Date of Award

2009

Degree Type

Dissertation

Department

Chemical and Biomedical Engineering

First Advisor

Calabro, Anthony

Subject Headings

Colloids in medicine, Hyaluronic acid, Magnetic resonance imaging, Tissue engineering, Hyaluronan hydrogels, Collagen hydrogels, MRI, T1 map, T2 map

Abstract

Novel tyramine-based hyaluronan (HA) and collagen hydrogels have been developed in which cross-linking is accomplished via peroxidase-mediated dityramine linkages allowing direct cross-linking in vivo. These TB hydrogels possess advantageous physical properties, which include excellent biocompatibility and the ability to mimic the biological, structural and mechanical properties of normal, healthy tissues, including cartilage, and thus provide for synthetic, implantable biomaterials suitable for a wide range of tissue types. The efficacy of these TB-hydrogels has been previously tested in a number of clinically relevant animal models, which have evaluated their applicability for the repair/replacement of various tissues, including cartilage. Nevertheless, there exists a fundamental need for non-destructive methods to identify, distinguish, quantify and trace these biomaterials in vivo. Magnetic Resonance Imaging (MRI) is a broadly used non-invasive clinical imaging methodology that allows direct visualization of soft tissues. Our results indicated that T1 and T2 mapping can differentiate and measure changes in HA and collagen concentration both alone and in combination with composite materials, composed of HA and collagen at the concentrations found in cartilage resulting in T1 values representative of cartilage. Furthermore, the dGEMRIC technique was able to quantify the HA concentration in phantoms of known HA concentration. These MRI techniques could detect and differentiate the tyramine-based hydrogels in implanted joints, and accurately quantify their volumes

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