Carrier systems compared

In brief

A carrier is the structure that holds an active ingredient inside a formula. The five families used in skincare are liposomes, niosomes, nanoemulsions, solid lipid nanoparticles and polymeric shells, and they differ in what they are built from and how they hold the active. Vegalab's NanoVeil is a multi-layer biopolymer shell, built layer by layer.

Each family has a long research record and a place in cosmetic and pharmaceutical formulation. The right carrier depends on the active, the base and the job.

The five families

Liposomes

A liposome is a hollow sphere whose wall is one or more phospholipid bilayers, the same kind of double layer that forms a cell membrane. Water-soluble actives sit in the watery core. Oil-soluble actives sit within the bilayer. Liposomes were first described by Bangham and colleagues in 1965 and are the most studied carrier in skincare. Phospholipids such as hydrogenated lecithin are the usual building blocks.

Niosomes

A niosome has the same bilayer architecture as a liposome, built from non-ionic surfactants instead of phospholipids, usually with cholesterol added for rigidity. The change of material makes niosomes chemically more robust and less costly to produce, and they can carry both water-soluble and oil-soluble actives.

Nanoemulsions

A nanoemulsion is an emulsion whose droplets are made very small, typically well under a micrometer. The active is dissolved in the droplet phase. There is no wall as such: the droplet is stabilized by an emulsifier layer at its surface. Nanoemulsions often look translucent and feel light, because the droplets are too small to scatter much light.

Solid lipid nanoparticles

A solid lipid nanoparticle (SLN) replaces the liquid oil of an emulsion droplet with a lipid that is solid at skin temperature. The active is trapped in the solid matrix, which slows its movement and can shield it from the surrounding water. A later variant, the nanostructured lipid carrier (NLC), blends solid and liquid lipids to hold more active.

Polymeric and layer-by-layer shells

Polymeric carriers use a polymer, natural or synthetic, as the wall or matrix. In the layer-by-layer method, oppositely charged polymers are deposited one after another around a core, each layer held to the last by electrostatic attraction. The method was set out by Decher in 1997 and extended to hollow capsules by Caruso, Donath, Sukhorukov and Möhwald in 1998. Its defining feature is control: the number, order and type of layers can be chosen, so the shell is designed rather than self-assembled.

Side by side

The table is a general summary of the literature. Properties vary with the specific materials and method used in each formula.

Where NanoVeil sits

NanoVeil is Vegalab's multi-layer nano-encapsulation platform. NanoVeil builds a multi-layer biopolymer shell around an active, up to 20 programmable layers, so the active is held stable until defined conditions release it. It belongs to the layer-by-layer family above. The mechanism, step by step, is on How encapsulation works, and the capsule's measured size is on Particle size. The platform is summarized on the Technology hub.

A single formula can use more than one carrier. Formulators often combine a shell for the most fragile active with a lipid system for the base. The ingredient declaration on each product page lists every material present, for example the Hyaluronic Skin Repair sealed vial set and the Hydrating NanoSerum sealed vial set.

Amount and performance

A carrier describes how an active is held. The amount of each active is set out in the ingredient declaration, and performance on skin is shown by testing of the finished product. How Vegalab grades each kind of evidence is on Evidence levels.

For protection and release, the two jobs a carrier is chosen to do, see Stability and protection and Controlled release. For the wider literature, see delivery systems. Terms are defined in the glossary.

References

The studies below describe the technology in general.

1. Bangham AD, Standish MM, Watkins JC. Diffusion of univalent ions across the lamellae of swollen phospholipids. Journal of Molecular Biology. 1965;13(1):238-252.
2. Uchegbu IF, Vyas SP. Non-ionic surfactant based vesicles (niosomes) in drug delivery. International Journal of Pharmaceutics. 1998;172(1-2):33-70.
3. Solans C, Izquierdo P, Nolla J, Azemar N, Garcia-Celma MJ. Nano-emulsions. Current Opinion in Colloid and Interface Science. 2005;10(3-4):102-110.
4. Müller RH, Mäder K, Gohla S. Solid lipid nanoparticles (SLN) for controlled drug delivery: a review of the state of the art. European Journal of Pharmaceutics and Biopharmaceutics. 2000;50(1):161-177.
5. Decher G. Fuzzy nanoassemblies: toward layered polymeric multicomposites. Science. 1997;277(5330):1232-1237.
6. Donath E, Sukhorukov GB, Caruso F, Davis SA, Möhwald H. Novel hollow polymer shells by colloid-templated assembly of polyelectrolytes. Angewandte Chemie International Edition. 1998;37(16):2201-2205.