Biomimetic layer-by-layer templates for calcium phosphate biomineralization

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Tuning cell adhesive properties via layer-by-layer assembly of chitosan and alginate

Understanding the mechanisms controlling cell-multilayer film interactions is crucial to the successful engineering of these coatings for biotechnological and biomedical applications. Herein, we present a strategy to tune the cell adhesive properties of multilayers based on marine polysaccharides with and without cross-linking and/or coating with extracellular matrix proteins. Chemical cross-linking of multilayers improved mechanical properties of the coatings but also elicited changes in surface chemistry that alter the adhesion of human umbilical vein endothelial cells. We evaluated a strategy to decouple the mechanical and chemical properties of these films, enabling the transition from cell-adhesive to cellresistant multilayers. Addition of chitosan/alginate multilayers on top of cross-linked films decreased endothelial cell adhesion, spreading, and proliferation to similar levels as uncross-linked films. Our findings highlight the key role of surface chemistry in cell-multilayer film interactions, and these engineered nanocoatings represent a tunable model of cell adhesive and non-adhesive multilayered films.The authors acknowledge the financial support by the LusoAmerican Foundation and the USA National Institutes of Health (R01 AR062920). Joana M. Silva would also like to acknowledge the Portuguese Foundation for Science and Technology (FCT) for her PhD grant.info:eu-repo/semantics/publishedVersio

Tailored freestanding multilayered membranes based on chitosan and alginate

Engineering metabolically demanding tissues requires the supply of nutrients, oxygen, and removal of metabolic byproducts, as well as adequate mechanical properties. In this work, we propose the development of chitosan (CHIT)/alginate (ALG) freestanding membranes fabricated by layer-by-layer (LbL) assembly. CHIT/ALG membranes were cross-linked with genipin at a concentration of 1 mg· mL−1 or 5 mg·mL−1. Mass transport properties of glucose and oxygen were evaluated on the freestanding membranes. The diffusion of glucose and oxygen decreases with increasing cross-linking concentration. Mechanical properties were also evaluated in physiological-simulated conditions. Increasing cross-linking density leads to an increase of storage modulus, Young modulus, and ultimate tensile strength, but to a decrease in the maximum hydrostatic pressure. The in vitro biological performance demonstrates that cross-linked films are more favorable for cell adhesion. This work demonstrates the versatility and feasibility of LbL assembly to generate nanostructured constructs with tunable permeability, mechanical, and biological properties.The authors acknowledge the financial support by the Portuguese Foundation for Science and Technology (FCT) through the doctoral and Postdoctoral grants with the reference numbers SFRH/BD/81372/2011 (JMS) and SFRH/BPD/96797/2013 (SGC), respectively. This work was financially supported by the FCT, by the project PTDC/FIS/115048/2009, and by the European Commission/FP7 programme (ERC Starting Grant, GA 259370 to C.P.). The authors would also like to acknowledge the project novel smart and biomimetic materials for innovative regenerative medicine approaches (ref.: RL1 - ABMR - NORTE-01-0124-FEDER-000016) cofinanced by the North Portugal Regional Operational Programme (ON.2 0 Novo Norte), under the National Strategic Reference Framework (NSRF), through the European Regional Development Fund (ERDF)