Department of Materials Science & Engineering
and Chemistry & Biochemistry
University of California, San Diego
Nathan C. Gianneschi received his B.Sc(Hons) at the University of Adelaide in 1999. In 2005 he completed his Ph.D at Northwestern University. Following a Dow Chemical postdoctoral fellowship at The Scripps Research Institute, in 2008 he began his independent career at University of California, San Diego where he is currently the Teddy Traylor Faculty Scholar and Professor of Chemistry & Biochemistry, Materials Science & Engineering, and a member of the Moores Cancer Center.
The Gianneschi group takes an interdisciplinary approach to nanomaterials research with a focus on multifunctional materials with interests that include biomedical applications, programmed interactions with biomolecules and cells, and basic research into nanoscale materials design, synthesis and characterization. For this work he has been awarded the NIH Director's New Innovator Award, the NIH Director's Transformative Research Award and the White House's highest honor for young scientists and engineers with a Presidential Early Career Award for Scientists and Engineers. Prof. Gianneschi was awarded a Dreyfus Foundation Fellowship, is a Kavli Fellow of the National Academy of Sciences, was awarded an Alfred P. Sloan Foundation Fellowship, and is a Fellow of the Royal Society of Chemistry.
The natural function and structure inherent to the biomaterial melanin has sparked interest in its utility across a broad range of applications. Recent work has shown that through the polymerization of dopamine synthetic mimics of natural melanin, with similar chemical structure as well as physical and biological properties, can be achieved. These polydopamine (PDA)-based synthetic nanoparticles retain many of the desirable properties of natural melanin and have been studied for use in catalysis, free radical quenching, inkjet printing, photothermal therapy, and structural coloration. However, despite the proliferation of work in this area, the complex, amorphous nature of the material necessitates new approaches to elucidate the physical, electronic, and magnetic structures responsible for the properties of melanin and its synthetic analogues. In this presentation we will describe methods for generating polydopamine nanostructures that mimic morphological and functional properties of naturally occurring melanins. The synthetic method allows for increasing and controlling the metal loading of synthetic melanin nanoparticles and we use the resulting materials to perform a systematic quantitative investigation on their structure-property relationships. A comprehensive analysis by magnetometry, electron paramagnetic resonance (EPR), and nuclear magnetic relaxation dispersion (NMRD) reveals the complexities of the magnetic behavior and how these intraparticle magnetic interactions manifest in useful material properties such as their performance as MRI contrast agents. This analysis allows predictions of optimal metal loadings through a quantitative modeling of antiferromagnetic coupling that arises from proximal ions. We will outline one such study focused on iron-loaded polydopamine nanoparticles, which provides a detailed understanding of this complex class of synthetic biomaterials and gives insight into interactions and structures prevalent in naturally occurring melanins. Finally, we will highlight our efforts to mimic melanosomes, the organelles responsible for pigmentation and protection of human skin from UV-induced nuclear DNA damage. We demonstrate that synthetic melanin-like nanoparticles are endocytosed, undergo perinuclear aggregation, and form a supranuclear cap, or so called microparasol in human epidermal keratinocytes (HEKa), mimicking the behavior of natural melananosomes in terms of cellular distribution and the fact that they serve to protect the cells from UV damage.