@article {25514,
	title = {Nanoindentation and finite element modelling of chitosan{\textendash}alginate multilayer coated hydrogels},
	journal = {Soft Matter},
	volume = {12},
	number = {35},
	year = {2017},
	pages = {7338-7349},
	publisher = {Royal Society of Chemestry},
	abstract = {Composite soft materials are used as compounds for determining the effects of mechanical cues on cell behavior and cell encapsulation and for controlling drug release. The appropriate composite soft materials are conventionally prepared by selective deposition of polymers at the surface of an ionic hydrogel. In the present study we address the impact of a mechanically stratified two-layer structure of these materials on their overall mechanical characterization by applying a combination of nanoindentation, confocal microscopy and finite element modelling. We prepare covalent cross-linked hydrogels based on acrylamide (AAM) and including an anionic group, and impregnate them using a multilayer deposition strategy of alternating exposure to cationic chitosan and anionic alginate. The thickness of the chitosan{\textendash}alginate layer on the hydrogels was determined to be 0.4 {\textpm} 0.05 μm for 4 bilayers, and 0.7 {\textpm} 0.1 μm for the 8 bilayer deposition procedure employing a fluorescently labelled chitosan and confocal microscopy. The force{\textendash}indentation data for the AAM gels were highly reproducible, whereas 77\% and 50\% of the force{\textendash}indentation data were reproducible following the 4 and 8 bilayer deposition. The main trends in the reproducible force{\textendash}distance data were found to yield an apparent increased Young{\textquoteright}s modulus after the deposition. Finite element modelling showed that adaption of a homogeneous Young{\textquoteright}s modulus for the specimens with deposited layers yields approximately three times too low stiffness compared to the estimate of the mechanical properties of the outer part in the two-layered mechanical model. The thickness of the multilayer region determined by confocal microscopy was used in the model. This study shows that the mechanical layered property needs to be included in the interpretation of the nanoindentation data when there is a significant mechanical contrast.},
	author = {Victorien Emile {Prot} and Bj{\o}rn Torger {Stokke} and Maurstad, Gjertrud and Sherstova, Tatyana and Bj{\o}rn H. {Skallerud}}
}
@article {Simula.sc.942,
	title = {The Fluid Phase of Morsellized Bone: Characterization of Viscosity and Chemical Composition},
	journal = {Journal of the Mechanical Behavior of Biomedical Materials},
	volume = {1},
	number = {2},
	year = {2008},
	pages = {199-205},
	abstract = {Morsellized bone is widely used in orthopaedics to fill skeletal defects. The material behaviour is highly time-dependent, due to the liquid consisting of fat and water present in the impacted graft layer. In this study this fluid was characterized with respect to viscosity and chemical composition. Bovine bone was ground in a bone mill, transferred to tubes and centrifuged. This procedure allowed to successfully extract the fluid present inside the ground bone. The fluid was found to have similar composition to yellow bone marrow and a temperature dependent viscosity that could be described by Andrade{\textquoteright}s equation with coefficients A = 1.3 * 10^-4 Pa s and B = 3950 C. The viscosity data can be used in quantitative modelling based on a mixture theory approach to simulate the mechanical behaviour of the graft during packing and cement filling in the femur.},
	doi = {10.1016/j.jmbbm.2007.10.001},
	author = {Knut B. {Lunde} and Sletmoen, Marit and Bj{\o}rn Torger {Stokke} and Bj{\o}rn H. {Skallerud}}
}
