Surface plasmon resonance based on molecularly imprinted nanoparticles for the picomolar detection of the iron regulating hormone Hepcidin-25

Objective: the study aimed at developing molecularly imprinted polymer nanoparticles (MIP NPs) for the recognition of Hepcidin-25 and at their further integration into an optical sensor based on surface plasmon resonance (SPR) suitable in the real time monitoring of the hormone. Materials and methods: MIP technique is a powerful mean to produce tailor made synthetic recognition sites. Here precipitation polymerization was exploited to produce a library of MIP NPs targeting the N terminus of the hormone Hepcidin-25. Biotinylated MIP NPs were immobilized onto a NeutrAvidin™ SPR sensor chip. The response of the MIP NP sensor to Hepcidin-25 was studied. Results: morphological analysis showed MIP NPs of 20-50 nm; MIP NPs exhibited high affinity and selectivity for the target analyte: low nanomolar Kds for the interaction with Hepcidin-25, but no interaction with the non-regulative Hepcidin-20. MIP NPs were integrated as recognition element in the SPR allowing the detection of Hepcidin-25 in 3 minutes. Linearity was observed with the logarithm of Hepcidin-25 concentration in the range 7.2-720 pM. The LOD was 5 pM. The response for Hepcidin-20 was limited. Hepcidin-25 determination in real serum samples spiked with known analyte concentrations was also attempted. Conclusion: the integration of MIP NPs to SPR allowed the determination of Hepcidin-25 at picomolar concentrations in short times outperforming the actual state of art. Optimization is still needed for real sample measurements in view of future clinical applications.