New Paper-Based Sensor Achieves Ultra-Sensitive Detection of Pesticides in Fruit Juice

A recent study conducted by researchers from the Taiyuan University of Technology (China) explored a new way to detect pesticide residues at very low levels. This study, which was published in the journal Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, demonstrated how a new paper-based sensing platform can improve food safety testing by detecting pesticide residues (1). The findings of this study showcase how technological innovation and engineering can improve food safety and quality inspection processes.

A refreshing glass of pear and lime juice with a slice of pear and lime on the rim, on a white background. Generated with AI. | Image Credit: Chandlerlikes -stock.adobe.com.

What role do pesticides play in the food industry?

Pesticides are routinely used to treat fruit and vegetables in order to prevent crops from being ruined by bugs and pests. However, because pesticides being used are common practice in the food industry, it is often that their residues remain on these food items (2). Although most pesticide residues on fruit and vegetables are low and nothing to be concerned about, excessive residues in fruits and vegetables pose a significant threat to both human health and the environment, requiring rapid, reliable, and cost-effective detection methods (2).

In the past, some of the more traditional techniques, such as high-performance liquid chromatography coupled with mass spectrometry (HPLC-MS/MS), were routinely used. However, the problem with these methods is that they require time-consuming sample preparation, expensive equipment, and skilled operators (1). The new study addresses these challenges by introducing a flexible surface-enhanced Raman scattering (SERS) platform composed of silver nanoparticles (AgNPs) and molybdenum disulfide (MoS₂) nanoflowers.

What did the researchers do in their study?

As part of the experimental procedure, the researchers designed their SERS platform using simple and effective steps. First, filter paper was treated with positively charged chitosan to enhance the adsorption of MoS₂ nanoflowers, creating a textured, high-surface-area substrate (1). To improve durability and water repellency, the surface was then made hydrophobic using perfluorodecanethiol (PFDT) (1). Finally, small-sized AgNPs and thiram molecules, which are found in fungicides, were co-deposited onto the modified paper.

The researchers sought to use the unique petal-like morphology of the MoS₂ nanoflowers and the hydrophobicity of the treated paper to facilitate the aggregation of AgNPs in the nanogaps of the petals. What this does is create numerous three-dimensional “hot spots,” which are microscopic regions where Raman signals are significantly amplified (1). At the same time, thiram molecules become enriched and concentrated in these hot spots, dramatically boosting their detectability (1).

What were the results that the research team achieved?

The researchers achieved encouraging results from their study. Using a portable Raman spectrometer, the team demonstrated that their platform could detect thiram in pear juice at concentrations as low as 1.01 nanograms per milliliter, which is an exceptionally low detection limit that rivals or surpasses conventional laboratory-based methods (1). Even more importantly, the recovery percentages obtained from the paper-based sensor closely matched those measured by HPLC-MS/MS, underscoring the accuracy and reliability of the new system (1).

What made this study unique?

This study was unique because of the hybridization of AgNPs and MoS₂. This integration provided an integrated enhancement effect, which helped it perform better compared to single-material SERS substrates (1). The combination of high sensitivity, stability, and portability makes the platform a strong candidate for on-site pesticide monitoring, particularly in agricultural and food production settings where rapid results are essential (1).

However, there are more implications apart from agricultural and food production. Biochemistry applications could also benefit from this platform because its low-cost paper-based design could aid the monitoring of biochemical molecules (1). Other applications where this platform could be used include environmental testing, clinical diagnostics, and safety assessments in food and beverages. By integrating multiple functions into a single platform, the technology offers a practical and scalable solution for real-world chemical analysis (1).

With its detection limits, field-ready design, and broad applicability, the Ag/MoS₂ hybrid SERS platform is just another example of how innovations in analytical technologies can lead to significant improvements in food safety and protecting consumer health.

References

1. Yan, F.; Deng, R.; Guo, S.; Li, X. Constructing Hot-spots Enriched Ag/MoS₂ Hybrid SERS Platform for Rapid Detection of Pesticide Residue in Juice. Spectrochimica Acta Part A: Mol. Biomol. Spectrosc. 2026, 346, 126825. DOI: 10.1016/j.saa.2025.126825
2. Gao, Q.; Wang, Y.; Li, Y.; et al. Residue Behaviors of Six Pesticides During Apple Juice Production and Storage. Food Res. Int. 2024, 177, 113894. DOI: 10.1016/j.foodres.2023.113894