生物材料-Biomaterials.ppt

Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Biomaterials,1,Biomaterials,Non-viable material used in a medical device intended to interact with biological systems,Material intended to interact with biological systems,2,Biomaterials Science,Physical and biological study of materials and their interaction with the biological environment,Synthesis,Optimization,Testing,Biology of host-material interactions,3,Ratner(1993)characterized body response to these materials as“blah”,Non specific,Sluggish kinetics,Broad spectrum of active processes occurring,Proteins 200+to choose from,Cells(neutrophils,macrophages,platelets)well adapted to respond to these proteins,4,What we get,What we really want,5,Development of engineered surfaces that elicit rapid and highly precise reactions with cells and proteins,Tailored to specific application,Resistance to blood clotting,Resistance to bacterial infection,Normal uncomplicated healing,6,Biomaterials History,“,Hero surgeons”,Ridley and IOLs,Hip and knee prostheses Canadian connection,Kidney dialysis,Breast implants,Vascular grafts,Stents,7,The Terylene,Orlon or nylon cloth is bought from a drapers shop and cut with pinking shears to the required shape.It is then sewn with thread of similar material into a tube and sterilized by autoclaving before use.,8,The Current State of Affairs,Medical devices are regulated by the FDA,Some devices are grandfathered based on being available prior to the legislation introduction,Classified based on safety and potential impact to human health,9,Materials Commonly Used in Biomaterials Applications,Synthetic Polymers,Hydrogels,Polyurethanes,Silicone based materials,Teflon,Dacron,Poly(ethylene oxide),Degradable materials,Natural Polymers and Other Natural Materials,10,Metals,Ceramics,glasses and glass-ceramics,Pyrolitic Carbon,Composite,11,Materials and Medical Uses,12,The Biomaterials Scientist:A Jack of All Trades,Computational chemistry,Molecular biology,Surface physics/chemistry,Nanofabrication,Materials science,13,Materials Properties,Bulk,Surface,14,Mechanical Properties of Materials,15,Elastic Behaviour of Materials,Solid material subjected to tensile force will extend in the direction of traction by an amount proportional to the load,16,Stress and Strain,Extension for a given load varies with geometry and composition,Normalization of load and deformation to allow comparison of different materials,Normalized load(force/area)is stress(,s,),normalized deformation is strain(,e,),Stress strain curve is generated from this data,17,Typical Stress Strain Curve,18,Other Properties,Tension and compression,Area supporting the load is perpendicular to the loading direction,change in length is parallel to original length,Shear,Applied load is parallel to the area supporting it,19,Tensile and Shear Modulus,20,Mechanical Testing,21,Other Bulk Properties,Porosity,Permeability,22,Surface Properties,Concerned with function(related to design),durability(related to bulk properties)and biocompatibility(related to surface properties),23,Biocompatibility,Overused term,Defined as,The ability of a material to perform with an appropriate host response in a specific application,The exploitation by materials of the proteins and cells of the body to meet a specific performance requirement,24,Surface properties direct the biological response,Not toxicology,Mechanical and functional design,while critical,are not central to biocompatibility,25,The Surface,Surface of a material is invariably different from its bulk,There is not much total mass on a surface,Microelectronics example:1 cm3 cube of Ti contains a 100 layer of oxide.This can be compared to a 5 m wide beach on each coast of the US,Surfaces readily contaminate with components from the vapour phase,26,Figure 2:Changes to PHEMA,27,Figure 3 Ratner,28,So,We need to control the surface,Create a surface that mimics the native biology in order to develop materials that are“biocompatible”,Need to characterize the surface,29,Biomimetics,Approaches that mimic or replicate the natural function of tissues are often the most successful,Complexity of natural tissues and organs is still far beyond the ability of science for replication,Precise function of every aspect of the tissue or organ is not known,General concepts have emerged from study of structural biology that provide design strategies and guidance,30,Cells are genetically programmed to build organs and tissues,Cells produce proteins,polysaccharides,glycoproteins,lipids that assemble into composite extracellular matrices,Cells communicate via growth factors and their recruitment,Blood vessels play a crucial role in tissue growth by providing nutrients,a means for waste removal and a supply of additional cells,Nervous system is responsible for the integration and control of all of the bodies functions,31,We therefore have some understanding of,Cell processes,Protein adsorption,Wound healing,Successful treatment of medical condition,But lacking understanding of the relationship between the events that occur at the surface and the final successful outcome,32,The Future,Biomaterials will not fight biology but will integrate into the biological system,Biomaterials science versus biomaterials engineering,Materials and biology working together,33,Self-assembled materials,Surface modified materials for promotion of cell interactions,Photonic materials,Materials which mimic the ECM,34,A New Definition of Biocompatibility,Biostable materials which pass routine toxicological tests heal indistinguishably when implanted in soft tissue,Integration rather than isolation of a biocompatible material,Maintenance of the ability to heal complex wounds,35,Elimination of long term macrophage response,Better understanding of the nature of the fibrotic response,Maintenance of normal wound healing,36,