Enhancement of the sensitivity of LSPR-based CRP immunosensors by Au nanoparticle antibody conjugation

We propose a design for a highly sensitive biosensor based on nanostructured anodicaluminum oxide (AAO) substrates. Gold nanoparticle (GNP)-labeled antibodies were used to enhance the sensitivity of the localized surface plasmon resonance (LSPR) biosensor. In the proposed model, the application of these optical properties and the GNP-labeled antibodies overcame problems due to limited sensitivity, selectivity, and dynamic range that are encountered in such biosensors. In order to ascertain the applicability of the sensor, a commercially available C-reactive protein (CRP) was applied as a biomarker and the enhancement in sensitivity was analyzed for varying concentrations of CRP. For this, a sandwich assay was carried out to detect the CRP antigen by using a fabricated sensor device. The sensitivity of the sensor increased 1.84 times according to the additional response to the GNP-labeled CRP antibody, and the limit of detection (LOD) was 100 ag/ml. The proposed immunosensor showed high sensitivity over a wide concentration range and enabled a selective immunoassay to be performed.