Abstract:
Nano-devices using varying nano-structured materials are investigated. In particular, the gold nanoparticle-decorated single carbon nanotube (CNT) tipped probe is used to study intracellular environments in situ using surface-enhanced Raman spectroscopy (SERS) (Nat Nanotechnol, 6, 2011, 57). The decorated CNT was assembled onto the tips of pulled glass capillaries to form a SERS-enabled endoscope. The high mechanical strength of the nano-scale endoscope made it possible to penetrate the cell membrane for intracellular probing without causing damage to the cell (Small, 7, 2011, 540). The SERS-enabled endoscopes exhibited high selectivity and sensitivity for detecting trace amounts of analytes in bio-fluid environments, highlighting its capabilities in areas that necessitate minimally invasive intra-cellular detection, drug delivery, single-cell surgery, and label-free biological sensors.
In-situ HRTEM study of LiFePO4 nanowire delithiation kinetics at atomistic scale will also be presented. Real-time observed 20nm solid solution (SS) contains no dislocations, so coherency stress accelerates Li+/e- transport. Large SS with a boundary could dominate the phase transformation at non-equilibrium condition; for larger particles, SS provides out-of-equilibrium but atomically wide avenues for Li+/e- transport (NanoLett, 2014).

Biography
Dr. JunjieNiu is an Assistant Professor in Department of Materials Science and Engineering at University of Wisconsin-Milwaukee. He received Ph.D. in Materials Science from Zhejiang University in 2005. From 2005 to 2009, he was a faculty at Shanghai JiaoTong University before joining Prof. YuryGogotsi group at Drexel as a Postdoc. From 2011, he moved to Prof. Ju Li group at UPenn and MIT, developing a new lab and leading the experimental research. Dr.Niu’s interdisciplinary research includes understanding fundamental science in physics/chemistry, and engineering nanomaterials in applications of energy storage, biomaterials and chemo-mechanics.