The ability to produce idealized cellular constructs is essential for understanding and controlling intercellular processes and ultimately for producing engineered tissue replacements. Preliminary results have been obtained on collagen modification by irradiation with single and multiple pulses of femtosecond laser with variable pulse duration. Irradiation of collagen thin film by single pulses of femtosecond duration results in creation of foam layer with micrometer thickness. The structure and thickness of the layer strongly depends on the number of the applied laser pulses. The surface properties of collagen thin films before and after Ti-sapphire irradiation with 800 nm were investigated by means of the technique Field Emission Scanning Electron Microscope (FESEM). Based on the FESEM results, it was possible to identify an energy density range as the ablation threshold for collagen thin films. The laser-induced foam formation was characterized over the intensity range 3 – 4.2x10<sup>11</sup> W/cm<sup>2</sup>. The results of the field emission scanning electron microscopy, showed that by tailoring the laser pulse duration, improved the uniformity of the pore network. Examination of the interaction of ultra-short laser pulses with collagen films is useful for controlling the chemical and microstructural modification of the created foam layer.
A critical challenge for the broader implementation of laser cleaning interventions in
modern paintings is the assessment of the extent of any photochemical or structural
modifications induced in the original substrate following laser irradiation. For this reason, we
investigate several polymeric materials (PMMA, Paraloid B72) doped with aromatic
photosensitisers (PhenI, POPOP) of known photochemistry, coated with uniform layers of
acrylics of different thicknesses to simulate real case scenarios. Following laser irradiation, a
variety of spectroscopic techniques LIF, MPEF are employed for the in depth monitoring of
any photochemical and structural modifications induced in the bulk material.