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Rapid and sensitive detection of nanoplastics via dual-positive-charged AIEgens: A simple filtration-assisted approach for environmental detection
Summary
Scientists have developed a new, fast, and highly sensitive test that can detect tiny plastic particles called nanoplastics in water within seconds, using special glowing molecules that stick to the plastic and light up. This matters because nanoplastics are so small they can potentially get into our bodies through food and water, but until now they've been hard to detect and measure—this new tool could help researchers track contamination in everyday items like water bottles and food packaging, which is a key step toward understanding and reducing our exposure to these pollutants.
Nanoplastics (NPs) have emerged as ubiquitous environmental contaminants with significant bioaccumulation potential, necessitating the development of rapid and sensitive detection methods. However, conventional fluorescent probes often suffer from limited water solubility, slow response kinetics, and poor adaptability to complex matrices. In this study, we report two novel quaternized aggregation-induced emission (AIE) probes, TPE-Hyd-PyQuat-6 and TPE-CN-PyQuat-6, engineered through precise modulation of charge density and molecular flexibility. The introduction of quaternized moieties imparts excellent water solubility and high-density positive charge centers. Zeta potential analysis confirmed an electrostatic-driven capture mechanism, where the binding of probes to negatively charged NPs (PS NPs, -22.37 mV) resulted in a distinct charge inversion (up to +9.51 mV). Both probes exhibited ultra-fast response times (5-20 s) and large Stokes shifts (119-136 nm) in purely aqueous systems, effectively eliminating background interference following simple filtration and sonication. Specifically, TPE-CN-PyQuat-6 demonstrated superior sensitivity (LOD = 0.029 mg/L). TPE-CN-PyQuat-6 maintains detectable fluorescence across the pH range of 2.0-14.0, whereas TPE-Hyd-PyQuat-6 exhibits optimal response under neutral to weakly alkaline conditions (pH 6.86-9.18), while TPE-Hyd-PyQuat-6 offered enhanced binding stability facilitated by the hydrogen-bonding sites of the CN linkage. The platform was successfully applied to detect NPs in food-contact material leachates and natural water bodies, providing a versatile strategy for the design of high-performance sensors for nanoscale environmental pollutants.