Biophysics, University of Michigan, Ann Arbor, MI, USA.
Analyst. 2011 Sep 21;136(18):3616-22. doi: 10.1039/c1an15046d. Epub 2011 Jul 20.
Intracellular pH mapping is of great importance as it plays a critical role in many cellular events. Also, in tissue, pH mapping can be an indicator for the onset of cancer. Here we describe a biocompatible, targeted, ratiometric, fluorescent, pH sensing nano-PEBBLE (Photonic Explorer for Biomedical use with Biologically Localized Embedding) that is based on two-photon excitation. Two-photon excitation minimizes the photobleaching and cell autofluorescence drastically, leading to an increase in the signal-to-noise ratio. PEBBLE nanosensors provide a novel approach for introducing membrane impermeant dyes, like HPTS, into cells. We use both non-targeted and F3 peptide targeted PEBBLE nanosensors for intracellular pH measurement of 9L cells. The intracellular measurements suggest that the non-targeted nanosensors are mostly trapped in endosomes, whereas the F3 peptide targeting enables them to escape/avoid these acidic compartments. Combining the advantages of pH sensitive PEBBLE nanoparticles, including their specific targeting, with the advantages of two-photon microscopy provides an attractive and promising prospect for non-invasive real-time monitoring of pH inside cancer cells and tissues.
细胞内 pH 测绘非常重要，因为它在许多细胞事件中起着关键作用。此外，在组织中，pH 测绘可以作为癌症发生的指标。在这里，我们描述了一种基于双光子激发的生物相容性、靶向、比率荧光、pH 感应纳米 PEBBLE（用于生物定位嵌入的生物医学光子探索器）。双光子激发可极大地减少光漂白和细胞自发荧光，从而提高信噪比。PEBBLE 纳米传感器为将膜不可渗透的染料（如 HPTS）引入细胞提供了一种新方法。我们使用非靶向和 F3 肽靶向 PEBBLE 纳米传感器对 9L 细胞进行细胞内 pH 测量。细胞内测量表明，非靶向纳米传感器主要被困在内体中，而 F3 肽靶向则使它们能够逃避/避免这些酸性隔室。将 pH 敏感的 PEBBLE 纳米粒子的优势（包括其特异性靶向）与双光子显微镜的优势相结合，为非侵入性实时监测癌细胞和组织内的 pH 提供了一个有吸引力和有前途的前景。
