Optical responses at the nanoparticle-biological interface with an introduction to optical microscopy in undergraduate analytical chemistry curriculum

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Augspurger, Ashley
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Ning Fang
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The Department of Chemistry seeks to provide students with a foundation in the fundamentals and application of chemical theories and processes of the lab. Thus prepared they me pursue careers as teachers, industry supervisors, or research chemists in a variety of domains (governmental, academic, etc).

The Department of Chemistry was founded in 1880.

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Plasmonic nanoparticles have been gaining attention in the medical field for their use as chemical and biological sensors, drug delivery vectors and contrast agents for cellular imaging; however, the ability to monitor the chemical binding events and drug delivery kinetics is limited. The majority of this body of work explores nanoparticles optical responses as they undergo energy transfer processes for biological sensing. The latter portion of this dissertation discusses optical microscopy in undergraduate analytical chemistry.

In the first experiment, plasmon resonance energy transfer between gold nanospheres and cytochrome c was investigated. As cytochrome c adsorbs to the surface of a nanoparticle, the plasmonic energy is transferred from the nanoparticle to cytochrome c, as a result there are spectral dips in the extinction spectrum of the gold nanoparticle. This optical phenomenon was studied in Hi-Fi microchannels and HeLa cells undergoing ethanol induced apoptosis.

The second set of experiments encompasses the observations of the optical changes of gold-capped mesoporous silica nanoparticles (MSNs) undergoing uncapping by dithiothreitol and glutathione. The uncapping process was studied in flow cells with dithiothreitol as the uncapping agent, and also in lung cancer cells using glutathione as the cleaving agent. Differential interference contrast (DIC) microscopy was employed to image the optical changes as gold is cleaved from MSNs.

As part of the chemical education project, an optical microscopy laboratory experiment was created, implemented and assessed in an instrumental analysis course for junior and senior level undergraduate chemistry students. Students were introduced to optical microscopy and nanoparticles through the use of a dark field microscope to image a reaction between copper wire and silver nitrate in the first section. In the second portion of the experiment, students imaged gold, silver and silica nanospheres with the aid of bandpass filters and were also introduced to the concept of localized surface plasmon resonances. There were two formats for the experiment, traditional and inquiry based. Students were split into two groups, each group performing one format of the experiment and their learning gains were monitored with the Chemical Optical Microscopy Assessment (COMA) that was created for this purpose. The learning outcomes based on the COMA and laboratory report scores were compared to determine with which instructional method students had higher learning gains.

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