Abstract:
The development of sensors assays for comprehensive characterisation of biological
samples and effective minimal-invasive diagnostics is highly prioritised. Last decade
this research area has been actively developing due to possibility of simultaneous, real-
time, in vivo detection and monitoring of diverse physicochemical parameters and
analytes.
The new approach which has been introduced in this thesis was to develop and examine
an optical diagnostic assay consisting of a mixture of environmental-sensitive
fluorescent dyes. The operating principle of the system has been inspired by electronic
nose and tongue devices which combine nonspecific (or semispecific) sensing elements
and chemometric techniques for multivariate data analysis. The performance of the
optical assay was based on the analysis of the spectrum of selected dyes with discreet
reading of their emission maxima. The variations in peaks intensities caused by
environmental changes provided distinctive fluorescence patterns, which could be
handled similar to the signals collected from nose/tongue devices.
The analytical capability of the assay was engendered by changes in fluorescence signal
of the dye mixture in response to changes in pH, temperature, ionic strength and the
presence of oxygen. Further findings have also proved the ability of optical assay to
estimate development phases and to discriminate between different strains of growing
cell cultures as well as identify various gastrointestinal diseases in human.
This novel fluorescence-based diagnostic tool offers a promising alternative to
electrochemical systems providing high sensitive measurements with broad dynamic
range, easy, inexpensive measurements and the possibility of remote sensing and
extreme assay miniaturisation. Additionally it does not require reference signal.
This new approach can impact on a number of applications such as routine minimal-
invasive diagnostics for medical samples, biomedical analysis, pharmaceutical or
cosmetic research, quality control and process monitoring of food or environmental
samples.
