Advanced Materials Engineering and Modelling Group, Faculty of Chemistry, Wroclaw University of Science and Technology, Wroclaw, 50-370, Poland.
Łukasiewicz Research Network - PORT Polish Center for Technology Development, Wroclaw, 54-066, Poland.
Int J Nanomedicine. 2021 May 27;16:3649-3660. doi: 10.2147/IJN.S298300. eCollection 2021.
Semiconductor nanoplatelets (NPLs) are promising materials for nonlinear optical microscopy since they feature good two-photon absorption (TPA) properties, narrow photoluminescence spectra and high quantum yields of luminescence. Nevertheless, the use of semiconductor NPLs is inevitably connected with concerns about heavy metal ion toxicity and their intrinsically hydrophobic character.
Our contribution focuses on the design and engineering of coloidal bionanomaterial consisting of two-dimensional highly luminescent CdSe semiconductor NPLs loaded into spherical and homogeneous polymeric nanocarriers (NCs) based on poly(ethylene oxide) and poly(propylene oxide) block co-polymer. The biocompatibility and usefulness of the NPLs-loaded polymeric NCs in two-photon induced bioimaging was demonstrated by cytotoxicity and two-photon microscopic studies using eukaryotic (normal fibroblasts and cancer ovarian) cells.
The encapsulated NPLs maintain their intensive and spectrally narrow photoluminescence, as well as preserve good TPA properties, while the surrounding polymer shell imparts hydrophilic character and non-toxicity towards eukaryotic cells. Specifically, TPA cross-sections of the colloidal NCs loaded with NPLs show large values reaching up to 2.0 × 10 GM, with simultaneously two-photon brightness reaching 2.2 × 10 GM at 870 nm. MTT proliferation assay performed on cell lines treated with encapsulated NPLs revealed at least 70% viability of normal human gingival fibroblast (HGF) and cancer ovarian (MDAH-2774) cells, while the results of multiphoton imaging of murine (L-929) fibroblasts suggest that the encapsulated NPLs are capable of labelling the target cells enabling their visualization.
As a result, we obtained water dispersible and temporally stable hydrophilic NPLs-loaded NCs that offer excellent, both one- and two-photon excited fluorescence preserving optical properties of the raw hydrophobic and colloidal NPLs. The biological responses upon eukaryotic cells indicate that the encapsulation process protects cells from the toxic influence of cadmium simultaneously preserving the unique multiphoton properties of the active cargo which opens a promising perspective for its application in multiphoton cancer bioimaging excited at the "optical transmission window" of biological tissues in near-infrared range.
半导体纳米板（NPLs）是用于非线性光学显微镜的有前途的材料，因为它们具有良好的双光子吸收（TPA）特性、窄的光致发光光谱和高的发光量子产率。然而，半导体 NPLs 的使用不可避免地与重金属离子毒性及其内在疏水性有关。
我们的贡献集中在设计和工程胶体生物纳米材料，该材料由二维高发光 CdSe 半导体 NPLs 负载到基于聚环氧乙烷和聚环氧丙烷嵌段共聚物的球形和均匀的聚合物纳米载体（NCs）中。通过使用真核（正常成纤维细胞和卵巢癌细胞）细胞进行细胞毒性和双光子显微镜研究，证明了负载 NPL 的聚合物 NCs 在双光子诱导生物成像中的生物相容性和实用性。
封装的 NPLs 保持其强烈的光谱窄光致发光，以及保留良好的 TPA 特性，而周围的聚合物壳赋予亲水性和对真核细胞的非毒性。具体地，负载 NPL 的胶体 NCs 的 TPA 截面显示出大的值，高达 2.0×10 GM，同时在 870nm 处双光子亮度达到 2.2×10 GM。对用封装 NPL 处理的细胞系进行的 MTT 增殖测定显示，正常人类牙龈成纤维细胞（HGF）和卵巢癌细胞（MDAH-2774）的存活率至少为 70%，而多光子成像的结果表明，负载 NPL 的封装物能够标记靶细胞，从而能够对其进行可视化。
因此，我们获得了水可分散的和时间稳定的亲水性负载 NPL 的 NCs，它们提供了极好的、单光子和双光子激发荧光，同时保留了原始疏水性和胶体 NPL 的光学性质。真核细胞的生物反应表明，封装过程保护细胞免受镉的毒性影响，同时保持活性货物的独特多光子特性，这为其在双光子癌症生物成像中的应用开辟了有前途的前景，该应用在近红外生物组织的“光学传输窗口”处激发。
