Description
PestiGuard is an innovative biosensor system designed to provide farmers with accessible technology for detecting pesticide residues in crops, promoting agricultural safety and enabling informed decisions. Our system utilizes a synthetic biology approach where an RNA aptamer, specific to target pesticides, undergoes conformational changes upon binding, blocking ribosome access to the RBS and suppressing EGFP reporter expression. This results in a quantifiable fluorescence decrease proportional to pesticide concentration. The complete solution integrates biological sensing with hardware and software: our custom Smartbox ensures consistent imaging conditions, while companion software analyzes test photos against calibrated references to determine contamination levels. With a running cost of <$1 per test, results within 24 hours, and Smartbox installation under $20, PestiGuard offers an affordable, rapid alternative to conventional laboratory methods.
In Hong Kong, pesticide contamination remains a pressing concern despite growing organic claims. The Hong Kong Consumer Council found that 37% of supposedly organic vegetable samples (28 out of 75) contained detectable pesticide residues.[1] This discrepancy between labeling and actual content underscores the urgent need for reliable verification methods. With common contamination found in staple produce like spinach and strawberries,[2] consumers and farmers alike require accessible tools to ensure food safety and validate farming practices.
Globally, pesticide use has steadily increased, reaching 3.69 million metric tons in 2022.[3] This widespread application comes with significant health consequences, as epidemiological studies link pesticide exposure to severe conditions including leukemia, thyroid cancer, brain tumors, Parkinson's disease, asthma, and endocrine disruption.[4] Particularly concerning is the transgenerational impact - pesticides can transfer from mother to fetus during pregnancy, potentially causing epigenetic changes and increasing childhood cancer risks. These findings highlight the critical need for accessible monitoring technologies worldwide.
Current conventional methods for pesticide detection—including gas chromatography, high-performance liquid chromatography, and chromatography-mass spectrometry—while sensitive and accurate, present significant limitations for widespread practical use. These techniques require complex sample processing, expensive equipment, and trained personnel, often taking considerable time to deliver results. [5] These constraints make them unsuitable for rapid, on-site testing needs in agricultural settings. Recognizing this gap between laboratory precision and real-world practicality inspired us to develop PestiGuard—an innovative biosensor that maintains high accuracy while offering rapid detection at minimal cost, effectively bridging the divide between sophisticated laboratory analysis and accessible field testing.
We engineered E. coli BL21 with a plasmid containing PlacUV5-MB7 promoter, lac operator, pesticide-binding aptamer, EGFP reporter gene, and T7 terminator. The mechanism employs an allosteric riboregulator strategy: when pesticides bind the transcribed RNA aptamer, it triggers a conformational change that physically blocks the RBS, preventing translation initiation and reducing fluorescence. In the absence of pesticides, the RBS remains accessible, allowing normal translation and strong fluorescent signal production.
Our custom-designed Smartbox provides standardized imaging conditions for accurate measurements. The foldable device features black walls to minimize reflection, integrated LED lighting for even illumination, and an orange filter for optimal fluorescence detection. Capable of accommodating both 1.5 mL Eppendorf tubes and 15 mL tubes with adaptors, the Smartbox ensures consistent results across different sample volumes while maintaining portability and affordability at <$20 per unit.
The companion software enables simple, intuitive analysis through image processing. Users capture photos of test results within the Smartbox, and the software automatically analyzes color intensity against calibrated reference scales to determine pesticide concentrations. The platform includes data management features, allowing users to track historical results while maintaining privacy through easy data deletion capabilities. This integrated system transforms complex laboratory testing into an accessible, user-friendly process suitable for farm-level implementation.
1. 37% vegetable samples with organic claim found containing pesticide residues. (n.d.). Consumer Council.
https://www.consumer.org.hk/2. Centre, I. C. E. (2022, January 1). Summary. NCBI Bookshelf.
https://www.ncbi.nlm.nih.gov/3. Global pesticide consumption 1990-202. (n.d.). Statista.
https://www.statista.com/statistics/4. Asghar, Usman & MF, Malik. (2016). Pesticide Exposure and Human Health: A Review. Journal of Ecosystem & Ecography. 01. 10.4172/2157-7625.S5-005.
5. 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/