Photodegradable Hydrogels for Capture, Detection, and Release of Live Cells

Abstract

Cells may be captured and released using a photodegradable hydrogel (photogel) functionalized with antibodies. Photogel substrates were used to first isolate human CD4 or CD8 T-cells from a heterogeneous cell suspension and then to release desired cells or groups of cells by UV-induced photodegradation. Flow cytometry analysis of the retrieved cells revealed approximately 95% purity of CD4 and CD8 T-cells, suggesting that this substrate had excellent specificity. To demonstrate the possibility of sorting cells according to their function, photogel substrates that were functionalized with anti-CD4 and anti-TNF-α antibodies were prepared. Single cells captured and stimulated on such substrates were identified by the fluorescence “halo” after immunofluorescent staining and could be retrieved by site-specific exposure to UV light through a microscope objective. Overall, it was demonstrated that functional photodegradable hydrogels enable the capture, analysis, and sorting of live cells.

Controlling the Release of Small, Bioactive Proteins via Dual Mechanisms with Therapeutic Potential

“…A decrease in the rate was expected since typically hydrogels containing o -NB groups conjugated to polymers with amide linkages have exhibited slower degradation rates; however, the rate of degradation did not decrease as much as previously reported when using an amide linkage. [25, 26] For example, Anseth and coworkers demonstrated ~15% degradation of an amide-linked photodegradable hydrogel in ~6 minutes using a 10-fold higher light intensity (102 mW/cm 2 ) than was needed to degrade an ester-linked photodegradable hydrogel network. [25] We hypothesize that the electron-withdrawing nature of the aryl-thiol substituent contributed to the faster degradation rate than typically observed for other amide linked o -NB groups.…”

Design of thiol- and light-sensitive degradable hydrogels using Michael-type addition reactions

“…45 Nitrobenzyl-based photolabile groups have been used in several applications as protective groups for uncaging of proteins, 46 spatiotemporally controlling hydrogel properties, 34, 38 and the release of live cells or bioactive proteins. 41, 47, 48 Aryl-thiol based thioether succinimide linkages are susceptible to thiol exchange in the presence of glutathione (GSH), which provides a reducing microenvironment (Fig. 1D).…”

Photodegradable Gelatin-Based Hydrogels Prepared by Bioorthogonal Click Chemistry for Cell Encapsulation and Release

“…1 To address this problem, light-induced degradation chemistry has been utilized for spatial and temporal degradation of hydrogel structures. 7,11,18,[29][30][31][32][33][34][35][36][37][38][39][40][41] This approach often utilizes a photolabile o-nitrobenzyl (NB) moiety which becomes reactive upon irradiation with ultraviolet (UV) light and induces the cleavage of the adjacent group.…”