Carbon dots with red emission as nanoprobe for sensing of heparin in biofluids and pharmaceutical samples

Heparin (HEP) is one of the oldest anticoagulant drugs, widely used in clinical settings, particularly in surgery and dialysis machines. Despite its long history, it remains extensively employed in medical practice. This study introduces a selective and cost-effective method for the rapid detection of HEP using red-emission carbon dots (R-CDs). These R-CDs were synthesized through a one-pot hydrothermal method, utilizing neutral red and thiourea for photostability, biocompatibility, and low cytotoxicity. Key parameters affecting the sensing process, including nanoprobe volume, pH, buffer type, and incubation time, were optimized to achieve potential assay conditions. The fluorescence intensity of the nanoprobe at 625 nm gradually decreased as the concentration of HEP increased from 60 to 240 nM. These changes in fluorescence intensity showed a linear relationship with HEP concentration within this range, achieving a limit of detection (LOD) of 5 nM. The proposed nanoprobes facilitate both quantitative and qualitative non-invasive analysis of HEP in various human biofluids, suggesting their potential for broader bioanalytical applications.