Emission Quenching of a Poly(Phenylene Ethynylene) (PPE) in the Solid State
- PDF / 118,854 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 115 Downloads / 159 Views
0888-V09-20.1
Emission Quenching of a Poly(Phenylene Ethynylene) (PPE) in the Solid State Wayne N. George1, Joachim H. G. Steinke1*, John C. de Mello1, Mark Giles2, Iain McCulloch2 1 Biological and Biophysical Chemistry Section, Department of Chemistry, Imperial College London, South Kensington Campus, London, SW7 2AZ, UK. 2 Merck Chemicals, UK, Chilworth Science Park, University Parkway, Chilworth, Southampton, Hampshire, SO16 7QD, UK. * [email protected] ABSTRACT The ability of a poly(phenylene ethynylene) conjugated polyelectrolyte to detect a small molecule quencher in the solid state was assessed by coating the polymer onto a plastic-backed, non-fluorescent, silica-gel TLC plate. The efficiency of the emission quenching process was quantified by noting the resulting loss of emission with increasing quencher concentration, in accordance with the Stern-Volmer relation. The emission quenching induced by the addition of the analyte occurred with Stern-Volmer constants in the range of 103 M-1. INTRODUCTION The use of electronic materials, specifically Conjugated Polymers (CPs), is rapidly emerging as an innovative approach for the development of a new class of highly sensitive biosensors.1, 2 The favourable emission properties of water soluble CPs (conjugated polyelectrolytes) have led to such materials being exploited in a range of biosensory schemes including DNA detection and enzyme monitoring.3-8 Such sophisticated sensor design stemmed from initial findings by Chen et al. who noted the highly sensitive emission quenching of a water-soluble PPV derivative upon exposure to the small molecule quencher methyl viologen.1 To explain the sharp decrease in fluorescence an electron transfer mechanism has been invoked whereby the complementary charged small molecule quencher is able to abstract an electron from the excited state polymer, through the formation of an ion-pair (static) complex.9, 10 This eliminates the ability of the polymer to decay to the ground state by other decay processes. The widespread applicability for this mode of quenching has been amply demonstrated by several elegant examples in the literature.11 However, transferring the emission quenching concept to a solid state sensor design has proved more problematic as issues regarding polymerpolymer interactions become more important.5 This has led to ever-increasing complexity being introduced into the polymer design in attempts to reduce inter-chain interactions which have a negative impact on the emission intensity and quantum yield.12 So far, most of the work on the use of such materials for sensing has concentrated on solution state studies. To broaden this scope and allow for the wider applicability of such technologies in, for example, field applications it is necessary to develop solid state methodologies which avoid the use of several solutions. Whitten et al. have already shown how poly(phenylene ethynylene) (PPE) polymers coated on microspheres can be used as a sensitive platform for the detection of oligomeric DNA strands in a ‘turn-
Data Loading...
