Natural polyphenol as radical inhibitors used for DLP-based 3D printing of photosensitive gels

As a promising 3D printing material, photosensitive gels have attracted wide attention in many fields, such as biomedicine, tissue engineering, soft robotics and so on. However, few studies focused on the radical inhibitors of photosensitive gels, which can remove free radicals produced in the non-printing condition and prevent the premature gelation of the photosensitive pre-hydrogel inks before printing. In this study, we designed natural polyphenols to be a kind of radical inhibitors. The polyphenol compounds including TA, PA, GA and HQ, showed good free radical scavenging ability. Especially, the TA as the radical inhibitor exhibits the excellent anti-polymerization effect due to the high density of catechol/pyrogallol groups and the dendritic structure. Additionally, by properly setting the concentration of polyphenols, the DLP-based 3D printing of photosensitive gels cannot be affected by the free radical scavenging performance of polyphenols. The polyphenols, as the radical inhibitor, can not only prevent the photosensitive gel ink from curing under natural illumination, but also ensure the success of 3D printing at specific wavelengths and intensity. Accordingly, the polyphenol compounds with radical scavenging properties will expand their potential applications as radical inhibitors in photocurable gel inks. • Polyphenols can prevent the photosensitive ink from curing under natural illumination. • Excessive polyphenols can affect the printability of photosensitive inks. • Due to its rich catechol/pyrogallol groups, TA exhibits excellent inhibition performance.