Integrative Biomedical Materials and Nanomedicine Lab, Department of Experimental and Health Sciences (DCEXS), Pompeu Fabra University, PRBB, Carrer Doctor Aiguader 88, 08003 Barcelona, Spain.
Department of Structure of Macromolecules, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CNB-CSIC), Cantoblanco, 28049, Madrid, Spain. Mistral Beamline, Experiment Division, ALBA Synchrotron (ALBA-CELLS), Barcelona, Spain.
Acta Biomater. 2022 Apr 1;142:308-319. doi: 10.1016/j.actbio.2022.01.052. Epub 2022 Jan 31.
We report the synthesis of plasmonic nanocapsules and the cellular responses they induce in 3D melanoma models for their perspective use as a photothermal therapeutic agent. The wall of the nanocapsules is composed of polyelectrolytes. The inner part is functionalized with discrete gold nanoislands. The cavity of the nanocapsules contains a fluorescent payload to show their ability for loading a cargo. The nanocapsules exhibit simultaneous two-photon luminescent, fluorescent properties and X-ray contrasting ability. The average fluorescence lifetime (τ) of the nanocapsules measured with FLIM (0.3 ns) is maintained regardless of the intracellular environment, thus proving their abilities for bioimaging of models such as 3D spheroids with a complex architecture. Their multimodal imaging properties are exploited for the first time to study tumorspheres cellular responses exposed to the nanocapsules. Specifically, we studied cellular uptake, toxicity, intracellular fate, generation of reactive oxygen species, and effect on the levels of hypoxia by using multi-photon and confocal laser scanning microscopy. Because of the high X-ray attenuation and atomic number of the gold nanostructure, we imaged the nanocapsule-cell interactions without processing the sample. We confirmed maintenance of the nanocapsules' geometry in the intracellular milieu with no impairment of the cellular ultrastructure. Furthermore, we observed the lack of cellular toxicity and no alteration in oxygen or reactive oxygen species levels. These results in 3D melanoma models contribute to the development of these nanocapsules for their exploitation in future applications as agents for imaging-guided photothermal therapy. STATEMENT OF SIGNIFICANCE: The novelty of the work is that our plasmonic nanocapsules are multimodal. They are responsive to X-ray and to multiphoton and single-photon excitation. This allowed us to study their interaction with 2D and 3D cellular structures and specifically to obtain information on tumor cell parameters such as hypoxia, reactive oxygen species, and toxicity. These nanocapsules will be further validated as imaging-guided photothermal probes.
我们报告了等离子体纳米胶囊的合成以及它们在 3D 黑色素瘤模型中诱导的细胞反应，以期将其用作光热治疗剂。纳米胶囊的壁由聚电解质组成。内部功能化有离散的金纳米岛。纳米胶囊的腔含有荧光有效负载物，以显示其负载货物的能力。纳米胶囊表现出同时的双光子发光、荧光特性和 X 射线对比能力。使用 FLIM 测量的纳米胶囊的平均荧光寿命（τ）（0.3ns）保持不变，无论细胞内环境如何，从而证明了它们对具有复杂结构的 3D 球体等模型进行生物成像的能力。首次利用它们的多模态成像特性来研究暴露于纳米胶囊的肿瘤球细胞反应。具体来说，我们使用多光子和共聚焦激光扫描显微镜研究了细胞摄取、毒性、细胞内命运、活性氧的产生以及对缺氧水平的影响。由于金纳米结构的高 X 射线衰减和原子数，我们在不处理样品的情况下对纳米胶囊-细胞相互作用进行成像。我们证实了纳米胶囊在细胞内环境中保持其几何形状，而不会损害细胞超微结构。此外，我们观察到没有细胞毒性，并且氧气或活性氧水平没有改变。这些 3D 黑色素瘤模型中的结果为这些纳米胶囊的开发做出了贡献，以期将其用于未来的成像引导光热治疗应用。
这项工作的新颖之处在于我们的等离子体纳米胶囊是多模态的。它们对 X 射线以及多光子和单光子激发有响应。这使我们能够研究它们与 2D 和 3D 细胞结构的相互作用，并特别获得有关肿瘤细胞参数（如缺氧、活性氧和毒性）的信息。这些纳米胶囊将进一步验证为成像引导光热探针。
