<i>In Situ</i> Dynamic Polymerization Spinning of All-Hydrogel Optrode with Stable Syncretic Interface for Long-Term Tolerance of Tissue Micromotion

Hydrogel optical fibers are widely utilized in photomedicine because of their high biocompatibility and optical waveguiding properties. However, their performance is susceptible to interfacial disruption caused by <i>in vivo</i> micromotion, which compromises the integrity of the basic sheath-core structures. Therefore, construction of a stable sheath-core interface within multiple structured hydrogel fibers is crucial for ensuring the long-term stability of photomedical treatment. Herein, <i>in situ</i> dynamic polymerization spinning was employed to fabricate an all-hydrogel optrode (AHO) with a stable syncretic interface capable of enduring tissue micromotion during prolonged implantation. Owing to an interpenetrating polymer network at the sheath-core interface formed via synergistic covalent and physical cross-linking, the AHO exhibits exceptional interfacial toughness (16.28 J/m²), efficient light-guiding property (0.523 dB/cm, λ = 473 nm), and biocompatibility (tissue-like Young's modulus and low cytotoxicity). Furthermore, a semiopen ceramic ferrule was developed to considerably reduce moisture loss from the AHO upon coupling, thereby enabling its use in long-term implantable devices. The fabricated AHO exhibits mechanical compliance, minimal inflammatory response, and stable light-guiding properties under physiological conditions, offering a promising platform for chronic neural-interfacing and biointegrated photonic devices.