Layer-by-layer (LBL) coating approaches relying
on electrostatic interactions between polymer chains and gold nanoparticle surface have been investigated to build up a hydrophilic polymer corona on gold nanoparticles. The colloidal core of gold nanoparticles was coated with layers of poly(allylamine) (PAH) and poly-(styrenesulfonate) (PSS). F-HPMA, a hydrophilic Inhibitors,research,lifescience,medical terpolymer composed by 90% mol of N-(2-hydroxypropyl) methacrylamide, was then conjugated to the amino groups of PAH to yield core/shell multifunctional nanoparticles. The terpolymer provides a highly water-solvated corona layer that minimizes the opsonisation process and bestows remarkable stealth properties on nanoparticles. The multifunctional nanoparticles did not show a significant degree of adsorption on the macrophage membrane or internalization by the cells [180]. PEG Inhibitors,research,lifescience,medical was grafted on gold nanoparticle surface according to a process named physisorption. PEG-NH2 and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine (DSPE) were conjugated to the backbone of polyglutamic acid (PGA) at 60% and 10% mol ratio with respect to the PGA monomers, respectively. Gold nanoparticle coating was achieved by exchanging the citrate adsorbed on gold particles, obtained by tetrachloroauric acid reduction, with the multifunctional Inhibitors,research,lifescience,medical polymer PGA-DSPE-mPEG.
These functionalized colloidal systems showed high stability to aggregation over 48 hours of incubation in 50% fetal calf serum [181]. Polyethylene glycol-block-poly(2,N,GSK1349572 supplier N-dimethylamino) ethyl methacrylate (PEG-b-PAMA) was shown to improve the long-term stability of gold nanoparticles. The tertiary amino group of PAMA can strongly adsorb to the Inhibitors,research,lifescience,medical surface of gold nanoparticles even though the Inhibitors,research,lifescience,medical mechanism of immobilization is not clear yet. The alkylation of pendant amino
groups along the polymer backbone seems to favour the interaction of the nitrogen atom with gold. The colloidal system was physically stable over 4 days of storage in 95% human serum [182]. Gold nanoshell can also be coated with a variety of polymers according to the same postproduction strategies reported for gold nanoparticles and nanorods. 2.6.4. Polymer Coating of Silica Nanoparticles Silica nanoparticles possessing an organosilica core and a PEG shell were prepared according Annual Review of Pharmacology and Toxicology to a one-pot procedure. The process includes the co-hydrolysis and copolycondensation reactions of ω-methoxy-(polyethyleneoxy)propyltrimethoxysilane and hydroxymethyltriethoxysilane mixtures in the presence of sodium hydroxide and a surfactant [183]. Alternatively, silica nanoparticles were also PEGylated by a postproduction procedure by mesoporus silica nanoparticle reaction with PEG-silanes. It was reported that the PEG coating inhibits the nonspecific binding of human serum proteins to PEGylated silica nanoparticles.