Chapter 47
Polymer Nanomaterials
Alexander V. Kabanov and Elena V. Batrakova
Questions
1.
What are the main features of the BBB that restrict drug transport to the brain?
2.
Describe the properties of polymers that are useful for drug delivery systems.
3.
What are the advantages of nanoscaled polymeric carriers?
4.
List types of nanocarriers for drug delivery. Describe their structure, principal differences, advantages
and limitations.
5.
Describe cell-mediated drug delivery to the CNS.
6.
Explain how the drug efflux transporters affect drug transport to the brain? List examples of drug efflux
transporters expressed in the BBB.
7.
Describe three generations of inhibitors of drug efflux transporters in the BBB.
8.
Describe the effects of Pluronic block copolymers on drug efflux transporters in the BBB.
9.
How is the chemical modification of polypeptides with fatty acids and amphiphilic block copolymers
applied to increase delivery of polypeptides to CNS?
10. Which of the following molecules can penetrate across the BBB through passive diffusion?
a. Lipophilic low molecular weight compounds
b. Hydrophilic low molecular weight compounds
c. Lipophilic high molecular weight compounds
d. Hydrophilic high molecular weight compounds
11. What size of polymer nanocarriers is the most appropriate for drug delivery?
a. 0.1-1 nm
b. 1-100 nm
c. 100-1000 nm
d. 1-100 µm
12. Which types of drugs can be incorporated into polymeric micelles?
a. lipophilic compounds
b. hydrophilic compounds
c. charged compounds
d. proteins compounds
13. What does CMC mean?
a. colloidal microemulsion complex
b. cell monocarrier
c. critical micelle concentration
d. contrast multi-compound
47. Polymer Nanomaterials
Alexander V. Kabanov and Elena V. Batrakova
14. Which polymer is used to stabilize nanoparticles in an aqueous dispersion?
a. polystyrene
b. polymethacrylic acid
c. DNA
d. PEG
e. polycyanoacrylate
15. Which type of cells can be used for cell-mediated delivery?
a. brain microvessel endothelial cells
b. neurons
c. macrophages
d. astrocytes
e. erythrocytes
2
47. Polymer Nanomaterials
Alexander V. Kabanov and Elena V. Batrakova
3
Answers
1.
What are the main features of the BBB that restrict drug transport to the brain?
The main features of brain microvessel endothelial cells (BMVEC) restricting drug transport across the BBB
are: tight extracellular junctions, low pinocytic activity, expression of drug efflux systems, and high activity of
enzymes that participate in the metabolism and inactivation of endogenous compounds.
2.
Describe the properties of polymers that are useful for drug delivery systems.
The properties of polymers that are useful for drug delivery systems are: multifunctionality, possibility for
modification with various targeting vectors, responsiveness to microenvironment for the controlled and
sustained drug release, and biological activity.
3.
What are the advantages of nanoscaled polymeric carriers?
The advantages of nanoscaled polymeric carriers are: entrapping small drugs or biopharmaceutical agents,
targeting to a particular cell or even an intracellular compartment, avoiding RES and therefore, extended
circulation time in the blood.
4.
List types of nanocarriers for drug delivery. Describe their structure, principal differences, advantages
and limitations.
liposomes; nanoparticles; nanospheres; nanosuspensions; polymer micelles; nanogel; block ionomer complexes;
nanofibers and nanotubes.
5.
Describe cell-mediated drug delivery to the CNS.
Cell-mediated drug delivery system to the CNS employs specific cells carriers that can incorporate micro- and
nano-containers loaded with drugs and act as Trojan horses by migrating across the BBB and carrying drugs to
the site of action.
6.
Explain how the drug efflux transporters affect drug transport to the brain? List examples of drug efflux
transporters expressed in the BBB.
Pgp, MRP1, and BCRP, MOAT efflux transport proteins actively remove a broad range of drug molecules
before they cross into the brain parenchyma.
7.
Describe three generations of inhibitors of drug efflux transporters in the BBB.
Three generations of inhibitors of drug efflux transporters are: low molecular weight Pgp inhibitors, which
compete for the active site with the therapeutic agent; non-competitive inhibitors, which allosterically bind to
Pgp, inactivating it and increasing drug transport to the brain; and biologically active nonionic polymer
surfactants incorporating into biological membranes and causing multiple effects resulting in the inhibition of
drug efflux transporters.
8.
Describe the effects of Pluronic block copolymers on drug efflux transporters in the BBB.
The effects of Pluronic block copolymers on drug efflux transporters include: (a) decrease in membrane
viscosity (“fluidization”) and (b) ATP depletion.
9.
How is the chemical modification of polypeptides with fatty acids and amphiphilic block copolymers
applied to increase delivery of polypeptides to CNS?
The chemical modification of polypeptides with fatty acids and amphiphilic block copolymers increase
hydrophobicity of polypeptides enhancing their interactions with biological membranes and therefore transport
across the BBB.
10.
a
11.
b
12.
a
47. Polymer Nanomaterials
Alexander V. Kabanov and Elena V. Batrakova
13.
c
14.
d
15.
c
4