Cardiolipin-Based Electrochemical Biosensor for Non-treponemal Antibody Detection Using Screen-Printed Electrodes: A Proof-of-Concept Study

Abstract Syphilis remains a major public health concern. Although non-treponemal tests are widely used for screening and treatment monitoring, their interpretation relies on visual assessment of flocculation. Here, an amperometric biosensor using isolated cardiolipin (0.03–0.12%) as the sole biorecognition element was developed on carbon/graphene screen-printed electrodes. The 0.06% concentration was selected for subsequent experiments, and the biosensor discriminated positive and negative control materials across two electrode batches. Progressive positive-control dilution produced a systematic electrochemical response (R2 = 0.921). Electrode functionalization significantly affected the response (p < 0.001), supporting the contribution of immobilized cardiolipin. Discrimination was maintained under physiological and pathological glucose conditions (adjusted p < 0.001). These findings provide a preliminary proof-of-concept for cardiolipin-based electrochemical assessment of non-treponemal antibody reactivity. Further studies using clinical samples are required to establish analytical and clinical performance and investigate semiquantitative evaluation by correlating electrochemical responses with defined serological titers.