pay for them. In other words, the productive cost of an encapsulation must be relatively economical in order to be able to market it globally and adapt the profit margins according to a specific region and a targeted customer.
- Less tangible aspects (but key): it must be taken into account that when a new encapsulation is launched to the market, this will have an associated expense not only of production but also of marketing, commercialization, consumer education (either B2B or B2C), and margin reduction by distribution agreements. Which should be accordingly forecasted previously.
The Cosmetic Company
Now, from the point of view of a cosmetic company, i.e the one that formulates and/or sells cosmetic formulas to the end-user or other companies, there are a number of properties and concepts that must be understood in order to be able to choose wisely the encapsulate to be added in a cosmetic formula, which will bring along those unique properties.
Figure 1. Biodegradable multi-walled nanocapsules. EcostratarTM proprietary technology developed by Ecopool Tech.
- In first place, it is of outmost importance to take into account the physical-chemical stability of the encapsulate in the cosmetic formula. For this it is necessary that the formulator or cosmetic brand has a clear ultimate goal of what to obtain by using an encapsulated active ingredient. And at the same time the encapsulator must be ready to ask the correct questions to elucidate what the formulator or cosmetic brand exactly requires (as described in the first part of this document). This may seem trivial, but it is often the lack of verbal communication instead of the lack of know-how that will determine the success of a technical-commercial relationship in which disruptive products are introduced to the market. Many times we, as encapsulators, have sent costly samples to a client that have not been tested appropriately, have not fit with what the customer wants, have not been explained correctly, among others. In this regard, by instance, if a customer is looking for an encapsulation compatible with a water-based cosmetic formula, as encapsulators, we must provide an encapsulation that is dispersible and miscible in water and clarify in which viscosities and pH ranges it can be formulated without affecting its efficacy and sensory properties. As a practical example: If a microencapsulate is used, it will generally be opaque and whitish and therefore not transparent, instead, a water-based nanoencapsulation of a size less than 100 nm should be almost fully transparent in water.
- The particle size of the encapsulation will directly affect its barrier properties, controlled release, opacity, degradation rate, etc. It is important that the cosmetic chemist/formulation chemist understands how the size will affect these properties and it is the responsibility of the encapsulator to explain it properly so that it is well understood. For example, generalizing, a nanoencapsulation of 100 nm containing 5% retinol is likely to be very yellow, semi-transparent, resistant to mechanical breakage but sensitive to UV-triggered retinol degradation, temperature and usually poorly stable to oxidation. On the contrary, a microencapsulation of 20 microns containing 5% retinol is likely to be less yellow, opaque-whitish, more sensitive to mechanical breakage but more resistant to UV-triggered retinol degradation, temperature and therefore a better overall antioxidant capsule for retinol. In addition, Nanoencapsulation will surely have better skin penetration properties than microencapsulation. Does that mean that there is one better than the other? No, it will depend on the cosmetic formula we are developing and our ultimate marketing and regulatory goals that we should select the nano or the micro-sized one.
- The type of controlled release system for the encapsulated active ingredient will determine the overall efficacy and safety of the cosmetic formula. Let's show an example to exemplify this: The maximum permitted concentration of all-trans retinol in EU for a face cosmetic is 0.3% (w/w). However, this concentration refers to non-encasulated retinol, and in most of cases, when retinol is applied to the skin it will quickly begin to oxidize and lose efficacy. If on the contrary 0.3% of encapsulated retinol was used, and it was proved through the adequate tests that retinol is slowly released during 12h on the skin, it would probably have better efficacy and tolerability, as well as lower dermal toxicity. Which would be a reliable indication that a lower concentration of encapsulated retinol (< 0.3%) could be cheaper, safer, and maintain efficacy compared to non-encapsulated retinol. Aspects that should be key for cosmetic companies to choose an encapsulate instead of the non-encapsulated version.
VIDEO 2. Example of the technical specs and advantages of an encapsulated retinol (CapsuretinolTM UHC from Ecopol Tech).
About me:
Organic chemist and Nanoscientist with a PhD in Nanoscience and Nanopharmacotherapy by IRB Barcelona - Institute for Research in Biomedicine. Currently, I live in Manhattan and head up business development for Ecopol Tech, our family business. Our company specializes in sustainable and effective polymer and encapsulation technologies for industrials, personal care, household and pharmaceutical sectors.