In situ mechanical and molecular investigations of collagen/apatite biomimetic composites combining Raman spectroscopy and stress-strain analysis

TY - JOUR

T1 - In situ mechanical and molecular investigations of collagen/apatite biomimetic composites combining Raman spectroscopy and stress-strain analysis

AU - Chatzipanagis, Konstantinos

AU - Baumann, Christoph George

AU - Sandri, Monica

AU - Sprio, Simone

AU - Tampieri, Anna

AU - Kröger, Roland

PY - 2016/9

Y1 - 2016/9

N2 - We report the design, fabrication and application of a novel micro-electromechanical device coupled to a confocal Raman microscope that enables in situ molecular investigations of micro-fibers under uniaxial tensile load. This device allows for the mechanical study of micro-fibers with diameters in the range between 10 and 100 lm and lengths of several hundred micrometers. By exerting forces in the mN range, the device enables an important force range to be accessed between that of atomic force microscopy and macroscopic stress-strain measurement devices. The load is varied using a stiffness-calibrated glassmicro-needle driven by a piezo-translator during simultaneous Raman microscopy imaging. The method enables experiments probing the molecular response of micro-fibers to external stress. This set-up was applied to biomimetic non-mineralized and mineralized collagen micro-fibers revealing that above30% mineralization the proline-related Raman band shows a pronounced response to stress, which isnot observed in non-mineralized collagen. This molecular response coincides with a strong increase inthe Young’s modulus from 0.5 to 6 GPa for 0% and 70% mineralized collagen, respectively. Our resultsare consistent with a progressive interlocking of the collagen triple-helices by apatite nanocrystals asthe degree of mineralization increases.

AB - We report the design, fabrication and application of a novel micro-electromechanical device coupled to a confocal Raman microscope that enables in situ molecular investigations of micro-fibers under uniaxial tensile load. This device allows for the mechanical study of micro-fibers with diameters in the range between 10 and 100 lm and lengths of several hundred micrometers. By exerting forces in the mN range, the device enables an important force range to be accessed between that of atomic force microscopy and macroscopic stress-strain measurement devices. The load is varied using a stiffness-calibrated glassmicro-needle driven by a piezo-translator during simultaneous Raman microscopy imaging. The method enables experiments probing the molecular response of micro-fibers to external stress. This set-up was applied to biomimetic non-mineralized and mineralized collagen micro-fibers revealing that above30% mineralization the proline-related Raman band shows a pronounced response to stress, which isnot observed in non-mineralized collagen. This molecular response coincides with a strong increase inthe Young’s modulus from 0.5 to 6 GPa for 0% and 70% mineralized collagen, respectively. Our resultsare consistent with a progressive interlocking of the collagen triple-helices by apatite nanocrystals asthe degree of mineralization increases.

U2 - 10.1016/j.actbio.2016.09.028

DO - 10.1016/j.actbio.2016.09.028

M3 - Article

SN - 1742-7061

JO - Acta Biomaterialia

JF - Acta Biomaterialia

ER -