Theranostic nanomedicine, which uses both imaging and therapeutic components for simultaneous disease diagnosis and treatment, is expected to improve patient treatment safety and outcomes by offering a more personalized approach to medicine. However, the poor reproducibilities of nanomedicines synthesized for optimized bioavailability and their potential toxicity are impeding clinical development. Moreover, milligram-scale synthetic methods are often inconsistent when transferred to mass production. To address these challenges, a facile, room temperature, aqueous phase synthesis of nanotheranostic agents using clinically validated mesoporous silica and naturally derived polydopamine has been developed. Since the synthetic procedure is simple and robust, and requires only simple mixing under ambient conditions, excellent batch-to-batch consistency has been achieved. As a result, this process can be easily scaled-up to produce gram-scale batches with physicochemical parameters similar to those of materials synthesized in smaller batches. The resulting nanotheranostic agents exhibit efficient X-ray tomography and T₁-weighted magnetic resonance image contrast enhancing abilities due to their chemically ligated, benign Bi³⁺ and Fe³⁺ ions. Furthermore, the inclusion of a polydopamine shell makes the nanoparticle surface easy to functionalize and renders these materials highly efficient as photothermal agents. These nanotheranostic agents are suitable for mass production and for potential applications in multimodal imaging-guided therapy in clinical settings.

Nanocomposites combining magnetic and plasmonic components have received widespread attention in recent years due to their potential applications in biomedical research. Herein, we describe a facile method for growing small iron oxide nanoparticles on various plasmonic core materials with different shapes and surfaces by utilizing a polypyrrole interlayer. By focusing on Au nanorod@polypyrrole@iron oxide (Au NR@PPy@Fe_xO) nanocomposites, we show that these systems exhibit a low r₂/r₁ ratio of 4.8, making them efficient T₁ positive contrast-enhancing agents for magnetic resonance imaging (MRI). Moreover, we show that the nanocomposites are excellent photothermal agents in the second near infrared region, with high photothermal conversion efficiency, reaching up to 46%. In addition, the Au NR@PPy@Fe_xO nanocomposites show very low cytotoxicity. In summary, the present results highlight the great potential of the synthetic method and the nanocomposites developed in this study for T₁ MRI and/or infrared thermal imaging-guided photothermal cancer therapeutic applications.