Description
We strive to provide consumers with accessible technology to detect pesticide residues in their food, promoting safety and enabling informed choices for healthier living. To address this need, we have developed an innovative biosensor capable of detecting pesticides in crops. Our design utilizes an aptamer combined with a reporter gene to produce a visual output. During transcription, a specific 3D structure forms at the aptamer, which interacts with the pesticide. This interaction disrupts ribosome binding at the RBS, resulting in a decrease in fluorescence. To accurately measure pesticide levels, crop samples are collected and tested using our kit. The intensity of the resulting signal indicates pesticide concentration: brighter signals signify lower levels, while dimmer signals suggest higher concentrations. To enhance user experience, we have developed advanced software that analyzes test results through image capture. By photographing the test result, the software evaluates the color intensity and compares it to a reference color bar to determine pesticide levels. Additionally, the software stores previous results for easy tracking and allows users to delete data quickly when needed.
Pesticide, a biological and chemical agent that is often used for preventing, destroying, or controlling pests in agricultural activities, has contaminated various fruits and vegetables such as spinach and strawberries.[1] According to the Hong Kong Consumer Council, 75 of the 127 samples of vegetables were claimed to be organic, of which 28 (37%) were found to contain pesticide residues.[2] According to the statistics published by Statista Research Development. It is estimated that the worldwide agricultural use of pesticides steadily increased from 1990 to 2022, reaching 3.69 million metric tons in 2022.[3] Furthermore, it is found that long-term exposure to pesticides has been associated with cancer, asthma and Parkinson’s disease. Given the significant harm and the ubiquity of the pesticides, it is crucial to accurately detect the pesticide levels.
Pesticide residues impose severe challenges on public health. Epidemiological studies show a strong link between pesticide exposure and increased risk of cancers such as leukemia, thyroid, and brain cancers. It is also found that pesticide exposure can be linked to a range of severe conditions, such as Parkinson’s and Alzheimer’s disease, asthma particularly in children, diabetes, and endocrine disruption, which can lead to reproductive issues and developmental defects. Moveover, pesticides can transfer from mother to fetus during pregnancy, elevating the child's future cancer risk. Exposure before conception can even cause epigenetic changes in parental gametes, while exposure during pregnancy may disrupt immune and hormonal functions and induce mutations in fetal cells, particularly increasing the risk of brain cancer.
By literature review, we found that the conventional methods for pesticide residue and metabolite detection mainly include gas chromatography, high-performance liquid chromatography, and chromatography-mass spectrometry. These detection methods have good sensitivity, accuracy, and reliability. However, their disadvantages include complex sample processing and pretreatment, high costs, the need for trained personnel, and the time taken for detection.These methods fall short of meeting the practical needs of the industry: fast, real-time, and low-cost detection. It is necessary to develop technologies for the rapid detection of pesticide residues. As a result, we are inspired to develop an innovative biosensor that shortens the required time, ensures high accuracy and incurs lower costs.
We transformed E.coli BL21 with a plasmid containing T7 promoter, lac operator , pesticide-binding aptamer, reporter gene (EGFP, RFP or GLuc) and T7 terminator. When a pesticide binds to the aptamer that is transcribed onto the mRNA, the pesticide triggers a conformational change that blocks the ribosome binding site and thus blocks the reporter gene translation. The reporter proteins therefore cannot be produced as effectively and the bacteria will glow dimmer. In the absence of pesticides, the RNA aptamer adopts a default conformation that leaves the RBS accessible. The ribosome can bind, initiate translation, and the cell produces the fluorescent protein, emitting a strong signal.
Users should mix food samples with bioengineered E.coli and IPTG and incubate the mixture. By capturing a photo of the test result and uploading on the software, it offers comprehensive colour analysis and a colour bar as reference to correlate brightness to pesticide concentration. The software also stores previous results for easy tracking and allows users to delete data quickly when needed.
In order to provide an ideal environment for accurate pesticide concentration measurement, Smartbox is designed by our team. Smartbox is a foldable box consisting of three main components, including black-walled box to minimize reflection, LED light source to give even illumination across samples and an orange filter. The design ensures validity and accuracy by eliminating any extra openings. Additionally, Smartbox is capable of accommodating 1.5 mL Eppendorf tubes and 15mL tubes with the use of an adaptor to make Smartbox suitable for different laboratory needs.
1. Centre, I. C. E. (2022, January 1). Summary. NCBI Bookshelf.
https://www.ncbi.nlm.nih.gov/2. 37% vegetable samples with organic claim found containing pesticide residues. (n.d.). Consumer Council.
https://www.consumer.org.hk/3. Global pesticide consumption 1990-202. (n.d.). Statista.
https://www.statista.com/statistics/4. LaMotte, S. (2023, November 8). Reducing pesticides in food: Major food manufacturers earn an F grade. CNN.
https://edition.cnn.com/5. Asghar, Usman & MF, Malik. (2016). Pesticide Exposure and Human Health: A Review. Journal of Ecosystem & Ecography. 01. 10.4172/2157-7625.S5-005.
6. Xu, L., Abd El-Aty, A. M., Eun, J.-B., Shim, J.-H., Zhao, J., Lei, X., Gao, S., She, Y., Jin, F., Wang, J., Jin, M., & Hammock, B. D. (2022). Recent advances in rapid detection techniques for pesticide residue: A review. Journal of Agricultural and Food Chemistry, 70(41), 13093–13117.
https://doi.org/10.1021/