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DNA-programmed nanogap 3D SERS aptasensor via silica monoliths for ultrasensitive detection of BPA leaching from microplastics
Summary
Scientists have developed a super-sensitive test that can detect tiny amounts of BPA—a hormone-disrupting chemical—leaking out of microplastics, even at concentrations far too low for older methods to catch. This matters because BPA exposure has been linked to hormone problems, and this new tool could help researchers and regulators quickly check water and other environments for this hidden contamination from plastic pollution. The test worked well even on real river water samples, showing it could be practical for real-world monitoring, not just lab experiments.
The environmental risks of microplastics are exacerbated by the leaching of endocrine-disrupting additives such as bisphenol A (BPA). Effective monitoring requires analytical methods that are ultrasensitive, specific, and suitable for on-site application, requirements that remain challenging for conventional techniques. Herein, we develop an integrated capillary-based SERS aptasensor for the rapid and specific detection of BPA leached from microplastics. The sensor core is a three-dimensional hierarchical porous silica monolith (3D-PSM) anchored inside a quartz capillary. A DNA-programmed nanogap SERS hotspot matrix is constructed on the 3D-PSM by immobilizing cDNA-modified Au nanoparticles, followed by hybridization with aptamer-conjugated Au@4-MBN@Ag nanotags. This design utilizes the cDNA-aptamer duplex as a programmable molecular spacer to create a uniform sub-10-nm gap, generating an intense initial SERS signal ("signal-on"). Competitive binding of BPA triggers nanotag release and quantifiable signal attenuation ("signal-off"). Benefiting from convective mass transport within the 3D architecture, the platform achieves a limit of detection (LOD) of 1.24 pM for BPA, exhibiting a linear range spanning five orders of magnitude (1.0 pM to 0.1 μM), with a recognition time of 10 min. Practical utility was demonstrated by analyzing BPA thermally liberated (70 °C) from polycarbonate microplastics (PC-MPs, 100 and 1000 mesh) in environmental water matrices. The method exhibited high specificity and satisfactory recoveries (93.7 ± 3.6% to 102.0 ± 7.6%) in spiked river water samples, demonstrating a positive correlation between leached BPA amounts and MP contamination levels. This work provides a reliable tool for the direct assessment of hazardous chemical leaching from microplastics.