RESEARCH PROGRAM OF CHRISTINE ORTIZ Multiscale Approach: single molecules →biomimetic assemblies...
-
Upload
sharon-paul -
Category
Documents
-
view
216 -
download
1
Transcript of RESEARCH PROGRAM OF CHRISTINE ORTIZ Multiscale Approach: single molecules →biomimetic assemblies...
RESEARCH PROGRAM OF CHRISTINE ORTIZ
Multiscale Approach:single molecules →biomimetic assemblies → matrix of single cells → in-tact tissue
Musculoskeletal (internal to the body)(e.g. cartilage, bone, etc.)
Exoskeletal (external to the body)(e.g. gastropod molluscs, armored fish, etc.)
Engineering motivation:
-Bio-inspiration and guidance for improved materials for
protective and structural
applications
Medical motivation:-to facilitate the
development of improved clinical treatments for
disease & injury through tissue repair and/or
replacement→ regenerative medicine /
tissue engineering
-nanoscale forces and displacements (F, ), constitutive laws ()-local, spatially-specific material properties (E, Y, H, energy dissipation, etc.)
-molecular-level structure-property relationships-novel mechanical phenomena (e.g. nanogranular friction, fracture localization, etc.)
Objective :A Fundamental, Mechanistic-Based Understanding of
Tissue Function, Quality, and Pathology
NANOMECHANICS OF STRUCTURAL BIOLOGICAL MATERIALS
SELECTED RECENT ACCOMPLISHMENTS
(MUSCULOSKELETAL)
● Prior to tenure: established the use ofnanomechanics in near-physiological conditionsapplied to healthy musculoskeletal tissues
● Post-tenure: application of nanomechanics to thefield of tissue engineering; temporal evolution of thequasistatic mechanical properties (Ng+ J. Biomech.2007) and dynamic visco(poro)elasticity (Lee+J. Biomech. 2009) of the tissue engineered cartilagematrix associated with individual cells
● Assessment of engineered tissue quality and
heterogeneity locally at unprecedented resolutions as a function of cell type, scaffold, growth factors, etc.
● Relevance to mechanotransduction
COLLABORATORS● A.J. Grodzinsky (MIT-BE), D. Gazit (Hebrew U.)
RESEARCH PROGRAM OF CHRISTINE ORTIZ NANOMECHANICS OF STRUCTURAL BIOLOGICAL MATERIALS
viscoelasticity + poroelasticity
(Buschmann+)
10 µm
2
p v
L
Hk
chondrocyte, stem cell
AFM colloidal tipmatrix
RESEARCH PROGRAM OF CHRISTINE ORTIZ NANOMECHANICS OF STRUCTURAL BIOLOGICAL MATERIALS
0
90
180
270
360
450
0 35 70 105 140Penetration Depth (nm)
Fo
rce
(µ
N)
BerkovichExperimentalφ = 15º, c = 100 MPa
FEA=15º, c =100 MPa
Mineralized Collagen Fibril
Mineral Particles
Cohesive Bonding
Frictional Contact
Mineralized Collagen Fibril
Mineral Particles
Cohesive Bonding
Frictional Contact
SELECTED RECENT ACCOMPLISHMENTS
(MUSCULOSKELETAL)
● Prior to tenure: established the experimental and theoretical methods for high resolution imaging and nanomechanics of bone
● Post-tenure Postulated a new theory for the strength on bone involving "nanogranular friction" (Tai+ Nano Lett., 2006, featured in Nat. Nanotech. News and Views, 2006, commentary; J. Am. Acad. Ortho. Surg. 2007); discovered a new energy dissipation mechanism in mineralized biological tissues; nanoscale heterogeneity (Tai+ Nat. Mater. 2007)→assessed nanoscale properties of stem cell-based tissue engineered bone (Tai+ J. Biomech., Pelled+ Tiss. Eng. 2008).
● Understanding the mechanisms that prevent our
bones from fracturing under physiological loading will aid in the treatment of problems that result from old age, disease, and injury.
COLLABORATORS● F. Ulm (MIT-CEE), S. Suresh (MIT-DMSE), D.
Gazit (Hebrew U.)
RESEARCH PROGRAM OF CHRISTINE ORTIZ NANOMECHANICS OF STRUCTURAL BIOLOGICAL MATERIALS
penetration ontop of fish scale
Ganoine
Dentin
Isopedine
Bone 10 μm
cross section of fish scale
SELECTED RECENT ACCOMPLISHMENTS
(EXOSKELETAL)
● Prior to tenure: established an experimental and theoretical framework for studies of mineralized biological materials at the nanoscale, using nacre as a model system
● Post-tenure Determined multilayered design (i.e. thickness, sequence, and material properties of individual layers) of a natural armor which facilitate circumferential fracture and prevent interfacial delamination under a penetrating load (bite from predator) in order to localize impact and prevent catastrophic failure (Bruet+ Nat. Mater. Cover 2008, Wang+ JMR 2009, Yao+ PNAS, 2009)
● Bio-inspiration and guidance for improved
materials for protective and structural applications (Ortiz & Boyce Science 2008)
COLLABORATORS● M.C. Boyce (MIT – MechE), D. Gazit (Hebrew
U.)
SELECTED RECENT ACCOMPLISHMENTS(EXOSKELETAL)
● Defense Science Study Group (DSSG) 2008-2009● Department of Defense National Security Science and Engineering
Faculty Fellows: NSSEFF (468 white papers resulted in 17 semifinalists being invited to submit full proposals and in person interviews → 10 awardees selected)→ $4.6M total
● MIT Institute for Soldier Nanotechnologies (Grantee, 2002-present)● Raytheon, Inc.
RESEARCH PROGRAM OF CHRISTINE ORTIZ NANOMECHANICS OF STRUCTURAL BIOLOGICAL MATERIALS
l1
l2
l3
l4
()1(CTE)1
durable functionally graded interphases − mitigates delamination
multilayered design (layer thickness, sequence) − penetration resistance, minimizes back-deformation into soft tissue, prevents catastrophic fracture (self-healing),
thermal management, weight reduction
interlocking articulation at reinforced joints
anisotropic constitutive models of individual layers − local stress
distributions
curved geometry (shape / size) of individual armor units – energy absorption, ergonomics
Rt
li
tissue finite viscoelastic deformation
(damage tolerance)
1
2
3
,E H
z z
, , , = ,
, , , ,1 2 3, 13 23, 12 12 32 31
Y,1 Y,2 Y,3 Y,3 Y,13 Y,23 Y,12
E = E E G = G G
z
anisotropic spatial arrangement of armor
units – cooperative deformation of entire
body
biomechanical flexibility
MOBILITY PROTECTION
()tgeometry and mechanical
properties of threat (e.g. penetrating indenter)
Ru
()2(CTE)2
()3(CTE)3
()4(CTE)4
unique organic-inorganic nanocomposite morphologies (e.g. fibrous, prismatic, nacreous etc.) - energy
dissipation
camouflage pigmentation
back deflection
4 Sub-Programsa) Flexible natural armorb) Transparent natural armorc) Natural armor for blastd) Natural armor for extremeenvironments (deep sea)