Jason E. Hawkes and Dr. Milton L. Lee, Chemistry and Biochemsitry
Bacillus anthracis, more commonly known as anthrax, poses a serious threat to the national security of the United States of America. In its weaponized form, anthrax spores are easily aerosolized, demonstrate long residence times in the atmosphere (typically variable for several days), and can be fatal if ingested or inhaled into the lungs. Following ingestion or inhalation, rapid growth and reproductive activity is triggered, releasing large amounts of deadly toxin. The lethal dose of anthrax spores is very small, approximately 10 nanograms of spores.1 As a result of its easy dispersal, long residence times, and high toxicity, anthrax is becoming increasingly more popular among rouge states and terrorists planning biological attacks.
There is a great need for portable technology that can rapidly detect and identify weaponized anthrax spores. Recently, pyrolytic techniques have been employed to produce biomarkers (detectable compounds that indicate biological origin) from anthrax spores.1, These techniques use thermal energy to break down spore components such as dipicolinic acid (DPA), lipids, and proteins; the reaction products are detected by gas chromatography (GC)-mass spectrometry (MS). Alternatively, thermal-hydrolysis/methylation (THM) has been used, which combines pyrolysis with a methylating agent, typically tetramethylammonium hydroxide (TMAH). , This technique is used to produce fatty acid methyl esters from the spore lipids, which are detected by either GC-MS or MS alone.
While these two techniques have had limited success in the detection and identification of anthrax, there is a clear need for better, faster, and lower power detection technology. One possibility for the advancement of this technology is to employ a heterogeneous catalyst for the production of biomarkers from the anthrax spores, which is the objective of this research. Superacids have previously been used, in a homogenous application, for the production methyl esters.
Several superacid catalysts were tested for the effective formation of methyl esters from fatty acids similar to those present in anthrax spores, as well as DPA (an important spore biomarker). The tests were done in a pyrolyzer (PY-2020iD, Frontier-Lab, Fukushima, Japan). Detection of the reaction products was accomplished by GC-MS and the results were analyzed to calculate the activity and selectivity of these reactions.
H3PW12O40, one of the Keggin-structure heteropolyacids (HPAs or superacids), demonstrated a high activity for heterogeneous methylation of fatty acids (C12 to C18). Approximate 90% conversion of fatty acids to fatty acid methyl esters can be achieved at 100°C for two minutes of pyrolysis when a 4:1 molar ratio of methanol:fatty acid is used. This catalyst also is active for the esterification of DPA. The results suggest that the catalytic production of biomarker has validity.
This research has great potential for the development of a hand-held biological weapons detector, which is in great demand. It also has the potential of significantly improving the speed, cost-effectiveness, and portability of anthrax detection methods, and may ultimately reduce or prevent future biological weapon attacks. Further, this is a new application of heterogeneous superacid catalysis, and as such, is groundbreaking research.
For our future research, we plan 1) to investigate the effectiveness of using supercritical fluid extraction (SFE) to isolate potential biomarkers from anthrax spores for future use in detection methods and 2) to investigate the selective properties of various solid phase microextraction (SPME) fiber materials, including nickel and platinum, for these biomarkers. Together, SFE and SPME offer a viable extraction and sampling method that could be used for anthrax spore detection. This future research could also significantly improve the speed, cost-effectiveness, and portability of anthrax detection methods, and may ultimately reduce or prevent future biological weapon attacks.
Overall, my participation in scientific research has been one of the single most rewarding aspects of my university experience. A deeper understanding of the importance of carefully designed experiments, training with key analytical techniques, and familiarity with scientific literature are a few of the many things I have gained. Undergraduate mentored research has also prepared me for the challenges I will face as a future medical student. Most importantly, my involvement has better equipped me for life-long learning.
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