Highly Fe³⁺-Selective Fluorescent Nanoprobe Based on Ultrabright N/P Codoped Carbon Dots and Its Application in Biological Samples

Measuring the levels of Fe³⁺ in human body has attracted considerable attention for health monitoring as it plays an essential role in many physiological processes. In this work, we reported a selective fluorescent nanoprobe for Fe³⁺ detection in biological samples based on ultrabright N/P codoped carbon dots. By employing adenosine 5′-triphosphate (ATP) as the carbon, nitrogen, and phosphorus source, the N/P codoped carbon dots could be simply prepared through hydrothermal treatment. The obtained carbon dots exhibited high quantum yields up to 43.2%, as well as excellent photostability, low toxicity, and water solubility. Because of the Fe–O–P bonds formed between Fe³⁺ and the N/P codoped carbon dots, this nanoprobe showed high selectivity toward Fe³⁺ against various potential interfering substances in the presence of EDTA. The fluorescence quenching of as-fabricated carbon dots was observed with the increasing Fe³⁺ concentration, and the calibration curve displayed a wide linear region over the range of 1–150 μM with a detection limit of 0.33 μM. The satisfactory accuracy was further confirmed with the river samples and ferrous sulfate tablets, respectively. With the above outstanding properties, these N/P codoped carbon dots were successfully applied for direct detection of Fe³⁺ in biological samples including human blood serum and living cells. As compared to the most reported carbon dots-based Fe³⁺ sensors, this nanoprobe showed high fluorescence, good accuracy, and excellent selectivity, which presents the potential practical application for diagnosis of Fe³⁺ related disease