An innovative POF-based device for real-time monitoring of binding processes at ultra-low concentrations via a plasmonic sensor combined with a microcuvette chip

Surface plasmonic sensors are widely utilized in bioanalytical and diagnostic laboratories to track interactions between analytes and receptors.¹ The primary advantage of plasmonic technology over traditional diagnostic methods is the possibility of label-free monitoring of binding events in real time. However, the expensive chip and the laborious surface chemistries required for functionalization are notable drawbacks.

In this study, a novel sensing approach is introduced to detect receptor-target interactions at extremely low concentrations without any kind of sensing surface functionalization. The biosensor operates using a sensitive chip based on a microcuvette device fabricated by drilling the core of a multimode polymer optical fibre (POF) with nanoholes. This is connected in series with a surface plasmon resonance (SPR) D-shaped POF probe, and the detection is performed using a broad-spectrum halogen lamp and a spectrometer. The microhole is filled with a solution containing specific receptors that selectively capture the target molecules from samples placed on top of the filled nanohole. Any changes over time due to analyte-receptor binding alter the mode profile of the light propagating through the POF core, affecting the plasmonic interactions and resulting in a time-dependent shift in the resonance wavelength.²

In particular, The interactions of estradiol and cortisol, with their respective receptors (Estrogen Receptor³ and Glucocorticoid Receptor⁴) were tested as proof of concept.² The resonance wavelength shift was monitored over time to trace the interactions between the receptor–target pairs at attomolar concentration.²

This advanced sensing approach acts as a new class of laboratory instruments offering distinctive capabilities in ultra-high sensitivity and affordability.

References:

[1] Homola, J et al. Sens. Actuators B Chem. 54 (1999) 3–15.

[2] Cennamo, N et al. Sens Actuators B Chem. 2024, 416, 136050.

[3] Arcadio, F et al. Biosensors 2023, 13, 432.

[4] Arcadio, F et al. Biosensors 2024, 14, 351.