A cocktail of vitamins for aqueous RAFT polymerization in an open-to-air microtiter plate

Abstract

In this manuscript, we report a highly biocompatible benchtop photoinitiation system for polymer synthesis by employing a combination of vitamin B₂ (riboflavin) and vitamin C (ascorbic acid) for conducting reversible addition–fragmentation chain transfer (RAFT) polymerization. Under blue LED irradiation (λ = 470 nm, 6.4 mW cm⁻²), the bioactive form of riboflavin, flavin mononucleotide (FMN), in the presence of ascorbic acid (AscA) was able to initiate the controlled RAFT polymerization of a range of water soluble monomers such as acrylamides, acrylates and methacrylates. These photopolymerizations were found to be accelerated by the presence of oxygen allowing for this two-component FMN/AscA initiation system to be conducted directly in an open-to-air 96-well plate. This high throughput, low reaction volume platform was highly conducive for reaction optimization of various experimental parameters, such as the concentration of FMN and AscA, allowing for good control over the molecular weight and molecular weight distribution to be obtained down to reaction volumes as low as 50 μL. Finally, we demonstrate the highly facile nature of this photopolymerization method by employing off-the-shelf vitamin supplements for initiating controlled RAFT polymerization under blue LED light and without the need for deoxygenation. Together, these results suggest the excellent potential for this mild and oxygen tolerant vitamin-based photoinitiation system to be applied in the biological arena.