Open Access

Advances in optogenetics and the increasing use of implantable devices for therapies and health monitoring are driving demand for compliant, biocompatible optical waveguides and scalable methods for their manufacture. Molding, thermal drawing, and dip-coating are the most prevalent approaches in recent literature. Here the authors demonstrate that extrusion printing at room temperature can be used for continuous fabrication of compliant optical waveguides with polydimethylsiloxane (PDMS) core and crosslinked Pluronic F127-diacrylate (Pluronic-DA) cladding. The optical fibers are printed from fluid precursor inks and stabilized by physical interactions and photoinitiated crosslinking in the Pluronic-DA. The printed fibers show optical loss values of 0.13–0.34 dB cm–1 in air and tissue within the wavelength range of 405–520 nm. The fibers have a Young's Modulus (Pluronic cladding) of 150 kPa and can be stretched to more than 5 times their length. The optical loss of the fibers shows little variation with extension. This work demonstrates how printing can simplify the fabrication of compliant and stretchable devices from materials approved for clinical use. These can be of interest for optogenetic or photopharmacology applications in extensible tissues, like muscles or heart.

Two-photon (2P) activable photocleavable protecting groups (PPGs) can be introduced in polymer networks as photodegradation sites or as blocking groups for active sites, which enable the alternation of mechanical properties and biochemical signals and allow to study consequent cell response in a spatiotemporal controlled manner. So far, the design of high efficient 2P activable hydrogels is challenging. This Thesis presents novel designs of photodegradable hydrogels that contain the 4’-methoxy-4-nitrobiphenyl-3-yleth-2-yl)methyl (PMNB) PPG. PMNB-gels formed under physiological conditions and showed tuneable hydrolytic stability and adequate rate for cell encapsulation. Moreover, PMNB-gels can be photodegraded efficiently upon 2P excitation (λ = 740 nm). Preliminary experiments of PMNB-gels as 4D matrices for the investigation of cell response are presented. In a second part, a 2P-activatable PPGs endowed with an extended π conjugation was demonstrated and introduced to yield the RGD cell adhesive peptide. The targeted peptide is obtained but only in low yield due to its low stability. The results of this Thesis provide new tools for instructing cells in 3D cultures using 2P-activated processes and demonstrate the potential of photochemistry for the realization of 4D biomaterials.