In Vivo Dynamic Hotspot-Enhanced Raman Spectroscopy via Reconfigurable Swarming Nanoprobes

Surface-enhanced Raman spectroscopy (SERS) has revolutionized molecular detection through plasmonic signal amplification, yet its translation to living systems remains constrained by two unresolved challenges: rigid substrates lack biological adaptability, while colloidal nanoprobes suffer from unreliable signal reproducibility and poor spatiotemporal control. Herein, we present a bioadaptive SERS platform leveraging magnetically guided swarming nanoprobes to generate dynamic electromagnetic hotspots in vivo. The nanoprobes integrate a magnetic core, plasmonic gold/silver layers, and biocompatible silica coating, enabling precise manipulation and Raman signal enhancement. Programmed magnetic fields drive hierarchical assembly of nanoprobes into chain-like nanostructures with interparticle gap-dependent hotspots, followed by coordinated reconfigurations into dynamically stable swarm geometries. Multiphysics simulations reveal that cyclic nanoprobe assembly-disassembly generates spatially uniform transient hotspots, eliminating the fixed spatial limitations of conventional substrates, while simultaneously inducing convective microflows that actively recruit analytes to enhancement zones. This dual mechanism achieves reproducible amplification with enhancement factors exceeding 2.9×107, over tenfold greater than colloidal systems. Crucially, the swarm’s reconfigurability enables efficient navigation through complex biological topologies, surpassing passive nanoprobes in targeting efficiency. In vivo validation via ultrasound-guided deployment of swarming nanoprobes in rabbit models demonstrates over 10.3-fold Raman signal amplification during intravascular detection, outperforming existing platforms in spatial resolution and operational stability. Our work establishes a new paradigm for in vivo SERS detection by leveraging active matter physics to synergize nanoscale sensing, opening new avenues for real-time molecular diagnostics in living organisms.表面增强拉曼光谱（Surface-enhanced Raman spectroscopy, SERS）通过等离激元信号放大革新了分子检测技术，但其向活体系统的转化仍受限于两项未解决的难题：刚性基底缺乏生物适配性，而胶体纳米探针则存在信号重现性不佳、时空控制能力薄弱的问题。本文中，我们提出一种生物适配型SERS平台，该平台借助磁引导集群纳米探针在活体内生成动态电磁热点（electromagnetic hotspots）。该纳米探针集成了磁性核、等离激元金/银层以及生物相容性二氧化硅涂层，可实现精准操控与拉曼信号增强。程序化磁场引导纳米探针逐级组装为链状纳米结构，该结构具有依赖粒子间距的热点，随后协同重排为动态稳定的集群构型。多物理场仿真显示，纳米探针的周期性组装-解组装过程可产生空间均匀的瞬态热点，破除了传统基底的固定空间限制，同时诱导对流微流，主动将分析物富集至增强区域。这种双重机制可实现重现性优异的信号放大，增强因子超过2.9×10^7，比胶体纳米探针系统高出一个数量级以上。尤为关键的是，集群的可重排特性使其能够高效穿越复杂的生物拓扑结构，在靶向效率上优于被动式纳米探针。通过在兔模型中开展超声引导的集群纳米探针部署进行活体验证，结果显示血管内检测过程中的拉曼信号放大倍数超过10.3倍，在空间分辨率与操作稳定性上均优于现有平台。本研究借助活性物质物理学协同纳米级传感，为活体SERS检测建立了全新范式，为活体内实时分子诊断开辟了新路径。