Facile Preparation of Photoactivatable Surfaces with Tuned Substrate Adhesiveness

Abstract

This paper describes a facile method for the preparation of photoactivatable substrates with tuned surface density of an extracellular matrix peptide to resolve the impacts of biochemical and mechanical cues on collective cell migration. The controllability of surface ligand density was validated by cell adhesion and migration tests, complemented with fluorescence observation of an alternative ligand. Depending on the surface ligand density, HeLa cells either kept or lost collective characteristics. The present materials will be useful to address mechanobiology of collective cell migration.

A Dynamic Biomaterial Based on a 2‐Nitrobenzyl Derivative with a tert‐Butyl Substituent at the Benzyl Position: Rapid Response and Minimized Phototoxicity

“…Thereafter, as a photoresponsive biomaterial, we conjugated poly(ethylene glycol) (PEG) to the glass substrate functionalized with the 2‐nitrobenzyl derivatives. In a similar fashion to our previous studies,, the conjugation of PEG to the photocleavable group made the surface switchable from non‐cell‐adhesive to cell‐adhesive in response to light (Figure B). The advantage of the newly developed photoresponsive biomaterials, in terms of rapid response and minimum phototoxicity, were demonstrated based on the cell migration applications and the reactive oxygen production, respectively.…”

“…Next, we studied how effective the tert ‐butyl derivative is for minimizing possible phototoxicity in photoresponsive culture platforms. In earlier reports on photoresponsive culture platforms based on the 2‐nitrobenzyl group, various doses of near‐UV light at 365 nm have been used, ranging from 3.6 or 6 J in stiffness‐tunable gels,, 24 J for caged cRGD, and 10 J in our photoactivatable 2D cell migration platforms ,,,. For applications to cell migration induction in particular, selective near‐UV irradiation at cell‐free regions is possible by using a photomask or laser light source to prevent direct near‐UV exposure of cells.…”

An Application of Photoactivatable Substrate for the Evaluation of Epithelial-mesenchymal Transition Inhibitors

“…21 The substrate surface was mixed self-assembled monolayers composed of three disulfide compounds bearing photocleavable PEG (PCP, Mw = 12k), cRGD, and EG6. 21 At the initial state, the celladhesive cRGD ligand is hidden under the umbrella of bulky PEG brushes, therefore cells cannot interact with the adhesive ligand, thereby the surface is non-cell-adhesive (Fig. 1D, left).…”

“…In addition to the geometrical control of cell clusters, their collective migration behaviors can be analyzed by releasing the geometrical confinement by the secondary irradiation of initially non-adhesive surrounding regions. This feature enabled us to study the effect of cluster geometry, 19 substrate adhesiveness, 20,21 or stiffness 22 on collective migration characteristics or to leader cells, 23 which actively produce lamellipodia and lead migration of cell collectives. Therefore, this platform will not only allow us to mechanically induce EMT to edge cells, but also analyze cluster expansion behaviors and the appearance of leader cells.…”

“…To test this hypothesis, in this study, we first assessed how known EMT inducers and inhibitors affect cluster expansion behaviors of Madin-Darby canine kidney (MDCK) cells, a typical cell line used for EMT studies, by using photoactivatable gold substrates. 21 Thereafter, we applied this methodology to naturally occurring compounds to identify potential EMT inhibitors.…”