Gold nanoparticles have attracted considerable attention due to their unique properties and potential applications as optical probes. When proteins that are adsorbed on gold nanoparticles subsequently get cross-linked by any interaction specific to that protein, the size of the aggregates increases and this enhancement of size have been used for sensitive, convenient and powerful tool to monitor the presence of the specific cross-linkers. Dynamic light scattering (DLS) is a technique that is routinely used for detecting aggregation in macromolecular solutions. In this work, we first applied DLS to identify specific glycoprotein–lectin interactions exclusively present in the serum of hepatocellular carcinoma patients compared to healthy controls that showed the altered fucosylation of a serum protein, Serum α-1-Acid glycoprotein. Further, based on the DLS data a simple, rapid, serological assay was developed based on antibody coated gold nanoparticle and fucose binding lectin (Aleuria aurantia lectin) as linker to asses the level of fucosylation of α-1-acid glycoprotein. As a consequence of the triggered aggregation of the GNP probes in presence of lectin, plasmon band was shifted from red to blue, which colorimetrically reported the enhanced fucosylation of α-1-acid glycoprotein and formed the basis of a rapid visual assay for hepatocellular carcinoma.