With the potential uses of photothermal therapy (PTT) in cancer treatment with excellent efficacy, and the growing concerns about the nanotoxicity of hyperthermia agents such as carbon nanotubes and gold-based nanomaterials, the importance of searching for a biocompatible hyperthermia agent cannot be emphasized too much. In this work, a novel promising hyperthermia agent employing magnetic Fe3O4 particles with fairly low toxicity was proposed. This hyperthermia agent showed rapid heat generation under NIR irradiation. After modification with carboxymethyl chitosan (CMCTS), the obtained Fe3O4@CMCTS particles could disperse stably in PBS and serum without any aggregation. The modification of CMCTS could decrease the adsorption of bovine serum albumin (BSA) and improve the cellular uptake. In a comparative study with hollow gold nanospheres (HAuNS), Fe3O4@CMCTS particles exhibited a comparable photothermal effect and fairly low cytotoxicity. The in vivo magnetic resonance (MR) images of mice revealed that by attaching a magnet to the tumor, Fe3O4@CMCTS particles accumulated in the tumor after intravenous injection and showed a low distribution in the liver. After being exposed to a 808 nm laser for 5 min at a low power density of 1.5 W cm(-2), the tumors on Fe3O4@CMCTS-injected mice reached a temperature of ~52 °C and were completely destroyed. Thus, a kind of multifunctional magnetic nanoparticle with extremely low toxicity and a simple structure for simultaneous MR imaging, targeted drug delivery and photothermal therapy can be easily fabricated.

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Dual-core@shell-structured Fe3O4–NaYF4@TiO2 nanocomposites as a magnetic targeting drug carrier for bioimaging and combined chemo-sonodynamic therapy.

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Photothermal therapy (PTT) is an effective approach to cancer therapy. However, the high temperature during the therapy increases the damage to surrounding normal tissues. Thermochromic material, which exhibits temperature-activated color change and optical absorption, is a promising photothermal agent for precisely temperature-controlled PTT. Nevertheless, the construction of nanosized thermochromic particles with an appropriate transition temperature (44−47 °C) is still a great challenge.Here, thermochromic nanoparticles with the transition temperature at 45 °C based on a leuco dye-developer-solvent system are developed for thermostatic photothermal tumor therapy. Below the temperature, the nanoparticles take a dark green color to absorb light and convert it into heat efficiently. Once the temperature reaches the transition point, the colored nanoparticles switch to a colorless state, maintaining the temperature at the predefined level and allowing deeper light penetration. The autoregulated nanoparticles exhibit a prominent therapeutic effect for the tumor without destroying normal tissues.