Long-Period Fiber Gratings coupled with Imprinted Biopolymers and Hydrogels for Advanced Biosensing Applications

Long-period fiber gratings (LPFGs) have emerged as highly sensitive optical platforms for biosensing due to their responsiveness to refractive index changes. However, achieving the necessary sensitivity and selectivity for detecting biomolecules in complex real samples remains challenging. To overcome this, natural and biomimetic biological recognition elements (BREs) have been integrated with LPFGs, with the key step being the formation of a selective biolayer tailored to the target analyte.

This work explores imprinted biopolymers novel synthetic antibody mimics produced via the spontaneous polymerization of endogenous neurotransmitters such as dopamine or serotonin in the presence of molecular templates. Using LPFG sensors, the polymerization kinetics and growth conditions of a serotonin-based imprintable biopolymer were monitored in both templated and non-templated conditions, demonstrating their potential as functional coatings for biosensing.

Additionally, LPFGs were employed to study the coupling of various polymers and hydrogels to develop functional layers for BRE immobilization. In particular, the photopolymerization of acrylamide into polyacrylamide hydrogels was characterized. These hydrogels offer a porous and reactive matrix for the immobilization of antibodies and aptamers, enabling the capture of bacteria and the investigation of their antibiotic resistance.

Finally, the integration of LPFG sensors with thermally stabilized, custom-designed microfluidic systems enabled the combined advantages of the investigated polymers and hydrogels. This synergy enhances the performance of LPFG-based biosensors while maintaining their inherent benefits versatility, low cost, and portability, thus presenting a promising approach for developing advanced, highly specific, and sensitive biosensing platforms.