In this work, a nanoscale reduced graphene oxide-iron oxide nanoparticle (RGO-IONP) complex is noncovalently functionalized with polyethylene glycol (PEG), obtaining a RGO-IONP-PEG nanocomposite with excellent physiological stability, strong NIR optical absorbance, and superparamagnetic properties. Using this theranostic nanoprobe, in-vivo triple modal fluorescence, photoacoustic, and magnetic resonance imaging are carried out, uncovering high passive tumor targeting, which is further used for effective photothermal ablation of tumors in mice.

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Enhanced near-field at noble metal nanoparticle surfaces due to localized surface plasmon resonance (LSPR) has been researched in fields ranging from biomedical to photoelectrical applications. However, it is rarely explored on nonmetallic nanomaterials discovered in recent years, which can also support LSPR by doping-induced free charge carriers, let alone the investigation of an intricate system involving both. Here we construct a dual plasmonic hybrid nanosystem Au-Cu9S5 with well controlled interfaces to study the coupling effect of LSPR originating from the collective electron and hole oscillations. Cu9S5 LSPR is enhanced by 50% in the presence of Au, and the simulation results confirm the coupling effect and the enhanced local field as well as the optical power absorption on Cu9S5 surface. This enhanced optical absorption cross section, high photothermal transduction efficiency (37%), large light penetration depth at 1064 nm, excellent X-ray attenuation ability, and low cytotoxicity enable Au-Cu9S5 hybrids for robust photothermal therapy in the second near-infrared (NIR) window with low nanomaterial dose and laser flux, making them potential theranostic nanomaterials with X-ray CT imaging capability. This study will benefit future design and optimization of photoabsorbers and photothermal nanoheaters utilizing surface plasmon resonance enhancement phenomena for a broad range of applications.

Jack of all trades: A multifunctional nanoparticle (MFNP) integrates an upconversion nanoparticle (see picture, green), a layer of iron oxide nanoparticles (black), and a gold shell (red). The system can be used for in vitro targeted upconversion luminescence, magnetic resonance, and light scattering multimodal imaging of cells. The near‐infrared optical absorption of MFNPs also enables photothermal destruction of cancer cells.

Multifunctional nanoplatforms that are safe and have multiple therapeutic functions together with imaging capabilities are highly demanded in the development of new cancer theranostic approaches. A number of near-infrared (NIR)-absorbing inorganic nanomaterials, although having shown great promise not only to photothermally ablate tumors but also to enhance the efficacy of other types of therapies, are not biodegradable and would be retained in the body for a long time. Herein, we develop a multifunctional nanocomposite by coating magnetic iron oxide nanoclusters with a near-infrared light-absorbing polymer polypyrrole (PPy), obtaining Fe3O4@PPy core-shell nanoparticles, which after functionalization with polyethylene glycol could be used for imaging-guided, remotely controlled cancer combination therapy. In this system, the Fe3O4 core, which could be gradually decomposed in physiological environments, is useful for magnetically controlled drug delivery as well as a magnetic resonance imaging contrast. The PPy shell, as an organic polymer, is able to load therapeutic molecules with aromatic structures and also exhibits a strong photothermal effect, which can be used to enhance the chemotherapeutic efficacy, showing an outstanding in vivo synergistic antitumor effect. Our work encourages further exploration of light-absorbing polymer-based nanocomposites for cancer combination therapy under remote physical controls.