The Business of Biomaterials:

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1 The Business of Biomaterials: Innovating at the Bottom of the Food Chain Bob Ward DSM PTG (Formerly The Polymer Technology Group) Part of DSM Biomedical Berkeley, CA

2 Lab and Pilot-Scale Synthesis Production-Scale Synthesis DSM PTG: Vertical Integration in Device Development Component Fab. Characterization and QC Device Assembly

3 (Implantable) Biomaterials as a Business Material is often enabling technology for the device or implant Influencing safety, efficacy, service life Tailored materials facilitate new designs Reduce Healthcare Costs Small market size and/or low-volume manufacturing Typically 1-2% of implantable device sales High unit costs Infrastructure requirements high volume non-medical markets High level of technical service required Must be compliant with Quality Systems (IS, cgmp) QA/QC requirements similar to device manufacturers Device manufacturer may under value the material Very long lead times for commercialization

4 Unconfigured Biomaterials: Specialty Chemicals Thermoplastic Pellets Liquid Resins and Solutions

5 Value-Added Biomaterials: e.g. Extruded or Molded and/or Partially Assembled Tubing for Pacemaker and Neuro- Stimulation Lead Insulation Sub-Assembly for a Cardiac Assist Device

6 (Mostly) Implantable Devices and Prostheses Intraaortic Balloon Sac-type VAD Vascular Graft Diaphragm-type VAD Pacemaker & Leads Dynamic Spinal Fixation Device Cervical Spinal Disc Si-Hy Contact Lens Lumbar Spinal Disc Hip Joint Axial Flow VAD Continuous Glucose Monitor

7 Total Biomaterials Market Size (All Uses) Worldwide Market $25.5 billion in 2008 >$28 billion 2009 $58.1 billion by 2014: growing at a CAGR of 15.0% Regional Markets: #1. USA: $22.8 billion by 2014 with a CAGR of 13.6% 2. Europe: $17.7 billion by 2014 with a CAGR of 14.6% 3. Asian market growth: highest CAGR at 18.2% * Global Biomaterials Market ( ), published by Markets and Markets

8 2010 U.S. Biomaterials Market Total $27 billion Implantable Medical Devices $10 billion = Added Value Implantable Biomaterials? 2010 Source: A.Brock, BCC Research, March 2007

9 Biomaterials Sales vs. Implant Market Size USA Medical Implants 2010 Sales: Implants: $100 billion = 100% Added-Value Biomaterials **: $10 billion = 10% Un-configured Biomaterials **: $1 billion = 1% USA Medical Implants 2010 Gross Profit: Implants: 75% of $100 billion = $75 billion Added-Value Biomaterials :** 40% of $10 billion = $4 billion Un-configured Biomaterials :** 50% of $1 billion = $0.5 billion * The Medical Device Market: USA pportunities and Challenges, Espicom, Jan ** Author s Estimate

10 Device Manufacturers are Conservative: Why would they use a new material in a chronic implant? Satisfy the bulk and surface property requirements of the device or prosthesis btain a performance advantage over competitive devices - Improve device safety, efficacy, and/or longevity Replace an unreliable or unwilling supplier Improve device manufacturing / reduce CG Strengthen IP position Facilitate regulatory approval FDA Material Master File IS and cgmp Quality Systems

11 Device Manufacturers Want More from Biomaterials Artificial Hearts and VADs: Increased flex life and thrombo-resitance for destination devices Pacemakers: More biostable low-modulus insulation materials for thinner, more flexible leads Contact Lenses: Low modulus, high 2 and ion permeability and inherentlywettable surface (without surface treatments) extended wear, generally increased comfort and corneal health at lower cost Glucose Sensors: Balanced 2 / glucose permeability, blocking of competitive analytes, without fibrous capsule formation accurate, linear response and longer operating life before changing sensor Prosthetic Joints: compliance, load distribution, abrasion resistance, compression strength much longer service life without osteolysis / bone loss in younger patients Drug Deliver Devices: Platform technology with easily-variable delivery rate for a variety of drugs Degradable Scaffolds: High initial strength, well-known time course of property change during degradation, non-inflammatory (liquid) degradation products. Vascular Catheters: Antimicrobial, thrombo-resistant, lubricious, low-cost

12 Many Possibilities with Polyurethanes: The most versatile biomaterial Widest range of possible bulk and surface properties: Large number of possible reactants Hard Segments Diisocyanates Diols» urethane and/or diamines» urea Soft Segments Single Polyol Chemistry Mixed Polyols End groups Pendant groups Many possible structures Linear Linear with pendant groups or end groups Branched or dendtritic Crosslinked Easily synthesized by batch or continuous polymerization May be designed for biostability or bio-resorption!

