JAIST successfully develops multifunctional nanocomposites through fusion of liquid metal and lactic acid bacteria — Cancer treatment effect through near-infrared laser irradiation

A research team led by Professor Eijiro Miyako from the Materials Chemistry Frontiers Research Area at Japan Advanced Institute of Science and Technology (JAIST) succeeded in developing multifunctional nanocomposites by coating liquid metal surfaces with lactic acid bacteria components and the near-infrared fluorescent dye indocyanine green. They demonstrated that irradiating these nanocomposites with a near-infrared laser produces cancer treatment effects. By transplanting colorectal cancer into mice and irradiating once every two days for five minutes for a total of two times, they successfully achieved complete tumor regression after five days. Furthermore, since the nanocomposites accumulate effectively within tumors, this work is expected to lead to the creation of innovative cancer photoimmunotherapy technology integrating diagnosis and treatment. The findings were published in Advanced Composites and Hybrid Materials.

Room-temperature liquid metals composed of gallium-indium alloys possess excellent biocompatibility and physicochemical properties, attracting global attention for their biomedical applications. Miyako and his colleagues began their research based on the idea that "if immune adjuvants could be combined with liquid metal and selectively delivered to cancer sites, it would be possible to achieve powerful antitumor effects and integration of diagnosis and treatment using near-infrared light."

Miyako and his colleagues have previously demonstrated that isolating specific bacteria from intratumoral bacterial flora and combining them with photosynthetic bacteria can exert cancer treatment effects.

The research team established a simple fabrication method that forms spherical nanoparticles just by mixing gallium-indium liquid metal, lactic acid bacteria components, and indocyanine green, followed by ultrasonic irradiation. The nanocomposites produced using this method maintained particle size stability for over seven days, possessed high membrane permeability and non-toxicity, and were found to generate heat upon near-infrared light irradiation.

In cytotoxicity tests using mouse colorectal cancer cells and human normal fibroblasts, no decrease in cell viability was observed 24 hours after nanocomposite administration, as measured by mitochondrial activity, confirming the absence of cytotoxicity. In biocompatibility tests, blood examinations (one week) and body weight measurements (approximately one month) following intravenous administration in mice revealed that adverse effects on living organisms were extremely minimal.

Furthermore, due to the enhanced permeability and retention (EPR) effect, the nanocomposites demonstrated excellent ability to target cancer cells and were confirmed to accumulate effectively within tumors in mice transplanted with colorectal cancer. Moreover, by irradiating with highly bio-penetrating near-infrared laser light, the researchers succeeded in achieving complete regression of transplanted cancer after five days.

This study demonstrated that the developed nanocomposites could serve as a foundational technology for next-generation cancer diagnosis and immunotherapy. Furthermore, as this is a new technological foundation for material design through interdisciplinary integration of nanotechnology, optics, and immunology, contributions to a wide range of research fields are expected. The research group states that they will advance further safety and efficacy verification as they work toward expanding application to other cancer types and clinical application, aiming to realize gentler and more effective cancer treatment methods for patients.

Journal Information
Publication: Advanced Composites and Hybrid Materials
Title: Bacterial-adjuvant liquid metal nanocomposites for synergistic photothermal immunotherapy
DOI: 10.1007/s42114-025-01434-7