Get extra-fast, ultra-sensitive results using gold nanoparticle sandwich assays on our fiber-optic biosensor.

Infliximab (IFX) is a monoclonal antibody used for the treatment of inflammatory bowel disease. Optimizing the therapeutic outcome requires concentration measurements which are currently obtained using the slow ELISA or less sensitive lateral flow-based immunotherapy techniques.

Tests using the fiber optic probes and an IFX-specific capture antibody showed that sensors alone were unable to detect concentrations lower than 1 μg/ml. Using the same technology with signal amplification via gold nanoparticles conjugated to detection antibody, a limit of detection (LOD) of 2.2 ng/ml was obtained in 100-fold diluted serum.

Multiplexing bioassays reduces the required sample volume, time, and cost of analysis. It also allows the accurate determination of target concentration ratios. To achieve this, users developed a novel assay methodology using stable, oriented co-immobilization of autoimmune antibodies.

Using NTA probes allowed them to accurately quantify the two targets in both buffer and plasma with a gold nanoparticle (AuNP) signal amplification sandwich assay. The LoD for two antibodies against oriented fragments of ADAMTS13 in 200-fold diluted plasma were 3.38 and 2.31 ng/ml respectively.