Graduate Studies
Date of this Version
7-2012
Document Type
Article
Abstract
DNA is used as self-assembling multifunctional building material for novel technologies, such as nanostructured sensing materials and field-effect transistors, or nanosized computers and functioning devices. While having the unique advantage of forming complex structures, the self-assembly process is hard to control. Electrospinning is an alternative top-down nanomanufacturing method, by which polymer nanofibers can be produced in high electric fields. Unlike self-assembly, electrospinning can provide continuous nanofibers, with ability to bridge the nano and micro scales.
This study presents the first systematic investigation of continuous electrospun DNA nanofibers. Two types of fibers from single stranded (ss) and double stranded (ds) DNA solutions with wide range of diameters were produced by electrospinning. Tensile tests of single DNA nanofibers were performed for the first time, revealing very high mechanical properties – exceeding 1GPa strength and 300MPa toughness for the best results. Mechanical tests also showed size effects on strain at failure and toughness which increase significantly as fiber diameters decrease. Based on mechanical response the differences of molecular networks were proposed. Structural studies using Raman spectroscopy, X-ray diffraction (XRD) and other methods provided additional insight on DNA nanofiber structure.
Electrospun collagen scaffolds are widely used in tissue engineering, with aim to replicate natural environment of the extracellular matrix (ECM). However, due to organic solvents used in production, the artificial collagen scaffolds are unable to mimic the mechanical properties and structure of the natural ECM. Fibers from collagen-DNA hybrid solutions were made to enhance the processing, structure, and properties of tissue engineering fibers. It was found that as little as 0.2% of DNA enabled electrospininning collagen fibers from aqueous solutions. XRD and thermogravimetric analyses exhibited close correspondence to natural collagen fiber results, unlike the results from conventionally produced fibers. Moreover, higher DNA concentrations produced extraordinary increases in ultimate strain and toughness up to three orders of magnitude in the hybrid nanofibers.
The results of this study show that continuous DNA and collagen-DNA nanofibers can serve as building blocks for novel high-performance biodegradable and biocompatible materials for tissue engineering and other bionanotechnology devices and applications.
Comments
A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Engineering Mechanics, Under the Supervision of Professor Yuris Dzenis. Lincoln, Nebraska: July, 2012
Copyright (c) 2012 Kaspars Maleckis