New Method for Rapid SERS Detection of Pesticides in Agricultural Products Unveiled

Neonicotinoid pesticides, used widely in U.S. agriculture since 2005, target insect nervous systems but may also affect mammals, including humans, because of shared nicotinic acetylcholine receptors (1). These chemicals are prevalent in corn and soybean crops and are used to control pests in livestock and pets (1). Concerns arise from their persistence in the environment and potential binding to human receptors, which could pose health risks with chronic, low-level exposure (1).

A recent research collaboration between Yantai University and the Institute of Quality Standard and Testing Technology for Agro-Products explored this topic. In their study, the research team, led by Xaolin Cao of Yantai University, investigated a novel surface-enhanced Raman spectroscopy (SERS) method that could conduct rapid analysis of neonicotinoid pesticides, specifically acetamiprid and thiacloprid, in agricultural products such as peaches and pears.

Farmers spraying pesticide in wheat field wearing protective clothing | Image Credit: © xb100 - stock.adobe.com.

This new method involves developing magnetic molecularly imprinted polymers combined with SERS (MMIPs-SERS). This approach harnesses the strengths of both techniques to deliver a highly sensitive, accurate, and efficient system for detecting trace amounts of pesticides (2). Neonicotinoids, including acetamiprid and thiacloprid, are widely used insecticides that have been under scrutiny for their potential environmental and health impacts (2). As a result, detecting these compounds is essential for safeguarding public health.

The research team began by synthesizing magnetic nanoparticles, onto which they polymerized imprinted layers. These layers were crafted using acetamiprid as the template molecule, methacrylic acid as the functional monomer, and trimethylolpropane trimethacrylate as the cross-linker (2). This process resulted in MMIPs with a core-shell structure that exhibited class-specific recognition and great magnetic separation performance (2).

In addition, the adsorption properties of the polymers were validated through binding experiments, which demonstrated the system's rapid adsorption and desorption capabilities. Notably, the MMIPs reached adsorption saturation within a minute, showcasing their efficiency in extracting target molecules from complex food matrices (2).

Once the MMIPs were synthesized and characterized, they were integrated with SERS. SERS uses inelastic light scattering by molecules absorbed onto metal surfaces; in this case, gold nanoparticles were used (3). These gold nanoparticles allowed for the detection of pesticides at extremely low concentrations. The combination of these two technologies resulted in a system that could detect acetamiprid and thiacloprid in a linear range of 1 to 20 μg/g, with limits of detection (LODs) ranging from 23.7 to 68.8 ng/g in peach and pear samples (2).

The significance of this study lies in its potential applications in the agricultural and food industries. Traditional methods for detecting neonicotinoids in food can be time-consuming, requiring complex sample preparation and long processing times (2). In contrast, the MMIPs-SERS method developed by Cao and his team offers a rapid, simple, and highly selective alternative. The system's ability to achieve rapid adsorption within just one minute is particularly noteworthy, making it suitable for on-site testing in agricultural settings (2).

Furthermore, the developed method was validated through a series of reusable and spiked experiments, demonstrating its robustness and reliability. The study highlights the potential for this technology to be used in the rapid analysis of neonicotinoids in various food products, providing a crucial tool for regulatory agencies and food safety inspectors (2).

Because of the method's high sensitivity, specificity, and rapid processing time, it makes it an attractive option for widespread adoption. The research team envisions that this technology could be adapted to detect a broader range of pesticides and other contaminants, further enhancing its utility in the field of food safety (2).

References

(1) National Toxicology Program, Neonicotinoid Pesticides & Adverse Health Outcomes. NIH.gov. Available at: https://ntp.niehs.nih.gov/whatwestudy/assessments/noncancer/completed/neonicotinoid (accessed 2024-08-22).

(2) Cao, X.; Hu, Y.; Yu, H.; et al. Detection of Neonicotinoids in Agricultural Products Using Magnetic Molecularly Imprinted Polymers-Surface Enhanced Raman Spectroscopy. Talanta 2024, 266 Part 1, 125000. DOI: 10.1016/j.talanta.2023.125000

(3) Langar, J.; Jimenez de Aberasturi, D.; Aizpurua, J.; et al. Present and Future of Surface-Enhanced Raman Scattering. ACS Nano 2019, 14 (1), 28–117. DOI: 10.1021/acsnano.9b04224