Guided mode resonance sensor for the parallel detection of multiple protein biomarkers in human urine with high sensitivity

The rising cost of global healthcare provision and new approaches to managing disease are driving the development of low-cost biosensing modalities, such as label-free photonic methods based on dielectric resonances. Here, we use the combined sensing and imaging capability of a guided mode resonance (GMR) sensor to detect multiple biomarkers (troponin, procalcitonin and C-Reactive Protein) in parallel in undiluted urine samples. A key requirement of such a biosensor is the simple and direct functionalization with suitable antibodies to ensure the disease-specific detection of protein biomarkers. Here, antibodies were immobilized using a succinimidyl-[(N-maleimidopropionamido)-hexaethyleneglycol] ester (SM(PEG)6) spacer. The polyethylene glycol (PEG) chemistry enables low detection limits of 10 pg mL-1 or better for all protein biomarkers, while minimizing non-specific binding compared to more commonly used strategies such as (3-Aminopropyl)triethoxysilane (APTES) or dextran. Our approach supports the vision of a simple yet highly sensitive diagnostic platform that could be used for pre-screening patients for a wide range of diseases at point-of-care, thereby relieving the pressure on overstretched healthcare services.