## 1 Introduction  
The ever-increasing demand for food production requires a widespread use of pesticides to prevent pests and boost agricultural productivity. Pesticides encompass a numerous and diverse group of chemical compounds that can be used to combat a wide variety of pests. Regarding insecticides, carbamates (CMs) and organophosphates (OPs) are commonly utilized because, compared to old-school organochlorines (OCs), they do not usually release toxic metabolites and are less persistent in the environment [1]. However, CMs and OPs show relatively high acute toxicity and their residues in food may result in chronic toxicity incidents [2]. The toxicity of CMs and OPs arises from the inhibition of acetylcholinesterase-A, a vital enzyme in the neural system of insects and mammals including humans. Typically, A.AChE hydrolyzes the neurotransmitter acetylcholine into choline and acetic acid (Figure 1a), an essential reaction that enables the cholinergic neuron to return to its resting state after activation. However, A.AChE activity is reduced in the presence of CMs or OPs, due to carbamylation or phosphorylation of serine hydroxyl group in the enzyme active cite [3], respectively. This results in acetylcholine accumulation, which can lead, in case of higher exposure, to health problems, including bradycardia, salivation, diarrhea or even coma [4]. A complete overview on AChE physiological function and inhibition mechanisms published by [PERSON] et al. [5] may provide a deeper understanding of the issue. Clearly, there is an urgent need to develop sensitive and accurate analytical methods for OPs and CMs detection considering their impact on health and the potential of dietary exposure as this was reflected in the latest European Food Safety Authority (EFSA) report on pesticides [6] and the EFSA pesticide residue intake model (PRIMo) [7]. Liquid and/or gas chromatography tandem mass spectrometry (LC-MS/MS and/or GC-MS/MS) are commonly applied for pesticide residues monitoring in food matrices [8]. Although these methods provide selectivity, sensitivity with high-throughput capabilities, LC/MS and GC/MS are also costly and time-consuming methodologies that require skilled personnel [9]. To counter these limitations, an ever-increased use of sensor-based methods has been noticed [10]. Various immunoassays were developed against specific CMs and OPs [11; 12]. Although this approach may be even more sensitive than chromatographic methods, it detects one or only a limited number of pesticides. Regarding electrochemical (EC) sensors, there were several studies using both enzymatic [13] and non-enzymatic pesticide recognition [14] employing different EC principles, such as amperometry [15] and voltammetry [16]. Despite reaching low limits of detection (LODs), mostly in buffers, these methods suffered from complicated manufacturing and problematic storage stability period [17]. Considering optical detection, surface-enhanced Raman spectroscopy (SERS), surface plasmon resonance (SPR) and spectroscopic methods have been used. SERS has been emerged as an attractive analytical choice due to its portability potential. However, pesticides detection only on fruit peels [18] was a major weakness limiting its application. Although SPR and fluorescent methods showed promising results, especially when combined with nanomaterials (NMs) [19], their sophisticated analytical configuration comes in contrast to the need for simplified alternative methods. AChE assays may be considered as a potential solution for the aforementioned analytical needs. These assays are based on the principle that the enzyme, in vitro, can produce a colored product (Figure 1b). Under relevant conditions, in the presence of an analyte the residual AChE activity (meaning less color production) can be correlated to an inhibitor concentration by comparing this response with a control sample.