Specific recognition schemes based on structure-activity relationship: Aniline-functionalized carbon dots for the...

Herein, an innovative approach was proposed for detecting pyrethroids, which pose potential health risks due to their long accumulation in environmental media. To solve their on-site rapid detection, a fluorescence sensor was developed based on aniline-functionalized carbon dots (CDs) specifically designed to detect 3-phenoxybenzaldehyde (3-PBD), one of the primary metabolites resulting from the hydrolysis of pyrethroids. Through screening 13 substituted anilines, 2-chloro-1,4-phenylenediamine (CPDA) was confirmed to have the highest quenching efficiency. By employing CPDA, red, green, and blue-emitting CDs were synthesized. The as-fabricated CDs exhibited excellent selectivity and sensitivity to 3-PBD, displaying highly anti-interfering effects. The fluorescence structure-activity relationship of the CDs was simulated using time-dependent density functional theory calculations, evidencing the underlying mechanisms of specific binding between CDs and 3-PBD. By integrating smartphones with portable fluorescence detectors, we achieved the rapid and quantitative analysis of pyrethroids' residues in meat samples and natural waters. By employing zebrafish (Danio rerio) as an invertebrate model organism, the evaluation on the CDs' environmental safety revealed no significant toxicity to aquatic organisms. These findings demonstrate the feasibilities of these CDs for their widespread applications with both efficacy and safety in practical use.