Interplay between a heptamethine cyanine dye sensitizer (IR806) and lanthanide upconversion nanoparticles

This folder contains all raw data underlying the results presented in a manuscript, submitted to Angewandte Chemie, and entitled: Interplay between a heptamethine cyanine dye sensitizer (IR806) and lanthanide upconversion nanoparticles Authored by: Haichun Liu1, Abhilash Kulkarni1, Uliana Kostiv1, Elin Sandberg1, Anbharasi Lakshmanan1, Georgios A. Sotiriou2, Jerker Widengren1,* 1 Department of Applied Physics, KTH Royal Institute of Technology, Roslagstullsbacken 21, SE-106 91, Stockholm, Sweden 2Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, SE-171 77, Stockholm, Sweden Corresponding author: *[e-mail] The data files containing raw data and results of the analysis are grouped according to the different figures in the manuscript where the extracted results are presented. ABSTRACT Lanthanide-doped upconversion nanoparticles (UCNPs) have attractive emission properties but suffer from weak light-absorbing capacities and thereby relatively low brightnesses. This motivates using strongly absorbing dye molecules as antennas and sensitizers. However, despite much effort, understanding of this dye-UCNP interplay is still limited. Major sensitization mechanisms are still under discussion, largely because there is a lack of effective means to observe key factors such as dark state transitions within the dyes. Here, we established a combined spectroscopic procedure to systematically investigate the photophysics behind the dye-UCNP interaction, embracing fluorescence-based transient-state excitation-modulation, lifetime and correlation spectroscopy, and spectrofluorometry/spectrophotometry. With this procedure we studied the heptamethine cyanine dye IR806, a typical UCNP sensitizer, established its photophysical model, deciphered its photophysics in UCL-sensitization-related environments and could identify energy transfer from the IR806 singlet excited state to Yb3+ (UCNP sensitizer ion) as the dominant sensitization mechanism. Our studies suggest that IR806 can form non-emissive H-aggregates at the nanoparticle surfaces, which can be dissociated after certain light excitation duration (typically>100µs). Moreover, buildup of a non-fluorescent, photo-redox state of IR806 after longer irradiation times (10–100ms) can deleteriously affect its UCL sensitization, inferring an optimal excitation duration for dye-sensitized UCNPs, relevant for e.g. optical imaging applications.本文件夹收录了提交给《Angewandte Chemie》（《应用化学》）的一篇手稿中所呈现研究结果的全部原始数据，该手稿标题为：七甲川花菁染料敏化剂（IR806）与镧系上转换纳米颗粒的相互作用。 作者为：Haichun Liu1, Abhilash Kulkarni1, Uliana Kostiv1, Elin Sandberg1, Anbharasi Lakshmanan1, Georgios A. Sotiriou2, Jerker Widengren1,* 1 瑞典斯德哥尔摩皇家理工学院（KTH Royal Institute of Technology）应用物理系，Roslagstullsbacken 21，邮编SE-106 91 2 瑞典斯德哥尔摩卡罗林斯卡学院（Karolinska Institutet）微生物学、肿瘤与细胞生物学系，邮编SE-171 77 通讯作者：*[e-mail] 包含原始数据与分析结果的数据文件，按照手稿中呈现对应结果的不同插图进行分组。 摘要 掺镧系元素上转换纳米颗粒（lanthanide-doped upconversion nanoparticles, UCNPs）具备优异的发射特性，但光吸收能力较弱，因此亮度相对较低。这推动了强吸收染料分子作为天线与敏化剂的应用研究。然而，尽管付出了大量研究努力，人们对染料与UCNPs之间相互作用的理解仍较为有限。主要的敏化机制仍处于学术讨论之中，这在很大程度上是因为缺乏有效手段来观测染料内部的暗态跃迁等关键因素。 在此，我们建立了一套组合光谱学分析方法，以系统研究染料与UCNPs相互作用背后的光物理过程，该方法涵盖基于荧光的瞬态激发调制、寿命与相关光谱学，以及荧光分光光度法/分光光度法。利用该方法，我们对典型的UCNPs敏化剂——七甲川花菁染料IR806开展了研究，建立了其光物理模型，解析了其在与上转换发光（upconversion luminescence, UCL）敏化相关环境中的光物理行为，并确认IR806单重激发态向Yb³+（UCNPs的敏化离子）的能量转移为主要的敏化机制。 我们的研究表明，IR806可在纳米颗粒表面形成非发射性H聚集体，该聚集体可在特定的光激发时长（通常大于100μs）后发生解离。此外，在更长的辐照时长（10~100ms）下，IR806会形成非荧光性的光氧化还原态，这会对其UCL敏化能力产生不利影响，由此可推导出染料敏化UCNPs的最优激发时长，该结果在光学成像等应用中具有重要参考价值。