| |
[摘要]：Ratiometric fluorescence-based sensors are widely sought after because they can effectively convert even relatively small changes in optical output into a strong and easy-to-read signal. However, ratiometric sensor mols. are usually difficult to make. The authors present a proof-of-principle expt. that shows that efficient ratiometric sensing may be achieved by an array of two chromophores, one providing an on-to-off response and the 2nd yielding an off-to-on response in a complementary fashion. In the case that both chromophores emit light of different color, the result is a switching of colors that may be used in the same way as from a true ratiometric probe. The chromophore array comprises two sensor elements: (i) a polyurethane membrane with embedded N-anthracen-9-yl-methyl-N-7-nitrobenz-oxa-[1,2,5]diazo-4-yl-N',N'-dimet hyl- ethylenediamine hydrochloride and (ii) a membrane with N,N-dimethyl-N'-(9-methylanthracenyl)ethylenediamine. A combination of photoinduced electron transfer (PET) and fluorescence resonance energy transfer (FRET) allows for green-to-blue emission switching in the presence of ZnII ions. The sensing expts. carried out with different ZnII salts at controlled pH revealed that the degree of color switching in the individual sensor elements depends on both the presence of ZnII ions and the counteranion. Probably sensing of both cations and anions may perhaps should be extended to different cation-anion pairs. |
|
