Laser-Patterned Slot-Die Carbon Electrodes Functionalized with Gold Nanostars for the Electrochemical Detection of C-Reactive Protein

We present a scalable and environmentally friendly approach for fabricating miniaturized electrochemical immunosensors by integrating slot-die/roll-to-roll (R2R) deposition with laser patterning to produce slot-die carbon electrodes (SDCEs) on flexible polyethylene terephthalate substrates. Conductive films of graphite and carbon black were continuously deposited and patterned by laser ablation to define precise electrode geometries, providing a photolithography-free, high-throughput process compatible with industrial-scale production. Gold nanostars immobilized on the SDC working electrodes enhanced electron transfer and enabled robust nanostructured interfaces for biofunctionalization. Using electrochemical impedance spectroscopy with charge transfer resistance as the transduction parameter, the platform enabled label-free detection of C-reactive protein (CRP), a biomarker associated with inflammation and various chronic diseases, including cardiovascular diseases. Physicochemical characterizations (Raman, XPS, UV–vis, SEM, TEM) confirmed the uniform integration of nanomaterials and device assembly. The nanoimmunosensor exhibited a linear response over the range of 0–2 ng/mL CRP, with a limit of detection of 11.5 pg/mL, demonstrating high sensitivity, selectivity, and reproducibility in human serum. These results underscore the potential of this continuous SDCE-based fabrication strategy to accelerate the transition of nanoimmunosensors from laboratory prototypes to scalable point-of-care diagnostics and wearable bioelectronic applications.