Chemical and Biochemical Silica Surface Modifications for the Development of Medical Analyses

This report can be divided into two parts. The first part studying the aggregation kinetics for citrate-reduced 15 nm gold nanoparticles at the native silica and modified silica-water interfaces. At the native, negatively charged silica-water interfaces a two-phase adsorption is observed: a pseudo-Langmurian adsorption phase and, after an acid wash to remove the citrate ligand from the adsorbed particles, a further pseudo-Langmurian adsorption phase. A kinetic analysis of these phases shows an average adsorption rate constant of (2.0 ± 2.5)  105 M 1 s 1 with no measurable desorption. The second part of this report describes protocol development for tethering DNA onto gold nanoparticles and the development of hybridization procedures. 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide/N-Hydroxysuccinimide (EDC/NHS) activation of a thioctic acid monolayer on a gold nanoparticle shows the most promising method.