Magnetic injectable hydrogels can serve as biocompatible and biomimetic substrates for the repair of various tissues in the body. These materials can be used to repair irregularly shaped tissue defects with minimal invasiveness [۱]. In this study, silk fibroin (F)-based hydrogels with increasing weight percentages of chitosan (C)- represented by CFX (x stands for the chitosan wt%), were prepared. Next, these hydrogels were loaded with superparamagnetic Fe۳O۴ nanoparticles (NPs) by in situ particle precipitation. The hydrogel samples included non-magnetic (C۵, CF۱, CF۳, CF۵) and magnetic ones (MCF۱, MCF۳, MCF۵). X-ray diffraction patterns confirmed the enhanced formation of Fe۳O۴ NPs at higher C weight percentages. Concurrently, vibrating sample magnetometry displayed superparamagnetic properties (Ms = ۳.۶۶ emu/g) of the NPs. Transmission Fourier transform infra-red spectroscopy results indicated the establishment of chemical bonds corresponding to the precipitation of the magnetic component. Viscosity vs shear rate evaluations proved that CF۳ sample had more favorable rheological properties. This was attributed to the better shear-thinning behavior of CF۳, rendering it suitable for injection and passage through a nozzle [۲]. Additional data implied that silk fibroin improved the rheological behavior. Upon examining the magnetic and non-magnetic CF۳ samples using field-emission scanning electron microscope, it was found that the magnetic hydrogel had a denser network and smaller pores compared to the non-magnetic hydrogel. The results indicated that a denser and stiffer polymer network, reinforced by nanoparticles, leads to the formation of smaller voids with stronger walls, unlike softer networks that results in larger pores. Moreover, energy dispersive X-ray spectroscopy, chemically proved the presence of magnetic NPs in the hydrogel network. Collectively, the results indicate that the developed injectable chitosan/silk fibroin hydrogel containing Fe۳O۴ magnetic nanoparticles exhibited favorable physicochemical properties for future investigations and potential applications in tissue engineering.
