Time resolved in cellulo studies on luminescent metal complex-based cell probes

在谢菲尔德，托马斯小组开发了一系列金属配合物，可以用作共聚焦显微镜的细胞光学成像探针。这些探针通过发光工作，所以它们的细胞位置只能在它们发光时被成像。与此同时，在耶拿，Dietzek小组开发了一种全新的、目前独一无二的显微镜技术：瞬态吸收显微镜。这种时间分辨技术允许在细胞内探测分子的光激发态。在这个为期六周的研究中，Thomas实验室开发的探针将在耶拿使用TAM进行研究。这项工作有许多目标。首先，由于探针具有独特的光吸收特征，即使它们在细胞的那一部分不发光，它们在细胞中的定位也可以被“绘制”出来。其中一种被研究的复合物只有在与核DNA结合时才会发光。高分辨率的地图将使我们能够研究探针定位在细胞的其他地方。在无细胞研究中，当第二个探针与DNA结合时，它的发射被“关闭”。这种效应以前已经看到，这是由于DNA猝灭探针发射通过光激活电子转移从DNA到金属配合物。当DNA暴露在阳光下受损时，也会发生这种过程，这是衰老甚至癌症发生的原因。在未发表的涉及细胞的研究中，很明显，探针被细胞吸收，并显示出细胞内几个位置的发光，但细胞核内的DNA没有发光。有可能探针根本没有进入细胞核，但这种效果似乎是由于细胞内的DNA猝灭造成的。德国的实验将解决这些问题，并有可能提供第一个机会来研究细胞内涉及DNA的重要光化学过程。

In Sheffield, the Thomas group have developed a series of metal complexes that can be used as cellular optical imaging probes for confocal microscopy. These probes work through luminescence, so their cell location can only be imaged when they are emissive. At the same time, in Jena, the Dietzek group have developed an entirely new, and currently unique, microscope technology: Transient Absorption Microscopy. This time resolved technique allows the photoexcited states of molecules to be probed within cells. In this six week study, probes developed in the Thomas lab will be investigated in Jena using TAM. This work has a number of aims. First, since the probes have distinctive photo-absorption profiles, their localization across a cell can be "mapped" even if they are not luminescent in that part of the cell. One of the complexes to be studied "turns on" its luminescence only when bound to nuclear DNA. The high-resolution maps will allow us to investigate where else in the cell the probe localization. In cell free studies, the emission from a second probe is "switched off" when it binds to DNA. This effect has been seen before and it is due to the DNA quenching the probe emission through a light activated electron transfer from the DNA to the metal complex. This kind of process is also known to occur when DNA is damaged by exposure to sunlight and is a cause of aging and even cancer genesis. In unpublished work involving cells, it is clear that the probe is taken up by cells and shows emission from several intracell locations, but there is no luminescence from DNA within the nucleus. It is possible that the probe does not get into the nucleus at all, but it seems likely that the effect is due to DNA quenching within cells. The experiments in Germany will resolve thus issue and potentially provide the first opportunity to investigate within cells an important photochemical process involving DNA.