13 Polyurethanes May Also Contain Urea Groups Polyurethane hard segment formed by reacting diisocyanates with low- MW diols (R 1 may be aromatic or aliphatic ): Diisocyanate Diol repeats repeats Urethane Urethane Urea formed by reacting a diisocyanate with an amine: Isocyanate Amine Urea

14 Common Diisocyanates for Synthesis of Biomedical Polyurethanes: Reaction w. low MW diol or diamine polyurethane or polyurea hard segment 4,4'-methylene diphenyl diisocyanate Diphenylmethane diisocyanate (MDI) Pure isomer available commercially High cohesive energy density hard segment with best phase separation Most biostable Best physical-mechanical properties 4,4 -diisocyanatodicyclohexylmethane Hydrogenated MDI (HMDI) nly isomeric mixtures available Lower cohesive energy / less phase separation Lower flex life Reduced biostability in chronic implantation

15 Common Polyurethane Soft Segments: Polyalkylene oxides Polyethylene oxide (PE, PEG) Polypropylene oxide (PP) Polytetramethylene oxide (PTM, PTMEG) Tg -60 C Primary -H Very hydrophilic xidizes in vivo Tg -66 C Slower reacting Secondary H No strain-induced crystallization Tg -75 C Primary H Exc. Hydrolytic Stability Reversible strain-induced crystallization

16 (Ether-free) Polyhexamethylene Carbonate CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 n Produces the strongest & toughest polyurethanes Compatible with bone and cartilage Abrasion resistant / low particulate generation Low permeability to water and gases Biostable Extreme oxidative stability Excellent hydrolytic stability Analogous polyetherurethane may have better flex life

17 Specialty Polyurethane Soft Segments: Polydimethylsiloxane YES: Urea YES: Urethane Presents hydrophobic methyl groups in surface Silicone rubber analog xidatively and hydrolytically stable Acts synergistically with organic soft segments to improve biostability (Ward et al, 1989) End groups on silicone oligomer is reactive with isocyanate to form urea or urethane bond: Amine or Carbinol > Yes Silanol > No! -Si-C- bonds are hydrolytically stable, Si--C bond aren t N!: Siloxane + polyurea

18 Specialty Polyurethane Soft Segments: Polyisobutylene CH 3 H CH 2 CH 2 C CH 2 H CH 3 n Presents hydrophobic methyl groups in surface Butyl rubber analog: very low permeability T g = -73 C Extremely stable to oxidation and hydrolysis Polyurethanes have lower strength than polyether or polycarbonate urethanes of otherwise similar composition. (Second soft segment needed?) No commercial source for oligomeric diols of reqd. MW?

19 Biomaterials for Implantable Devices: Satisfying Bulk and Surface Property Requirements ptimum Bulk ptimum Surface Potential Solutions: After Device Fabrication: Apply topical treatments or coatings Before Device Fabrication: Modify polymers during synthesis Use surface activity and self assembly to achieve the desired surface properties.

20 Surface Activity and Self Assembly Defined Surface-activity: The process in which a substance, dispersed as a minor ingredient in the bulk of a liquid or solid, populates the surface in a concentration (much) greater than its concentration in the bulk. Self-assembly: The processes in which a disordered system of components forms an organized structure as a result of specific, localized interactions among the components themselves, without external direction.

