Fluorescent sensor based on collagen fiber-derived carbon quantum dots and carboxymethylated nanocellulose for Fe3+ detection

Detection of Fe 3+ is essential for environmental and food safety monitoring. However, conventional detection methods often require costly equipment and lengthy processes, limiting their on-site applications. To address these challenges, a fluorescent sensor was developed using carboxymethylated nanocellulose (CMCNF) and collagen fiber-based carbon quantum dots (CCQDs). The CCQDs, with a fluorescence quantum yield of 25.04 %, were synthesized via a microwave hydrothermal method using secondary collagen fibers. A selective and sensitive CMCNF/CCQDs sensor was fabricated by incorporating CCQDs into a CMCNF matrix through a simple solution-casting method. The CMCNF matrix ensured uniform dispersion and stability of the CCQDs, optimizing sensor performance. The sensor exhibited a linear detection range for Fe 3+ between 0 μM and 180 μM, with a corresponding linear equation of y = 0.3532 x + 0.6496 R 2 = 0.9932 . The limit of detection (LOD) for Fe 3+ was determined to be 3.84 μM. Excellent detection performance was demonstrated in real water samples, achieving recoveries from 99.45 % to 105.23 % and an RSD below 2 %. The fluorescence quenching mechanism underlying CCQDs and Fe 3+ interactions was systematically explored. This study provides a sustainable strategy for the high-value utilization of biomass waste and offers a portable approach for Fe 3+ detection.