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Dr. Alagiriswamy A A , (M.Sc, PhD, PDF) Asst. Professor (Sr. Grade),

This lecture explores the classification and properties of biomaterials, including bioinert, bioactive, and bioresorbable materials. It also covers the concept of surface energy and its importance in determining surface properties and biocompatibility.

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Dr. Alagiriswamy A A , (M.Sc, PhD, PDF) Asst. Professor (Sr. Grade),

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  1. Dr. Alagiriswamy A A, (M.Sc, PhD, PDF) Asst. Professor (Sr. Grade), Dept. of Physics, SRM-University, Kattankulathur campus, Chennai ABCs of Biomaterials UNIT III Lecture 2

  2. Interesting cues • A simple “THANK YOU” makes a difference • Display supportive behavior to ensure team success • To keep up efficiency limit your work : - FATIGUE • Key to people related problems is always with you • Betrayal, however small, causes displeasure among staffs Courtesy : - The Hindu, opportunities, Mar. 18/2014

  3. Outline of the presentation • CLASSIFICATION OF BIOMATERIALS • COMPARISON OF PROPERTIES OF BIOMATERIALS • EFFECT OF PHYSIOLOGICAL FLUIDS • BIOLOGICAL RESPONSES

  4. TYPICAL BIOMATERIAL APPLICATIONs a biomaterial should not GIVE OFF its mass unless it is specifically designed to do so

  5. BIOMATERIALS- CLASSIFICATION • Bioinert Biomaterials : -minimal interaction with the tissue • stainless steel, titanium, alumina, partially stabilized zirconia, and ultra high molecular weight polyethylene • Bioactive Biomaterials : - maximum functionality • synthetic hydroxyapatite [Ca 10 (PO4)6(OH)2], glass ceramic and bioglass • Bioresorbable Biomaterials : - maximum absorption and dissolves leads to the maximum advantage of bones • tricalcium phosphate [Ca3(PO4)2] and polylactic- polyglycolic acid copolymers rely on surface, mechanical, thermal properties atleast

  6. SURFACE PROPERTIES • Surface Energy • What is a true surface ? • At the surfaces, there are asymmetric forces involved • Quantification of disruption of bonds/surfaces • Metals/ceramics:- high surface energies ranging from 102 to 104 ergs/cm2. • Polymers/plastics have much smaller surface energies, usually <100 ergs/cm2. • Adsorption of gases and/or organic species makes the quantification tougher even for simpler systems. • Why don’t you think off some acute remedies????????????????????????

  7. Liquid/Gas Liquid/Liquid Solid/Solid Solid/Gas Solid/Solid Surfaces and Interfaces “A region of space in which the system undergoes transition from one phase to another” Surface: Region between condensed phase (S or L) and a gas phase Interface: Region between two condensed phases

  8. Some more surface properties • Contact Angle • quantitative measure of the WETTING of a solid by a liquid • angle at which a liquid/vapor interface MEETS the solid surface • Three interfaces determines the interactions and so angle • used to discriminate hydrophobics and hydrophilics • Contact angle analysis characterizes the wettability of a surface by measuring the surface tension of a solvent droplet at its interface with a homogenous surface

  9. Goniometry

  10. Contact angle analysis • Young-Dupree equation depicts at equilibrium conditions • s/g, s/l and l/g are the interfacial free energy between the solid and gas; solid and liquid, liquid and gas respectively and  the contact angle s/g = s/l + l/g cos  • The wetting characteristic can be generalized as •  = 0, complete wetting ; •  0  900, partial wetting ; •  > 900 , no wetting. Factors: surface roughness, adsorption, contamination

  11. Critical Surface Tension: - • Surface tension is a measurement of the cohesive energy present at an interface • bulk of a liquid are balanced by an equal attractive force in all directions • Molecules on the surface of a liquid experience an imbalance of forces • Polar liquids, such as water, have strong intermolecular interactions and thus high surface tensions. • If temperature increase, surface energy decreases, system collapses

  12. Critical surface tension by Zisman plot • A concept developed in the 1960`s by Walter Zisman • The surface tension of a liquid that would completely wet the solid of interest. • Surface energy of surface can be expressed by critical surface tension. • Low critical surface tension means that the surface has a low energy. • Measure on one surface for a series of liquids varying in surface tension • Plot cos  Vs lv. • Extrapolate to cos  = 1.0 ( = 0˚ ) • Define c at cos  = 1.0 ( = 0˚ )

  13. Determination of Surface Energy Using Contact Angle (Zisman Plot) Contact angle measurement of a solid with various liquids of known surface tension Cos  = 1 – b(l - c)  – Contact angle b – 0.03 –0.04 l – Surface tension of liquid c – Critical surface tension Cos  1 Extrapolate curve to Cos  = 1, obtain c , characteristic of Surface Energy (Adamson, 1997)

  14. Critical Surface Tension • Why critical surface tension is so important • Thrombus formation • Blood clotting studies • Other tissue related studies how to figure it out the biocompatibility, bioinert issues???

  15. Examples of interfacial phenomenon • Food • Texture • Structure - Creaming - Settling • Paper • Quality • Uniformity • Strength • Paints • Opacity • Color Strength • Gloss • Viscosity • Microelectronics • Chemical Mechanical Polishing (CMP) • Stabilization / dispersion of particulate systems impact the performance of industrial processes.

  16. Sincerely AAA

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