麻省理工大学：《生物工程》教学讲义（英文版）lec 1 Molecular Cellular

Molecular, cellular Tissue biomechanics Patrick Doyle(ChemE), Roger Kamm ME Be Maxine Jonas( BE) Goal: Develop a fundamental understanding of biomechanics over a wide range of length scales

Molecular, Cellular & Tissue Biomechanics Goal: Develop a fundamental understanding of biomechanics over a wide range of length scales. Patrick Doyle (ChemE), Roger Kamm (ME & BE) Maxine Jonas (BE)

MOLECULAR MECHANICS Biomolecules and intermolecular forces Single molecule biopolymer mechanics Ⅲl Formation and dissolution of bonds Motion at the molecular/macromolecular level ISSUE MECHANICS Molecular structure--> physical properties IL Continuum, elastic models(stress, strain, constitutive laws) Viscoelasticity Poroelasticity Electrochemical effects on tissue properties CELLULAR MECHANICS Structure/function/properties of the cell Biomembranes The cytoskeleton Cell adhesion and aggregation Cell migration Mechanotransduction

I Biomolecules and intermolecular forces II Single molecule biopolymer mechanics III Formation and dissolution of bonds IV Motion at the molecular/macromolecular level MOLECULAR MECHANICS I Structure/function/properties of the cell II Biomembranes III The cytoskeleton IV Cell adhesion and aggregation V Cell migration VI Mechanotransduction CELLULAR MECHANICS TISSUE MECHANICS I Molecular structure --> physical properties II Continuum, elastic models (stress, strain, constitutive laws) III Viscoelasticity IV Poroelasticity V Electrochemical effects on tissue properties

Typical Length Scales in Biology microtubule DNA WIdth width typical animal cell length of DNA in a chromosome human 10 10 -5 10 10 1↑10mees histone chromatin nucleus proteins width length of DNA contained in typical human ce‖l Similar spectra exist in time scales or energy scales

Typical Length Scales in Biology 10-9 10-7 10-5 10-3 10-1 101 meters human typical animal cell nucleus DNA width microtubule width length of DNA contained in a typical human cell chromatin width histone proteins length of DNA in a chromosome Similar spectra exist in time scales or energy scales

Muscles: Spanning from macro to nano Collection of myofibers Z disk Z disk Actin thin filament Myosin thick filament 000000 000 Myofiber (single cell 50 000 20099800000 Nucleus Plasma membrane Mlin Myofibril Sarcomere + A-band I band Z disk Actin: semiflexible polymer A band Myosin: molecular motor Titin: resting elasticity

Muscles: Spanning from Macro to Nano molecular motor semiflexible polymer Actin: semiflexible polymer Myosin: molecular motor Titin: resting elasticity

Macro-scale applications Cardiovascular mechanics 108 bpm 72 DDm Computational fluid mechanics used to study shear stresses in the carotid artery Image removed due to Image removed due to copyright considerations copyright considerations Peak floy Maximum Image removed due to Image removed due to copyright considerations copyright considerations deceleration

Cardiovascular mechanics Computational fluid mechanics used to study shear stresses in the carotid artery Peak flow Maximum deceleration 108 bpm 72 bpm Macro-scale applications Image removed due to copyright considerations. Image removed due to copyright considerations. Image removed due to copyright considerations. Image removed due to copyright considerations

or tissue stresses in the wall of a diseased vessel Image removed due to copyright considerations Stress(Pa) Computational 58500 mesh for finite 49500 element 40500. analysis mage removed due to copyright considerations 31500 22500 13500 4500 Image removed due to copyright considerations Histological section obtained from surgery

…or tissue stresses in the wall of a diseased vessel Stress (Pa) Histological section obtained from surgery Computational mesh for finite element analysis Image removed due to copyright considerations. Image removed due to copyright considerations. Image removed due to copyright considerations

MRI imag e Vessel cross-sections IGes boundary Quilting/Knitting finite element mesh 3D model 日 v我线口三口行6倍 ParaSolid model

Boundary data (x,y,z) IGES boundary : Quilting / Knitting MRI images Vessel cross-sections Finite element mesh 3D model ParaSolid Model

Modeling Complex Material Properties D Continuum Microstructural bending plate entangled polymer Constitutive relations and force balance Viscoelastic or poroelastic strut model solid elements T21()

† Modeling Complex Material Properties� Continuum Microstructural� bending plate entangled polymer force balance Constitutive relations and Viscoelastic or poroelastic strut model solid t 21(t)

ypical EuKaryotIc cel Plasma membrane 5nm Rough ER Smooth er Nucleus -3-10 um Nu cleolus Nuclear pore Golgi complex Cilia 10-30um 1 um Mitochondrian Cytoskeletal fibers nm 1A=1010ma

Typical Eukaryotic Cell� 10-30 mm 1 mm = 10-6 m� 1 nm = 10-9 m� 1 Å = 10-10m�

H| asma membrane口 Plasma Membrane Smooth ER Nucleus -3-10 um Nucleolus Nuclear pore Golgi complex 2-D Elastic Plate Extracellular Oligosaccharide Glycoprotein Peripheral Glycolipid Integral 2 .5 nm Hydrophobic Hydrophilic olar head Peripheral proteins pre Intracellular

Plasma Membrane� Plasma Membrane ~5 nm 2-D Elastic Plate