Gold Nanorods Based LSPR Biosensor for Label-Free Detection of Alpha-Fetoprotein

A label-free immunosensor was designed and fabricated for sensitive detection of alpha-fetoprotein (AFP) based on the localized surface plasmon resonance (LSPR) of gold nanorods (GNRs). GNRs were fabricated through seedmediated growth and surface activation by alkanethiols for the attachment of antibodies that could directly capture of the target. A novel strategy using the absorbance ratio of transverse and longitudinal LSPR peak of GNRs as a function of AFP contraction was performed for AFP quantification. The limit of detection of the sensor is 0.25 nM in the PBS, and the dynamic range spans 0.25 nM to 14.3 nM. It is expected that this simple and cost-effective LSPR biosensor can also be applicable to the detection of several other tumor markers that are present at low concentrations.