This possible effect can further contribute to the clearance of the polymer-coated
nanocarriers. For a given triblock polymer, it was found that both surface polymer density and coating layer thickness are affected by the particle size: smaller particles (below 100nm) adsorb fewer polymer molecules per unit area than larger particles. Therefore, the polymer surface density decreases as the particle size decreases. Additionally, Pluronic adsorption on larger particles is relatively weaker than on smaller particles, which can affect the rate and extent of displacement of adsorbed Inhibitors,research,lifescience,medical polymers by blood components . The surface adsorption efficiency and the stability of the polymer coating are strictly related to the polymer composition, namely, PO/EO molar ratio and PPO and PEO chain length . Pluronic Inhibitors,research,lifescience,medical F-108 NF (poloxamer 338) has a bulkier central
hydrophobic block and longer side hydrophilic arms (122 monomers of PEO; 56 monomers of PPO) as compared to Pluronic F-68 NF (76 monomers of PEO; 30 monomers of PPO). Accordingly, Pluronic F-108 NF forms more stable coating layers than Pluronic F-68 NF. In vivo, Pluronic F-68 NF-modified nanoparticles accumulate at 74% of the dose in the liver in Inhibitors,research,lifescience,medical 1h, while the liver accumulation of Pluronic F-108 NF-modified nanoparticles was 67% . 2.2.3. Dextran Dextran is a polysaccharide largely used for biomedical applications including for the decoration of nanoparticulate drug delivery systems . Dextran coating was found to bestow Inhibitors,research,lifescience,medical long circulating properties on liposomes . Similarly to PEG, the steric brush of the dextran on the vesicle surface reduces the protein adsorption. This effect results in enhanced liposome stability in the blood , which depends on the density of dextran molecules. this website Interestingly, 70kDa dextran coating was also found to reduce the burst of drug release from liposomes . Dextran was used Inhibitors,research,lifescience,medical to coat superparamagnetic iron oxide nanoparticles for magnetic resonance
imaging [51, 52]. Particles of 4 to 5nm were coated with 20 to 30 dextran chains organized in “brush-like” structures, which reduced the removal from the bloodstream by Kupffer cells and splenic macrophages. The circulation half-life was prolonged to 3-4 hours . The slight macrophage recognition of the dextran-coated Bay 11-7085 superparamagnetic iron oxide nanoparticles was attributed to antidextran antibody opsonisation. 2.2.4. Sialic Acid Derivatives to Mimic the Nature Sialic acid derivatives received considerable interest as potential materials to confer stealth properties to nanoparticles for drug delivery applications. Sialic acid is a component of eukaryotic cell surface and plays an important role in preventing the removal of self-tissue by low level of complement activation through the alternative pathway.