Diagnostics

Immunoassays

The dense presentation of terminal functional groups found on the surface of dendrimers makes these nano-structures ideal for enhancement of signal amplification in diagnostic applications. For example, in solid-phase bioassays, dendrimers may be used as structural components to increase the density of immobilized detector molecules. This increases the ability to bind smaller amounts of target analytes in a biological sample, thereby increasing assay sensitivity. Furthermore, in monitoring of critical biological events during the assay, dendrimers are interesting candidates as unique scaffolds for fluorophore groups. This is important where the dense fluorophoric surface presentation of the dendrimer may lead to increased quantum yields (i.e. depending on Stokes’ shift), and in turn fluorescence intensity. For this reason, a broad range of assays involving dendrimers is being investigated as critical components in new more highly sensitive assays.

Dendrimers may be used to enhance both the covalent and non-covalent binding capacities of surfaces used for heterogeneous assays. For example, they are being considered in such enzyme-linked immuno-sorbent assays as ELISA, (polystyrene), microarray (glass) types as well as certain biosensor protocols involving gold surfaces and plasmon surface resonance spectroscopy. In all cases these protocols involve non-covalent binding of detection molecules to the surface; however, an alternative, covalent binding may be used to increase the stability and selectivity of the assay. In most cases, however, simply increasing the surface binding capacity markedly enhances the assay sensitivity. Therefore, by introducing higher concentrations of biological detector molecules at these surfaces one may generally expect to enhance both kinetics and analytical sensitivities for these assays. It is from this perspective that polyvalent nano-structures such as dendrimers with their dense multivalent surfaces are expected to be ideal candidates for this purpose.