Supra-Carbon dots for methyl-paraoxon detection using a new controllable IFE-based method

Pesticide residues pose a significant threat to human health. Inner filter effect (IFE) stands out for its ability to enable the rapid and cost-effective establishment of fluorescent detection systems. Nevertheless, the practical implementation is often hindered by issues such as low spectral overlap and interference from impurities, which can compromise its effectiveness.

To develop novel AIEE-type CDs and apply them to improve the efficiency of IFE-based strategies. With the aid of AIEE-type CDs, we aim to develop a multi-channel detection platform that provides more reliable fluorescent probes for real samples and imaging applications.

Preparation of N, S-CDs was achieved using a novel combination of sources. The activation mechanism of Supra-CDs' AIEE characteristics was verified. In the methodological experiments, detection performance of Supra-CDs was tested to confirm their improvement in the IFE-based strategy, practical applicability for real sample detection, and imaging capability.

In this work, p-PA and thiourea were used for the first time to prepare N, S-CDs. After adding water, the fluorescence intensity of Supra-CDs increased by nearly 360 % compared to N, S-CDs. Spectral overlap rates of the target and probe in the controllable IFE-based system improved from 1.80 % to 33.11 %, indicating superior analytical performance in aqueous solutions compared to ethanol. The fluorescent method exhibited a linear range of 0.5-100 μM, with a detection limit of 0.5 μM. Furthermore, a smartphone-based system has been proposed for the colorimetric analysis of methyl paraoxon, offering a more convenient and efficient alternative. Additionally, Supra-CD demonstrated exceptional capabilities in cell imaging, specifically targeting intracellular lipids within HepG2 cells.

This study unveils a new type of Supra-CDs that exhibit AIEE property. It also introduces a creative fluorescent sensor with tunable IFE. In summary, this research delivers important insights into AIEE-type Supra-CDs and affirms their potential to inspire broader applications.