Photothermal Therapy and Photoacoustic Imaging in Nanoparticle Systems

Photothermal therapy harnesses light-absorbing nanomaterials to induce localised heating for selective tumour ablation, while photoacoustic imaging couples pulsed optical excitation with ultrasound detection to visualise deep-tissue structures with high contrast. Nanoparticle systems have emerged as versatile platforms that integrate diagnostic and therapeutic functions within a single agent, exploiting the reduced scattering and absorption in the near-infrared biological windows to achieve enhanced penetration depths. Advances encompass inorganic constructs such as gold nanorods and carbon-based hollow spheres, as well as organic semiconducting polymer nanoparticles tailored for second near-infrared (NIR-II) applications. By tuning particle size, surface chemistry and optical properties, researchers have optimised photothermal conversion efficiency and photoacoustic signal strength. Multifunctional strategies include the co-delivery of nitric oxide donors, magnetic components for targeted accumulation, and synergistic combination with immunotherapies. These developments underscore the global significance of such theranostic agents for non-invasive cancer treatment, vascular interventions and real-time monitoring of therapeutic outcomes.

Research from Nature Portfolio

Recent studies have showcased a semiconducting homopolymer nanoprobe engineered for the NIR-II window, bearing a fibrin-specific ligand and a thermoresponsive nitric oxide donor. This platform exhibits strong NIR-II absorption and elevated photothermal conversion, producing bright photoacoustic signals for high-sensitivity thrombus detection. Under laser irradiation, the system achieves efficient blood clot ablation and on-demand nitric oxide release, restoring flow in thrombosis models and demonstrating a promising theranostic approach for cardiovascular disorders.

Photothermal Therapy and Photoacoustic Imaging in Nanoparticle Systems publication trend

The graph below shows the total number of articles in photothermal therapy and photoacoustic imaging in nanoparticle systems across all publications each year (not limited to Nature Index journals).

Technical terms

Photothermal therapy (PTT): use of light-absorbing agents to convert optical energy into localized heat for targeted tissue ablation.

Photoacoustic imaging (PAI): imaging technique that employs pulsed light absorption to generate acoustic waves, enabling deep-tissue visualisation with high contrast.

Near-infrared biological window: spectral regions (NIR-I: 650–950 nm; NIR-II: 1000–1700 nm) characterised by minimal tissue absorption and scattering, permitting enhanced imaging depth.

Photothermal conversion efficiency: ratio of generated thermal energy to absorbed optical energy by a photothermal agent, indicative of heating performance.

Semiconducting polymer nanoparticles (SPNs): organic nanomaterials composed of π-conjugated polymers that offer tuneable absorption, excellent photostability and biocompatibility for theranostic applications.

References

1. Near-infrared-II photoacoustic imaging and photo-triggered synergistic treatment of thrombosis via fibrin-specific homopolymer nanoparticles. Nature Communications (2023).
2. NIR‐II absorbing organic nanoagents for photoacoustic imaging and photothermal therapy. BMEMat (2023).
3. Deep-Tissue Photothermal Therapy Using Laser Illumination at NIR-IIa Window. Nano-Micro Letters (2020).
4. Magnetic targeted near-infrared II PA/MR imaging guided photothermal therapy to trigger cancer immunotherapy. Theranostics (2020).