Parallel Detection of Mixed Pesticides Based on Dual Quantum Dot/Porous Silicon Optical Biosensors
Pesticide contamination in food and water is a growing concern, posing serious risks to human health and environmental safety. This issue underscores the need for rapid and efficient detection of harmful chemicals.
However, conventional analytical techniques, including chromatography and mass spectrometry, are inherently expensive, time-consuming, and require specialized equipment, limiting their accessibility for routine monitoring.
A novel optical biosensing platform integrating dual quantum dot (QD) and porous silicon (PSi) technology offers an innovative and cost-effective approach for real-time, simultaneous detection of mixed pesticides. Designed to detect acetamiprid and profenofos concurrently, this biosensor overcomes the limitations of conventional methods, which typically focus on single-target screening.
By leveraging the complementary optical properties of QDs and PSi, the system enables multi-analyte detection in a single step, significantly enhancing analytical efficiency. It utilizes the unique optical characteristics of QDs, which provide strong fluorescence signals, while the PSi Bragg mirror structure amplifies these signals through precise reflectivity.
The PSi Bragg mirror was meticulously engineered by optimizing the refractive index and layer thickness, broadening the reflection spectrum for enhanced multi-target fluorescence detection. Expanding the forbidden band of the Bragg mirror enables fluorescence amplification across multiple wavelengths, facilitating a multi-wavelength detection mechanism capable of distinguishing between various pesticides.
A key advancement of this biosensor is its aptamer-based detection mechanism. Aptamers, short synthetic DNA sequences with high specificity for target molecules, are conjugated with QDs to enable the selective recognition of acetamiprid and profenofos. Fabrication involved electrochemical etching and surface functionalization to ensure strong aptamer-pesticide binding.
When pesticides bind to their respective aptamers, they displace them from the QD complex, leading to a measurable decrease in fluorescence intensity. This change provides a direct quantitative assessment of pesticide concentration.
The detection process is straightforward and highly efficient, employing digital image processing to analyze fluorescence changes before and after pesticide exposure. Experimental results demonstrated strong linear correlations for acetamiprid (2.64 nM) and profenofos (1.05 nM), with minimal cross-reactivity, ensuring specificity for real-world applications.
Beyond its high sensitivity, this biosensor exhibits remarkable stability and reproducibility. Fluorescence intensity remained consistent over 25 days, with relative standard deviations of 4.72% and 4.01%. Additionally, five independently fabricated sensors tested at 1 µg/L demonstrated reproducible performance, with standard deviations ranging from 4.21% to 4.65%, highlighting the method’s reliability for routine pesticide monitoring.
This dual QD/PSi biosensor represents a significant advancement in pesticide detection technology. It offers rapid, cost-effective, and highly sensitive multi-analyte detection, eliminating the need for expensive laboratory infrastructure.
In conclusion, this biosensor provides a fast, cost-effective solution for detecting mixed pesticides in real time, enhancing food safety, environmental monitoring, and agricultural compliance while minimizing contamination risks and reducing dependence on costly laboratory analysis.
As pesticide contamination remains a global concern, this technology has the potential to revolutionize food and water safety, particularly in resource-limited regions. Future advancements could enhance its sensitivity, broaden its applicability to a broader range of contaminants, and enable automated monitoring systems.