The Charger Blog
My involvement in the University’s Summer Undergraduate Research Fellowship (SURF) program has enabled me to conduct cutting-edge research while making important connections in the field of forensic science.
Sept 2, 2021
The importance of Raman spectroscopy and its applications are well demonstrated in scientific literature. Additionally, numerous published studies have investigated DNA degradation within bone samples and optimal DNA extraction techniques for these challenging sample types.
However, there is no known research that has attempted to use Raman spectroscopy as a pre-screening tool for assessing DNA quantity and quality for forensic casework applications. That’s why developing a Raman-based pre-screening tool for bones/teeth is the focus of my Summer Undergraduate Research Fellowship (SURF) project.
The two main components of bone are calcium hydroxyapatite and collagen. Calcium hydroxyapatite is the major inorganic crystalline matrix of bone, while collagen, a protein, is the primary organic phase. Similar to degradation of the DNA molecule, changes occur to both components of bone microstructure over time and in response to environmental conditions. This alteration of bone microstructure occurs in a process known as diagenesis, and these collective diagenetic processes are purported to directly correlate to the quality and quantity of DNA encompassed within skeletal remains.
My research design involves a three-step holistic view, including Raman spectroscopy, DNA extraction, and DNA quantification, the latter two of which will comprise the laboratory investigation portion of my Honors Thesis this academic year.
As part of my SURF project, I conducted a comprehensive survey containing a variety of questions to gauge the thoughts of the participants. I employed a multidisciplinary approach, distributing the survey to a variety of experts in the disciplines of chemistry, biology, forensic science, and archaeology. Participants’ insights and expertise provided guidance in my quest to develop better methods for identification of human remains.
The purpose of my SURF research is to evaluate optimal analysis parameters for my upcoming Honors Thesis project and to understand the quantity and quality of information about bone that is provided via a Raman spectrum. It will further the understanding of the best way to recover DNA from bone and its correlation with the microstructural components of calcium hydroxyapatite and collagen.
Currently, a reliable screening method for DNA extraction from bones does not exist. Previous studies demonstrate that certain skeletal elements (i.e., weight-bearing long bones or molar teeth) are preferred for DNA preservation. However, once these skeletal elements are selected for testing, the sampling technique is blind. Moreover, the external physical appearance of bone has been proven to not be a reliable predictor of DNA recovery potential.
The microstructure of bone decomposes in a non-uniform (heterogeneous) manner postmortem, so there is no accurate way of determining which cuttings or regions of a long bone’s diaphysis (shaft) contain the most intact microstructure, and presumably, the most DNA. With Raman spectroscopy, it is proposed that multiple parts of the diaphysis can be scanned, providing data that will indicate the state of the calcium hydroxyapatite and collagen bone matrix, and thus serving as a guide to regions along the shaft that likely contain the most intact DNA.
Forensic DNA analysis is time-consuming, labor-intensive, and very expensive. This pre-screening tool could reduce the amount of destructive sampling necessary to obtain sufficient genetic data for an identification. Thus, it would be a revolutionary advancement to find a dependable pre-screening tool to assess the potential for DNA recovery from bone.
This methodology could serve as a strategic compass to guide analysts in making more informed decisions regarding the location of optimal sampling sites. If successful, this screening tool could expedite and streamline the processing of identifying unidentified skeletal remains in casework.
A great part of the SURF experience was the connections I have made. This research has allowed me to connect with many different types of experts, and it has been a great way to get my name out in the forensic science community.
Results from the survey have made me more aware of possible limitations, but respondents’ enthusiasm has also convinced me that I am pursuing research that could change the world of forensic DNA analysis. Because of SURF I feel more prepared to continue my research for my Honors Thesis this fall and spring.
Cody Silverman ’22, a forensic science major with minor in chemistry, has been working under the mentorship of Angie Ambers, Ph.D., and Brooke Kammrath, Ph.D., D-ABC. His SURF project is titled “Compositional Analysis of Human Skeletal Samples Using Raman Spectroscopy and Correlation to DNA Recovery.”
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