Clasen Anne, Wenderoth Sarah, Tavernaro Isabella, Fleddermann Jana, Kraegeloh Annette, Jung Gregor
Biophysical Chemistry, Saarland University Campus B2 2 66123 Saarbrücken Germany
INM - Leibniz-Institute for New Materials Campus D2 2 66123 Saarbrücken Germany.
RSC Adv. 2019 Nov 4;9(61):35695-35705. doi: 10.1039/c9ra06047b. eCollection 2019 Oct 31.
Intracellular pH sensing with fluorescent nanoparticles is an emerging topic as pH plays several roles in physiology and pathologic processes. Here, nanoparticle-sized pH sensors (diameter far below 50 nm) for fluorescence imaging have been described. Consequently, a fluorescent derivative of pH-sensitive hydroxypyrene with p = 6.1 was synthesized and subsequently embedded in core and core-shell silica nanoparticles a modified Stöber process. The detailed fluorescence spectroscopic characterization of the produced nanoparticles was carried out for retrieving information about the environment within the nanoparticle core. Several steady-state and time-resolved fluorescence spectroscopic methods hint to the screening of the probe molecule from the solvent, but it sustained interactions with hydrogen bonds similar to that of water. The incorporation of the indicator dye in the water-rich silica matrix neither changes the acidity constant nor dramatically slows down the protonation kinetics. However, cladding by another SiO shell leads to the partial substitution of water and decelerating the response of the probe molecule toward pH. The sensor is capable of monitoring pH changes in a physiological range by using ratiometric fluorescence excitation with = 405 nm and = 488 nm, as confirmed by the confocal fluorescence imaging of intracellular nanoparticle uptake.
利用荧光纳米颗粒进行细胞内pH传感是一个新兴的研究领域，因为pH在生理和病理过程中发挥着多种作用。在此，已报道了用于荧光成像的纳米颗粒尺寸的pH传感器（直径远低于50 nm）。因此，合成了一种pKa = 6.1的pH敏感型羟基芘荧光衍生物，随后通过改进的Stöber法将其嵌入核壳型二氧化硅纳米颗粒中。对制备的纳米颗粒进行了详细的荧光光谱表征，以获取有关纳米颗粒核心内环境的信息。几种稳态和时间分辨荧光光谱方法表明，探针分子与溶剂被隔开，但它与氢键保持着类似于与水的相互作用。将指示剂染料掺入富水的二氧化硅基质中既不会改变酸度常数，也不会显著减慢质子化动力学。然而，用另一个SiO壳层包覆会导致部分水被取代，并减缓探针分子对pH的响应。通过细胞内纳米颗粒摄取的共聚焦荧光成像证实，该传感器能够通过使用405 nm和488 nm的比率荧光激发来监测生理范围内的pH变化。
