Advancements in SPR biosensing technology: An overview of recent trends in smart layers design, multiplexing concepts, continuous monitoring and in vivo sensing.

Inspired by the rapid progress and existing limitations in surface plasmon resonance (SPR) biosensing technology, we have summarized the recent trends in the fields of both chip-SPR and fiber optic (FO)-SPR biosensors during the past five years, primarily regarding smart layers design, multiplexing, continuous monitoring and in vivo sensing. Versatile surface chemistries, biomaterials and nanomaterials have been utilized thus far to generate smart layers on SPR platforms and as such achieve oriented immobilization of bioreceptors, improved fouling resistance and sensitivity enhancement, collectively aiming to improve the biosensing performance. Furthermore, often driven by the desires for time- and cost-effective quantification of multiple targets in a single measurement, efforts have been made to implement multiplex bioassays on SPR platforms. While this aspect largely remains difficult to attain, numerous alternative strategies arose for obtaining parallel analysis of multiple analytes in one single device. Additionally, one of the upcoming challenges in this field will be to succeed in using SPR platforms for continuous measurements and in vivo sensing, and as such match up other biosensing platforms where these goals have been already conquered. Overall, this review will give insight into multiple possibilities that have become available over the years for boosting the performance of SPR biosensors. However, because combining them all into one optimal sensor is practically not feasible, the final application needs to be considered while designing an SPR biosensor, as this will determine the requirements of the bioassay and will thus help in selecting the essential elements from the recent progress made in SPR sensing.

Development and validation of an optical biosensor for rapid monitoring of adalimumab in serum of patients with Crohn's disease.

Therapeutic drug monitoring of adalimumab is recommended to improve therapeutic outcome in patients with Crohn's disease. Performing an ELISA requires a rather long time-to-result and the necessity of collecting multiple samples to decrease the cost per adalimumab determination. In this study, we aim to develop and validate a rapid assay suitable for measuring a single adalimumab serum sample using a fiber-optic surface plasmon resonance (FO-SPR) based sensor. Therefore, we have immobilized MA-ADM28B8 as capture antibody on an FO-probe and conjugated MA-ADM40D8 as detecting antibody to gold nanoparticles. A dose-response curve ranging from 2.5 to 40 ng/mL adalimumab was obtained in 1/400 diluted serum. Serum samples of patients with adalimumab concentrations between 1 and 16 µg/mL were measured whereas the negative control, a sample spiked with infliximab at a concentration of 16 µg/mL, showed no significant signal. Using a pre-functionalized FO-probe, the technology requires less than 45 minutes for measuring a single sample. Comparison of measurements between the biosensor and the ELISA revealed an excellent agreement with a Pearson r coefficient of 0.99 and an intra-class coefficient of 0.99. The reduced assay time and the possibility of measuring a single sample are major advantages compared to the ELISA. The developed and validated optical adalimumab biosensor could be a valuable point-of-care diagnostic tool for adalimumab quantification in patients with Crohn's disease.