Plasmonic gold (Au) nanotriangular arrays, functionalized with a near infrared (NIR) fuorophoreconjugated
immunoassay to Carbohydrate Antigen 19-9 (CA 19-9), a pancreatic cancer biomarker,
produce optically tunable substrates with two orders of magnitude fuorescence enhancement.
Through nanoscale morphological control, the sensitivities of the plasmonic nanotriangular arrays
are controllable, paving the way of such optical platforms for multiplexing. Here, we report a limit of
detection (LOD) of 7.7×10−7 U.mL−1 for CA 19–9 by using such tunable Au nanotriangular arrays, a
great improvement compared to commercially available CA 19–9 immunoassays. The linear dynamic
range was from 1×10−6 U.mL−1 to 1 U.mL−1, i.e. up to six orders of magnitude. Moreover, high
specifcity was demonstrated, together with successful validation in serum samples. Their superior
tunable sensitivity, along with eforts to combine CA 19–9 with other biomarkers for improved accuracy,
open up the possibility for multiplexed NIR-fuorescence enhancement microarrays, for early cancer
diagnosis and therapeutic monitoring.