[Zurück]

M. Lunzer, L. Shi, P. Gruber, M. Markovic, D. Ossipov, R. Liska, A. Ovsianikov:
"Sensitized Two-Photon Micropatterning in Presence of Cells";
Poster: International Conference of Biofabricaton 2018, Würzburg; 28.10.2018 - 31.10.2018; in: "International Conference of Biofabricaton 2018 Würzburg", (2018), S. 42.

Multiphoton lithography is a powerful approach that permits the processing of light-sensitive materials by the use of femtosecond-pulsed near-infrared laser light. Owing to its unique features, including free-form 3D-patterning and the non-invasiveness to areas outside the focal volume, this method is particularly suited for micropatterning of hydrogels in the presence of cells. Besides two-photon polymerization where scaffolds-like constructs are built in a bottom-up approach from a macromer solution, two-photon degradation of pre-formed photoactive hydrogels allows for localized microchannel formation or in-situ modification of cell surroundings.[1]
Nevertheless, due to the high resolution this emerging techniques offers and the resulting small feature sizes of created constructs, maximizing the achievable writing speed, with the aim to push the feasible spatial dimensions in the cubic centimetre regime, is a current key challenge.[2]
In this contribution, an approach for the improvement of the two-photon induced degradation of o-nitrobenzyl ester (oNB) containing hydrogels is presented. oNB derivatives are photocleavable groups commonly included in photosensitive materials for tissue engineering applications and mechanobiology studies.[3] However, as the two-photon absorption cross-sections δa of these functionalities are usually rather low,3 relatively high laser intensities and long irradiation times are required for their cleavage that can harm living cells encapsulated in the material.
To increase the reactivity towards pulsed laser light, we developed a modular system permitting the sensitization of the two-photon induced oNB photocleavage. By adding the water-soluble small molecule two-photon sensitizer P2CK,[4] we demonstrate that the efficiency of the oNB photo-scission can be effectively promoted in a concentration dependent manner and demonstrate the efficacy of this method in the presence of encapsulated stem cell spheroids (ASC/TERT1).
The photosensitive biomaterial used in this study is based on thiol modified hyaluronic acid and a linear photodegradable oNB-containing polyethylene glycol linker with terminal acrylates that can be crosslinked by thiol-ene Michael addition.
The presented approach provides a useful tool for two-photon micropatterning of photodegradable hydrogels at moderate laser powers in presence of encapsulated cells.

Multiphoton lithography, light-sensitive materials, use of femtosecond-pulsed near-infrared laser light, 3D-patterning, 3D-patterning