Casey Dougherty, Ph.D., Research
If you are interested in pursuing research in the Dougherty lab, please contact Dr. Casey Dougherty at firstname.lastname@example.org.
Research Project 1: Antibody-Polymer Conjugates for Biomedical Imaging Applications
This research is a combination of biochemistry, organic synthesis, and analytical characterization
Macromolecules have become a material of interest in the development of novel imaging agents and therapeutics in medicine. Many macromolecules, such as synthetic multivalent polymers and biologically interesting antibodies, can have multiple copies of small molecules, such as fluorescent dyes and drugs, attached to them. This can provide a higher efficiency for delivering a drug or better detection of an imaging agent than using just small molecule treatment.
However, the inherent random nature of conjugating small molecules to a macromolecule leads to a large mixture of different ratios of small molecules to macromolecule. Since the small molecules used for imaging and therapeutics are typically hydrophobic and the macromolecule is typically hydrophilic, the different ratios of small molecule to macromolecule can lead to very different degrees of hydrophobicity of the molecule. The degree of hydrophobicity has the ability to alter a macromolecule’s biological behavior, and controlling the ratio of hydrophobicity has been a major obstacle in developing effective macromolecules for biomedical applications.
Our work will focus on the synthesis and characterization of antibody fragments and antibody-polymer conjugates with controlled ratios of fluorophores/drugs (shown below). We will show the difference in fluorescence and absorption of the different materials based on a having a distribution versus a precise ratio of small molecules to macromolecule. Biological controls will be conducted, and the materials could be applied in cell studies to see how their behavior (amount of uptake, where it goes in the cell, etc.) changes based on hydrophobic ratio.
Figure 1. A depiction of antibody conjugates with different ratios of dyes attached and the associated fluorescence properties and cellular uptake behavior based on antibody to fluorophore ratio.
Research Project 2: Oil and Water Polymer Demulsifiers for Environmental Chemistry Applications
The project has been supported by the American Chemical Society Petroleum Research Fund.
This research is a combination of polymer synthesis, materials chemistry, and analytical characterization.
The petroleum and oil industry plays a significant role in everyday lives. Crude oil can exist as an emulsion with water, and the mixture is a significant obstacle to overcome when trying to extract pure oil. Extraction and separation of oil is necessary when trying to obtain oil for the application of the oil and also to purify natural waters during oil spills. One of largest oil spills in the United States occurred as recently as 2010 in the Gulf of Mexico from the Deepwater Horizon. Residual oil can still remain in 0.04 - 0.50 μm thickness on the water even when bulk extraction is considered effective. Because of the risk of contamination and presence of water in oil, there is a continual need to develop and better understand the reagents used in enhanced oil demulsification and oil recovery.
Several polymers have been successfully applied to the demulsification of oil and water mixtures, but many have shown limitations in their demulsification efficiency due to stability issues with dependence on salinity, temperature, and water solubility. Successful polymers to be used for oil demulsification and extraction must have a high molecular weight, be considered non-toxic, and have a resistance to degradation from salinity and temperature with complete solubility in water. Dendrimers are hyperbranched polymers consisting of a hydrophobic core with hydrophilic branches, and the number of branches is determined by the generation of the dendrimer, with increasing generation increasing the number of branches (shown below). The amphiphilic nature of dendrimers also makes them ideal polymers to demulsify oil and water emulsions and extract oil.
Our work will utilize commercially available dendrimers to develop highly purified and well characterized polymer materials to provide a comprehensive study on the molecular weight and functionalization dependence to have an effective oil and water demulsification and then subsequently apply these materials to synthesizing oil recovering dendrimer iron oxide hybrid nanoparticles (shown below). All materials will be fully characterized and applied to oil and water emulsion systems to determine demulsification efficiency and interfacial tension based on generation of dendrimer, branch functionalization, concentration of polymer material, and temperature of solution.
Figure 2. Illustration of G3 PAMAM (MW = 6,909 and 32 amines), G4 PAMAM (MW = 14,215 and 64 amines), G5 PAMAM (MW = 28,826 and 128 amines), G6 PAMAM (MW = 58,048 and 156 amines) dendrimers, and G3-G6 PAMAM dendrimers conjugated to PEG and iron nanoparticles.
Meet the Team
Dr. Dougherty received her BS in Chemistry and a minor in Mathematics from the University of Pittsburgh in 2010. From there she moved to the Midwest to pursue her Ph.D. in Chemistry at the University of Michigan in Ann Arbor, Mich. There, she developed and applied highly controlled fluorescent polymers to biological systems to determine their photophysical and biological properties. Deciding to stay at the University of Michigan for her post-doctoral career, she developed novel PET imaging agents to better detect breast, lung, and prostate cancers.
Current Undergraduate Students:
Antibody-Polymer Research Students
Polymer Oil and Water Demulsifier Research Students
Chemical Education Research Students
• Bruna De Carvalho ’21
• Camila Fernandez ’21 (with Dr. Sunghee Lee)
• Alyssa Gayapa ’19 (with Dr. Sunghee Lee)
Andrew Maxwell ’19
• Hannah McGowen ’20 (with Dr. Marius Draeger)
Previous Undergraduate Students
See a listing of Dr. Dougherty’s publications on Google Scholar: