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The biocompatibility assessment of biomaterials or the dynamic response of implanted constructs entails inflammatory events primary reflected in cell behavior at the microcirculatory system. Current protocols are based on histopathology which are over 40 years old and require the sacrifice of a huge number of laboratory animal with an unsustainable ethical burden of animal research. Intravital microscopy techniques are actually used to study implantation outcomes in real time. However, no device providing a specific tracking geometry to reposition the field of view of the microscope, for repeated analyses, exists yet. The synthetic photoresist SZ2080 is characterized here, allowing the development and in vivo validation of a miniaturized imaging window, the Microatlas, that, fabricated via two-photon polymerization, is implanted in living chicken embryos and imaged by fluorescence microscopy 3 and 4 days after the implant. The characterization of their elastomechanical and fluorescence properties highlights planar raster spacing as the most important parameter in tuning the mechanical and spectroscopic features of the structures. The quantification of cell infiltration inside the Microatlas demonstrates its potential as novel scaffold for tissue regeneration and as beacon for 3D repositioning of the microscope field of view and correction of optical aberrations.

The current protocols for biocompatibility assessment of biomaterials, based on histopathology, require the sacrifice of a huge number of laboratory animals with an unsustainable ethical burden and remarkable cost. Intravital microscopy techniques can be used to study implantation outcomes in real time though with limited capabilities of quantification in longitudinal studies, mainly restricted by the light penetration and the spatial resolution in deep tissues. We present the outline and first tests of a novel chip which aims to enable longitudinal studies of the reaction to the biomaterial implant. The chip is composed of a regular reference microstructure fabricated via two-photon polymerization in the SZ2080 resist. The geometrical design and the planar raster spacing largely determine the mechanical and spectroscopic features of the microstructures. The development, in-vitro characterization and in vivo validation of the Microatlas is performed in living chicken embryos by fluorescence microscopy 3 and 4 days after the implant; the quantification of cell infiltration inside the Microatlas demonstrates its potential as novel scaffold for tissue regeneration.