A biomimetic photonic crystal sensor for label-free detection of urinary venous thromboembolism biomarker

This work reports a novel label-free sensor combining photonic crystals and molecularly-imprinted polymer materials for targeting a protein in human samples within levels of clinical interest. This concept was applied to detect fibrinopeptide B (FPB) in urine, a biomarker of venous thromboembolism, which is a disease of great concern and demands innovative point-of-care devices for improved diagnosis. The molecularly-imprinted photonic polymer (MIPP) was obtained by tailoring an imprinted polymer on highly ordered silica nanoparticles assembled by vertical deposition. Owing to the hierarchical structure, the resulting MIPP exhibited optical properties that changed upon rebinding of the target analyte, FPB. Thus, the changes in reflectance intensity enabled a rapid and sensitive detection of FPB in human urine. The observed response was linear between 0.2 ng mL(-1) and 22 ng mL(-1) and showed a limit of detection of 0.13 ng mL(-1). These features of the sensing material allow the assessment of urinary FPB at relevant clinical levels. In addition, the sensor was selective for FPB compared to the standard biomarker of venous thromboembolism, D-Dimer. The stability of the material was evidenced by the reusability study, which demonstrated reversibility of the maximum intensity after three cycles of recognition and regeneration. Moreover, the sensor showed good performance for the spiked FPB detection in control human urine. Overall, the application of such label-free sensor offers high selectivity and stability, as well as easy operation. It may constitute an alternative method for non-invasive and real-time detection of various protein biomarkers in point-of-care.