Photolatently modulable hydrogels using unilamellar titania nanosheets as photocatalytic crosslinkers.

Hydrogels, postmodulable in controlled time and space domains, attract particular attention due to their potential in bio-related applications. Towards this goal, photolatently reactive hydrogels are very promising. Here we develop photolatently modulable hydrogels, composed of a polymer network accommodating photocatalytic titania nanosheets at every crosslinking point. As titania nanosheets can utilize gelling water as their source of radicals, its long-lasting photocatalysis makes the hydrogels readily modulable. Benefiting from the hydrogelation mechanism, the gel network is finely compartmentalized, leading to sharp thermoresponses. As demonstrated by photo-micropatterning, non-diffusible titania nanosheets at the crosslinking points enable pointwise modulations with an excellent spatial resolution. The photolatent nature also makes it possible to conjugate them with other hydrogels and polymers.