Determination of human serum albumin using a single-walled carbon nanotube-FET modified with bromocresol green

We developed a nanoscale-based assay for the detection of human serum albumin (HSA) by placing the HSA indicator probe, bromocresol green (BCG) on the single-walled carbon nanotubes on a field effect transistor (swCNT-FET) via simple coating. Bovine serum albumin (BSA) was used as a blocking agent to reduce non-specific binding. The selective binding of HSA onto BCG alters the charge of the dye and the surface, and this causes a change in the conductance of the swCNT-FET. The assay is highly sensitive and selective for HSA, with an 18.6 ng⋅mL−1 detection limit. The high sensitivity and selectivity of the assay is ascribed to appropriate BSA blocking and the instantaneous response of sensitive swCNT-FET to rapid BCG-HSA binding, which minimizes non-specific binding and overcomes the time-sensitivity of BCG-HSA binding, respectively.