Fiber-Optic SPR for Smarter Production and Analysis

Karen Leirs, Research Expert at KU Leuven Biosensors Group demonstrated how fibre optic surface plasmon resonance technology can assist in improved production and characterization of biopharmaceuticals. The Biosensors Group was formed in 2005 and has obtained over 37 million euros of funding from international and national funding agencies. The group’s research has led to over 280 publications and aims to develop innovative in vitro diagnostic solutions and life science research tools that have a high application potential both in industrial and clinical settings. Fibre optic surface plasmon resonance (FO-SPR) is a highly versatile and effective tool for various applications including therapeutic drug monitoring of biologics, small molecule quantification, and DNA-based detection. FO-SPR uses an optical fibre coated with a gold layer through which light is shone. Leirs explained that: “On the surface of this fibre there will be surface plasmons created similarly as the other SPR systems and this causes a dip in the reflectance spectrum at this resonance wavelength.” She added that based on the interactions happening on the surface this dip in the reflective spectrum will shift allowing the researchers to monitor the binding reactions. Thus, the technology allows real-time and fast detection of targets and is very flexible due to the different types of targets that can be detected. FOx biosystems applications can be applied to immune-based detection, specifically the therapeutic drug monitoring of biologics. Biologics are becoming increasingly popular in the treatment of autoimmune diseases, but it is crucial to recognise that one dose does not fit all. So, the organisation has come up with a way to monitor the reaction of patients to treatments that uses a COOH surface to immobilise antibodies that are then specifically binding in this case on the TNF antibody in the patient sample. Furthermore, KU Leuven has also conducted small molecule quantification by implementing a competitive assay. They immobilise BSA molecules labelled with progesterone and the more progesterone present the lower the signal generation. DNA-based detection relies on developing DNA origami structures; at certain positions strands protruding from the surface can bind the gold surface allowing for controlled surface functionalization. The group has also been developing novel nano-switches and DNAzyme-based detection for signal amplification. Regarding how FO-SPR can improve biopharmaceuticals it improves sensitivity enhancement. Leirs commented: “We have an increased sensitivity which we also shown by three times increased binding shift upon target binding for example here shown for this thrombin assay where we have for the etched fibre indeed a higher signal shift.” Overall, Leirs gave real-world examples of how FO-SPR technology can reshape biopharmaceutical development by enabling faster, more accurate, and continuous monitoring systems. Its ability to conduct kinetic profiling and inline and online monitoring for continuous assessment are key advancements in the manufacturing field.