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Magnetic hydrogel that can respond to a magnetic stimulus is a promising biomaterial for tissue regeneration and cancer treatment. In this study, a novel magnetic hydrogel is formed by simply mixing bisphosphonate (BP)-modified hyaluronic acid (i.e., HA-BP) polymeric solution and iron oxide (Fe 3 O 4 ) nanoparticle dispersion, in which the hydrogel networks are cross-linked by BP groups and iron atoms on the surface of particle. The iron-BP coordination chemistry affords a dynamic network, characterized by self-healing, shear-thinning, and smoothly injectable properties. Moreover, the HA-BP·Fe 3 O 4 magnetic hydrogel demonstrates heat-generation characterization under an alternating magnetic field. The animal experiments confirm the biocompatibilities of HA-BP·Fe 3 O 4 hydrogel, which presents the hydrogels potential for tissue regeneration and anticancer treatment applications.

Magnetic hydrogels have promising applications in flexible electronics, biomedical devices, and soft robotics. However, most existing magnetic hydrogels are fragile and suffer insufficient magnetic response. In this paper, we present a new approach to fabricate a strong, tough, and adhesive magnetic hydrogel with nontoxic polyacrylamide (PAAm) hydrogel as the matrix and the functional additive [3-(trimethoxysilyl)propyl methacrylate coated Fe 3 O 4 ] as the inclusions. This magnetic hydrogel not only offers a relatively high modulus and toughness compared to the pure hydrogel but also responds to the magnetic field rapidly because of high magnetic particle content (up to 60%, with respect to the total weight of the polymers and water). The hydrogel can be bonded to hydroxyl-rich hard and soft surfaces. Magnetic hydrogel with polydimethylsiloxane (PDMS) coating exhibits excellent underwater performance. The bonding between magnetic hydrogel and PDMS is very stable even under cyclic loading. An artificial muscle and its magnetomechanical coupling performance are demonstrated using this hydrogel. The adhesive tough magnetic hydrogel will open up extensive applications in many fields, such as controlled drug delivery systems, coating of soft devices, and microfluidics. The strategy is applicable to other functional soft materials.

Integration of two or more drugs into a multiagent delivery system has been considered to have profound impact on both in vitro and in vivo cancer treatment due to their efficient synergistic effect. This study presents a cheap and simple chitosan hydrogel cross-linked with telechelic difunctional poly(ethylene glycol) (DF-PEG-DF) for synthesis of an injectable and self-healing thermosensitive dual-drug-loaded magnetic hydrogel (DDMH), which contains both doxorubicin (DOX) and docetaxel (DTX) for chemotherapy and iron oxide for magnetic hyperthermia induced stimuli responsive drug release. The as-prepared DDMH not only have good biocompatibility but also exhibit unique self-healing, injectable, asynchronous control release properties. Meanwhile, it shows an excellent magnetic field responsive heat-inducing property, which means that DDMH will produce a large amount of heat to control the surrounding temperature under the alternative magnetic field (AMF). A remarkably improved synergistic effect to triple negative breast cancer cell line is obtained by comparing the therapeutic effect of codelivery of DOX and DTX/PLGA nanoparticles (DTX/PLGA NPs) with DOX or DTX/PLGA NPs alone. In vivo results showed that DDMH exhibited significant higher antitumor efficacy of reducing tumor size compared to single drug-loaded hydrogel. Meanwhile, the AMF-trigger control release of drugs in codelivery system has a more efficient antitumor effect of cancer chemotherapy, indicating that DDMH was a promising multiagent codelivery system for synergistic chemotherapy in the cancer treatment field.

Cell-adhesive properties are of great significance to materials serving as extracellular matrix mimics. Appropriate cell-adhesive property of material interface can balance the cell-matrix interaction and cell-cell interaction and can promote cells to form 3D structures. Herein, a novel magnetic polyacrylamide (PAM) hydrogel fabricated via combining magnetostatic field induced magnetic nanoparticles assembly and hydrogel gelation was applied as a multicellular spheroids culturing platform. When cultured on the cell-adhesive microarray interface of sliced magnetic hydrogel, normal and tumor cells from different cell lines could rapidly form multicellular spheroids spontaneously. Furthermore, cells which could only form loose cell aggregates in a classic 3D cell culture model (such as hanging drop system) were able to be promoted to form multicellular spheroids on this platform. In the light of its simplicity in fabricating as well as its effectiveness in promoting formation of multicellular spheroids which was considered as a prevailing tool in the study of the microenvironmental regulation of tumor cell physiology and therapeutic problems, this composite material holds promise in anticancer drugs or hyperthermia therapy evaluation in vitro in the future.