OSU 2007 Research Week Award Winners

Several ChE students won awards at the annual OSU Research Week display of talent.  (February, 2007)

Ben Lawrence, PhD candidate for Sundar Madihally, received first place in the Biological Sciences category.  Undergraduates Ashi Samli and Kristin Wallace placed second in the poster contest.

Composite Scaffolds for Tissue Engineering

Over 93,000 people are waiting for organ transplants in the United States, and each day 17 die, waiting. Tissue engineering is a novel field that seeks to find an alternative to organ transplantation. In tissue engineering, biodegradable materials are used as a scaffolding to guide cell growth that produces their own supporting matrix and healthy tissue.  The goal of this research is to create a synthetic scaffold with the desired properties.

Composite structures with 3D architecture were developed by sandwiching 50:50 PLGA film between porous chitosan matrices. The outer chitosan layers provide biological activity while the inner PLGA layer provides mechanical strength. PLGA films were initially perforated and porous chitosan matrix was formed sequentially on each side by controlled rate freezing and lyophilization technique. Surface microarchitecture of formed matrices confirmed that chitosan passed through the perforations of PLGA membrane. Formed matrices were analyzed for tensile strength which showed that matrices formed using 160 kDa PLGA had sufficient break stress (~4.5MPa). Over an eight hour period, the composites were largely impermeable to urea. Formed scaffolds were analyzed for degradation characteristics over the course of four weeks in presence of 10 mg/L lysozyme. These results showed no significant difference in the weight loss and dimension changes. The typical spindle shape was apparent when cellular adhesion and actin distribution of mouse embryonic fibroblasts were evaluated in the 3D scaffolds. Redistribution of actin fibers was also observed on 3-D chitosan matrices. In summary, by forming a three layer composite structure the strengths of each polymer are accentuated while the weaknesses are minimized.

Blending Chitosan with Polycaprolactone: Porous Scaffold Generation and Cytocompatibility

To form functional tissues, biomaterials direct the growth of cells by providing chemical compatibility and similar mechanical properties at the site of implantation.  For this purpose, tissue engineering techniques require the use of scaffolds with open pore morphology to ensure the cells and nutrients could pass into and out of the scaffolds while also supporting the structure of the tissue where it is implanted.  Strategies for developing new biomaterials that exhibit unique and desired properties in tissue regeneration applications would be greatly aided by blending polymers.  By blending polymers we could complement them and overcome the individual deficiencies either polymer might have.

In this study, 25% aqueous acetic acid solvent were used to prepare porous scaffolds from chitosan-PCL blends in order to improve the stability and strength of the scaffolds.  For this purpose, we explored freeze extraction, freeze gelation, and freeze drying techniques.  We found that chloroform assisted dissolution of PCL in conjunction with 25% aqueous acetic acid solvent resulted in formation of structurally stable scaffolds via lyophilization.  These scaffolds were tested for cytocompatibility using chicken chorioallantoic membrane (CAM) assays in situ.  The observed 3D morphology and formation of vasculature suggests these scaffolds are cytocompatilble.

Research Week is jointly organized by The Graduate & Professional Student Government Association (GPSGA), the Vice-President of Research and Technology Transfer, and the OSU Graduate College.  A committee of GPSGA members chose winners based on rank, scores, and feedback from the judges.  There are separate categories for OSU graduate student presenters and OSU undergraduate presenters.

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