Two-Photon Direct Laser Writing for Proteinaceous Microstructures with Additional Sensitizer

We report our findings of proteinaceous microstructures polymerized by two-photon direct laser writing (DLW) using an additional sensitizer for rapid fabrication. Conventionally, a solution of protein and one type of photosensitizer or photo-initiator is exposed to laser light for protein cross-linking. We introduce an additional photosensitizer of different absorption properties and potential for radicalization to create a three-component photosensitizing system. The advantage of a three-component system is an enhancement of photopolymerization performance. Due to the enhancement, rapid polymerization is achieved without increasing the amount of available monomer in pre-polymer solution. Depending on the target protein, obtaining sufficient amounts of protein might require financial or purification effort. Therefore, a three-component photosensitizing system is promising to avoid raising protein concentration in solution. We characterize the photosensitizing system based on a previously introduced fitting model and measurement method; thickness and height of fully restrained beam microstructures are analyzed by scanning electron microscopy in dependency of the applied laser power and exposure time. We compare the fit-obtained results of two three-component proteinaceous pre-polymer solutions with a previously introduced two-component system to elaborate on the application of the model. Proteinaceous three-component photosensitizing systems enable rapid fabrication simultaneously with a reduction of protein concentration in solution.