Hydrogel optical light-guides have received substantial interest for applications such as deep-tissue biosensors, optogenetic stimulation and photomedicine due to their biocompatibility, (micro)structure control and tissue-like Young's modulus. However, despite recent developments, the large-scale fabrication with a continuous synthetic methodology, which could produce core-sheath hydrogel fibers with the desired optical and mechanical properties suitable for deep-tissue applications has yet to be achieved. In this study, we report a versatile concept of integrated light-triggered dynamic wet spinning (ILDWS), which capable of continuously producing core-sheath hydrogel optical fibers with tunable fiber diameters, mechanical and optical-propagation properties. Furthermore, this concept also exhibited versatility for various kinds of core-sheath functional fibers. The wet spinning synthetic procedure and fabrication process were optimized with the rational design of the core/sheath material interface compatibility [core = poly(ethylene glycol diacrylate-co-acrylamide); sheath = Ca-alginate], optical transparency, refractive index and spinning solution viscosity. The resulting hydrogel optical fibers exhibited desirable low optical attenuation (0.18 ± 0.01 dB cm−1 with 650 nm laser light), excellent biocompatibility and tissue-like Young's modulus (< 2.60 MPa). The optical-waveguide hydrogel fibers (OWHFs) were successfully employed for deep-tissue cancer therapy and brain optogenetic stimulation, confirming that they could serve as an efficient versatile tool for diverse deep-tissue therapy and brain optogenetic applications.

Magnetic hydrogel actuators have promising applications in soft robots, wastewater treatment, and underwater detection due to the advantages of their remote control and high magnetic penetration. However, their controllability is limited by the general fabrication methods of doping paramagnetic nanoparticles and nonuniform ferromagnetic nanoparticles with a weak or nonconfigurable magnetic distribution. Herein, we report a kind of ferromagnetic hydrogel actuator comprising oriented ferromagnetic Co nanorods with high magnetic anisotropy, and the magnetic domains can be flexibly programmed by external fields. To demonstrate the generality of the approach and to research how the flexibility of the hydrogel hosts influences the behavior of the actuators, three kinds of hydrogel hosts have been used, including silica hydrogel, cellulose hydrogel, and clay hydrogel. The silica hydrogel actuators provide a holistic response. The cellulose hydrogel actuator can achieve a certain degree of deformation. The clay hydrogel actuators are capable of achieving large deformations such as the knot and the bow-knot. Furthermore, biomimetic actuators with the capacities for wriggling, paddling, and climbing simple obstacles are designed by utilizing the bending deformations of the clay hydrogel. In conclusion, this work provides an alternative strategy for designing and fabricating magnetically actuated hydrogel actuators for imitating biological units or constructing soft robots by regulating the orientation and distribution of ferromagnetic nanoparticles.

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Diatomite has been verified as an economical adsorbent to treat wastewater. Unfortunately, limited by poor regeneration and an inert surface with less active silanol groups, the retrievable and efficient diatomite-based adsorbent needs to be further explored. Here, on the basis of the thorough activation treatments of the raw diatomite, we developed a diatomite-based adsorbent with a uniform assembly of Fe3O4 nanoparticles on the surface. The nanocomposite possesses a high specific surface area, the trait of magnetic separation, and more functional groups for adsorption. The maximum adsorption capacities of Pb2+, Ni2+, and Cd2+ at 314 K reached 0.97, 1.18, and 0.88 mmol/g, respectively, which were more competitive than those of previously reported diatomite-based adsorbents. The experimental data fitted well with the pseudo-second-order kinetic model and Freundlich isotherm model, demonstrating that the adsorption was mainly derived from the electrostatic interaction and chelation between the hydroxyl/carboxyl groups on multilayer surfaces and the hazardous metal ions. According to the analytical results of the adsorption isotherms and response surface optimization, the removal efficiency can exceed 94%, obtained by increasing the pH and reaction temperature. The activation-enhanced surface engineering can arouse the adsorption potential of a diatomite-based adsorbent and provide universal perspectives into the concept design of a nanocomposite adsorbent with lower cost recovery and higher adsorption efficiency.