**11. Polymerization of Vitamins**

Reversible addition-fragmentation chain transfer (RAFT) is suitable for the Vitamin C and B2 mediated polymerization of synthetic monomers such as methacrylates, acrylates, and acrylamides under LED irradiation. The efficiency of the polymerization process is contingent on the optimization of the irrational wavelength and oxygen. Zhang et al. linked the high throughput in vitamin-mediated polymerization to the low reaction volume platform, molecular weight distribution, low reaction volumes and the concentrations of Vitamin B<sup>2</sup> and C [109]. The costs of the synthetic process can be offset by the inclusion of off-the-shelf vitamin supplements in place of reagent/analytical grade Vitamin C and B2. The free radical-initiated chain polymerization of biomolecules has critical implications on disease prevalence, given that the progression of Alzheimer's disease and other neurodegenerative diseases can be linked to free radical damage of cells. On a positive note, this process can be offset by anti-oxygenic nutrients, such as vitamin-rich (C, E and co-enzyme Q) fruits and vegetables, which offer protective benefits against free radical damage [110]. The polymerization of compounds with complex architectures has been augmented by advances in technology, particularly photo-induced electron/energy transfer–reversible addition-fragmentation chain-transfer (PET-RAFT) polymerization.

The PET-RAFT process is remarkably superior relative to RAFT in isolation due to higher oxygen tolerance [111]. However, other issues remain unresolved, including the experimental testing of oxygen tolerant species. Most of the documented experiments were conducted in water—a factor that limits the utility of the process in the presence of organic solvents. The initiation of vitamin polymerization in the presence of organic solvents is critical in biological processes, given that vitamins and biological molecules comprise organic functional groups. The constraint was partially resolved by Gormley et al. [109], who documented successful polymerization of oxygen resistant compounds in organic solvents, dimethyl sulfoxide (DMSO). Nonetheless, it is of note that the initiation of the process requires a zinc tetraphenyl porphyrin (ZnTPP) catalyst. From an industrial and commercial perspective, the additional costs linked to catalysis pale in comparison relative to the additional benefits associated with successful PET-RAFT in organic solvents. The findings documented by Zhang et al. [110], Tappel et al. [111], and Gormley et al. [109] demonstrate the excellent potential of oxygen tolerant PET-RAFT and RAFT vitamin-based photo-initiation mechanism in biological applications.
