Perfluorooctanoic acid (PFOA), the most environmentally ubiquitous representative of per- and polyfluoroalkyl substances (PFAS), has posed global environmental and health risks due to its persistence. To address the challenges of insufficient adsorption, low intrinsic Raman activity and poor specific recognition of PFOA, this study designed a multifunctional surface-enhanced Raman scattering (SERS) platform based on hollow bowl-like fluorinated covalent organic framework with in-situ grown gold nanoparticles (F-BHCOF/AuNPs) at molecular, interfacial and electronic levels. This material was synthesized via an “amorphous-to-crystalline induced transformation” method. First, fluorinated monomers achieve fluorination at the molecular level. Moreover, the controllably synthesized hollow bowl-like structure, at the interfacial level, not only utilizes the “eddy effect” to enhance mass transfer at low concentrations, but also synergistically enhances the electromagnetic field via dual “confinement effects” throughout the structure. Combined with the “polarization induction” mechanism at the electronic level to mediate photoinduced charge transfer, this platform achieves nearly complete adsorption and specific, direct SERS detection of PFOA at environmentally relevant concentrations, with a detection limit of 1.6 ng/L. This platform can be further extended to the rapid screening and exposure risk assessment of PFOA in environmental water samples and daily consumer products including non-stick pan coatings and waterproof outdoor jackets. Furthermore, this work provides a paradigm for the tailored design of functional materials and for overcoming the technical bottleneck of simultaneous adsorption and detection of PFOA and other similar trace-level pollutants with weak response.

The excessive reactive oxygen species (ROS) accumulation and overactivated osteoclastogenesis in subchondral bone has proved to be a major cause of osteoarthritis (OA). Scavenging of ROS microenvironment to inhibit the osteoclastogenesis is highly valued in the therapeutic process of osteoarthritis. Despite the excellent ability of polyphenolic colloidal to scavenge reactive oxygen species and its affinity for macrophages, the preparation of polyphenolic colloidal nanoparticles is limited by the complex intermolecular forces between phenol molecules and the lack of understanding of polymerization/sol-gel chemistry. Herein, our work introduces a novel poly-tannin-phenylboronic colloidal nanoparticle (PTA) exclusively linked by ROS-responsive bondings. Nanocolloidal PTA has a uniform particle size, is easy and scalable to synthesize, has excellent scavenging of ROS, and can be slowly degraded. For in vitro experiments, we demonstrated that, PTA could eliminate ROS within RAW264.7 cells and impede osteoclastogenesis and bone resorption. RNA sequencing results of PTA-treated RAW264.7 cells further reveal the promotion of antioxidant activity and inhibition of osteoclastogenesis. For in vivo experiments, PTA could eliminate the ROS environment and reduce the number of osteoclasts in the subchondral bone, thereby alleviating the damage of subchondral bone and symptoms of osteoarthritis. Our research, by delving into the formation of polyphenol colloidal nanoparticles and validating their role in ROS scavenging to inhibit osteoclastogenesis in subchondral bone, may open new avenues for OA treatment in the future.