15-Crown-5 Functionalized Au Nanoparticles Synthesized via Single Molecule Exchange on Silica Nanoparticles: Its Application to Probe 15-Crown-5/K+/15-Crown-5 Sandwiches as Linking Mechanisms

Single 15-crown-5 functionalized Au nanoparticles (NPs) were synthesized with assistance of silica particles. The use of silica particles renders intrinsic advantages in that each step along the product formation can be monitored by, for example, a transmission electron microscope, and large surface-to-volume ratio of silica particles leads to a better yield of Au NP attachment than the glass substrate. The as prepared Au NPs, providing access to fundamental analysis, were readily applied in K+ recognition and proved to be free from aggregation. Accordingly, a sandwich type of complexation is resolved and the corresponding thermodynamics can be extracted.