Development and Use of Optical Sensors in
Modern Analytical Chemistry
Aron Hakonen
Thesis for the degree of doctor of philosophy in Chemistry, Analytical
Chemistry
The thesis will be presented in English
Friday, April 23 at 14:00 in KA, Kemigården 4, Göteborg
Faculty opponent is Professor Colette McDonagh
Dublin City University, Ireland
Department of Chemistry
University of Gothenburg
2010
Abstract
A successful long-term high resolution imaging experiment in marine sediments was
performed (17 days within the sample; Paper I). The time correlated calibration procedure
was evolved to include parametric sigmoidal and logarithmic functions to provide three of the
best performing (optical) pH sensors available up to date (Papers II, III and IV), precision of
these sensors were in the 0.0029 – 0.0057 pH units range. New pH sensors have been
developed using three different immobilization techniques (Papers II, III and IV). The first
experiments using a pH optode to image cellular responses were demonstrated (Paper III). A
long (over 3 pH units) linear dynamic range (for an optode) with high performance was
shown (Paper IV). Possibly a simple linear normalization method for salinity within the
sample matrix was realized (Paper IV). Photoacidity and its change due to immobilization
was recognized and utilized as an important feature for optical pH measurements (Paper II). A
plasmon enhancement/quenching based fluorescent technique using functionalized gold
nanoparticles was developed and implemented on a co-extraction based ammonium sensor
(Paper V). This technique demonstrated a limit of detection three orders of magnitude better
than previous ammonium sensors (LOD = 1.7 nM vs. ~ 1 µM), and can directly be
implemented on more than 25 other cationic species.
KEYWORDS: Optical sensors, Optodes, Imaging sensors, Fluorescence, pH, Ammonium,
Sensing, Nanoparticle enhancement, Plasmonics