Protein functionalized titania particle as a nanocarrier in a multiple signal antibody amplification strategy for ultrasensitive chemiluminescent immunoassay

A simple and sensitive method for amplified chemiluminescent immunoassay has been developed by using multiple signal antibodies functionalized titania nanoparticle as tracer. This nanocomposite was fabricated by sequentially conjugating bovine serum albumin and horseradish peroxidase-labeled antibody onto the surface of titania nanoparticles using glutaraldehyde as the linkage. After a sandwich immuno-binding process, the captured nanocomposite tracer greatly catalyzed the luminol chemiluminescence reaction to produce a strong signal. Human IgG was detected as a model analyte, and a linear range of 0.5–200 ng mL−1 was obtained. The detection limit of the proposed method was 0.1 ng mL−1, which was 50-folds lower than that using the traditional tracer. The reproducibility, the stability and the specificity of the proposed immunoassay method were acceptable. The results for real sample analysis also demonstrated its application potential in some important areas such as clinical diagnosis.