A three step process gives a series of poly(amidoamine) (PAMAM) dendrimer-modified silica nanoparticles (SNP) with appended organic dyes fluorescein isothiocyanate (FITC ) or rhodamine B isothiocyanate (RITC). The SNP were dispersed into a buffered water/ethanol solution and tested as “turn off” sensors for copper (II) and subsequent “turn on” sensors for cyanide ion. The SNP fluorescence was quenched by copper ion binding to the dendrimer and was dependent upon the dendrimer generation attached to the surface. The addition of one equivalent of cyanide ion fully restored the fluorescence and, remarkably, cyanide ion was more effective than EDTA despite its strong copper (II) binding constant. Stern-Volmer quenching analysis only gives linear correlations at very low copper (II) ion concentrations, leading to a limit of detection of 0.38 µM. The effect of bound organic dye and surface charge are currently being studied, as well as the ability of the system to function as a FRET sensor for electrostatic binding of dyes in solution.

Dendrimer modified silica nanoparticles as fluorescent chemosensors for the detection of copper and cyanide

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.