Biotinylated Au Nanoparticle-Based Artificial Antibody for Detection of Lysozyme by the Lateral Flow Immunoassay and Enzyme-Linked Immunosorbent Assay

Antibody-based immunoassays such as the lateral flow immunoassay (LFIA) and enzyme-linked immunosorbent assay (ELISA) are currently indispensable analytical methods widely used in many fields, mainly due to the high sensitivity and specificity of antibodies. However, the high cost of monoclonal antibodies and their susceptibility to high temperature limit the application of immunoassays. Previously, we developed a class of gold nanoparticle (AuNP)-based artificial antibodies, called Goldbody. Goldbodies not only bind antigens as specifically as monoclonal antibodies do but also have far better stability than monoclonal antibodies. To take advantage of the excellent specificity, stability, and easy functionalization of Goldbodies and use them for the substitution of monoclonal antibodies in immunoassays, herein, we synthesize a biotinylated anti-lysozyme Goldbody and successfully construct a competitive LFIA for the detection of lysozyme in the range of 17.98–226.49 ng·mL–1. At the same time, the biotinylated anti-lysozyme Goldbody can easily replace the detection antibody in the commercial BA (biotinylated antibody)-ELISA kit for the detection of lysozyme with a lower detection limit of 0.34 ng·mL–1 and a wider detection range of 0.89–20 ng·mL–1 compared with the commercial BA-ELISA kit. In addition, the biotinylated anti-lysozyme Goldbody has good thermal stability in both assays and can accurately detect spiked samples even after pretreatment at 100 °C, demonstrating the high potential of Goldbodies as a good replacement of monoclonal antibodies in immunoassays.