title: Photo-selective delivery of model therapeutics from hydrogels.
abstract: Hydrogels are commonly used in biomedical applications to sequester and release therapeutics. Covalently tethering therapeutic agents to a hydrogel through a degradable linkage allows their controlled release, but temporally separating the release of multiple therapeutics from a single hydrogel remains a major challenge. In this report, we use of a series of photodegradableortho-nitrobenzyl (o-NB) groups with varying structures to link model therapeutic agents (fluorescein, rhodamine and aminomethylcoumarin acetate) to poly(ethylene glycol) macromers. We polymerized the macromers into hydrogel networks via redox polymerization and quantified the apparent rate constants of degradation (kapp) of each of the photoreleasable compounds. By exploiting differences in reactivity of the differento-NB groups, we are able to create complex, multi-stage release profiles. We demonstrate the ability to switch between concurrent and biased release of model therapeutics simply by switching wavelengths. We also demonstrate a complex four-stage release profile in which the release of three separate model therapeutics is controlled by varying wavelength, intensity and exposure time. This is the first report of photo-selective release of therapeutics from a hydrogel, allowing user-dictated real-time spatial and temporal control overmultiplechemical signals in a cell microenvironment in 2D and 3D.
authors.affiliation: Department of Bioengineering, University of California, Los Angeles, 410 Westwood Plaza, 5121 Eng V, Los Angeles, CA 90095 United States Tel. +1 310 794 6341 fax +1 310 794 5956.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Griffin
authors.affiliation: Department of Bioengineering, University of California, Los Angeles, 410 Westwood Plaza, 5121 Eng V, Los Angeles, CA 90095 United States Tel. +1 310 794 6341 fax +1 310 794 5956.
authors.forename: Andrea M
authors.initials: AM
authors.lastname: Kasko
keywords: drug delivery; ortho-nitrobenzyl; photo-selective