Defense Date


Document Type


Degree Name

Master of Science


Biomedical Engineering

First Advisor

Dr. Parthasarathy Madurantakam

Second Advisor

Dr. Christopher Lemmon

Third Advisor

Dr. Ning Zhang


Sterilization of tissue engineered scaffolds is an important regulatory issue and is at the heart of patient safety. With the introduction of new biomaterials and micro/nano structured scaffolds, it is critical that the mode of sterilization preserve these built-in features. Conventional sterilization methods are not optimal for engineered polymeric systems and hence alternate systems need to be identified and validated. PCL is polyester with a low melting point (heat labile), susceptible to hydrolysis and is popular in tissue engineering. Electrospinning generates some nanoscale features within the scaffold, the integrity of which can be affected by sterilization method. Chapter 1 explores the possibility of using Peracetic acid (PAA) to sterilize polymeric scaffolds that are sensitive to heat or moisture. PAA is a strong oxidizing agent that has been approved for sterilizing catheters and endoscopes. The ability of PAA to sterilize at room temperature, its breakdown into non-toxic end products and effectiveness at low concentrations are major advantages.

Chapter 2 evaluates the ability of PAA-sterilized PCL scaffolds (PAA-PCL) to support survival and proliferation of mouse calvarial osteoblast cell line, MC3T3. While Ctrl-PCL scaffolds (ethanol-disinfected) showed robust cell survival, PAA-PCL scaffolds induced massive cell death. Following interrelated hypotheses are tested: the observed cytotoxicity was due adsorption of PAA and/or hydrogen peroxide onto PCL fibers during sterilization; and elimination of adsorbed residues will restore scaffold cytocompatibility. Neither extensive aeration nor chemical neutralization with sodium thiosulfate and catalase were effective in improving cell survival. However, quenching PAA-PCL scaffolds in 70% ethanol for 30 minutes effectively removed adsorbed PAA residues and completely restored cell viability and proliferation over a 7 day period. In order to test if PAA-induced toxicity was limited to electrospun PCL scaffolds, commercially available, porous polystyrene scaffolds (Alvetex®) was treated with PAA. Interestingly, a statistically significant increase in cell survival and proliferation resulted with PAA treatment and this was abolished by ethanol quenching. Combined, these results illustrate that PAA treatment can produce diametrically opposite effects on cell survival depending on substrate chemistry and that PAA can be used to effectively sterilize tissue engineering scaffolds without compromising cell viability.


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