Recent Advances in 3D Printing of Pure Proteinaceous Microstructures by Femtosecond Laser Direct Write

Recent advances in three-dimensional (3D) printing of pure proteinaceous microstructures by femtosecond laser direct write (fs-LDW) are presented. Fs-LDW utilizes light-matter interaction to fabricate micro- and nanostructures along the designated path of the focused laser light. Extremely short pulses suppress heat effects while enhancing the likelihood of non-linear light absorption processes. Fs-LDW thereby allows the fabrication with spatially well-confined features and nearly arbitrary shapes in 3D with a high resolution for diverse materials including protein. Mixtures of protein and photoactivator were usually used so far as precursors to fabricate proteinaceous 3D microstructures. Here, we show that proteinaceous 3D microstructure can be fabricated using the precursor without photoactivator. Such omission of photoactivator might be relevant for biomedical and microfluidic applications because the use of photoactivator is accompanied with the undesired side-effects of photoactivator molecules leaching from created structures and cause physical alteration in the device or allergic reactions for medical use. Raman spectroscopy reveals the absence of photoactivator in the created structures and acid-catalyzed hydrolysis verifies covalent cross-linking as the printing mechanism. We further demonstrate our recent findings in terms of function retention by antibody staining. Due to the diverse abundance of proteins with different native protein functions, we believe fs-LDW of pure proteinaceous microstructures offers many applications in biological studies and medical applications.