Self-doping synthesis of iodine–carbon quantum dots for sensitive detection of Fe(iii) and cellular imaging

Abstract

Carbon quantum dots (CQDs) are carbon nanomaterials with fluorescent properties. Due to their unique structure and optical properties, CQDs have become a research hotspot in recent years. In this paper, iodine-doped CQDs (I-CQDs) with high photoluminescence (PL) (fluorescence quantum yield ∼ 36.2%) were innovatively prepared using a self-doping method with p-iodobenzoic acid as the only precursor. The average particle size of the I-CQDs is 6.42 nm, the maximum excitation wavelength is 330 nm, and the maximum emission wavelength is 408 nm. Fluorescence-sensing experiments showed that the I-CQDs could be used as a ‘turn-off’ fluorescence sensor for Fe³⁺, with a detection limit of 0.47 μM. The cause of the fluorescence quenching can be attributed to dynamic quenching and the inner filter effect. When the sensor detects ferric ions in actual water samples, the spiked recoveries are 99.2% to 107.5%, with good reproducibility and high accuracy. Moreover, I-CQDs with their lower cytotoxicity could be used for the imaging of HeLa cells over longer times and as a new type of fluorescent labeling material for environment monitoring, cell labeling, and cellular imaging.