We used copper-catalyzed azomethine imine–alkyne cycloaddition (CuAIAC) to prepare five novel cycloadducts that exhibited fluorescence under UV light. As alkynes in CuAIAC we used two ynones that we synthesized one from succinic anhydride and the other from propiolic acid. The ynones were activated with either N-hydroxysuccinimide (NHS) or benzotriazole (BtH) in order to facilitate a covalent bonding with amine groups of biomolecules, thus making bioconjugation possible. Ynones were cyclized with various N,N-cyclic azomethine imines and the reaction was catalyzed with Cu0 in the form of copper particles or copper wire.
NHS and BtH activated fluorescent cycloadducts were first bonded to (aminomethyl)polystyrene (AMP) as a preliminary test of bioconjugation. We also bonded AMP with activated ynones and then performed CuAIAC on the ynone-marked AMP to again yield a fluorescent polystyrene.
Lastly, we bonded BtH activated cycloadducts onto amine groups of bovine serum albumin (BSA) and measured their emission spectra.
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