In the past decade, iron oxide nanoparticles (IONPs) have attracted more and more attention for their excellent physicochemical properties and promising biomedical applications. In this review, we summarize and highlight recent progress in the design, synthesis, biocompatibility evaluation and magnetic theranostic applications of IONPs, with a special focus on cancer treatment. Firstly, we provide an overview of the controlling synthesis strategies for fabricating zero-, one- and three-dimensional IONPs with different shapes, sizes and structures. Then, the in vitro and in vivo biocompatibility evaluation and biotranslocation of IONPs are discussed in relation to their chemo-physical properties including particle size, surface properties, shape and structure. Finally, we also highlight significant achievements in magnetic theranostic applications including magnetic resonance imaging (MRI), magnetic hyperthermia and targeted drug delivery. This review provides a background on the controlled synthesis, biocompatibility evaluation and applications of IONPs as cancer theranostic agents and an overview of the most up-to-date developments in this area.

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.

Tannic acid (TA), a large polyphenolic molecule, has long been known for using in food additive, antioxidants, bio-sorbents, animal feeding and adhesive making due to its intrinsic properties such as...

Engineering biocompatible hydrogels using functional nanoparticles has attracted considerable attention because of their uniquely appealing cooperative effects that can enable multimodality imaging and treatment with improved efficacy against serious diseases. However, the effects of high‐content nanoparticle dopants on the rheological properties of hydrogels frequently lead to an unsatisfactory therapeutic result, which is particularly notable in the design of magnetic hydrogel formulations for cancer therapy. Herein is reported a novel magnetic hydrogel functionalized by ferromagnetic vortex‐domain iron oxide (FVIOs) with optimally adaptive functions for prevention of breast cancer recurrence. The FVIOs can perfectly incorporate into the dynamic hydrogel networks with an extremely low concentration (0.6 mg mL−1), 17 times lower than that of conventional superparamagnetic iron oxide nanoparticles with sufficient heating capacity. Such magnetic hydrogels exhibit high inductive heating and remarkable rheological properties simultaneously. Moreover, the self‐healing, self‐conformal ability, controlled release of loaded doxorubicin, biodegradation, and pH‐responsiveness of the magnetic hydrogel project their efficient sustainable therapeutic ability. In vivo postoperative treatment has further demonstrated the high efficacy of FVIO‐based magnetic hydrogels, as evidenced by the significant suppression of the local tumor recurrences compared to chemotherapy or hyperthermia alone. This unique magnetic hydrogel formulation with optimally adaptive functions shows strong potential in preventing relapses of various cancers.

Scheme 1. Schematic illustration of combined therapy in breast cancer with liquid metal (LM) and drug loaded mesoporous silica hybrid (DOX-MS/LM) 1900511 (10 of 11) www.advancedsciencenews.com Small 2019, 15, 1900511cytotoxic and anti-tumor effect, both in vitro and in vivo. The high density of LM enabled it to be scanned for CT scan, and the CT-enhanced effect can last for a longer time, up to 5 days. The systematic biological evaluation of LM according to ISO10993 and GB/T16886 proved the ideal biocompatibility of LM as an implantable device. This study explored a new transformable LMbased biomedical platform as an effective candidate for low-toxic and multifunctional cancer theranostic applications.

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The interference effect and lack of selectivity are the bottlenecks for dual-mode magnetic resonance imaging (MRI) contrast agent development. To address these challenges and overcome the single mode imaging contrast limitations, a novel MgMnAl-layered double hydroxide@iron oxide nanoparticle (MgMnAl-LDH@IO NP) has been successfully synthesized as a concurrently enhanced dual-mode contrast agent for MRI of tumor tissues with sensitive pH response and high efficacy. The attachment of iron oxide nanoparticles on the surface of MgMnAl-LDH NPs led to the increased local magnetic field intensity, inducing the concurrent enhancement of both T 1 and T 2 relaxivity. The in vitro MRI demonstrated that the MgMnAl-LDH@IO NP could act as a pH-sensitive contrast agent for both T 1- and T 2-weighted MR imaging (r 1, 5.67 mM–1 s–1 under pH 5.0 and 1.98 mM–1 s–1 under pH 7.4; r 2, 369.12 mM–1 s–1 under pH 5.0 and 225.29 mM–1 s–1 under pH 7.4). The biocompatibility of the dual-mode contrast agent was revealed by the cytotoxicity test on fibroblast cells. Further in vivo dual-mode MR imaging exhibited that the MgMnAl-LDH@IO NP showed clear T 1- and T 2-weighted MR imaging of tumor tissues in breast-tumor-bearing mice. The facile synthetic method, desirable biocompatibility, sensitive stimuli response, and concurrently enhanced T 1/T 2 MRI signals both in vitro and in vivo encourage the great potential biomedical and clinical applications of MgMnAl-LDH@IO NP in MR imaging with improved accuracy.

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