Harnessing Boron‐Mediated Ti Valence Cycling in TiB2‐PEG‐DOX: A Multimodal CDT/PTT/CT Platform for Colorectal Cancer Therapy

Why It Matters

The platform demonstrates how titanium‑based nanomaterials can deliver synergistic multimodal therapy, addressing the limited CDT activity of existing agents. Its high efficacy and safety profile could accelerate clinical translation of metal‑boride nanomedicines for solid tumors.

Key Takeaways

• TiB2 nanosheets functionalized with PEG and DOX.
• Boron induces Ti4+ to Ti2+ valence cycling.
• Fenton-like reaction produces •OH radicals in tumor microenvironment.
• 53.53% photothermal conversion efficiency under 808 nm NIR.
• In vivo, near‑complete tumor ablation with excellent biocompatibility.

Pulse Analysis

Titanium’s biocompatibility has long made it attractive for biomedical implants, yet its catalytic potential in cancer therapy remains underexploited. Recent work leverages titanium diboride (TiB2), a metal boride whose lattice incorporates boron atoms capable of modulating titanium’s oxidation state. By facilitating a Ti4+→Ti2+ valence shift, boron enhances the Fenton‑like conversion of tumor‑derived hydrogen peroxide into highly toxic hydroxyl radicals, effectively turning TiB2 into a potent chemodynamic catalyst without compromising safety.

The TiB2‑PEG‑DOX platform integrates three therapeutic modalities. Surface grafting with amino‑terminated polyethylene glycol improves colloidal stability and enables electrostatic loading of doxorubicin, while also providing an EPR‑driven tumor‑accumulation route. Under 808 nm near‑infrared irradiation, the nanosheets achieve a 53.53% photothermal conversion efficiency, raising local temperatures enough for effective photothermal ablation and simultaneously triggering rapid DOX release. In vitro studies on HCT‑116 colorectal cancer cells reveal an 86.32% kill rate, underscoring the synergistic impact of CDT, PTT, and chemotherapy.

In vivo experiments confirm near‑complete tumor regression in murine models, with histology showing negligible damage to major organs, highlighting the system’s biocompatibility. This multimodal approach not only overcomes the intrinsic CDT limitations of titanium‑based materials but also establishes a broader paradigm: boron‑mediated metal valence cycling can be harnessed to amplify therapeutic reactivity across nanomedicine platforms. Future research may extend this strategy to other metal borides, paving the way for highly efficient, low‑toxicity treatments for a range of solid tumors.