Bone substitute materials Surface modifications S.M.Fatemi , DDS, PhD Tehran Medical Sciences Branch Iranian Academic Centre of Education, Culture and Research

Introduction Biomaterials : Bio-inert, Bioactive, Biodegradable Bulk characteristics : mechanical Surface characteristics: topography, surface energy, wettability, hydrophilicity

Surface Treatment of Biomaterials Radiation Grafting and Photo Grafting :Strilization, Photo polymerization Plasma Surface Modification : glow discharge plasma, ions, electrons , radicals, metastables …

Surface Treatment of Biomaterials Ion Beam Processing : 1-10 million volt Better hardness, toughness, less corrosion ….

Surface Treatment of Biomaterials Silanization Self-Assembled Monolayers Additives and Coatings

LASERs chemical cleanliness controlled thermal penetration and distortion controlled thermal profile and, therefore, shape and location of the heat affected region less after-machining is required remote noncontact processing is usually possible relatively easy to automate.

LASER surface modification Both organic and inorganic materials pulsed (100 nanoseconds to picoseconds pulse times) and continuous wave (CW) interaction times often less than 1 microsecond. surface alterations include annealing, etching, deposition and polymerisation

Laser Surface Treatment Laser patterning and micro fabrication Pulsed laser deposition (PLD) of biocompatible ceramics Matrix-assisted pulsed laser evaporation (MAPLE) and MAPLE direct write (MDW) Laser surface treatment for improving corrosion Laser grafting Laser treatment of plasma sprayed HA coatings

LASER surface modification Laser Patterning : photolithography, cell adhesion

LASER surface modification Pulsed Laser Deposition (PLD) Biocompatible Ceramics , CNT

LASER surface modification Matrix-Assisted Pulsed Laser Evaporation (MAPLE)

LASER surface modification MAPLE Direct Write : ribbon : 10 micron

LASER surface modification Laser Grafting :improved surface hydrophilicity and biocompatibility Laser bio printing Selective laser melting: dental implants

Gamma Ray Electromagnetic Radiation Extremely High Frequency High Energy: Ionizing Radiation Frequencies > 1019Hz Energies above 100 keV Wavelengths less than 10 picometers less than the diameter of an atom!

Effect of Gamma Ray on Materials Reduction of molecular weights of polymers Radical Production and chain scissoring Higher doses > cross-linking Increase in enthalpy in bioceramics Biocompatibility , bioactivity ,Bio-conductivity, and absorption

Synthesis and characterization Hydroxyapatite common wet chemical method [Ca(NO3)2 +4 H2O] [(NH4)2HPO4] Ca/P ratio of 1.67 h K ℓ 2θ ICDD HAp Peak Intensity % 2θ Synthesized HAp 2 25.879 40 25.893 36.90 1 31.773 100 31.698 32.196 60 32.351 69.43 3 32.902 32.914 63.10 34.048 25 34.169 23.81 39.818 20 39.978 21.43 46.711 30 46.783 32.14 49.468 49.409 40.48 50.493 50.448 22.62 4 53.143 53.173

Hydroxyapatite DSC increase its enthalpy

Hydroxyapatite Wettability and contact angle Material Non-irradiated samples 25KGy irradiated samples 50KGy irradiated samples Hydroxyapatite 26.16 º ± 2.51 º 20.35 º ±1.35 º 12.62 º ±1.4 º

Hydroxyapatite Cell viability (MTT Assay) and Cell Toxicity More viable cells via decrease in crystallite size Material Non-irradiated samples 25KGy irradiated samples 50KGy irradiated samples Day3 Day7 Day 14 Day 21 hydroxyapatite 47.7±4.66 40.79±10.66 39.43±1.23 159.73±43.4 64.3±12.8 49.42±7.08 71±15.2 95.33±0618 47.28±2 60.77±3.55 65.4±12 143.33±30.6

Hydroxyapatite Cell viability (MTT Assay) and Cell Toxicity 7th Day 21st Day

Cell viability (MTT Assay) and ALP activity Control Group Cell viability (MTT Assay) and ALP activity

Hydroxyapatite Alkaline phosphatase activity Less alkaline phosphatase activity Material Non-irradiated 25KGy irradiation 50KGy irradiation Day 7 Day 14 Day 21 Day21 Hydroxyapatite 99.22±4.52 130.2±19.88 125.14±27.5 87±12.25 105.58±8.54 126.94±38.7 77.77±3.6 113.72±1.7 125±23.19

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