David Whitten

Superquenching of fluorescent polyelectrolytes and its applications for chemical and biological sensing

We report on the phenomenon of superquenching observed for fluorescent polyelectrolytes -- conjugated and J-aggregate polymers -- in aqueous solution and in supported interfacial formats. Thus we find that for a number of substrates quenching by oppositely charged ions can occur with Stern- Volmer quenching constants that are a million fold or greater than those for the quenching of similar molecular chromophores by the same quenchers. The quenching can be tuned by a variety of techniques. The superquenching results from a combination of nonspecific but moderately strong association (due to a combination of Coulombic and hydrophobic interactions) between the quencher and polyelectrolyte with efficient excitonic or energy migration in the excited polymer. The effects reported here can be used in chemical and biological sensing applications.