Research progress on the detection of aflatoxin B1 in agricultural by-products using electrochemical sensors

Aflatoxin B1 is one of the most common fungal toxins in agricultural by-products, due to mutagenic, teratogenic, immunosuppressive, and carcinogenic effects. It is very necessary to develop reliable detection of aflatoxin B1 in agricultural by-products, in order to reduce the harm caused by aflatoxin B1. Traditional methods cannot fully meet the requirements of on-site and rapid detection in modern agriculture. Fortunately, electrochemical sensors have attracted much attention in recent years, due mainly to the simple preparation, easy portability, high sensitivity, and strong selectivity. According to the different recognition components, electrochemical sensors for aflatoxin B1 can be divided into aptamer-, immune response-, and molecular imprinting-based sensors. The recognition elements of these three sensors are antibodies, aptamers, and molecularly imprinted polymers, respectively. Various types of electrochemical sensors have also been developed for aflatoxin B1 using different perception strategies and nanomaterials, such as aptamer electrochemical sensors using competitive strategy, and aptamer electrochemical sensors using ratio strategy. This study aims to review the progress of electrochemical sensors for aflatoxin B1 over the past five years (2019-2023), thereby listing the representative examples, the sensing mechanisms, and signal generation strategies of sensors using different recognition elements. The performance of these sensors was compared to analyze the advantages and disadvantages of different recognition elements. The recommendations and development direction were discussed for the electrochemical sensors of aflatoxin B1 using different principles. The main conclusions were as follows: 1) The recognition components of AFB1 sensors mainly included adaptors, antibodies, and molecularly imprinted membranes at present. The preparation technology of recognition components and new recognition elements should be developed to further improve the performance of AFB1 sensors. 2) The high sensitivity of AFB1 sensors often required signal amplification using one or more nanocomposite materials. The performance of the AFB1 sensor depended mainly on nanomaterials. In addition, these types of sensors were still lacking in the structural stability and complex processing of high-quality nanomaterials. Therefore, there is a high demand to develop novel nanomaterials with excellent performance. Preparation technology of nanomaterials can be expected to greatly improve the performance of AFB1 electrochemical sensors. 3) It is very necessary to combine different recognition components or perception strategies. The aptamers and antibodies were used in combination, together with the aptamers and MIP. More joint applications were explored in the future. 4) Most AFB1 sensors were used to detect a single toxin. However, multiple toxins often coexist in nature. Therefore, the sensors should be developed to simultaneously detect the multiple toxins in real matrices. This requirement can be fully met by integrating the electrodes with high-throughput technologies. 5) The AFB1 sensor is still in the laboratory research stage, and thus a lot of work needs to be done for the true commercial application. The preparation process of the AFB1 electrochemical sensor should be simplified with the sensitivity. The stability and generalization of the sensor should be improved to promote large-scale production and utilization.