Method for amine-amine attachment in nanodevice preparation

A process for covalent attachment of amines to other amines is described for nanodevice preparation. This method utilizes a linker with aldehyde and N-hydroxysuccinimide ester terminals separated by a heptyl spacer. Nanodevices consisting of amine or hydrazide-containing molecules (Lucifer Yellow, fluorescein-5-thiosemicarbazide, and 2-hydrazinopyridine) attached to the surface of a generation 4 amine-terminated poly(amidoamine) dendrimer were prepared as model compounds. In spite of the numerous amine groups present on the dendrimer, aggregate formation was negligible, yielding well-defined nanoconstructs. This negligible aggregation was attributed to the reversible imine bonds formed between the surface amine groups of the dendrimer and the aldehyde group of the linker. We also prepared a dual fluorophore-dendritic nanodevice in which fluorescein was attached to the dendrimer surface via the linker while rhodamine was directly bound to the dendrimer surface. Fluorescence, UV-visible spectrophotometry, size exclusion chromatography, electrophoresis, and dynamic light scattering were used to analyze these nanodevices.