13 biomaterials
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Transcript of 13 biomaterials
BiomaterialsTissue Engineering Nanotechnology
Liu Nanobionics Lab
Biomaterials
Biomaterials encompasses aspects of medicine, biology, chemistry, engineering and materials science.
Biomaterials are : “Non-viable materials used in a medical devices intended to interact with biological systems” [D.F. Williams, 1987]
Disease (e.g cancer, infection, degenerative diseases).
Trauma (e.g accidental, surgery). Congenital abnormalities (e.g birth
defects).
Current clinical treatment based on:
Human Tissue Damage
Grafts and Transplants
Artificial Biomaterials
Tissue loss as a result of injury or disease, provides reduced quality
of life for many at significant socioeconomic cost.
Thus a shift is needed from tissue replacement to tissue regeneration by stimulation the body’s natural regenerative mechanisms.
Biomaterials: Examples Joint replacements Bone plates Bone cement Hip Joint Artificial ligaments
and tendons Dental implants for
tooth fixation Blood vessel
prostheses Heart valves Skin repair devices Cochlear
replacements Contact lenses
Hip jointHeart valve
Knee joint Skin
Biomaterials
Prostheses have significantly improved the quality of life ( Joint replacement, Cartilage meniscal repair, Large diameter blood vessels, dental)
However, incompatibility due to elastic mismatch leads to biomaterials failure.
National Science Foundation first defined tissue engineering in 1987 as “ an interdisciplinary field that applies the principles of engineering and the life sciences towards the development of biological substitutes that restore, maintain or improve tissue function”
Tissue Engineering
Tissue engineering
Potential advantages: unlimited supply no rejection issuescost-effective
Tissue Engineering
Remove cells from the body.
Expand number in culture
Seed onto an appropriate scaffold with suitable growth factors and cytokines
Place into culture
Re-implant engineered tissue repair damaged site
SCAFFOLDS
PLGA Scaffold
Synthetic polymers
More controllable from a compositional and materials processing viewpoint.
Scaffold architecture are widely recognized as important parameters when designing a scaffold
They may not be recognized by cells due to the absence of biological signals.
Natural polymers
Natural materials are readily recognized by cells.
Interactions between cells and biological materials are catalysts to many critical functions in tissues
These materials have poor mechanical properties.
Tissue engineering scaffold: controlled architecture
Featured with: Pre-defined channels;
with highly porous structured matrix;
With suitable chemistry for tissue growth – Collagen or HA
No toxic solvent involved, it offers a strong potential to integrate cells/growth factors with the scaffold fabrication process.
Architecture of Hard Tissue
Staggered mineral platelets (hydroxyapataite) embedded in a collagen matrix
Arrangement of platelets in preferred orientations makes biocomposites intrinsically anisotropic
Under an applied tensile stress, the mineral platelets carry most of the tensile load
Protein matrix transfers the load between mineral crystals via shear
Tissue engineering scaffold: Electrospinning
This process involves the ejection of a charged polymer fluid onto an oppositely charged surface.
Multiple polymers can be combined Control over fiber diameter and scaffold architecture
Printing Techniques for Tissue Engineering
Techniques to study scaffolds:Scanning Probe Microscopy
Atomic Force Microscopy :Surface irregularities
Scanning Tunneling Microscopy: Conducting Surfaces
Adhesion Force Microscopy: Functionalised tips
Surface Modification of Biomaterials
Enhanced intrinsic biomechanical properties of osteoblasticmineralized tissue on roughened titanium surface
Nano-indentation
Acid-etched vs. Machined surfaces
culturing osteoblasts on rougher titanium surfaces enhances hardness and elastic modulus of the mineralized tissue
Protecting Bionic Implants
Immunoisolation for Cell-encapsulation therapy
Liver Dysfunction: Encapsulation of Hepatic Cells
Pancreas Dysfunction: Encapsulation of Islets of Langerham
Disorders of the CNS: Parkinson’s, Alzheimer’s
Pre-requisites for cell encapsulation
continued and optimal tissue/cell supply
maintenance of cell viability and function
successful prevention of immune rejection
Nanoporous Silicone-based biocapsules serves as Artificial Pancreas(Desai et al. 2001)
What are the drawbacks of such an artificial pancreas?
Nanoengineering Bio-analogous Structures
Bone-cartilage composite ?
Muscle ?
Brain-machine Interface ?
An Ink-Jet Printer for Tissue Engineering?