TY - JOUR
T1 - Nanomechanical Mapping of Hard Tissues by Atomic Force Microscopy: An Application to Cortical Bone
AU - Bontempi, Marco
AU - Salamanna, Francesca
AU - Capozza, Rosario
AU - Visani, Andrea
AU - Fini, Milena
AU - Gambardella, Alessandro
N1 - Funding Information:
This research was funded by the Italian Ministry of Health-5 x 1000 Anno 2019 Redditi 2018 “Medicina rigenerativa e riparativa personalizzata per le patologie dei tessuti muscolo-scheletrici e la chirurgia ricostruttiva ortopedica”.
Publisher Copyright:
© 2022 by the authors.
PY - 2022/11/1
Y1 - 2022/11/1
N2 - Force mapping of biological tissues via atomic force microscopy (AFM) probes the mechanical properties of samples within a given topography, revealing the interplay between tissue organization and nanometer-level composition. Despite considerable attention to soft biological samples, constructing elasticity maps on hard tissues is not routine for standard AFM equipment due to the difficulty of interpreting nanoindentation data in light of the available models of surface deformation. To tackle this issue, we proposed a protocol to construct elasticity maps of surfaces up to several GPa in moduli by AFM nanoindentation using standard experimental conditions (air operation, nanometrically sharp spherical tips, and cantilever stiffness below 30 N/m). We showed how to process both elastic and inelastic sample deformations simultaneously and independently and quantify the degree of elasticity of the sample to decide which regime is more suitable for moduli calculation. Afterwards, we used the frequency distributions of Young’s moduli to quantitatively assess differences between sample regions different for structure and composition, and to evaluate the presence of mechanical inhomogeneities. We tested our method on histological sections of sheep cortical bone, measuring the mechanical response of different osseous districts, and mapped the surface down to the single collagen fibril level.
AB - Force mapping of biological tissues via atomic force microscopy (AFM) probes the mechanical properties of samples within a given topography, revealing the interplay between tissue organization and nanometer-level composition. Despite considerable attention to soft biological samples, constructing elasticity maps on hard tissues is not routine for standard AFM equipment due to the difficulty of interpreting nanoindentation data in light of the available models of surface deformation. To tackle this issue, we proposed a protocol to construct elasticity maps of surfaces up to several GPa in moduli by AFM nanoindentation using standard experimental conditions (air operation, nanometrically sharp spherical tips, and cantilever stiffness below 30 N/m). We showed how to process both elastic and inelastic sample deformations simultaneously and independently and quantify the degree of elasticity of the sample to decide which regime is more suitable for moduli calculation. Afterwards, we used the frequency distributions of Young’s moduli to quantitatively assess differences between sample regions different for structure and composition, and to evaluate the presence of mechanical inhomogeneities. We tested our method on histological sections of sheep cortical bone, measuring the mechanical response of different osseous districts, and mapped the surface down to the single collagen fibril level.
KW - nanomechanical mapping
KW - atomic force microscopy
KW - force mapping
KW - tissue nanoindentation
KW - nano biomechanics
KW - biomaterials
KW - cortical bone
KW - elasticity
U2 - 10.3390/ma15217512
DO - 10.3390/ma15217512
M3 - Article
C2 - 36363104
VL - 15
JO - Materials
JF - Materials
SN - 1996-1944
IS - 21
M1 - 7512
ER -