Injectable hydrogel composites for biotechnological applications

Hydrogel materials, thanks to their biocompatibility and biodegradability, are very promising for the development of new biocompatible scaffolds for controlled drug release, tissue regeneration and tissue engineering. Low molecular weight peptide-based hydrogels (LMWPGs) are an interesting class of soft materials for the preparation of versatile systems that can be easily modified, both chemically and biologically. Recently, we developed an enzymatic approach for the preparation of injectable, self-assembling materials based on Fmoc-oligopeptides1. The reaction products (Fmoc peptides) spontaneously self-assemble in water to originate fibrils, that become entangled to form a three-dimensional structure of fibers with a diameter of approximately 7 nm, as evidenced by atomic force microscopy (AFM) measurements. Macroscopically, a stable, self-supporting hydrogel material is produced. These materials can be used as controlled drug delivery systems for a wide spectrum of bioactive molecules2,3 and may enhance cell production of growth factors4. For biomedical applications, hydrogel biomaterials require adequate structural stability, sufficient mechanical properties and biocompatibility. To this aim, hydrogel materials can incorporate nanofillers, such as polymeric or inorganic nanoparticles and nanocarbon based structures. We have employed Fmoc-oligopeptide hydrogels for the preparation of composite materials specifically designed for bone tissue regeneration. These tailor-made hydrogel systems contain biopolymeric spheres delivering bioactive molecules, as well as pure and substituted calcium phosphate (CaP) nanoparticles to provide bioactivity, osteoconductivity and improved mechanical properties. The morphological and viscoelastic properties of the synthesized hydrogels were investigated by SEM and rheological measurements. The biocompatibility of the composite materials with different mammalian cells was also assessed. The injectability of the prepared materials makes them suitable for in vivo applications. Ongoing work is aimed at investigating the biological properties of the composite hydrogel systems, in terms of adhesion, growth and differentiation of human mesenchymal stem cells. Moreover, we are developing new hydrogel composites through the incorporation of graphene based nanofillers, that offer the potential to tailor the mechanical strength of the native material, adding binding sites for further bio-functionalization with biological molecules, and supplying additional properties such as conductivity for regulating cell behaviors such as cell proliferation, differentiation or protein synthesis. References 1. L. Chronopoulou, S. Lorenzoni, G. Masci, M. Dentini, A.R. Togna, G.I. Togna, F. Bordi, C. Palocci, Soft Matter, 2010, 6, 2525. 2. L. Chronopoulou, S. Sennato, F. Bordi, D. Giannella, A. Di Nitto, A. Barbetta, M. Dentini, A. R. Togna, G. I. Togna, S. Moschini, C. Palocci, Soft Matter, 2014, 10, 1944. 3. L. Chronopoulou, Y. Toumia, B. Cerroni, D. Pandolfi, G. Paradossi, C. Palocci, New Biotechnology, 2017, 37, 138. 4. 4. L. Chronopoulou, A. R. Togna, G. Guarguaglini, G. Masci, F. Giammaruco, G. I. Togna, C. Palocci, Soft Matter, 2012, 8, 5784.