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The dermal equivalent (DE), a dermis substitute consisting of human skin fibroblasts growing into a three-dimensional collagen matrix, is extensively used in many applications: wound-healing response, pharmacological studies, skin grafting, fibroblast proliferation and migration, extracellular matrix remodeling, and efficacy of cosmetic products. The widespread growth of numerical modeling in biomechanical research has placed a heightened emphasis on accurate material property data for soft biological tissues, in particular for equivalent dermis which has not been so thoroughly investigated. Under unconfined compression loading, the effects of the strain rate, time culture, and cytoskeleton-disrupting agents are experimentally investigated. In order to model the observed mechanical behavior of the DE under the above conditions, the internal state variable approach is adopted for finite deformation viscoelasticity and the optimized material parameters are identified with respect to the stated thermodynamic restriction (i.e. positive viscous dissipation).

A dermal equivalent having a trilayered structure was designed by combining a silver nanoparticles incorporated chitosan film with a bilayer collagen-chitosan/silicon membrane dermal equivalent (BDE). The silver nanoparticles prepared at different conditions were characterized by UV-Vis and transmission electron microscopy (TEM). The macroscopic sharp and the microstructure of the trilayer dermal equivalent (TDE) were also studied. Then, the in vitro antibacterial property of TDE was evaluated by the antibacterial zone test. The effect of the incorporated silver nanoparticles on the resistance of wound infection was further studied by the in vivo animal test. The results prove that the silver nanoparticles incorporated TDE has a better antibacterial property, thus may be potentially applied to a broader field in skin repair such as full thickness defect and burn.