Innovative Cerium and Chromium Co-doped Carbon Quantum Dots: Synthesis, Smartphone-Compatible and Sensitive Fluorescence Approach for Detection of Vitamin B12.

Abstract

Carbon quantum dots (CQDs) have acquired significant attention recently due to their unique properties and wide-ranging applications. These nanoscale carbon-based materials exhibit exceptional photoluminescence, excellent biocompatibility, and remarkable chemical stability, making them promising candidates for various technological advancements. The present study describes novel heteroatom co-doped carbon quantum dots as sensors to probe VitB₁₂ biomolecules in an aqueous solution by employing sensitive and straightforward fluorescence quenching measurements. The designed CQDs were characterised with UV-Vis absorption spectroscopy, FT-IR, XRD, HR-TEM, SEM, EDS, XPS, TCS-PC and fluorescence spectroscopy. The current work aims to modify size distribution and heteroatom doping to create cerium and chromium co-doped CQDs (Ce/Cr-CQDs) with improved sensing capabilities. One-step hydrothermal calcination was used to generate cerium and chromium co-doped carbon quantum dots (Ce/Cr-CQDs), which were then investigated as sensing biomolecules for biological applications. The correlation coefficient(R²) and limit of detection (LOD) were 0.993 and 1.88 µM, respectively, for VitB₁₂ over a concentration range of 3 µM to 50 µM. Real sample analyses were performed with mean recoveries ranging from 97.5 to 99% of physiologically relevant VitB₁₂ for developing Ce/Cr-CQDs based fluorescence sensors/probes. The significant and observable color variations of the CQDs have been effectively coupled to the smartphone app "RGB color detector," and promising results were reproduced.