Functionalized nanoporous gold as a new biosensor platform for ultra-low quantitative detection of human serum albumin

•Proof of concept of an ultra-sensitive biosensors for analytical devices with SERS.•Nanoporous gold functionalized with a target-directed antibody (Ab anti-HSA).•Acquisition of detailed SERS maps at different HSA concentration.•Chemometric approach to data analysis and sensor calibration.•Biosensor gives quantitative analysis in ultra-low concentrations (0.1 ng/l).