Fe(3+)-ATP-CK cascade-regulated carbon dots fluorescent probe for dynamic monitoring of creatine kinase activity.

Creatine kinase (CK) plays a crucial role in the rapid screening of diseases such as myocardial infarction. Conventional fluorescence detection often relies on ATP as an intermediate, where CK activity alters ATP levels to allow indirect CK measurement. However, these methods still suffer from poor anti-interference capability and are susceptible to interference from ATP analogues such as ADP and AMP. To address this, a highly specific fluorescence sensing system based on boron-nitrogen-doped yellow carbon dots (B, N-CDs) was constructed. This system exhibits an "On-Off-On-Off" four-state fluorescence response: initially quenched by Fe, restored upon ATP addition due to Fe-ATP binding, and quenched again as CK consumes ATP. By taking advantage of the highly selective competitive binding between Fe and ATP, the system effectively eliminated the interference from ATP analogues, further enhancing specificity. Additionally, the triple fluorescence signal variations (Fe quenching → ATP recovery → CK re-quenching) established a multiple verification mechanism, reducing misjudgment caused by single-signal fluctuations and improving the reliability of detection results. Moreover, a portable visualization platform was constructed by coupling the fluorescent probe with a mobile phone application, which facilitated point-of-care (POC) analysis and promoted its application in clinical diagnosis.