Application of flow-through sold-phase-synthesis to the fluorescent labeling of amines with carboxylic and funtionalized bodipy dyes

Abstract

The use of fluorophores for the labelling of biomolecules in living cells has become a key method for understanding processes in cellular biology. Synthetic fluorescent molecules can be introduced non-specifically to uniformly stain cells or selectively label a protein of interest to visualize cellular activity and metabolism using fluorescent microscopy. An increasingly popular small molecule fluorophore at the forefront of fluorescent cellular observation is the group known as the 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dyes. This particular family of fluorophores are known to be strongly UV-absorbing and emit sharp fluorescent peaks with high quantum yields. Characteristics that make BODIPY dyes even more desirable for biological imaging are their insensitivity to the polarity and pH of their environment allowing them to stay reasonably stable at physiological conditions. Structural modifications to the BODIPY core allow for the fine tuning of its photochemical properties and allow a certain level of fluorescence control – however these changes can result in

long, often low-yielding syntheses. As part of this research, a solid-phase- synthesis (SPS) method was developed as a flow through system to efficiently

attach a variety of BODIPY fluorophores to amine-functionalized compounds. In order for this reaction to occur, the fluorophore requires a carboxylic acid moiety available to attach to the resin and subsequently couple to an amine through amide bond linkage. The synthesis of these BODIPY derivatives will also be described. This work demonstrates an efficient method for coupling different BODIPY dyes to a variety of amines as well as the preparation of an AMPS-DCT resin used for amide coupling using SPS. The resulting fluorescent compounds will be tested for fluorescent characteristics to provide further insight into the effects that structural modification has on the fluorophore’s attractive photochemical properties.