[Zurück]

M. Lunzer, L. Shi, P. Gruber, M. Markovic, D. Ossipov, R. Liska, A. Ovsianikov:
"A Modular Approach to Sensitized Two-Photon Micropatterning of Photolabile Hydrogels";
Poster: 682. WE-Heraeus-Seminar, Bad Honnef; 25.11.2018 - 28.11.2018; in: "Micro- and Nanostructured Biointerfaces", (2018), S. PO17.

Multiphoton lithography is a powerful approach that permits the processing of light-sensitive materials by the use of fs-pulsed NIR-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 presence of cells. Besides two-photon (2P) polymerization where scaffolds-like constructs are built in a bottom-up approach from a macromer solution, 2P-degradation of pre-formed photoactive hydrogels allows for localized micro-channel formation or in-situ modification of cell surroundings.1 Nevertheless, due to the high resolution this 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 cm regime, is a current key challenge.2
In this contribution, an approach for the improvement of the 2P-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.1 However, as the 2P-absorption cross-sections δa of these functionalities are usually rather low, 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 2P induced oNB photocleavage. By adding the water-soluble small molecule 2P sensitizer P2CK,3 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 presented approach provides a useful tool for two-photon micropatterning of photodegradable hydrogels at moderate laser powers in presence of cells.

Multiphoton lithography, light-sensitive materials, free-form 3D-patterning, micropatterning of hydrogels in presence of cells