Filtern
Dokumenttyp
- Vortrag (3) (entfernen)
Sprache
- Englisch (3)
Referierte Publikation
- nein (3) (entfernen)
Schlagworte
- Sensing (3) (entfernen)
Organisationseinheit der BAM
Eingeladener Vortrag
- nein (3)
Molecularly imprinted polymers (MIPs) are an established and powerful matrix for the selective enrichment and separation of chemical species, especially of small organic molecules. Because MIPs contain cavities in their matrix that are complementary in size, shape and electronic/electrostatic or hydrogen bonding demand to the imprinted target molecule or template, they are frequently termed “artificial antibodies”. Compared to natural antibodies, they are chemically and physically much more robust. MIP formation proceeds through the polymerization of a mixture of functional monomers and cross-linkers in the presence of the template with subsequent extraction of the latter. While this strategy has been successfully employed for separation MIPs since decades, the development of sensory MIPs has long been limited to the combination of a MIP as enrichment phase with a separate signalling element in a discontinuous fashion, being unsuitable for many sensing applications. Only very recently, the implementation of specifically designed fluorescent probes into MIPs has been successfully accomplished, fluorescence being one of the most versatile, sensitive and easily miniaturizable techniques. This presentation will introduce basic design considerations, challenges, limitations and the potential that lies with such sensor materials on the background of the work carried out in our group.
The reversible analyte-induced switching between a colourless leuco form of a dye and its coloured all-π-conjugated form is one of the oldest concepts in probe- or indicator-based optical analysis,1 constituting so-called “one-color indicators”.2 In contrast to colour changes in the visible region, for which usually a bond-forming or a non-covalent interaction between a functional group on an indicator and an analyte is responsible, the extraordinarily large shifts of 150–250 nm seen for leuco-to-all-π-conjugated transformation are only possible when the reaction takes place directly at a site that is an intrinsic part of a dye’s π-system; the classic case are triphenylmethane dyes.3 Despite its obvious potential, this approach has not been a very popular area of scientific research for decades, perhaps because it is much more difficult to implement selectivity than by modifying terminal functional groups. However, in recent years, reaction-based fluorescence probes have attracted increasing attention by virtue of their superior sensitivity.4,5
Nowadays, rhodamines and fluoresceins are by far the most prominent groups of reaction-based indicators.5 They are usually switched between a colourless and non-fluorescent and a greenish-yellowish absorbing and yellowish-reddish emitting form. Typically, the coloured and fluorescent form is ionic, while the colourless form is neutral, reactions having mainly be designed to occur at the end groups of the xanthenoid π-system. BODIPY dyes, with their favourable spectroscopic and chemical properties as well as facile wavelength tunability features have only very recently been explored into this direction.6,7 Reaction at the core dipyrrin framework of these dyes led to strong colour and fluorescence modulations with potential applications in materials sciences6 and cell imaging.7 The present contribution will highlight the mechanisms at play and the sensing performance realized so far, and will compare core-reactive approaches to reaction-based signalling that involves π-extension of BODIPYs.8,9
Biopolymers are the building blocks of life. Their properties are exploited for material functionalization on the nanoscale in a flexible manner. An overview over current research activities in the field of sensing, nanostrcuturing, radiation damage measurements on DNA and proteins and microfluidics is given.