Nanocosmetics and nanomedicine for topical use

Question 1

Mention key details of the definition of a “nanomaterial” in EU regulations for cosmetic use.

Answer 1

• one or more dimensions 1 - 100 nm
• insoluble
• biopersistent

Question 2

What benefits may nanotechnology bring when used in cosmetics?

Answer 2

Question 3

Mention 9 types of soft nanoparticles which may be used for topical use.

Answer 3

SLNP = solid-liquid nanoparticle

NLC = nanostructures lipid carriers.

Question 4

• Describe the anatomy of the skin.
• Describe 7 functions of the skin.

Answer 4

Question 5

Which 3 major transport routes exist in the skin?

Answer 5

1. transcellular
2. intercellular
3. transappendageal

Note: Transappendageal route = transportation of drug via the sweat glands and the hair follicles.

Question 6

What is the largest challenge if you want to transport a drug across the skin?

Answer 6

The stratum corneum is the toughest permeability barrier.

Question 7

Describe the anatomy of the stratum corneum, including sizes.

Answer 7

dead keratinocytes

tight lamellar lipid matrix

between layers: 70 nm

between keratinocytes: 36 nm

tickness of stratum corneum: 13.5 micrometers

Question 8

What type of molecules are needed for the passive diffusion through the skin?

Answer 8

1. small (NPs larger than 20 nm do not penetrate the skin)
2. lipophilic
3. non-charged

Question 9

I have a hydrophilic substance that I would like to penetrate the skin. What could I try?

Answer 9

Using a vesicular lipid nanocarrier.

This may enhance the permeability through the skin by 2-3 fold.

Question 10

How can you enhance drug delivery through the skin?

Answer 10

Disrupt the skin; either chemically or physically.

Question 11

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?

Answer 11

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.

Question 12

Describe 3 different types of vesicular nanocarriers.

Answer 12

• 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

Question 13

There are 3 types of surfactants. Which?

Answer 13

neutral, anionic, cationic

Question 14

Mention 3 types of nanoemulsions.

Answer 14

1. oil-in-water
2. water-in-oil
3. bi-continuous

Question 15

Mention 4 benefits of nanomicelles and nanoemulsions.

Answer 15

1. ease of preparation
2. solubilisationof poorly soluble drugs
3. enhanced permeability through the skin
4. stability (low thermadynamically stable but highly kineticically stable)

Question 16

Mention 4 methods for the production of nanoemulsions.

Answer 16

High energy:

1. high shear homogenisation
2. sonication

Low energy

3) emulsion inversion point (EIT)
4) phase inversion temperature (PIT)

Question 17

Give an example of a bi-catenar system.

Answer 17

catanionic self-assembled vesicles.

Question 18

Mention 3 types of liposomes.

Answer 18

1. SUV (small unilamellar vehicles)
2. LUV (Large unilamellar vehicles)
3. MLV (multilayer vehicles)

Note: there is a mistake on the slide for LUV.

Question 20

Describe methods of liposome production.

Answer 20

Question 21

What are niosomes, and what are they used for?

Answer 21

Non-ionic surfactant-based vesicles.

They fuse and mix with the lipids of the stratum corneum; delivery of relativeky large molecules across the skin.

Question 22

I added an edge activator to my liposomes. What happens?

Answer 22

The fluidity of the lipid bilayer enhances.

Question 23

• What are the differences between niosomes and liposomes (5)?
• Which use do they have in common?

Answer 23

Question 24

“New generation” liposomes have been developed. Name and describe these. Mention how they differ from liposomes.

Answer 24

Question 25

• What is a Pickering emulsion?
• What can you use it for?

Answer 25

Question 26

What type of NPs can you use for a Pickering emulsion?

Answer 26

1. clay 2. silica 3. metal oxides (ZnO, CeO₂, TiO₂) 4. nanocellulose 5. protein

Question 27

What is the stabilising factor of NPs in pickering emulsions?

Answer 27

Energy of attachment depends on R², surface tension (gammaow), and the contact angle (theta).

Question 28

Mention 4 important characteristics of a NP for forming Pickering emulsions.

Answer 28

1. particle size 2. shape 3. hydrophobicity 4. contact angle

Question 29

What are the properties, benefits, and limitations of solid lipid NPs?

Answer 29

Question 30

How do you produce solid lipid nanoparticles (SLPs)?

Answer 30

melting - nanoemulsion - cooling - crystalisation

Question 31

What are nanostructured lipid carriers?

Answer 31

Question 32

Describe the occlussion effect.

Answer 32

Question 33

The occlusion effect usually enhances absorption of drug through the skin. Why is this effect detrimental for transferosomes?

Answer 33

The driving force for translocation of transferosomes is a hydration gradient or osmosis. (slide 20)

Question 34

What substances are used for suncreens? What is their mode of action? How can you prevent systemic exposure?

Answer 34

Question 35

Mention 3 useful sunscreen properties and how you can achieve these with eg TiO_2.

Answer 35

Question 36

When absorbing UV light, the active substance in sunscreen may induce free radical formation. How can you prevent damage from these ROS?

Answer 36

a silica shell. Moreover, the photocatalytic activity depends on crystal phase and particle size (slide 32).