Author ORCID Identifier

https://orcid.org/0000-0003-3702-9838

Year of Publication

2020

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Engineering

Department

Mechanical Engineering

First Advisor

Dr. Christine A. Trinkle

Abstract

The creation of chemical micropatterns on surfaces makes it possible to add unique chemical functionality to surfaces, modifying properties such as wettability, or even adding the ability to selectively bind other molecules. The creation of biochemical surface patterning in particular is useful in a variety of fields including tissue engineering and highthroughput drug screening. There are many existing surface patterning techniques which focus on precise control over the patterned geometry, even down to submicron scale features, but they do not allow local control over chemical concentration. So the results are high resolution patterns with binary concentration. There are also existing methods to generate surface gradients of chemicals, but the focus there is to produce unidirectional concentration variation over a large surface. Normally these two methods—surface patterning and surface gradient generation—are incompatible with each other. So despite the large number of applications where simultaneous control over chemical placement and concentration would be useful, there is a dearth of options for doing so. In addition, it would be valuable to make micro patterned surfaces in a simple and approachable way, because fields where it could be most beneficial (such as tissue culture) are populated by individuals who are typically not microfabrication experts.

The goal of this research is to develop an easy and low cost method for creating biochemical surface patterns with microscale feature resolution and local control over chemical concentration. The method described here leverages the force on charged protein molecules in an electric field to drive the molecules in a given direction. The speed with which these molecules move depends on the properties of the molecules themselves and the medium through which they travel. By creating a material with heterogeneous regions—in this work, a hydrogel with different mesh densities—it is possible to have local spatial control over the speed of protein movement. In this work, this concept was used to drive biomolecules (proteins) onto a target paper surface, and then local protein concentration was measured using fluorescence or intensity of a protein stain. In addition, these patterns were achieved using materials and methods that are easily accessible to individuals in most biochemical or tissue culture laboratories.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2020.169

Funding Information

This research was initiated by the National Science Foundation grant No. CMMI-1125722. (2012-2016)

Some materials and equipment in this research were provided by the National Cancer Institute grants CA20772 (2017-2022) and CA209045. (2016-2018)

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