Riboflavin is of vital significance in living processes as a precursor of two important coenzymes flavin mononucleotide and flavin adenosine dinucleotide.  The isoalloxazine ring in riboflavin plays a critical role in energy supplementation and cellular respiration as an electron acceptor in redox reactions.  Thus the electrochemical reduction process of riboflavin has drawn increasing attention.  In this work, the mechanism of the riboflavin reduction in the aqueous solution has been investigated by using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and the electrochemical version of System for Analysis at the Liquid Vacuum Interface (SALVI).  The dynamic electrochemical process has been monitored at the electrode-electrolyte interface simultaneously using cyclic voltammetry (CV) and in situ liquid ToF-SIMS.  Positive and negative ion mode mass spectra provide the molecular information on the buried surface of the working electrode in the electrolyte solution containing riboflavin.  The distribution of key reduction intermediates is observed using the unique depth profiling of ToF-SIMS with high lateral and z-direction resolution.  Furthermore, gold and graphite electrodes are both investigated as working electrodes to study the electron transfer mechanisms during reduction, which are hypothesized to be different.  Our dynamic observations of the electrode-electrolyte interface potentially bring new insights to the electron transfer process between the cell surface and its surrounding aqueous environment.

In situ probing of electron transfer in the riboflavin reduction process by dynamic liquid ToF-SIMS

254th National Meeting (2017)

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