Hierarchically structured electrochemical biosensing interface for real-time monitoring of macrophage polarization

Direct electrochemical detection of low-abundance biomarkers in serum necessitates the combination of sensitivity, anti-fouling capability, and biocompatibility. In this study, a hierarchically structured biosensing interface of AuNRs@PEG@PEDOT:Hep is constructed that incorporates vertically aligned gold nanorod arrays to enhance conductivity through plasmonic effects, a PEG-based hydration layer to minimize fouling that results in a 92% reduction in nonspecific adsorption), and a heparin-doped poly(3, 4-ethylenedioxythiophene) (PEDOT:Hep) matrix that ensures hemocompatibility with activated partial thromboplastin time (APTT) exceeding 43 s. Functionalized with anti-CD86 and anti-CD206 antibodies, the sensor enables label-free detection of macrophage polarization markers in serum, achieving a linear detection range of 1 pg/mL ∼ 1 μg/mL and a detection limit of 0.41-0.66 pg/mL (S/N = 3). Real-time monitoring in a murine inflammation model demonstrates dynamic transitions between M1 and M2 phenotypes, which closely correlate with disease progression. This study offers a scalable interfacial design for sensitive and robust point-of-care biosensing in complex biological media.