Lanthanide-Amino Coordination Nanoplatforms with Tunable Crystal Phases for Synergistic Photothermal Tumor Ablation and Fluorescence Imaging

Lanthanide-based nanomaterials have attracted increasing attention as photothermal agents for cancer therapy. However, achieving high photothermal conversion efficiency while maintaining good biocompatibility remains a significant challenge. In this work, lanthanide coordination nanocrystals with a silver ragwort-like architecture were constructed through the coordination of La 3+ ions with an amino ligand, 1,5-diaminonaphthalene, forming a La–amine coordination platform (LN5). Through crystal phase modulation via ultrasonic treatment and heterometal co-doping with Eu 3+ and Gd 3+ ions, two types of coordination nanocrystals, LN5(I) and LN5Eu 3+ Gd 3+ , were successfully engineered with controlled particle sizes of approximately 15 ± 5 nm and 20 ± 5 nm, respectively. The heterometal doping strategy not only regulated the crystallographic evolution of the coordination framework but also altered the energy dissipation pathways, leading to distinct optical and photothermal properties. LN5(I) exhibited yellow fluorescence emission centered at approximately 569 nm, whereas LN5Eu 3+ Gd 3+ displayed a purple emission band within the range of 350–450 nm, enabling potential dual-modal imaging capabilities. Importantly, both coordination nanocrystals demonstrated remarkable photothermal conversion efficiencies under 808 nm near-infrared (NIR) irradiation, reaching 63.9% for LN5 and 67.1% for LN5Eu 3+ Gd 3+ . In vitro photothermal experiments revealed that the temperature of the nanocrystal dispersion increased to above 60 °C within 10 min of NIR irradiation. In vivo thermal imaging further confirmed that the tumor-site temperature rapidly exceeded 50 °C under the same irradiation conditions, leading to effective thermal ablation of tumor tissues.Comprehensive biosafety assessments indicated low cytotoxicity and minimal immune interference. In vivo antitumor studies demonstrated significant tumor growth suppression, particularly in the LN5Eu 3+ Gd 3+ combined with laser irradiation group. Overall, this work establishes amino-ligand coordinated lanthanide nanocrystals as promising photothermal theranostic platforms, integrating efficient photothermal therapy with fluorescence imaging capabilities for potential applications in cancer nanomedicine.