3D photografting with aromatic azides: A comparison between three-photon and two-photon case

The final publication is available via https://doi.org/10.1016/j.optmat.2013.04.007.Photografting is a method utilizing light activation for covalent incorporation of functional molecules to a polymer surface or polymer matrix. It has been widely applied as a simple and versatile method for tailoring physical–chemical properties of various surfaces. Grafting induced via multi-photon absorption provides additional advantages of spatial and temporal control of the process. Here, a novel fluoroaryl azide photografting compound (AFA) was synthesized and compared with the commercially available azide BAC-M. Using Z-scan technique, it was determined that AFA is a two-photon absorber at 798 nm, whereas BAC-M is a three-photon absorber at this wavelength. Both azides were employed for 3D photografting within a PEG-based matrix using femtosecond laser pulses. Both Z-scan measurements and 3D photografting tests indicated that, the intensity threshold for nonlinear absorption and photografting process is lower for AFA. As a result the processing window of AFA is much broader than that of BACM. But on the other hand, since BAC-M is characterized by the three-photon absorption (3PA) process, patterns with finer features can be produced using this molecule. The choice of the appropriate compound for 3D grafting will depend on the final application and the requirements associated with the resolution and post-modification protocol

Defined nano-structuring with ultrashort pulses in gelatin biopolymer films for tissue-engineering

We compare the morphological modifications in gelatin films, induced with an 800nm femtosecond amplifier, in subject of the number of input pulses and the input pulse duration. Foam is formed in all cases, but only under certain conditions the desirable structures that mimic the native subcellular matrix are formed. The number of input pulses significantly changes the foam structure, allowing a well-defined nano-structuring for optimal tissue-engineering

Defined nano-structuring with ultrashort pulses in gelatin biopolymer films for tissue-engineering

We compare the morphological modifications in gelatin films, induced with an 800nm femtosecond amplifier, in subject of the number of input pulses and the input pulse duration. Foam is formed in all cases, but only under certain conditions the desirable structures that mimic the native subcellular matrix are formed. The number of input pulses significantly changes the foam structure, allowing a well-defined nano-structuring for optimal tissue-engineering