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.

Near-Infrared Light-Responsive Hydrogel for Specific Recognition and Photothermal Site-Release of Circulating Tumor Cells

“…[30][31][32] However, the site-release using photo-responsive system is still scarcely reported. 14,[33][34][35][36] Furthermore, currently used UV irradiation is unfriendly to biosystem. This severely affects viability and cell functions, and usually causes genetic mutation which is very unfavorable for further analysis of CTCs.…”

Biosensors for Cell Analysis

“…The adhesion of individual micropallets to the substrate can be disrupted by laser light, which can be used to dislodge a pallet with immobilized cells. Another light-directed cell-retrieval strategy has been demonstrated (80,85,90,91),which employed photosensitive hydrogels impregnated with cell-adhesive peptide motifs or antibodies. As seen in Figure 3b, subpanel ii, a specific spot of photoactive hydrogels can be degraded by UV light (365-405 nm) from a fluorescence microscope, thus releasing a single cell which had been adhered to the exposed hydrogel spot.…”

“…A number of dynamic substrates employing electrical potential (79)(80)(81)(82)(83)(84), chemical composition (85-87), or light irradiation (88)(89)(90) have been introduced to retrieve cells. Although these are promising, electrochemical detachment strategies are somewhat challenging to adapt to retrieve specific, single cells.…”

Hydrogels: soft matters in photomedicine

“…287 Light can also be used for site-specific degradation of cross-linked hydrogel matrices, 245,246 such as PEG. 288 Here, an intriguing example by Shin, Revzin and coworkers used an antibody-appended hydrogels to capture human CD4 or CD8 T-cells and then to release those cells upon UV-induced photodegradation of these "photogels". 288 Key step was the use of the photocleavable ortho-nitrobenzyl, which has also been used earlier for the release of porphyrin photosensitizers.…”