Nanocomposites constitute an interesting class of materials for tissue engineering , where the embedding of nanoparticles into a biocompatible polymer adds novel functionality and hence, improves viability and proliferation of relevant adhered cells. Our group has developed an elegant method for the fabrication of nanocomposites based on laser ablation in liquids in polymer and monomer solutions, yielding nanocomposites with outstanding purity and biocompatibility [1]. In previous works we could already demonstrate improved cytocompatibility of these materials through two separate pathways I) local changes  in surface charge and stiffness [2] and II) Release of metal ions [3].
In this work we focused on alginate and PEG hydrogel-based biomaterials loaded with iron nanoparticles and examined the mechanism of metal ion release from these biomaterials. We identified a unique release behavior of iron ions from alginate-based composites, primarily driven by oxide solubility and interactions between iron ions and the alginate hydrogel matrix. Furthermore, we could find a significantly enhanced adhesion of model serum proteins to the biomaterial surface, which, interestingly already occurs at very low nanoparticle loadings (< 0.1 wt%). This seems to indicate that a mechanism based on locally elevated iron ion concentrations is responsible for the enhanced biocompatibility of these nanoparticle-loaded biomaterials. [4] We further verified the suitability of these materials for 3D bioprinting applications where the nanoparticles had no adverse effects on printability. [3] [4] These findings were complemented by recent examinations with   hematopoietic stem and progenitor cells in 2D and 3D culture. Here we found a significant influence of iron nanoparticles in the biomaterial on the early stage of in vitro erythropoiesis relevant for applications in in vitro blood farming.[5]

1. Maurer, E.; Barcikowski, S.; Gokce, B. Chemical Engineering & Technology 2017, 40, 1535-1543.
2. Hess, C.; Schwenke, A.; Wagener, P.; Franzka, S.; Sajti, C. L.; Pflaum, M.; Wiegmann, B.; Haverich, A.; Barcikowski, S. Journal of Biomedical Materials Research Part A 2014, 102, 1909-1920.
3. Blaeser, A.; Million, N.; Campos, D. F. D.; Gamrad, L.; Kopf, M.; Rehbock, C.; Nachev, M.; Sures, B.; Barcikowski, S.; Fischer, H. Nano Research 2016, 9, 3407-3427.
4. Li, Y. Y.; Rehbock, C.; Nachev, M.; Stamm, J.; Sures, B.; Blaeser, A.; Barcikowski, S. Nanotechnology 2020, 31.
5. Brändle, K.; Bergmann, T. C.; Raic, A.; Li, Y.; Million, N.; Rehbock, C.; Barcikowski, S.; Lee-Thedieck, C. ACS Applied Bio Materials 2020, 3, 4766-4778.