University of Colorado

Andrea M Kasko

Kristi S Anseth

Mark W Tibbitt

April M Kloxin

Balaji Sridhar

Here, we present a photodegradable microparticle system that can be employed to entrap and deliver bioactive proteins to cells during culture. By using a photosensitive delivery system, experimenters can achieve a wide variety of spatiotemporally regulated release profiles with a single microparticle formulation, thereby enabling one to probe many questions as to how protein presentation can be manipulated to regulate cell function. Photodegradable microparticles were synthesized via inverse suspension polymerization with a mean diameter of 22 &#x3bc;m, and degradation was demonstrated upon exposure to several irradiation conditions. The protein-loaded depots were incorporated into cell cultures and release of bioactive protein was quantified during the photodegradation process. This phototriggered release allowed for the delivery of TGF-&#x3b2;1 to stimulate PE25 cells and for the delivery of fluorescently labeled Annexin V to assay apoptotic 3T3 fibroblasts during culture. By incorporating these photoresponsive protein delivery depots into cell culture, new types of experiments are now possible to test hypotheses about how individual or multiple soluble factors might affect cell function when presented in a uniform, temporally varying, or gradient manner.

Photodegradable groups for tunable polymeric materials

Provided is a method that provides both spatial and temporal control of a polymer degradation process using mono- and multifunctional macromolecular monomers ('macromers') that degrade via single- and multi-photon photolysis mechanisms over a broad range of wavelengths. The macromers can form or be incorporated into networks via covalent, non-covalent and/or ionic interactions. The spatial and temporal degradation of these networks can be controlled. More specifically, provided is a photodegradable macromer, comprising: (a) a photodegradable group; (b) a backbone structure comprising one or more repeating units that may be the same or different, which backbone structure is attached to the photodegradable group directly or through a linker; (c) one or more reactive end groups at one or more ends of the macromer; and optionally, (d) one or more therapeutic agents; and optionally (e) one or more caged groups. Also provided are polymers and networks incorporating macromers of the invention and optionally other substituents such as other polymeric structures. Also provided is a method of controlled degradation of a polymer comprising: providing a photodegradable polymer as described herein and exposing the photodegradable polymer to photoradiation of the appropriate wavelength and energy to cause one or more of the photodegradable groups to photodegrade.

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Boulder, CO, United States of America

Andrea M Kasko