BIOCOMPATIBLE POLYMERS: DESIGN, FUNCTION AND USES R. James Christie Oct. 4, 2008 Utsunomiya Girls High School
Biomaterials: Materials that Function with Living Organisms Materials that imitate natural function Artificial organs, bone, tissue Biosensors Drug delivery vehicles artificial virus
Types of Biomaterials metals ceramics polymers Source: Dentainium.com Source: totalhipreplacement.com
Biomaterials Are Widely Used Source: http://www.uweb.engr.washington.edu/research/tutorials/introbiomat.html
What is a Biocompatible Polymer? A plastic that is tolerated by living organisms Many forms are man made Possible properties: Implantable solid Coated Surface Injectable liquid Possible characteristics Does not initiate iti t immune response Controls cell adhesion Controlled water content
What are Polymers? Polymers: Large molecules made up of small repeating units. poly = many, mer = units Plastics Single molecule: monomer mono = one mer = unit Polymer molecule repeat attachment of monomers Two molecules: dimer di = two mer = unit
Natural Polymers Proteins: chemical structures: O H 2 N CH C OH 2 Source: Protein Data Bank CH 3 O DNA: N C C NH HC HO CH 2 C C N N NH 2 O C H H C H C C H O H Complex sugars (polysaccharides): Most natural polymers are high in carbon, oxygen and nitrogen Source: Dr. Ronald E. Hurlbert O P O - O - H HO HO OH H H guanine OH O H H HO
Synthetic Biocompatible Polymers CH 2 CH H 2 C CH H 2 C CH CH 2 CH OH OH OH OH poly(vinyl alcohol) O CH 2 H 2 C O H 2 C CH 2 poly(ethylene glycol) O CH 3 CH 3 CH 3 C C NH C H 2 O C C O NH C H 2 O C C NH Man made in laboratories High oxygen and/or nitrogen content Sterile products H 2 C CH OH H 2 C CH OH H 2 C CH OH CH 3 CH3 CH 3 poly(n-2-hydroxypropyl methacrylamide)
Examples of Biocompatible Polymer Applications 1) Growing cell sheets 2) Tissue scaffolds 3) Wildlife vaccination 4) Treating genetic disease
Biocompatible Polymer for Tissue Culture Poly(N isopropylacrylamide) PIPAAm 37 o C 32 o C collapsed expanded structure structure PIPAAm changes properties at different temperatures How could this property be used for medical applications?
Growing Cell Sheets Using PIPAAm PIPAAm polymer surface surface surface 1) coat surface 2) apply live cells 3) allow cells to grow with polymer 37 o C 4) reduce temperaturet 32 o C Source: Prof. Teruo Okano surface 5) harvest cells Cells can be grown outside of the body
Examples of Cell Sheets Source: http://www.ptei.org/interior.php?pageid=171 heart (cardiac) cells skin (epithelial) cells skin cell graft on patient Cell sheets have great potential to treat many injuries/diseases
Biocompatible Polymer Tissue Scaffolds Poly(lactic acid) PLLA live cells 1) Prepare a cast 2) Apply live cells 3) Allow cells to grow of desired ed shape Cells grow over scaffold to create live tissue
Growing a New Ear Damaged ear Source: Institute of Science & Technology in Medicine Keele University Source: Prof. Yongniam Yan Rehabilitated ear Source: Wake Forest School of Medicine Seed cells onto scaffold Source: Stelios Arcadiou Grow cells Harvest ear
Biocompatible Polymers for Wildlife Vaccination? 40 meters How to vaccinate wild bison at a distance?
Vaccine Delivery to Animals Solution: Biobullets Sugar bullets Air rifle delivery e Bullet penetrates target, degrades and releases contents
Vaccine Carrier: Hydrogel Bison vaccine = live bacteria Need aqueous environment? Need a solid structure t to place into biobulletb Solution = HYDROGEL Hydro = water Gel = semi solid reaction How to load live bacteria into bullet? Polymer solution Connected polymer chains Solid gel
Vaccine Encapsulation/Bullet Loading liquid solid Hydrogels can be formed in biobullets Hydrogels contain live vaccine within high water environment
Result: Vaccination Worked! 80% of vaccinated bison protected against brucellosis Higher calf birth rate
Treating Genetic Diseases disease source disease effect CELL DNA RNA protein nucleus Genetic disease can be treated by: 1) altering DNA 2) preventing RNA formation 3) preventing protein formation
sirna Therapy Strategy sirna = killer RNA Source: The Nobel Committee for Physiology or Medicine sirna therapy inhibits protein formation
Formation of sirna Nanocarrier Oppositely charged polymers associate into organized structures Polymers designed contain specific properties E.g.: poly(ethylene l glycol) l) enhances biocompatibility Thiol groups generate reversible crosslinks
Analysis of Efficacy Monitor the formation of 2 proteins Inhibit one, then determine expression ratio Artificial i sirna loaded d particle il inhibits >50% protein expression
Conclusions Biocompatible polymer properties can be changed to meet specific requirements Biocompatible polymers improve quality of life tools to treat injury and disease You will probably use a biocompatible in your lifetime!
About Me Crater Lake Hometown: Central Point, Oregon, USA Population = 17,000 Rogue River rafting
Education Ashland, OR Colorado Rocky Mountains BS B.S. 2000, Biochemistry, Southern Oregon University Ph.D. 2006, Chemistry, Colorado State University Current research appointment: Kataoka Lab, University of Tokyo
Why Become a Scientist? Knowledge of how stuff works Create commodities that improve the quality of life for all Opportunity to meet many interesting people p during studies/research Travel opportunities What does it take to become a scientist? Curiosity Ability to learn Interest in academics patience
Thank you for your attention!