Synthesis and Properties of Water-Soluble Gold Colloids Covalently Derivatized with Neutral Polymer Monolayers

Abstract

Citrate-capped gold nanoparticles as well as planar gold surfaces can be efficiently grafted with a covalently attached polymer monolayer a few nanometers thick, by simple contact of the metal surface with dilute aqueous solutions of hydrophilic polymers that are end-capped with disulfide moieties, as shown by UV/vis absorption, dynamic light scattering, and surface plasmon resonance studies. The hydrophilic polymer-coated gold colloids can be freeze-dried and stored as powders that can be subsequently dissolved to yield stable aqueous dispersions, even at very large concentrations. They allow for applying filtrations, gel permeation chromatography, or centrifugation. They do not suffer from undesirable nonspecific adsorption of proteins while allowing the diffusion of small species within the hydrogel surface coating. In addition, specific properties of the original hydrophilic polymers are retained such as a lower critical solution temperature. The latter feature could be useful to enhance optical responses of functionalized gold surfaces toward interaction with various substrates.

Targeted Delivery of Gemcitabine to Pancreatic Adenocarcinoma Using Cetuximab as a Targeting Agent

“…The shift in the E max values and change in the absorbance of the AuNP solution with a gradual increase in antibody concentration suggest that the saturation concentration of C225 on AuNP is 4 Ag/mL. The observed red shift in the E max value and an increase in plasmon resonance are consistent with a increase in the dielectric constant of the medium surrounding the AuNPs and suggest the conjugation of C225 to AuNP (36). The saturation concentration of gemcitabine on AuNPs was also determined separately as described above and it is found to be 20 Ag/mL (data not shown).…”

Toward Greener Nanosynthesis

“…Candidates for postsynthetic modifications are generally produced by direct synthesis (ω-functionalized particles created by Brust preparations) or sometimes ligand exchange methods (usually involving the introduction of a ligand bearing a reactive pendant functional group). Modification reactions include polymerizations, [213][214][215][216] coupling reactions, 40,48,[217][218][219][220][221] or transformation of an existing chemical moiety. 48,[222][223][224] In all cases, the success of such modifications relies not only on the nanoparticles' tolerance for various reaction conditions but also on the overall reactivity and steric environment presented by functional groups that are constrained through binding to a nanoparticle.…”

Thermally Responsive Amphiphilic Conetworks and Gels Based on Poly(N-isopropylacrylamide) and Polyisobutylene

“…[1][2][3][4][5][6][7][8][9][10][11][12] This polymer in aqueous solution, as well as its gel in swollen state, is sensitive to the temperature of the environment. 2,3 Above a certain temperature, the hydrophilic PNiPAAm changes its philicity, rapidly becomes hydrophobic, 4 and the polymer and the gel precipitates and collapses, respectively.…”