se8b00034_si_001.pdf (257.39 kB)
Modified Organosilica Core–Shell Nanoparticles for Stable pH Sensing in Biological Solutions
journal contribution
posted on 2018-04-10, 00:00 authored by Kye J. Robinson, Gabriel T. Huynh, Betty P. Kouskousis, Nicholas L. Fletcher, Zachary H. Houston, Kristofer J. Thurecht, Simon R. CorrieContinuous
monitoring using nanoparticle-based sensors has been
successfully employed in complex biological systems, yet the sensors
still suffer from poor long-term stability partially because of the
scaffold materials chosen to date. Organosilica core–shell
nanoparticles containing a mixture of covalently incorporated pH-sensitive
(shell) and pH-insensitive (core) fluorophores is presented as a continuous
pH sensor for application in biological media. In contrast to previous
studies focusing on similar materials, we sought to investigate the
sensor characteristics (dynamic range, sensitivity, response time,
stability) as a function of material properties. The ratio of the
fluorescence intensities at specific wavelengths was found to be highly
sensitive to pH over a physiologically relevant range (4.5–8)
with a response time of <100 ms, significantly faster than that
of previously reported response times using silica-based particles.
Particles produced stable, pH-specific signals when stored at room
temperature for more than 80 days. Finally, we demonstrated that the
nanosensors successfully monitored the pH of a bacterial culture over
15 h and that pH changes in the skin of mouse cadavers could also
be observed via in vivo fluorescence imaging following subcutaneous
injection. The understanding gained from linking sensor characteristics
and material properties will inform the next generation of optical
nanosensors for continuous-monitoring applications.