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Kinetic and spectroscopic responses of pH-sensitive nanoparticles: influence of the silica matrix

  • 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 pKa = 6.1 was synthesized and subsequently embedded in core and core–shell silica nanoparticles via 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 SiO2 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 λex = 405 nm and λex = 488 nm, as confirmed by the confocal fluorescence imaging of intracellular nanoparticle uptake.

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Document Type:Article
Author:Anne Clasen, Sarah Wenderoth, Isabella Tavernaro, Jana Fleddermann, Annette KraegelohORCiD, Gregor Jung
Parent Title (English):RSC Advances
First Page:35695
Last Page:35705
Publisher:The Royal Society of Chemistry
Year of first Publication:2019
Release Date:2022/11/18
Impact:03.119 (2019)
Groups:Nano Zell Interaktionen
Open Access:Open Access
Signature:INM 2019/166
Licence (German):License LogoCreative Commons - CC BY-NC - Namensnennung - Nicht kommerziell 4.0 International