V.S. Teodorescu*, M.G. Blanchin**, - PowerPoint PPT Presentation

Title: V.S. Teodorescu*, M.G. Blanchin**,


1
TEM and SEM studies on nano- and micro-capsules
from biodegradable polymers for drug encapsulation

• V.S. Teodorescu, M.G. Blanchin,
• S. Guinebretière, S. Briançon, H. Fessi
• INCDFM, Bucharest-Magurele, ROMANIA
• Laboratoire de Physique de la Matière Condensée
  et Nanostructures, Université Claude
  Bernard Lyon 1,Villeurbanne, FRANCE
• Laboratoire d Automatique et de Génie des
  Procédés, Université Claude Bernard Lyon
  1,Villeurbanne, FRANCE

2
Vectorisation , encapsulaion, electron
microscopy TEM and SEM

• Polymeric capsules are increasingly used as
  vectors for applications in chemistry, pharmacy,
  cosmetics
• Pharmaceutical applications for intravenous
  vectorisation require capsule sizes down to the
  nanometer range
• SEM and also TEM should be used to study of the
  structure and the morphology of nano- and
  micro-capsules

3
Encapsulation
Nanocapsules as containers
Nanospheres as matrices
10 - 1000 nm
- protection of the drug - vectorisation toward
the target - control of drug release
4
Preparation of nanocapsules

• Water and solvent partially miscibles (ethyl
  acetate)
• Polymer soluble in solvent, insoluble in
  water (biodegradable polyesters / e.g.
  poly-e-caprolactone PCL)
• Oil miscible with polymer solution, dissolves
  the drug (triglycerides)
• Tensio active compound as stabilizer in the
  aqueous phase (PVA, copolymer)
• Water and solvent initially saturated ? stable
  emulsion
• Dilution with distilled water
• ? Diffusion of the solvent
• ? Drops ? capsules i.e. coreoil drug polymer
  membrane around the core

5
Preparation of nanocapsules
Oil drug Polymer
Oil polymer solvent drug
solvent
DROP? 1 mm
CAPSULE ? 500 nm
external phase saturated water sabilizer
external phase distilled water stabilizer
6
TEM study of the nanocapsules negativation method
7
TEM size distribution measurements
8
Positive TEM observationsDirect deposition of
the NC on the carbon gride
The NC membrane can be estimated from to the
dark halo due to the stabilizer
Image of a broken NC ( during TEM observation)
revealing the oil content. A halo of liquid
expands around the NC on the carbon film
9
Positive TEM observations
Spongeous structure inside the NC
10
Crystallization of polymer inside the NC
Monocrystal polymer capsule
Polycrystalline sponge polymer inside the
capsule
11
Micro- capsules
SEM image
The black points on the capsule surface are holes
connecing the internal pores to the surface
TEM images
12
CONCLUSIONS

• TEM structural and morphological study of
  polymeric NC for drug encapsulation can be made
  using the classic negativation method, but also
  by direct observations
• Direct deposition of the NC on the TEM grids
  provides data about all the components of the NC
• The polymeric membrane of the NC can be resolved
  using TEM direct observation
• TEM observations are complementary to the SEM
  images in the case of capsules in the range of 1
  to 10 mm.

13
Spongeous polymer nanocapsule