Fluorescence Quenching/Enhancement Gold & Silver Nanoparticles

Every day different ideas are constantly being explored and tested to see if they can have benefit in the modern world. The search to find new and better ways to deliver medicine to the human body is one of these areas. A possible solution to this cause could be to use something so small, that it can only be seen when millions of them are together at one time. These tiny objects are called nanoparticles.

Nanoparticles are a part of everyday life—most people just don’t realize it because they can’t see them. This Creative Inquiry, Design and Synthesis of Advanced Nanomaterials to Address the Global Challenges of the 21st Century, is led by Dr. Christopher Kitchens, associate professor in the Chemical and Biomolecular Engineering Department. Kitchens’ vision is to use nanoparticles to choose the specific time that medicine is released inside of the body.

Dr. Kitchens is working with his Creative Inquiry team, as well as graduate students, to see if nanoparticles can be used to coat lipid vesicles that are filled with some sort of medicine, then have those lipid vesicles sent to a problem area inside of the body. From there, they would use the nanoparticles to rupture the vesicle on command, thereby releasing the medicine inside. This concept may seem complicated, but it is quite simple. When asked to describe a lipid vesicle so that a 10-year old could understand, Matthew Stonaker, a Chemical Engineering undergraduate student, explained, “A lipid vesicle is like a water balloon, and the water inside the balloon, in this case, would be the medicine.”

The students in Dr. Kitchens’ Creative Inquiry are working to make this goal a reality. They are very proficient in synthesizing several different types of nanoparticle solutions, with both gold and silver nanoparticles. The process of synthesizing nanoparticles can be as simple as mixing together water with one or two chemicals, or as complicated as having to mix multiple chemicals while boiling the solution then letting it sit for a few days. Synthesizing the nanoparticles, though, is just the tip of the iceberg in this research.

After each solution of nanoparticles is made, they have to be characterized. Characterizing the nanoparticles is crucial because it lets the students know all of the properties of the individual nanoparticle. There are many ways to characterize the nanoparticles. One option is Dynamic Light Scattering (DLS), which measures the diameter and other size qualities of the nanoparticle. Another option is ultra-violet visual spectroscopy (UV-Vis), which uses the light absorbency of the solution to determine the type of particles in the solution. Characterization is important because two different solutions could look identical, but have different sizes of nanoparticles and have different effects on the lipid vesicles.

The Creative Inquiry team is also conducting leakage studies for each different type of nanoparticle. These leakage studies are used to see how whatever is inside of the lipid vesicles will be released when in contact with the nanoparticles. Fluorescein dye is used for this purpose because, when a light is shined through the dye, it emits light at a different wavelength and color than the light that was absorbed. This is called fluorescence. The dye is tested to see how it will react with each separate type of nanoparticle—whether or not the nanoparticle will quench or enhance the emission of the dye. This testing can take up to two hours per each unique nanoparticle solution, and has to be replicated three times for each solution. After the dye is tested to see how it will react with just the nanoparticle, it will be encapsulated in the vesicles to see how they will react with the different types of nanoparticles.

Nanoparticle research is a vast frontier waiting to be fully explored and understood. People are fascinated by the mysteries of objects that can’t be seen with the human eye. This Creative Inquiry team is exploring this vast unknown and may someday see their work applied to progress in medical or other fields.