While light-responsive materials promise to enable on-demand, precisely localized delivery of molecules in living systems, such applications remain elusive because few materials respond to wavelengths that appreciably penetrate tissues. A photocage efficiently cleaved upon near infrared (NIR) irradiation, bromohydroxycoumarin (Bhc), requires water for photocleavage and thus is not useful for triggered degradation of hydrophobic polymer assemblies. To apply this chemistry, we have designed and synthesized a Bhc-bearing crosslinker to create light-degradable nanogels, which allow ample water access to support photocleavage. To enable rapid response to NIR, we designed the crosslinker to break by cyclization in a manner similar to our recent ornithine-inspired polymers. Our long term goal is to use this crosslinker to control release from small, monodisperse, biomaterial-based nanogels; a similar system without light sensitivity has previously been employed in vaccine and growth factor delivery. Towards this end, we have examined feasibility in polyacrylamide nanogels. These nanogels are highly stable in the absence of irradiation and disassemble within a few hours upon brief laser exposure at 750 nm. This design promises to enable precise spatiotemporal control over the release of proteins within engineered tissues.

Near infrared-degradable crosslinkers for on-demand delivery of hydrophilic molecules

249th National Meeting (2015)

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