MOF-SERS hybrid architecture integrated on Fiber-Optic probes for quantification of plasma dopamine in human blood.

Dopamine (DA) is an essential neurochemical marker, yet its reliable quantification in complex biofluids remains challenging for fiber-based sensors due to limited signal return and bio-interference. Here, we present a MOF-SERS hybrid architecture integrated onto a fiber-optic probe for DA detection in human plasma. The platform employs polyhedral Au@Ag nanostars coated with an ultrathin MIL-100(Fe) shell, enabling synergistic plasmonic amplification and molecular enrichment at the sensing interface. This engineered interface delivers a high SERS enhancement factor of 3.2 × 108, an ultralow detection limit of 1.22 × 10-10 M, and excellent linearity (R2 = 0.988), while maintaining selectivity against competing neurotransmitters. Importantly, this system enables direct, quantification of DA in human plasma, demonstrating practical applicability in real samples, not previously reported, yielding physiologically relevant concentrations (1.43 × 10-9 M). These results establish the MOF-SERS-integrated fiber probe as a potential powerful platform for remote and flexible neurochemical sensing in complex biological matrices, with strong promising for clinically relevant bioanalysis.