Dr. Brown

at

University of Wisconsin-Whitewater 

Research Interests & Equipment (Techniques)

* Broadly speaking, our lab uses biologically and chemically modified nanoparticles to target, manipulate, and/or destroy unwanted biological targets. Below are three specific research interests:

Research Interest #1) We modify TiO2 and core-shell TiO2 nanoparticles with targeting moieties and fluorescent dyes, so they can be 'targeted' and 'activated' by specified wavelengths of visible light (as opposed to UV light activation that bare TiO2 nanoparticles require). In environmental applications, visible light activation of TiO2 nanoparticles enables their use in the presence of humans or other organisms. In biomedical applications, visible light activation of TiO2 nanoparticles allows destruction of unwanted cells/tissues while leaving surrounding cells/tissues unharmed. To assess the interactions of targeting moieties and dyes with nanoparticles, we use centrifugation, spectrophotometry, electrophoresis, and atomic force microscopy techniques. [Image to Left: Panels a, b, and c show three examples of successful dye-nanoparticles interactions, while panel d shows a negative control. 1 = dH2O, 2 = dye of interest, 3 = TiO2 nanoparticles, 4 = dye of interest + TiO2 nanoparticles]


Research Interest #2) We use the dye coating on the nanoparticle surface to visualize the localization of both untargeted and targeted TiO2 and core-shell TiO2 nanoparticles on surfaces (for environmental applications) and in biological samples. To track localization of nanoparticles, we use techiques such as flourescence confocal microscopy, flow cytometry, and atomic force microscopy. [Image to Left: Dye-coated TiO2 nanoparticles (red) demonstrate perinuclear localization (white arrows) in a human cervical cancer cell in this 3D reconstruction (nuclear membrane associated protein, emerin = green; DNA = blue). Unique interactions between nanoparticles and biological cells can often be viewed. In this case, the nuclear membrane can also be seen encompassing the TiO2 nanoparticles, yielding a "donut effect" through the center of the nucleus (yellow arrow).]




Research Interest #3) We activate TiO2 and core-shell TiO2 nanoparticles with visible light to degrade unwanted neighboring biological agents, such as cancer cells and bacteria, through localized production of reactive oxygen species or generation of electropositive holes. [Image to Left: Visible light activation of dye-coated TiO2 nanoparticles (red) alters the integrity and localization pattern of a nuclear membrane associated protein (emerin = green) as well as results in nuclear enlargement and DNA condensation (DNA = blue).]