Next-Generation Photothermal Nanoagent for Safe Systemic Tumor Ablation

A resonance energy transfer (RET)–engineered nanoplatform enabling complete tumor ablation using near-infrared irradiation

Background
Photothermal therapy (PTT) uses NIR light to generate localized tumor heating. However, many systems require elevated laser power densities to achieve therapeutic temperatures, limiting translational feasibility. A systemically deliverable photothermal agent capable of operating within low-power irradiation parameters is needed to advance oncology applications.

Technology Description
This technology enables systemic, image-guided photothermal tumor ablation using near-infrared (NIR) irradiation at clinically relevant laser power levels (0.25 W/cm²). The platform uses resonance energy transfer (RET) between plasmonic nanorods and a near-infrared dye to amplify photothermal heating while retaining fluorescence imaging capability.

In an aggressive transgenic melanoma mouse model, a single treatment following intravenous administration resulted in complete tumor ablation under low-power irradiation conditions.

The invention is a resonance energy transfer (RET)-engineered nanoplatform composed of:

• Gold nanorods (AuNRs)
• An ultrathin (~3.5 nm) iron/cobalt (Fe/Co) nanoshell
• Silicon naphthalocyanine (SiNc) NIR dye
• A biodegradable PEG–PCL polymer carrier

The Fe/Co shell red-shifts the nanorod surface plasmon resonance (~783 nm) to align with the SiNc absorption peak (~780 nm), enabling efficient non-radiative RET. This spectral alignment enhances light-to-heat conversion under 780 nm irradiation at 0.25 W/cm².

Under these conditions, the co-loaded nanoagent demonstrated:

• 6.6-fold higher photothermal performance compared to dye alone
• 3.3-fold higher performance compared to Fe/Co-AuNRs alone
• 2.3-fold higher performance compared to AuNR + dye without the Fe/Co shell

The PEG–PCL carrier enables aqueous stability and intravenous administration, with a hydrodynamic diameter of approximately 115 nm. Fluorescence imaging capability is retained, supporting image-guided treatment.

_{Under low-power NIR irradiation (780 nm, 0.25 W/cm²), the RET-engineered PC-Fe/Co-AuNRs@SiNc nanoagent demonstrated rapid temperature elevation and reached ~80 °C (ΔT ≈ 55 °C) after 10 minutes of irradiation. In comparison, dye alone and Fe/Co-AuNRs alone achieved maximum temperatures of ~46 °C and ~51 °C, respectively. These results demonstrate enhanced photothermal heating under low-power NIR irradiation (0.25 W/cm²). Repeated laser on/off cycling showed no measurable loss of heating performance across irradiation cycles.}

Further Details:

• Advanced Functional Materials - “Resonance Energy Transfer-Driven Photothermal Nanoagent Enables Melanoma Ablation Under Low-Power Near-Infrared Irradiation" - https://advanced.onlinelibrary.wiley.com/doi/10.1002/adfm.202522663
• Lab Website - https://www.olenataratulalab.org
• Oregon State University Newsroom - "New nanoparticles enable melanoma tumors to be removed with low-power laser light" https://news.oregonstate.edu/news/new-nanoparticles-enable-melanoma-tumors-be-removed-low-power-laser-light
• MedPath - "Oregon State Researchers Develop Gold Nanoparticles for Safe Low-Power Melanoma Therapy" - https://trial.medpath.com/news/416816a3623f0bb7/oregon-state-researchers-develop-gold-nanoparticles-for-safe-low-power-melanoma-therapy

Features & Benefits

• Operates at low-power NIR irradiation within commonly referenced skin exposure limits /span>
• Demonstrated in vivo therapeutic efficacy
• Systemically deliverable formulation
• Mechanistically defined RET-driven enhancement

Applications

• Image-guided photothermal therapy for melanoma
• Treatment of solid tumors accessible to NIR irradiation
• Theranostic oncology platforms
• Combination strategis integrating imaging and localized tumor ablation

Stage of Development

• Preclinical in vivo efficacy demonstrated
• Systemic (IV) administration validated
• Complete tumor ablation achieved in a transgenic melanoma mouse model
• Manuscript submitted