Graphene-oxide-microfiber aptasensor for dynamic neutrophil monitoring: Bridging cytokine release syndrome and point-of-care sepsis diagnosis

Neutrophil granule release is critical for host defense, yet its dysregulation underpins cytokine release syndrome (CRS) in both acute (such as sepsis) and sustained inflammatory states. Distinguishing these phases requires real-time monitoring of early markers like neutrophil elastase (ELANE) and lactoferrin (LF), but conventional assays lack requisite sensitivity. Here, we developed a graphene-oxide-functionalized optical microfiber biosensor with high-affinity DNA aptamers (NE-AP and LF-AP) to quantify ELANE and LF via aptamer-protein binding-induced spectral red shifts. The sensor achieved ultralow detection limits (3.57 × 10-20 M for ELANE and 1.28 × 10-19 M for LF), eight orders below ELISA, with excellent selectivity. In a lipopolysaccharide-induced murine model, it resolved distinct temporal release profiles of ELANE and LF, and in clinical validation, it showed distinct spectral responses between septic patients and healthy controls in a preliminary clinical cohort. This platform provides a highly sensitive, real-time tool for decoding neutrophil dynamics, with preliminary translational potential for early sepsis diagnosis.