Kimberly Riddick – Seminar/Ph.D. Thesis Defense – Tuesday, June 27, 2017 at 11:00 A.M.

JSNN – Kimberly Riddick – Ph.D. Thesis Defense/Tuesday Seminar

Candidate: Kimberly Riddick

Advisor and Committee Chair: Ajit Kelkar, Ph.D.

Department: Nanoengineering

Date: Tuesday, June 27, 2017

Time: 11:00 A.M. – 1:00 P.M.

Location: JSNN Auditorium

2907 E. Gate City Blvd., Greensboro, NC 27401

Title: “The Self-Assembly, Organization, and Alignment of Collagen and a Collagen-Chitin Biocomposite.”

Abstract:

A goal of biomedical research is to innovate means of replacing diseased or damaged organs and tissue within the body, through either encouraging the body to regenerate them on its own or by artificially growing viable replacements in the lab, thus eliminating the need for donors. Methods to do this include, seeding cells on a “scaffold,” a structural skeleton made of non-toxic, biodegradable material that encourages the cells to grow with the shape and organization found in endogenous tissue. Hierarchical, anisotropic, nanofibrous materials are relevant constructs for tissue and regenerative engineering applications, as they can morphologically resemble extracellular matrix components in tissues. These nanofibrous scaffolds not only provide structural support for cells, but can also provide the environmental and physical cues required to promote the cellular growth and function necessary for the synthesis of extracellular matrices over time.

Collagen and chitin are both naturally obtained, biological materials that assemble into nanoscale fibers. If these fibrous systems are properly aligned, they have potential to direct cellular growth and orientation. Self-assembly lends itself to the construction of functional biomaterials, as it employs multiple noncovalent interactions that are inherently coded into the molecular design of the constituent components, allowing for the fabrication of complex, adaptable, and highly tunable materials with potent biological effects.

The primary objective of this present study is to construct nanofibrous films of collagen and chitin through use of soft lithography with sonication-assisted solution embossing (SASE). The subsequent quality of organization and alignment are characterized through use of Atomic Force Microscopy. Further, this research seeks to study the fundamental science substantiating the assembly and alignment of these nanofibers for the purpose of developing complex tissue scaffolds. In this study, we find that the introduction of chitin into the collagenous matrix interrupts the hierarchical bundling of collagen, leaving the fibrils in a reduced state and thereby more amendable to organization and alignment through use of this method. Further, annealing of the resultant substrate in a sodium phosphate buffer causes the reassembly of amorphous collagen into fibrous systems that conform to the original pattern in the absence of the template.

These biocomposite films were found to be biocompatible, and cultured cells could sense and respond to nanoscale structures. The results indicate that ordered and continuous nanostructures on substrates can pattern and guide cell alignment and oriented growth along definite directions. The ability to align nanofibrils via this method gives rise to the possibility of controlling macroscopic cellular behavior or material properties by tuning the directionality of interactions at the nanometer scale.