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Unveiling the Self-Assembling Behavior of 5‑Fluorouracil and its N,N′‑Dimethyl Derivative: A Spectroscopic and Microscopic Approach

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journal contribution
posted on 20.09.2017, 00:00 by Pavel Banerjee, Devdeep Mukherjee, Tapas Kumar Maiti, Nilmoni Sarkar
Under physiological conditions, 5-fluorouracil (5-FU), an anticancer drug, self-assembles into fibrils by strong hydrogen-bonding network, whereas its N,N′-dimethyl derivative, 5-fluoro-1,3-dimethyluracil (5-FDMU), does not make fibrils due to lack of strong hydrogen-bonding motif. In vitro, 5-FU self-assembly is sensitive to physicochemical conditions like the pH and ionic strength of the solution, which tune the strength of the noncovalent driving forces. Here we report a surprising finding that the buffer, which is necessary to control the pH and is typically considered to be inert, also significantly influences 5-FU self-assembly, which indicates an important role of counterions in the fibril formation. We have also monitored concentration- and time-dependent fibrillar growth of 5-FU. Again, fibril growth process is probed under dynamic conditions using microfluidic platform. The self-assembly of 5-FU compared with its N,N′-dimethyl derivative shows lower cytotoxicity to the cultured human erythroleukemic cells (K562 cells), which plausibly states the reason behind the greater effectiveness of 5-FU derivative drugs than 5-FU itself.