Sensors for pesticides with high sensitivity have been urgently required to control food safety, protect ecosystem and prevent disease. In this review, we provide an overview of recent advances and new trends in optical sensors for the detection of pesticide based on fluorescence, colorimetric and surface enhanced Raman scattering, surface plasmon resonance and chemiluminescent strategies. These methods will be classified by the types of recognition elements, including enzyme, antibody, molecularly-imprinted polymers, aptamer and host-guest reaction. This review explores the basic features of established strategies through assessment of their performance. In addition, we provide brief summary of the entire review, the drawbacks of present sensor and future prospects, as well as the ongoing efforts to pesticide optical sensors.

Introduction

Pesticide are primarily used to prevent, control, or eliminate pests and weeds for boosting agricultural productivity in modern agricultural practices [1,2]. According to the literatures [3,4], the use of pesticides helps in securing almost one-third of crop production globally. However, the residue of pesticide even at trace levels not only seriously cause food contamination, but also severely breakdown the ecosystem, posing a great danger to people’s daily life [5e7]. As a result, pesticide pollution has attracted more and more concern and become one of the most alarming challenges. For proper management of pesticide, Governments have set lots of policies for guiding pesticide use and have regulated maximum residue levels on foods and agricultural commodities [2,8,9]. Although most pesticide were detected to be within recommended limits, the bioaccumulation effect and continuous exposure can rise safety risks to human health [10]. In addition, some new types of pesticides with highly effective activity, whose toxic mechanism have not clear understood, are being continuously brought into market [11]. Therefore, the analysis of pesticide residues is an urgent demand to ensure food quality and safety, safeguard the ecosystem and protect human health from possible hazards. Pesticide detection have traditionally been carried out by employing conventional chromatographic techniques, including high-performance liquid chromatography (HPLC) [12e14], gas chromatography (GC) [15e17] and mass spectrometry (MS) [18e20]. Although these techniques offer powerful trace analysis with excellent sensitivity and high reproducibility, many drawbacks, such as sophisticated equipment, time consuming, tedious sample preparation and purification steps, obviously limited their on-site and real-time application, particularly emergency cases. Thus, vast endeavors have been devoted to investigating alternative strategies for realizing pesticide in a facile, speedy, sensitive, selective, accurate and user-friendly manner. In fact, significant attention has been drawn to the fabrication of optical sensors for pesticide detection. For pesticide analysis, myriad optical strategies have been established utilizing recognition elements, such as enzyme, antibody, molecularly-imprinted polymers, aptamer and host-guest recognizer, which employed to directly capture and identify the target pesticide. Moreover, the integration of recognition elements and nanomaterials possess high sensitivity and excellent selectivity in terms of real-time analysis, which is in high demand for pesticide detection. This Review focuses on the recent development of sensitive pesticide optical sensor, with a particular emphasis on the fluorescence (FL), colorimetric (CL), surface-enhanced Raman scattering (SERS), and other strategies including surface plasmon resonance (SPR) sensor and chemiluminescence strategy (Fig. 1), which provide comprehensive coverage of current standings of pesticide detection. Rather than summarizing either enzyme-based sensors [1,2,21,22] or nanomaterials-based strategies [4,11,23e26] as performed in other excellent reviews, we highlight the latest achievements in pesticide optical sensor and provided readers with a high-impact recent advances in the developing field from our point of view. Enzyme, antibody, and host-guest chemistry as recognizer have been frequently employed in pesticide optical sensor to achieve high sensitivity and good selectivity, which exhibited great superiority.