Organ in vitro synthesis is one of the last bottlenecks between tissue engineering and transplantation of synthetic organs. Bioprinting has proven its capacity to produce 3D objects composed of living cells but highly organized tissues such as full thickness skin (dermis + epidermis) are rarely attained. The focus of the present study is to demonstrate the capability of a newly developed ink formulation and the use of an open source printer, for the production of a really complete skin model. Proofs are given through immunostaining and electronic microscopy that the bioprinted skin presents all characteristics of human skin, both at the molecular and macromolecular level. Finally, the printability of large skin objects is demonstrated with the printing of an adult-size ear.

Doubly luminescent core/shell structure nanoparticles were synthesized for biological detection. In the first step gadolinium oxide (Gd 2 O 3 ) core doped with the luminescent Tb 3+ ions was obtained by applying, with modifications, the polyol route, which allows direct precipitation of oxide nanoparticles in a polyalcohol medium. The presence of Tb 3+ ions in the Gd 2 O 3 crystalline matrix confers attractive optical properties for long-term studies and multilabeling such as a high photostability and narrow emission bands. The water sensitivity of these particles, which is detrimental for the Tb ion's luminescence, was overcome by embedding the oxide core in a functionalized polysiloxane shell prepared by hydrolysis condensation of a mixture of APTES and TEOS. This protective layer allows the dispersion of the particles in aqueous solution without loss of luminescence intensity. Moreover, the luminescence of polysiloxanecoated Gd 2 O 3 nanoparticles is more intense than that in the case of the naked Gd 2 O 3 core. Due to the presence of amino groups, organic dyes and biotargeting groups (nucleic acid, biotin, streptavidin) were covalently linked to the polysiloxane network. These particles are efficient for detection of biomolecules whose presence is revealed by the high fluorescence of organic dyes and/or the photostable Tb 3+ ion's luminescence.