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Hierarchical Ag NPs@BNC aerogels with multiscale porosity and plasmonic hotspots for applications to synergistic microplastic capture and SERS sensing
Summary
Scientists have created a sponge-like material made from silver nanoparticles and bacteria-grown cellulose (a natural, eco-friendly fiber) that can trap tiny plastic particles and then help detect them using a laser-based technique. This matters because microplastics are increasingly found in our food and drinks—like the tea bags tested in this study—and having a cheap, sustainable tool to catch and measure them is a key step toward understanding and reducing our exposure to these pollutants. The technology is still a lab-based detection tool, not a filter you'd use at home, but it could help researchers and regulators better track microplastic contam
The escalating prevalence of microplastics in environmental matrices necessitates the development of sensitive, sustainable detection platforms. This study presents a green-synthesized aerogel composite (Ag NPs@BNC) engineered as a multifunctional surface-enhanced Raman spectroscopy (SERS) substrate, synergizing adsorption and sensing functionalities for micro-nano plastic (MNP) detection. Bacterial nanocellulose (BNC), a renewable biopolymer, serves as a three-dimensional scaffold enabling in-situ growth of uniformly distributed silver nanoparticles (Ag NPs), while freeze-drying generates hierarchical porous structures to optimize analyte entrapment. Three distinct adsorption mechanisms were elucidated: size exclusion and surface attachment, capillary force-mediated entrapment within interconnected pores, and hydrogen bonding-assisted physical adsorption at cellulose nanofiber junctions. Adsorption kinetics followed a pseudo-second-order model (R²=0.99). The substrate demonstrated exceptional sensitivity (limit of detection: 87 mg/L) and reproducibility (RSD < 3%), validated through practical analysis of MNPs in commercial tea bags. Finite-difference time-domain (FDTD) simulations confirmed electromagnetic hotspot formation at Ag NPs-MNPs interfaces, while BNC’s three-dimensional confinement enhanced signal uniformity by localizing analytes near plasmonic sites. The synergistic integration of physical entrapment, electrostatic adhesion, and localized surface plasmon resonance (LSPR) effect enables precise identification of microplastics in complex environmental samples. This work advances eco-friendly SERS platforms for sustainable pollution monitoring, bridging material innovation with environmental stewardship.