Colloidal gold is extensively used for molecular sensing because that the surface plasmon resonance (SPR) bands are affected by changes in the dielectric properties in the close vicinity of these structures due to the binding of ligands to the corresponding receptor molecules immobilized onto the nanostructures through chemi- or physisorption. We describe a simple method for the detection of Alpha-Fetoprotein-L3 which is a new generation of tumor marker for hepatocellular carcinoma (HCC) based on the aggregation of Lens culinaris agglutinin (LCA) Immobilized Gold Nanoparticles. The LCA conjugated GNPs obtained were 15-20 nm in diameter. The visible color change of the gold nanoparticles from purple to blue on interaction with 100 ng/mL of AFP-L3 is the principle applied here for the sensing of AFP-L3 level. UV/Vis spectroscopy also allows assay monitoring by quantifying the red shift of the plasmon resonance wavelength. With this method, the protein AFP-L3 can be rapidly detected as demanded for clinical diagnosis.
