Preparation of phosphine-fluorophore conjugates as fluorescent probes, using literature methods.
An important part of our initial proposal has been a big problem. We proposed a series of phosphine-based fluorescent probes for developing drug discovery assays for important liver and kidney enzymes. The assays were based on using electron transfer from phosphines to quench emission from fluorophores. If the positive signal for an assay involved oxidation of a phosphine to a phosphine oxide, it would stop electron transfer quenching. This would lead to increased fluorescence emission as the positive signal for substrate or drug transport.
We have had serious problems reproducing the literature that was the precedent for our proposal. (Dozens of papers – seriously!) Some of these problems are synthetic. For example, an important paper we relied on involved coupling a neutral aminoethyl-phosphine to a fluorophore precursor. After months of effort, we quit doing this chemistry. |