LS-1-P-3129 SHG Imaging as a Method for Precision Characterization of Collagen Structures in Combination with Nanoindentation

Studying the mechanical properties of native biological tissues is a great challenge in the field of biomechanics. Studying hardly accessible structures that play a very important role within a locomotive system, such as cartilaginous endplates (CEP), is especially challenging. Experimental techniques in biomechanics have undergone a hlarge evolution recently. CEP is approximately a 0.6mm thin layer of hyaline cartilage located between an intervertebral disc (IVD) and a vertebral body (VB). Calcification or any mechanical damage of a CEP can cause nutritional and metabolic waste flow restrictions both inward and outward from the IVD, respectively. Degenerative processes influence the mechanical properties of the tissue and therefore, this paper will aim towards understanding the material properties of CEPs. Information about local mechanical properties could help identify CEP malfunction and provide possible designs for IVD replacement.
Due to the very small thickness of CEPs, instrumented nanoindentation is a suitable method for determining mechanical properties. This is especially the case when using nanoscale Dynamic Mechanical Analysis (nanoDMA), which was developed to test viscoelastic materials. The aim of this work is to determine CEP localization using optical imaging methods and Second Harmonic Generation imaging (SHG) in combination with nanoindentation. The local mechanical properties of native CEP were measured and related to the inner microstructure. It is evident that the large scattering of CEP mechanical properties is due to the inhomogeneity of the microstructure.