Bioinspired Hierarchical Cellulose/MXene Fibers for Integrated Capture and Ultrasensitive Detection of Microplastics in Complex Biological Matrices

The long‐standing disconnection between enrichment and identification processes fundamentally limits the reliable tracing of microplastics (MPs) in complex aqueous and biological environments. Inspired by the synergistic structure–function design of bee leg villi, we report a bioinspired hierarchical fiber composed of tunicate nanocellulose (TNC) and PDDA‐modified positively charged MXene (P‐MXene) that seamlessly integrates active capture with molecular identification. Through microfluidic spinning combined with interfacial electrostatic engineering, the hierarchical fiber is endowed with a biomimetic wrinkled topology and a rationally designed positively charged architecture, enabling spontaneous sequestration of negatively charged MPs with an ultrahigh adsorption capacity of 978.9 mg/g, a 9‐fold enhancement over pristine fibers. Concurrently, the MXene‐functionalized surface serves as an efficient surface‐enhanced Raman scattering substrate, delivering an enhancement factor of 1.2 × 10 5 and enabling a 128‐fold improvement in detection sensitivity. Benefiting from this integrated trap‐and‐sense mechanism, the platform effectively suppresses interference from complex biological matrices and enables trace‐level detection of MPs accumulation in plant tissues, such as bean sprouts, revealing preferential retention in the root systems. This work establishes a versatile biomimetic hierarchical fiber‐based material platform for detecting trace‐level contaminants in realistic biological systems and beyond.