21 Mechanisms of Interfacial Energy Minimization in Liquids and Solids Surface Area Minimization Formation of Spherical Drops Fire Polishing and Solvent Polishing Minimization of Unit Interfacial Energy Migration of Bulk of Components to the Surface: Surface-Activity Spontaneous rdering of Surface Molecules: Self-Assembly Exchange of Surface Molecules Under an Adsorbate Surface Chemical Reactions Adsorption / Contamination from the Environment

22 Surface Activity in a Two-Component System Surface Concentration Typical Low-MW Solution No Surface Activity Bulk Concentration Surface Concentration Polymer-Polymer Blend Bulk Concentration

23 Surface Modification Without Additives: Block Copolymers with (Surface-Active) Self-Assembling Monolayer End Groups (SAME ) SAME [ ] SAME Polymer Backbone n ] Surface Properties Bulk Properties ] = SAME # 1 = SAME # 2 = Soft Segment # 1 = Soft Segment # 2 = Hard Block n

24 What End Groups Can Do In Step Growth Polymers Modify Surface Properties Control Biological Interactions Affect protein adsorption Improve thromboresistance Provide antimicrobial properties Increase Biostability Affect wettability / contact angle Reduce coefficient of friction Increase abrasion resistance Improve Consistency Mono-functional end groups are chain stoppers Concentration in reaction mixture determines MW Improve Thermoplastic Processing By limiting molecular weight Via internal lubrication without the use of low MW additives By improving mold release and reducing self adhesion

25 Water Contact Angle and Coefficient of Friction: Bionate PCU Control vs. Bionate II PCU with (CH 2 ) 17 CH 3 End Groups With -C18 w/o -C18 PLYMER Mean CA [ ] Std. Dev. Bionate 55D PCU Bionate 90A PCU Bionate 80A PCU Bionate II 55D PCU Bionate II 90A PCU Bionate II 80A PCU UHMWPE Bionate II PCU is Hydrophobic Bionate PCU is Hydrophilic Kinetic CF (ASTM 1894) Without C 18 End Groups: 1.52 With C 18 End Groups: 0.41 Surface active, self assembling alkyl groups end groups affect wettability and sliding friction

26 Improving Biostability with (Fluorocarbon) End Groups: Polyetherurethanes: Intramuscular Rabbit 400 % Strain End Group = -(CF 2 ) n CF 3 Polyether-urethane Control: 3-month explant Ward, et al, JBMR 2006 Polyether-urethane with fluorocarbon end groups: 6-month explant

27 Antimicrobial Activity: Surface Active, Self Assembling Covalently- Bonded Alkylammonium Halide End Groups Impart Antimicrobial Activity to Thermoplastic Polycarbonate-urethanes R 1 : R 2 : PCU: Polycarbonate urethane

28 Extruded Polycarbonate-urethane Tubing with Non-leaching Antimicrobial End Groups Antimicrobial Activity Per ASTM E : Six log reduction of Staph. aureus Bionate 80A Control Tubing n Innoculated Media in Culture Dish Bionate Tubing with 0.5 wt% Antimicrobial End Groups Zone of Inhibition Indicates No Leaching: Test rganism: Staphylococcus aureus (ATCC 6538)

29 Self Assembling End Groups: Self Assembly on Extruded Polyurethane Tubing, e.g. Bionate II Not to scale

30 Some DSM PTG Thermoplastic Polyurethanes Bionate polycarbonate-urethane CarboSil silicone-polycarbonate-urethane CarboSil AL aliphatic silicone-polycarbonate-urethane Bionate II polycarbonate-urethane (PCU) with SAME technology Elasthane polyether-urethane with low MW wax PurSil silicone-polyether-urethane PurSil AL aliphatic silicone-polyether-urethane Elasthane II polyether-urethane with SAME technology* Note: All polymer families have FDA Master Files * Developmental material

31 Continual Improvement of Thermoplastic Polyurethanes for Chronic Implants Platform Compositions Aromatic (MDI) Polyether-urethane Strong and hydrolytically stable Aromatic (MDI) Polycarbonate-urethanes Very strong and oxidatively stable (when ether free) DSM PTG Enhancements Via Composition Changes Mixed Soft Segments: Silicone-urethane copolymers with enhanced biostability (Proven in NIH SBIR 1989) Use of surface activity and self assembly (of end groups) for surface modification: Ether-free polycarbonate soft segments Improved oxidative stability Increased toughness

32 Synthesis of Ether-Free Polycarbonate Diol from Ethylene Carbonate H (CH 2 ) 6 H + K Bu 2 Sn or NaCl H (CH 2 ) 6 H H (CH 2 ) 6 H + H (CH 2 ) 6 H (CH 2 ) 6 (CH 2 ) 6 + H H Removal of ethylene glycol in final stage drives the equilibrium from C-2 to form C-6 carbonate (CH 2) 6 + H(CH 2 ) 6 H (CH 2) 6 (CH 2) 6 + H H

