Portable high-sensitivity Raman-electrochemical microsensor utilizing a polarization shift strategy for anti-interference detection of 5-hydroxytryptamine

Abstract

As a critical biomarker in neuropsychiatric disorders, abnormal levels of 5-hydroxytryptamine (5-HT) are closely associated with pathological conditions including depression and irritable bowel syndrome. Therefore, accurate and dynamic measurement of 5-HT is vital for early diagnosis. However, the detection of 5-HT in complex biological fluids encounters substantial interference due to overlapping oxidation peaks of uric acid (UA) and 5-HT. Traditional anti-interference techniques typically depend on chemical modification methods, which involve complicated procedures and elevated costs. In this study, a novel sensing platform is developed using laser-induced graphene (LIG), adopting an entirely physical polarization shift strategy (0 V potential-binding flushing) to effectively minimize UA interference. Moreover, the plasmon resonance effect of electrodeposited gold nanoparticles (Au NPs) significantly enhances both electrochemical and Raman signals, achieving an enhancement factor (EF) of 4.67 × 10⁵. The designed platform exhibits precise quantitative detection capability for 5-HT, characterized by a low detection limit of 2.23 nM and a wide linear response range of 50 nM to 50 µM, supplemented by qualitative Raman fingerprint verification. When applied to actual serum samples, the microsensor demonstrates recoveries ranging between 97.1% and 99.6%, highlighting its efficiency and potential for rapid, point-of-care neurotransmitter analysis.