ChemNews - Department of Chemistry - University of Minnesota

RESEARCHInteraction of nanoparticles with biological cellsRecent research from the group of Professor Christy HaynesNanoscale materials are facilitating novel biomedical applications in the areas of therapeutics and assay development.Characterizing the basic interaction of these nanoparticles with biological cells is critical for data interpretationand further technological development. This characterization of nanoparticle-cell interaction suffers froma paucity of analytical chemistry studies and presents interesting measurement challenges based on the complexbiological environment, the dynamic nature of the nanoparticle-cell interaction, and the high sensitivities requiredfor single cell assays.The Haynes group has recentlydemonstrated that carbon-fiber microelectrodeamperometry can be used toassess critical cellular function of primaryculture immune system cells afternanoparticle exposure. Gold nanoparticlesare the focus of Haynes groupstudies to date based on their wide applicationin the areas of DNA and drugdelivery, direct inhibition of cancer cell proliferation, photodynamic therapy, and as both intra- and extracellularbiomarker probes. The group’s electron microscopy and amperometry studies reveal that mast cells, a critical immunesystem effector cell, take up gold nanoparticles, these gold nanoparticles interrupt the granular matrix, andthe disrupted matrix triggers abnormal chemical messenger secretion. Understanding the mechanistic interactionof the nanoparticle and the intracellular environment will facilitate future design and fabrication of non-cytotoxicnanoscale materials.Fluidic and air-stable supported lipid bilayer and cellmimickingmicroarraysRecent research from the group of Professor Xiaoyang ZhuAn academic-industrial research team led by Professor Xiaoyang Zhu ofUMN and Dr. Athena Guo of MicroSurfaces, Inc. reported a ground-breakingdiscovery on biomaterials and biotechnology in the latest issue of the Journalof the American Chemical Society (DOI:10.1021/ja800049f). The first authoron the paper was chemistry graduate student Yang Deng. As drug delivery,therapy, and medical imaging are becoming increasingly cell-specific, thereis a critical need for high fidelity and high-throughput screening methodsfor cell surface interactions. Cell membrane-mimicking surfaces, i.e., supportedlipid bilayers (SLBs), were not sufficiently robust to meet this need.Learning from nature, particular biophysics of the magic molecule cholesterol, this research team designed anddeveloped a novel surface with tethered and dispersed cholesterol groups. They discovered that SLBs formedon such a designer surface became air-stable due to the cooperative stabilizing effect of the tethered cholesterolgroups incorporated into the bottom leaflet. Achieving air-stability allowed the team to easily fabricate SLB microarraysfrom direct robotic spotting of vesicle solutions. They further demonstrated the application of the SLBsas cell membrane-mimicking microarrays by reconstituting peripheral as well as integral membrane componentsthat can be recognized by their respective targets. These demonstrations established the viability of the fluidic andair-stable SLB platform for generating content microarrays in high throughput studies, e.g., the screening of drugsand nanomedicine targeting cell surface receptors.Page 22