Biomedical Engineering Reference
In-Depth Information
TABLE 8.1
Common Soft Nanomaterials for Drug-Delivery Systems
Material
Properties
Micelles
21
Description: aggregate of surfactant molecules
dispersed in a liquid colloid
Easy preparation
Good stability
Increase the aqueous solubility of hydrophobic drugs
Reduce hydrolytic and enzymatic drug degradation
Control the drug release rate
Permit many administration routes
Face risk of disintegration after administration or dilution
Liposomes
25
Size: 25-2500 nm
Description: vesicles made from single or multi
bilayered phospholipid
membranes enclosing an aqueous cavity
Capable of delivery for both water-soluble (e.g., proteins) and oil-soluble drugs by entrapping substances
in either the membrane or in the cavity
Permit many administration routes
Include sufi cient PEO derivatives to reduce opsonin adsorption at the surface 17, and, as a result, overcome
the following shortcomings with liposome systems: (1) short bloodstream circulation time (2) dose-limiting local toxicity
in RES-related tissues, and (3) low bioavailability in tissues other than RES-related ones
Biomimetic artii cial system (model for cell membranes when made of natural phospholipids)
Responsive transitions possible (e.g., temperature-sensitive liposome systems)
Complex preparation
Suffer from limited physical stability and drug leakage
Solid lipid nanoparticles (SLNs)
24
Size: 50-1000 nm
Description: particles made from solid lipids (in
contrast to emulsions, where the lipid phase is
liquid) with surfactants added as stabilizers
Controlled drug release rate by particle size and composition
Excellent tolerability
Excellent physical stability
Good protection against drug degradation
Rare burst release: particularly suitable for cancer therapies to avoid high peak concentrations
SLN formulations found to be signii cantly more efi cient than the free drug in solution, suggesting that
particle-mediated uptake plays a role
Permit many administration routes and are particularly suitable for parenteral drug delivery
Insufi cient loading capacity
Modii cations of SLN, the nanostructured lipid carriers (NLC), and the lipid drug conjugate (LDC)
nanoparticles, overcome limitations of conventional SLN
