Green Chemistry for Crosslinking Biopolymers: Recent Advances in Riboflavin-Mediated Photochemistry

Abstract

Riboflavin (RF), which is also known as vitamin B2, is a water-soluble vitamin. RF is a nontoxic and biocompatible natural substance. It absorbs light (at wavelengths of 380 and 450 nm) in the presence of oxygen to form reactive singlet oxygen (1O2). The generated singlet oxygen acts as a photoinitiator to induce the oxidation of biomolecules, such as amino acids, proteins, and nucleotides, or to initiate chemical reactions, such as the thiol-ene reaction and crosslinking of tyramine and furfuryl groups. In this review, we focus on the chemical mechanism and utilization of the photochemistry of RF, such as protein crosslinking and hydrogel formation. Currently, the crosslinking method using RF as a photoinitiator is actively employed in ophthalmic clinics. However, a significant broadening is expected in its range of applications, such as in tissue engineering and drug delivery.

Advances and Trends of Photoresponsive Hydrogels for Bone Tissue Engineering

“…The primary consideration in the selection of photoinitiators is whether the free radicals produced by the photoinitiators have cytotoxic effects . Due to their high reactivity, these free radicals can easily bind to nucleic acids or proteins in cells, causing DNA damage and subsequent cell death. , Recently, numerous studies have been done on visible-light sensitive photoinitiators to reduce the potential adverse effects of continuous UV irradiation on cells. , Visible-light-sensitive photoinitiators, including eosin-Y, , riboflavin, and camphor quinone, exhibit superior water solubility and lower cytotoxicity . Compared to radical polymerization, the thiol–ene click reaction has ideal selectivity and milder reaction conditions .…”

Preliminary Evaluation of Poly-(Sorbitol-Co-Citrate Adipate) Properties for Application as Biomaterial

“…Thus, based on the definition proposed by [19] citric acid [10] should be used as a crosslinking agent, i.e., as a "bridge" between macromolecular chains [22,23]. Furthermore, this same acid, for the system in question, did not prove to be a satisfactory building block for chain increase [3].…”

Photo-cross-linked Hydrogels for Cartilage and Osteochondral Repair

“…The processes are nontoxic, easy to obtain in the natural environment, and benign to the environment of various biomedical applications. 42 VA-086 is a type I photoinitiator, typically cured with UV light between 365 and 385 nm wavelength. 43 According to a previous report, VA-086 is less toxic than Irgacure2959.…”

“…Under UV irradiation, the photo-cross-linked material can be glued. The processes are nontoxic, easy to obtain in the natural environment, and benign to the environment of various biomedical applications …”