Effects of Therapeutic Radiation on Polymeric Scaffolds

High levels of ionizing radiation are known to cause degradation and/or cross-linking in polymers. Lower levels of ionizing radiation, such as x-rays, are commonly used in the treatment of cancers. Material characterization has not been fully explored for polymeric materials exposed to therapeutic radiation levels. This study investigated the effects of therapeutic radiation on three porous scaffolds: polycaprolactone (PCL), polyurethane (PU) and gelatin. Porous scaffolds were fabricated using solvent casting and/or salt leaching techniques. Scaffolds were placed in phosphate buffered saline (PBS) and exposed to a typical cancer radiotherapy schedule. A total dose of 50 Gy was broken into 25 dosages over a three-month period. PBS was collected over time and tested for polymer degradation through high performance liquid chromatography (HPLC) and bicinchoninic acid (BCA) protein assay. Scaffolds were characterized by changes in microstructure using Scanning Electron Microscopy (SEM), and crystallization using Differential Scanning Calorimetry (DSC). Additionally, gelatin ε-amine content was analyzed using Trinitrobenzene Sulfonic Acid Assay (TNBSA). Gelatin scaffolds immersed in PBS for three months without radiation served as a control. Each scaffold responded differently to radiation. PCL showed no change in molecular weight or microstructure. However, the degree of crystallinity decreased 32% from the non-irradiated control. PU displayed both changes in microstructure and a decrease in crystallinity (85.15%). Gelatin scaffolds responded the most dramatically to radiotherapy. Samples were observed to swell, yet maintain shape after exposure. As gelatin was considered a tissue equivalent, further studies on tissues are needed to better understand the effects of radiotherapy.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Materials Science and Engineering

Department dc:contributor.department

Materials Science and Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2014

Author dc:creator

• Cooke, Shelley L.

Chair dc:contributor.committeechair

• Whittington, Abby R.

Committee members dc:contributor.committeemember

• Corcoran, Sean G.
• Edgar, Kevin J.

• radiation aging
• gelatin
• polycaprolactone
• polyurethane
• porous scaffolds
• tissue engineering

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

vt_gsexam:1837

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/54540