We hypothesized that the aromatic structure of many colored enzymatic substrates and products of ELISAs/western blots could interact with the hydrophobic surface of SWCNTs. As the fluorescence of SWCNTs is highly sensitive to the chemical environment this would translate into fluorescent changes in the beneficial NIR spectral window (Figure ). Furthermore, if the modified SWCNT surface has a certain affinity for the analyte, the local 'effective' concentration of the analyte should be higher (in terms of the optical measurement) than in bulk and therefore higher sensitivities are expected. Compared to other techniques requiring major adaptation of the assay, this system could be combined with advanced coating and read-out techniques and amplify signals of reactions used for in vitro diagnostics. In diagnostic assays, enzymatic reactions are commonly used to quantify the concentration of an analyte. To this end, they are attached to antibodies that bind to the target molecule and convert a (colorless) substrate into a colored product. The NIR-fluorescence of single-walled carbon nanotubes (SWCNTs) can be tailored to be sensitive to certain small molecules. Such a SWCNT-biopolymer hybrid with affinity for specific analytes could translate the signal into the NIR and amplify it by local analyte enrichment.