A green carbon dot-based chemiluminescent sensor for salivary calcium ion detection via CRET.

This study presents the design and implementation of an innovative optical sensor based on Chemiluminescence Resonance Energy Transfer (CRET) utilising luminol, green carbon dots, and K₃Fe(CN)₆ for the specific detection of calcium ions (Ca²⁺) in human saliva. The sensor exploits the unique photoluminescent properties of green carbon dots, which serve as the acceptor in the CRET mechanism, while luminol acts as a chemiluminescent donor. Upon binding of calcium ions, a significant change in the luminescence intensity was observed, indicating a successful interaction between the target ion and the sensor components. Experimental results demonstrated a high sensitivity with a limit of detection (LOD) of 0.71 mg L^-1, showcasing a linear response within the concentration range of 10.02-240.04 mg L^-1. The sensor exhibited excellent selectivity for calcium ions over other common ions present in saliva.