Two-photon micropatterning of amines within an agarose hydrogel

The ability to create three-dimensional micropatterns within polymeric materials is applicable in a wide number of fields, from photonic bandgaps to tissue engineering. We are particularly interested in three-dimensional chemical patterning of soft materials with a view towards their use in regenerative medicine. To this end, we created three-dimensional micropatterns of amines within an agarose hydrogel using two-photon patterning. Agarose was first modified with caged amines, using a derivative of 6-bromo-7-hydroxycoumarin, which upon two-photon excitation cleaved the coumarin molecule thereby yielding primary amine-functionalized agarose. Three-dimensional micropatterns were achieved because the excitation/deprotection reaction was limited to the focal volume of the two-photon laser absorbance. The three-dimensional amines serve as reactive sites for further water-based chemistry and may also render agarose cell adhesive in those amine-containing volumes.