A Novel Nano-Scale Biosensor for Measuring Hemoglobin Oxygen Saturation Using Carbon Quantum Dots

Hemoglobin oxygen (HbO₂) saturation is a critical biomarker in patient care, yet conventional measurement approaches are often costly and require extensive calibration. To address these limitations, the present study proposes a novel biosensor derived from paper-based carbon quantum dots (CQDs) fabricated through a one-step thermal treatment. CQDs are carbon-based nanoparticles renowned for their excellent biocompatibility, low toxicity, thermal stability, and remarkable optical properties. To quantify HbO₂ saturation, we exploit their photoluminescence, which enables photoinduced electron transfer and fluorescence quenching with hemoglobin. Our results demonstrated that the peak fluorescence intensity of CQDs shows a strong linear correlation with HbO₂ saturation. Variations in HbO₂ saturation levels were achieved with sodium dithionite and determined using Winterbourn's equations. Our CQD-based HbO₂ saturation measurements closely agreed with those obtained from conventional spectrophotometric analysis. Thus, this investigation highlights the potential of CQDs as a biosensor for effective HbO₂ saturation measuring without extensive calibration.