## 3 Application of AIEgens in the Detection of Pesticide Residues in Fluorescence Sensors
### Detection of pesticides Using Organic Fluorescent Small-Molecule Sensors Based on AIEgens  
Organic small-molecule sensors utilizing AIEgens rely on the AIE properties of these compounds. By selecting AIEgens with specific optical properties or those that interact with pesticide molecules and by designing and synthesizing these molecules to tailor their luminescence properties and sensitivity, these sensors achieve high sensitivity and selective detection of pesticides. For instance, [PERSON] et al. synthesized tetraphenylethylene derivatives TPE-1 (A1-1) and TPE-2 (A1-2) with different aldehyde groups (Figure 1a) [27]. Both probes exhibited notable AIE characteristics, but A1-2 demonstrated lower quantum yield and sensitivity to pH compared to A1-1. Consequently, A1-1 was selected for detecting organophosphorus pesticides (OPs) (Figure 1b,c). The detection mechanism of A1-1 is based on the irreversible inhibition effect of OPs on the activity of acetylcholinesterasecholinesteraseerase (AChE). This inhibition reduces the hydrolysis of acetylcholinesterasecholine iodide (ATCh) to acetic acid, diminishing the protonation of A1-1 and thereby initiating a fluorescence signal for OP detection (Figure 1d). Essentially, the presence of OPs inhibits AChE, decreases acetic acid production, reduces  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Sensor Type** & **Sensor** & **Analytic** & **LOD** & **Detection Range** & **Sensing Type** & **Mechanism** & **Ref. ** \\ \hline \multirow{8}{*}{Small molecules} & A1 & Organophosphorus pesticides & 0.008 mg/L & 0.009–22.5 mg/L & Turn-on & Specific recognition and chemical interaction & [27] \\  & A2 & Carbamate pesticides & 27.8 ng/mL & 0 \(\mu\)g/mL–50 g/mL & Turn-off & Specific recognition and chemical interaction & [69] \\  & A3 & Trifluralin & 6.28 ug/L & 20–90 ug/L & Turn-off & Photophysical quenching process & [70] \\  & A4 & Padebutrazol & 9.3 \(\times\) 10\({}^{-8}\) M & 2 \(\times\) 10\({}^{-7}\)–9 \(\times\) 10\({}^{-6}\) M & Turn-on & Change process and solubility change & [71] \\ \hline \multirow{8}{*}{Nanocomposites} & \multirow{4}{*}{A5} & Organophosphorus pesticides & 0.4 ug/L & 1–50 mg/L & \multirow{4}{*}{Turn-off} & Specific recognition and molecular self-assembly & [72] \\  & & Organophosphorus pesticides & (Fluorescence) & (Fluorescence) & & & \\  & A6 & Paraooxon & 0.08 ug/mL & 0.8–60 mg/mL & Turn-off & Specific recognition and molecular self-assembly & [73] \\  & A7 & Ethion & 0.96 mM & 0–50.0 mM & Turn-on & Chemical interaction & [74] \\  & A8 & Organophosphorus pesticides & 1 ug/L & 1–100 ug/L & Turn-off & Specific recognition & [75] \\  & A9 & / & / & / & / & Specific recognition & [28] \\ \hline \multirow{8}{*}{Organic metal frameworks} & A10 & Thalidomide (TM) & 5.57 ug/L (IM) & 1–20,000 ug/L & / & solubility change & [76] \\  & Thianethosam (TE) & 0.98 ug/L (TH) & & & & & \\  & & & 0.98 ug/L (TH) & & & & \\  & & & & & & & \\  & A11 & Methyl parathion & 1.3 \(\times\) 10\({}^{-3}\) mg/L & 0.1–5 mg/L & Turn-off & Noncovalent interaction & [77] \\  & A12 & Glyphosate & 0.28 mM & 0–100 nM & Turn-off & Specific recognition and chemical interaction & [78] \\ \hline \multirow{8}{*}{Superramolecular assemblies} & A13 & Carbaryl & 0.007 ug/L & 0.02–200 ug/L & Ratiometric & Specific recognition and photophysical change process & [79] \\  & & & & &A1-1 protonation, and restores fluorescence, enabling \"turn-on\" detection of OPs. Practical applicability was further validated through standard addition experiments in real water samples, with recoveries ranging from 98% to 112%, highlighting the potential of A1-1 as an effective pesticide detection probe. [PERSON] et al. designed and synthesized the probe CBZ-FP (A2) based on a chromophore of AIE fluorescent protein (Figure 2a inset) [69]. This probe has a large Stokes shift, enhanced fluorescence, and low background noise (Figure 2a,b). It can indirectly detect carbamates by assessing the activity of carboxylesterases (CESs). The ester group in A2 serves as a specific reactive substrate for CESs.