33 Synthesis of Polycarbonate Diol using Ethylene Carbonate with Ether Formation Under certain reaction conditions side reactions form ether linkages susceptable to in vivo oxidative degradation: H + (CH 2) 6 (CH 2) 6 H Fast -C 2 (CH 2) 6 H + C 2 (CH 2 ) 6 H + (CH 2 ) 6 H Fast (CH 2 ) 6 H +C 2

34 Effect of Ether Contaminant on Biostability of Polyhexmethylenecarbonate-urethane With Ether: H-CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 --C--CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 --C--CH 2 CH 2 CH 2 CH 2 -H n m xidization Here Resulting polyurethane may be prone to surface oxidation and stress cracking (that generally does not penetrate the bulk beyond ca. 100 µm) Ether-free: H-CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 --C--CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 -H x Extremely tough polyurethanes are resistant to surface and bulk oxidation

35 Improving Accelerated In Vitro Stability with Ether-free Polyol: Polycarbonate urethanes after 407 Hours of Stokes Testing Note: Ether-free PCU Polycarbonate-urethane Control (without C 18 End Groups): 407 hours exposure Ether-free Polycarbonateurethane (with 0.6 wt % C 18 End Groups): 407 hours exposure

36 Bionate II Polycarbonate Urethane (PCU) Properties Hardness 55D 90A 80A Bionate PCU Bionate II PCU 6,000 6,500 7,000 7,500 8,000 8,500 9,000 9,500 10,000 Ultimate Tensile Strength (Psi) Stress (PSI) TS Bionate II PCU 55D Tensile Stress vs. Strain Avg. 17% Tougher for the three grades Strain (%) 80A 90A 55D UE Molecular Weight [kg/mole] Melt Flow Rate 224 C, 2160g load Ultimate Tensile Strength (TS) [psi] Ultimate Elongation (UE) [%]

37 Improved Properties Through Manufacturing Process Changes Prepolymer Synthesis Continuous Synthesis

38 Continual Improvement of Thermoplastic Polyurethanes for Chronic Implants DSM PTG Enhancements Via Processing Improvements: Replace batch synthesis with continuous synthesis by reactive extrusion n-line feedback for MW control Reduced particulates Rapid development of custom polymers Gel reduction technologies for higher yields During polymer synthesis During extrusion of tubing

39 Batch Synthesis of Thermoplastic Polyurethanes Start Reaction in Batch Reactor Empty Before Solidification Complete Rxn. in ven Grind Slabs in Wood Chipper Feed Granules to Extruder Collect Pelletized Polymer Single-Screw Extruder / Pelletizer

40 Continuous Reactor-Extruder Used to Synthesize SAME Polymers, e.g., with C 18 End Groups Cleanroom Collection Extruder/Reactor Reactant Feed

41 Three-Steps to Surface Modified Tubing: Tubing Extruded from Pre-dried SAME Polymer Pellets Made by Continuous Synthesis 1. Continuous Synthesis of Pellets 2. Dry Polymer Pellets Tubing Ready for Use 3. Tubing Extrusion and Collection

42 Conclusion: The Importance of Biomaterials in Implanted Devices Biomaterials are enabling technology in implantable devices and the key to improved safety, efficacy, longevity and therefore reduced healthcare costs. PUs with Self Assembling Monolayer End Groups (SAME ) are a Biomaterials Toolkit for rapidly optimizing bulk and surface properties for specific device applications SAME technology combined with minor (but significant) composition changes and processing improvements created a step improvement in a well-established biomaterial: Bionate II PCU is stronger, more oxidatively stable, more consitant, and more easily processed The economics of the biomaterials business, and the conservative nature of device manufacturers and regulators favors the continual improvement of proven platform technologies unless serious short comings are encountered.

43 Thank You Additional information at DSM PTG th Street Berkeley, CA (510)

44 Polyurethane Soft Segments: Aliphatic Polycarbonate CH 2 CH 2 CH 2 CH 2 CH 2 CH 2 poly(hexamethylenecarbonate) xidatively stable when (ether free) Low permeability Degradation limited to surface region Gives very high tensile strength TPUs Polyol is commercially available NT! : poly(bisphenol-a carbonate) H H bisphenol-a monomer: a hormone-like endocrine disruptor