Caged retinoids as photoinducible activators: implications for cell differentiation and neurite outgrowth.

Aiming to control neurite formation and navigate the axonal growth by an extrinsic guidance, we report on the design, synthesis and biological evaluation of caged retinoids. Agonists of RARβ have been temporarily blocked either by the [(α-methyl-2-nitropiperonyl)oxy]carbonyl (MeNPOC) group or by immobilization using nitrocatechol linkers on TiO2 particles. Release on demand has been achieved by release under UV irradiation, leading to the biologically active compounds, which have been shown to induce neuronal differentiation and neurite outgrowth.