Magnetic manipulation for spatially patternel alginate hydrogel microfibers

Alginate hydrogel finds widespread applications in tissue engineering, cancer therapy, wound management and drug/cell/growth factor delivery due to its biocompatibility, hydrated environment and desirable viscoelastic properties. However Lack of controllability is still an obstacle for utilizing it in the fabrication of 3D tissue constructs and accurate targeting in mass delivery. Here, we proposed a new method for achieving magnetic alginate hydrogel microfiber by encapsulating magnetic nanoparticles inside alginate solution and solidifying the magnetic alginate into hydrogel fiber inside microfluidic chips and micro syringe system. The fabrication method for 3 layered microfluidic channel was given. In the experiments, the magnetic nanoparticles and alginate solution present to be a uniform suspension, no aggregation of magnetic nanoparticles was found, which is crucial for flow control inside microfluidic chips. By regulating the flow rate of different solutions inside the chip, magnetic hydrogel fiber and pure hydrogel fiber are achieved with controllable diameters. Patterning device and magnetic pillar were employed as a magnetic guidance to pattern and align the magnetic fibers. The proposed method for fabricating magnetic hydrogel fiber holds great potentials to engineer 3D tissue constructs with complex architectures and hierarchical vascular networks to mimic the native tissue microenvironment.