Polymers: Biomedical Applications Bryan Orellana September 16, 2010.

Polymers: Biomedical Polymers: Biomedical ApplicationsApplications

Bryan Orellana

September 16, 2010

Where can you find uses for polymers?

• Everywhere!– There seems to be endless

uses for polymers

• Why?– Easier to produce– Biocompatibility– Often cheaper– Designed to mimic– Replacement to old practices– Designed to prevent additional

surgery/trauma to patient

http://www.sharecourseware.org/%28A%28a0C4BeKFywEkAAAAMWYxNTBiZjYtNTUwZS00N2MzLTlkNjQtY2NlOGM2Njc0MDBh8_JtaPeKutpFEQQVUOeBje6glDI1%29%29/ShowLecture.aspx?ID=454&CatID=1&SubCatID=35

Polymers in Drug Delivery

• Pill coatings• Rapid dissolving capsules

– Fluid driven– pH driven

• Degradable delivery vesicles in composite systems

http://www.flickr.com/photos/vancelucas/galleries/72157622318592067http://www.pharmainfo.net/raghanaveen/parenteral-controlled-drug-delivery-system

A11/1.4 Poly β-Amino Ester Hydrogel

• Purpose:– Used as a degradable carrying vessel for bioactive molecules

• Macromer:– Synthesized by a condensation reaction between Diethylene

Glycol Diacrylate and 3-Morpholinopropyl-amine at 85°C for 16hrs

– Diacrylate : Amine ratio:

Amine

Diacrylate079.2

g

g

Hydrogel Polymerization

• Hydrogel polymer produced from a mixture of macromer and DMPA (2,2-dimethoxy-2-phenyl acetophenone), a free radical initiator dissolved in ethanol

• Solution sandwiched between glass plates (1.5mm thick)

• Photo-polymerized with UV radiation for 5min

• Polymerized gel is washed in ethanol and dried

• Gel is grounded down to obtain particles (average diameters of 53 - 150 µm and 150-250 µm)

Photo-polymerization

• DMPA cleaves when exposed to UV energy producing free radical complexes

• Excitation causes complexes to bombard with macromer• Double bonds break and binds with either another radical

terminating the process or another polymer chain causing a further chain reaction

http://www.usm.maine.edu/~newton/Chy251_253/Lectures/Free%20Radicals/RadicalPolymerization.GIF

Composite Formation

• Composite consisted of Calcium Sulfate (structural support) and varying wt. percentage (1% and 10%) of All/1.4 poly(β-amino ester) hydrogel particles (delivery component)

• Mixtures are mixed with DI water and placed into a mold.

• Samples are allowed to dry in a 43°C oven for 24hrs

• Sample dimensions:– Diameter ~4.7mm– Height ~6.5mm

μ-CT3-D Image Construction

• Images were contoured and analyzed to produce 3-dimensional images

• These images allowed for determination of hydrogel distribution

The Problem: Oral Deficiencies

• Oral bone deficiencies are a major Issue!– High prevalence of periodontitis– Injury/trauma to jaw bone or teeth

– Other deficiencies from birth defects (i.e. cleft

palate/lip)

http://www.rad.washington.edu/staticpix/mskbook/MandibleFx.gifhttp://www.ohiohealth.com/mayo/images/image_popup/fl7_cleft_palate.jpg

The Solution: Bone Augmentation

• Performed to increase the amount of bone to allow for secure implant placement

• Common procedures:1) Alveolar process augmentation of mandible and/or

maxilla

2) Maxillary sinus augmentation

http://davidhan.info/yahoo_site_admin/assets/images/bf-Picture4.242141428_std.jpg

http://www.dr.agravat.com/images/bone_grafting02.jpg

http://www.drleonedds.com/images/photos/bonegraft1.jpg

Problem with bone graft augmentationDonor site morbidity

http://scottfross.com/wp-content/uploads/2009/12/bone-graft1.jpg

Bone AugmenationExample

Courtesy of Scott Price, D.M.D.

Two weeks post-op

Courtesy of Scott Price, D.M.D.

7 months post-op

Courtesy of Scott Price, D.M.D.

Conclusion

• Seemingly endless possibilities with new advances in polymer chemistry and medicine

• Being a patient conscience field, new polymer innovations have helped make these individuals’ lives easier

What to Remember for Final Exam!!

• What polymerization process was used to produce the Poly(β-amino ester) hydrogel? Give a brief explanation of how the process works.

– Photo-polymerization• DMPA (Photo Initiator) cleaves when exposed to UV energy

producing free radical complexes• Excitation causes complexes to bombard with macromer• Double bonds break and binds with either another radical

terminating the process or another polymer chain causing a further chain reaction

References

• Borrell, Luisa N., and Natalie D. Crawford. "Social Disparities in Periodontitis Among United States Adults 1999-2004." Community Dent Oral Epidemiol 36 (2008): 383-91.

• Chapple, Iain L.C., Mike R. Milward, and Thomas Dietrich. "The Prevalence of Inflammatory Periodontitis Is Negatively Associated with Serum Antioxidant Concentrations." Journal of Nutrition 137 (2007): 657-64.

• Karadag, Erdener, and Dursun Saraydm. "Swelling Studies of Super Water Retainer Acrylamide/crotonic Acid Hydrogels Crosslinked by Trimethylolpropane Triacrylate and 1,4-butanediol Dimethacrylate." Polymer

Bulletin 48 (2002): 299-307.

• Tonetti, Maurizio S., and Andrea Mombelli. "Early-Onset Periodontitis." Ann Periodontol 4.1 (1999): 39-52.