7. Nanocosmetics and nanomedicine for topical use Flashcards
Mention key details of the definition of a “nanomaterial” in EU regulations for cosmetic use.
- one or more dimensions 1 - 100 nm
- insoluble
- biopersistent
What benefits may nanotechnology bring when used in cosmetics?
Mention 9 types of soft nanoparticles which may be used for topical use.
SLNP = solid-liquid nanoparticle
NLC = nanostructured lipid carriers.
- Describe the anatomy of the skin.
- Describe 7 functions of the skin.
Which 3 major transport routes exist in the skin?
- transcellular
- intercellular
- transappendageal
Note: Transappendageal route = transportation of drug via the sweat glands and the hair follicles.
What is the largest challenge if you want to transport a drug across the skin?
The stratum corneum is the toughest permeability barrier.
Describe the anatomy of the stratum corneum, including sizes.
dead keratinocytes
tight lamellar lipid matrix
between layers: 70 nm
between keratinocytes: 36 nm
tickness of stratum corneum: 13.5 micrometers
What type of molecules are needed for the passive diffusion through the skin?
- small (NPs larger than 20 nm do not penetrate the skin)
- lipophilic
- non-charged
I have a hydrophilic substance that I would like to penetrate the skin. What could I try?
Using a vesicular lipid nanocarrier.
This may enhance the permeability through the skin by 2-3 fold.
How can you enhance drug delivery through the skin?
Disrupt the skin; either chemically or physically.
After skin poration, a NP may be delivered through the skin and being uptaken by a dendritic cell. Why would you want to target dendric cells (Langerhans cells) in the skin?
For delivery of vaccines and of drugs which interact with the immune system
After activation, the Langerhans cells initiate and shape the adaptive immune response.
Describe 3 different types of vesicular nanocarriers.
- amphiphilic molecules (polar head, lipophilic tail)
- conically shaped amphiphilic molecules (with 1 tail) give micelles
- cylindrically shaped amphiphilic molecules (with 2 tails) give liposomes
- conically shaped amphiphilic molecules (small head, with 2 long tails) give inverse micelles
There are 3 types of surfactants. Which?
neutral, anionic, cationic
Mention 3 types of nanoemulsions.
- oil-in-water
- water-in-oil
- bi-continuous
Mention 4 benefits of nanomicelles and nanoemulsions.
- ease of preparation
- solubilisationof poorly soluble drugs
- enhanced permeability through the skin
- stability (low thermadynamically stable but highly kineticically stable)
Mention 4 methods for the production of nanoemulsions.
High energy:
- high shear homogenisation
- sonication
Low energy
3) emulsion inversion point (EIT)
4) phase inversion temperature (PIT)
Give an example of a bi-catenar system.
catanionic self-assembled vesicles.
Mention 3 types of liposomes.
- SUV (small unilamellar vehicles)
- LUV (Large unilamellar vehicles)
- MLV (multilayer vehicles)
Note: there is a mistake on the slide for LUV.
Describe methods of liposome production.
What are niosomes, and what are they used for?
Non-ionic surfactant-based vesicles.
They fuse and mix with the lipids of the stratum corneum; delivery of relativeky large molecules across the skin.
I added an edge activator to my liposomes. What happens?
The fluidity of the lipid bilayer enhances.
- What are the differences between niosomes and liposomes (5)?
- Which use do they have in common?
“New generation” liposomes have been developed. Name and describe these. Mention how they differ from liposomes.
- What is a Pickering emulsion?
- What can you use it for?
What type of NPs can you use for a Pickering emulsion?
- clay
- silica
- metal oxides (ZnO, CeO2, TiO2)
- nanocellulose
- protein
What is the stabilising factor of NPs in pickering emulsions?
Energy of attachment depends on R2, surface tension (gammaow), and the contact angle (theta).
What are the properties, benefits, and limitations of solid lipid NPs?
How do you produce solid lipid nanoparticles (SLPs)?
melting - nanoemulsion - cooling - crystalisation
What are nanostructured lipid carriers?
Describe the occlussion effect.
The occlusion effect usually enhances absorption of drug through the skin. Why is this effect detrimental for transferosomes?
The driving force for translocation of transferosomes is a hydration gradient or osmosis. (slide 20)
What substances are used for suncreens? What is their mode of action?
How can you prevent systemic exposure?
Mention 3 useful sunscreen properties and how you can achieve these with eg TiO2.
When absorbing UV light, the active substance in sunscreen may induce free radical formation. How can you prevent damage from these ROS?
a silica shell.
Moreover, the photocatalytic activity depends on crystal phase and particle size (slide 32).
