Gemini SERS for Cross-Category Biomarker Detection and Early Warning of Sudden Cardiac Death in Acute Coronary Syndrome

Simultaneous detection of metabolites and proteins─two chemically and functionally distinct classes of biomolecules─in complex biofluids remains a significant analytical hurdle, yet is critical for early and accurate disease diagnosis. These difficulties arise from intrinsic disparities in molecular abundance, physicochemical properties, and detection mechanisms. Such analytical limitations span a wide range of disease contexts and are exemplified by acute coronary syndrome-induced sudden cardiac death (ACS-SCD), where intertwined metabolic and proteomic dysregulation obscures early diagnostic cues and necessitates robust, multiplexed detection strategies. Here, we present a dual-signal surface-enhanced Raman scattering (SERS) platform─termed Gemini─for ultrasensitive, cross-category quantification of pyruvate (a metabolite) and lactate dehydrogenase B (LDHB, a protein) in plasma-derived exosomes. The system integrates antibody-functionalized gold nanoparticles for LDHB recognition with a boronate-based SERS nanotag responsive to hydrogen peroxide (H₂O₂) generated from a pyruvate oxidase (PO<i>x</i>)-mediated cascade. This strategy yields two spectrally distinct Raman signals within a single assay, enabling ratiometric and interference-free detection. Gemini achieves detection limits of 2.415 μM for pyruvate and 0.032 ng/mL for LDHB. When combined with a support vector machine (SVM) classifier, the platform accurately distinguishes ACS-SCD patients from healthy controls with 85% accuracy (90% sensitivity, 80% specificity), showing diagnostic performance comparable to conventional methods (AUC = 0.82 vs 0.79). This study demonstrates a multiplexed SERS framework for integrated metabolic-proteomic diagnostics and provides a clinically scalable strategy for early cardiovascular risk assessment. Moreover, the Gemini platform offers a broadly applicable paradigm for precision diagnostics across diverse pathophysiological conditions.