1. September 23, 2015 1 Dr. Alagiriswamy A A, (M.Sc, PhD, PDF) Asst. Professor (Sr. Grade), Dept. of Physics, SRM-University, Kattankulathur campus, Chennai UNIT III Lecture 2 ABCs of Biomaterials

2. September 23, 2015 2  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 Interesting cues Courtesy : - The Hindu, opportunities, Mar. 18/2014

3. September 23, 2015 3  CLASSIFICATION OF BIOMATERIALS  COMPARISON OF PROPERTIES OF BIOMATERIALS  EFFECT OF PHYSIOLOGICAL FLUIDS  BIOLOGICAL RESPONSES Outline of the presentation

4. September 23, 2015 4 TYPICAL BIOMATERIAL APPLICATIONs a biomaterial should not GIVE OFF its mass unless it is specifically designed to do so

5. September 23, 2015 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

6. September 23, 2015 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 10 2 to 10 4 ergs/cm 2.  Polymers/plastics have much smaller surface energies, usually <100 ergs/cm 2.  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. September 23, 2015 7 Surfaces and Interfaces “A region of space in which the system undergoes transition from one phase to another” Liquid/GasLiquid/LiquidSolid/Solid Solid/GasSolid/Solid Surface: Region between condensed phase (S or L) and a gas phase Interface: Region between two condensed phases

8. September 23, 2015 8

9. September 23, 2015 9  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 Some more surface properties

10. September 23, 2015 10 Goniometry

11. September 23, 2015 11 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  Contact angle analysis The wetting characteristic can be generalized as   = 0, complete wetting ;    0  900, partial wetting ;   > 900, no wetting.

12. September 23, 2015 12  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

13. September 23, 2015 13 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˚ )

14. September 23, 2015 14 Determination of Surface Energy Using Contact Angle (Zisman Plot) Contact angle measurement of a solid with various liquids of known surface tension (Adamson, 1997) Cos  = 1 – b(  l -  c )  – Contact angle b – 0.03 –0.04  l – Surface tension of liquid  c – Critical surface tension 11 Cos  Extrapolate curve to Cos  = 1, obtain  c, characteristic of Surface Energy

15. September 23, 2015 15 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??? Critical Surface Tension

16. September 23, 2015 16 Examples of interfacial phenomenon Paints  Opacity  Color Strength  Gloss  Viscosity Food  Texture  Structure - Creaming - Settling Paper  Quality  Uniformity  Strength Microelectronics  Chemical Mechanical Polishing (CMP)  Stabilization / dispersion of particulate systems impact the performance of industrial processes.

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