Figure 4. A gold nanoparticle-based detection strategy for biomarkers associated with lung cancer using an immunosensor assay on a microchip.

(1) Gold nanoparticles functionalized with a specific lung cancer antibody attached to the microchip channel surface. (2) Gold nanoparticles are exposed to serum from blood of a patient with lung cancer containing the specific biomarker. (3) The sample is washed out and only the specific biomarker remains attached to the antibodies on the GNPs. (4) The attachment of the biomarkers to the GNPs changes their physicochemical character and produces a red shift in their surface plasmon resonance. On irradiation, a characteristic, readable signal is produced that can be used for the diagnosis of lung cancer. (Original image).