Mechanics and Physiological Adaptation of Hard and Soft Biomaterials and Biological Tissues: Bone Mineralization & Hard Tissue Mechanics
Sponsored by: TMS Functional Materials Division, TMS Structural Materials Division, TMS: Biomaterials Committee
Program Organizers: Bernd Gludovatz, UNSW Sydney; Elizabeth Zimmermann, McGill University; Steven Naleway, University of Utah
Monday 2:00 PM
March 20, 2023
Room: Sapphire 400B
Location: Hilton
Session Chair: Bernd Gludovatz, UNSW Sydney; Elizabeth Zimmermann, McGill University
2:00 PM Invited
Bone Quality and Mineralization from Vibrational Spectroscopy: Eve Donnelly1; 1Cornell University
Vibrational spectroscopic techniques, such as Raman spectroscopy and Fourier transform infrared (FTIR) spectroscopy, offer important capabilities for compositional characterization of bone tissues. Furthermore, technological advancements have allowed collection of grids of spectra in a spatially resolved fashion to generate compositional images and correlate with spatially resolved assays of mechanical properties. We have leveraged these sensitive techniques to evaluate changes in bone tissue properties associated with skeletal development, aging, disease, and drug treatment. We have interrogated the material properties of many different systems with these tools, including human clinical specimens and animal models of skeletal disease. Some representative examples include clinical specimens from individuals with type 2 diabetes and from individuals with osteoporosis undergoing long-term antiresorptive treatment; mouse models of altered gut microbiome; and pathologic mineralization in aortic valves. Finally, we discuss emerging technical developments in spectroscopic imaging which provide new opportunities to establish structure-property relationships in biological tissues.
2:30 PM Invited
Multi-scale Characterization of Ear Bone Mechanics: Alessandra Carriero1; 1The City College of New York
Bone is the major component of the human body, operating as its protective load-bearing framework, but also as fundamental parts of its auditory system that through vibrations and conduction allow hearing. Composition and structure of the bone over many length-scales are responsible for its strength, toughness, ability to adapt to mechanical loads and thus capacity to transfer sound to the brain. Aging, disease and abnormal loads on bone alter its composition and disrupt its hierarchical structure, affecting bone’s mechanical environment and biological properties, thus increasing its vulnerability to fractures and deformities that in turn generate disabilities, such as reduced mobility and hearing loss. We examined ear bone structure, composition and mechanics at multiple length scales, in order to determine how small changes at the molecular level in osteogenesis imperfecta (OI or brittle bone disease) drastically ramifies at larger length scales, resulting in auditory impairments.
3:00 PM Invited
Mineral Ellipsoids and Nanochannel Structures in Bone: Tengteng (Toni) Tang1; Alyssa Williams1; Chiara Micheletti1; Mike Phaneuf2; Nabil Bassim1; Aurelien Gourrier3; Kathryn Grandfield1; 1McMaster University; 2Fibics Inc.; 3Université Grenoble Alpes
The mechanical competence of bone is attributable to its organic and inorganic constituents and their three-dimensional (3D) organization at each length scale. Recent advances in (plasma) focused ion beam-scanning electron microscopy have allowed the investigation of bone architecture in 3D at the meso- and nanoscale and provide new insight into the structure-function relationships in bone. Here, we demonstrate and discuss the recently discovered mineral ellipsoids and nanochannels in bone and their potential role in mineralization. The omnipresent mineral ellipsoids have a distinct packing pattern across the layers of bone lamellae and their orientation and shape are closely related to the collagen fibrils organization. These mineral ellipsoids also seem to be associated with and surrounded by an extensive network of nanochannels which are ten times smaller than the bone canaliculi. These nanochannels could potentially provide ion and molecule access to the mineral ellipsoids and facilitate their growth and mineralization.
3:30 PM Break
3:50 PM Keynote
Learning from Nature - How Biological Hard Tissues Cope with Stress: Rizhi Wang1; 1University of British Columbia
In its millions of years of evolution, nature has created biological hard tissues we have not been able to synthesize in the lab in terms of their well-controlled ultrastructure. Examples are mollusc shells, bone, and teeth. As a result of their complicated hierarchical structures, biological hard tissues often exhibit extraordinary mechanical performance. For example, pores exist in bones and teeth. From the viewpoint of fracture mechanics, these “defects” are stress concentration sites and may be detrimental to their strength. However, defects are well tolerated by those hard tissues and do not readily develop into fracture. The fascinating structure-function relations of biological tissues have been a contact inspiration to the materials community in its quest for better designs of high performance materials. This presentation introduces some of the specific structural designs adapted by seashell, various teeth, and bone to resist fracture. Potential applications to materials designs will also be discussed.
4:30 PM
Impact of Test Environment on the Fracture Resistance of Cortical Bone: Bernd Gludovatz1; Mihee Shin1; Min Zhang1; Annika vom Scheidt2; Matthew Pelletier1; William Walsh1; Penny Martens1; Jamie Kruzic1; Björn Busse2; 1UNSW Sydney; 2University Medical Center Hamburg
Water is crucial for the interplay of collagen and minerals and consequently influences bone strength and ductility. Dehydration alters bone’s mechanical properties; however, studies comparing dehydrating environments on fracture toughness are scarce. Crack resistance of human and sheep cortical bone was characterized in a bio-bath, in ambient conditions, and in scanning electron microscopes (SEMs) under three different conditions (water vapor pressure, air pressure, and high-vacuum) to better understand the impact of test environments on crack initiation toughness, K0, and crack growth resistance. Results show significantly lower K0 values and lower crack growth resistance for samples that were tested inside any SEM environment compared to air. Testing of hydrated samples in ambient air revealed elevated crack growth resistance relative to the bio-bath while K0 was similar for both environments. Our data reveals the experimental difficulties to directly observe microscale crack propagation that resembles the in vivo situation in cortical bone.
4:50 PM
Mimicking the Structure and Properties of Bone with Freeze Casting: Steven Naleway1; Tony Yin1; Josh Fernquist1; Debora Lyn Porter1; Maddie Schmitz1; Elise Hotz1; 1University of Utah
Freeze casting is a bioinspired technique for the fabrication of tailored, porous ceramic materials with structuring down to the nanoscale. Mimetic of the growth of mammalian bone and other biomaterials where biopolymers template the deposit of biominerals to create complex composites, freeze casting employs a template of growing ice crystals to create a complex porous microstructure in any ceramic. We propose that this bioinspired technique can be controlled through either intrinsic (those that modify from within by altering the constituents) or extrinsic (those that apply external forces or templates) means. Through these classifications, examples of extrinsic (through energized external fields) freeze cast, bioinspired structures will be discussed with a focus mimicking the structure of natural bone. In vitro results and applications as bone filler materials will be discussed.