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Younan XiaProfessor; Brock Family Chair and GRA Eminent Joint Appointment in the Department of Biomedical Engineering and School of Chemistry and Biochemistry Office: MSE 3100J |
B.S. in Chemical Physics, University of Science and Technology of China (USTC); M.S.in Inorganic Chemistry, University of Pennsylvania; Ph.D. in Physical Chemistry, Harvard University
Research Interests
Innovative technologies are emerging from nanoscale materials and devices that will improve the way we live just as microtechnology has done over past several decades.
Our current research centers on the development of new chemistry, physics, and technological applications of nanostructured materials -- a novel class of materials with feature sizes <100 nm.
1. The Chemistry and Physics of Nanomaterial Synthesis
This research focuses on a long-standing problem in chemistry and physics -- understanding and control of the nucleation/growth steps involved in the chemical synthesis of nanomaterials. We aim to bring revolutionary advances to this field by developing new tools capable of capturing, identifying, and quantifying the nuclei (small clusters) and seeds that bridge atomic species and nanostructures. This research requires the integration of chemical synthesis, theoretical modeling, cluster speciation using mass spectrometry and electron microscopic analysis. It will provide an atomistic picture of the evolution pathway from atoms to clusters and nanostructures, as well as the design rules for synthesizing metal and semiconductor nanomaterials with well-controlled electronic, magnetic, catalytic and optical properties. The ultimate goal of this work is to build a scientific base for large-scale production of nanomaterials with the specific properties sought for applications in areas such as electronics, photonics, catalysis, information storage, optical sensing, biomedical research.
2. Putting Nanomaterials to Work for Biomedical Research
Because of their small sizes and unique properties, nanomaterials are finding widespread use in studying complex biological systems. This work aims to advance biomedical research by developing new tools and methods based on functional nanomaterials. Our current efforts include development of gold nanocages as contrast agents for optical imaging (e.g., optical coherence tomography, photoacoustic tomography, and multi-photon luminescence), and as photothermal agents for therapeutic treatment. We are exploring the use of gold nanocages and other metal nanostructures as substrates for SERS- and LSPR-based detection. We are developing nanoscale capsules by integrating gold nanocages with smart polymers and/or phase-change materials for targeted delivery and controlled release with superb spatial/temporal resolutions. We are applying electrospun nanofibers to neural tissue engineering, drug release, stem cell, and tendon-to-bone insertion site repair. We are also designing new colloidal particles with superparamagnetic features for separation, detection, manipulation, and tracking of biological species and cellular events. All these research activities will contribute to the emerging fields of nanomedicine and regenerative medicine.
3. Nanomaterials and Environmental Research
Nanomaterials also hold the key to the continuous progress toward a cleaner environment and sustainability. We aim to demonstrate the fabrication of functional nanomaterials with optimized properties for a range of related applications. For example, we are exploring the use of nanomaterials for improving the performance of solar cells, fuel cells, catalytic converters, and water-splitting devices. This research requires a superb understanding of structure-property relationships that guide the design and synthesis of novel nanomaterials with well-controlled sizes and shapes for specific applications.
Representative Publications in 2011
(1) Silver nanocrystals with concave surfaces and their optical and surface-enhanced Raman scattering properties
Xia, X.; Zeng, J.; McDearmon, B.; Zheng, Y.; Li, Q. and Xia, Y. Angewandte Chemie International Edition 2011, 50, 12542-12546 (VIP article, highlighted on the inside cover).
(2) Shape-controlled synthesis of copper nanocrystals in an aqueous solution with glucose as a reducing agent and hexadecylamine as a capping agent
Jin, M.; He, G.; Zhang, H.; Zeng, J.; Xie, Z. and Xia, Y. Angewandte Chemie International Edition 2011, 50, 10560-10564.
(3) Facile synthesis of Pd-Pt alloy nanocages and their enhanced performance for preferential oxidation of CO in excess hydrogen
Zhang, H.; Jin, M.; Liu, H.; Wang, J.; Kim, M. J.; Yang, D.; Xie, Z.; Liu , J. and Xia, Y. ACS Nano 2011, 5, 8212-8222.
(4) On-chip screening of experimental conditions for the synthesis of noble-metal nanostructures with different morphologies
Zhou, J.; Zeng, J.; Grant, J.; Wu, H. and Xia, Y. Small, 2011, 7, 3308-3316 (VIP article, it was highlighted on the cover and in Materials Views).
(5) Palladium concave nanocubes with high-Index facets and their enhanced catalytic properties
Jin, M.; Zhang, H.; Xie, Z. and Xia, Y. Angewandte Chemie International Edition 2011, 50, 7850-7855.
(6) Nanocrystals comprised of alternating shells of Pd and Pt can be obtained by sequentially adding different precursors
Zhang, H.; Jin, M.; Wang, J.; Kim, M. J.; Yang, D. and Xia, Y. Journal of the American Chemical Society 2011, 133, 10422-10425.
(7) Selective sulfuration at the corner sites of a silver nanocrystal and its use in stabilization of the shape
Zeng, J.; Tao, J.; Su, D.; Zhu, Y.; Qin, D. and Xia, Y. Nano Letters 2011, 11, 3010-3015.
(8) Enhancing the Stiffness of Electrospun Nanofiber Scaffolds with Controlled Surface Coating and Mineralization
Liu, W.; Yeh, Y.-C.; Lipner, J.; Xie, J.; Sung, H.-W.; Thomopoulos, S. and Xia, Y. Langmuir 2011, 27, 9088-9093.
(9) Non-invasive photoacoustic microscopy of living cells in two and three dimensions through enhancement by a metabolite dye
Zhang, Y.; Cai, X.; Wang, Y.; Zhang, C.; Li, L.; Choi, S.-W.; Wang, L. V. and Xia, Y. Angewandte Chemie International Edition 2011, 50, 7359-7363.
(10) Synthesis of gold nano-hexapods with controllable arm lengths and their tunable optical properties
Kim, D. Y.; Yu, T.; Cho, E. C.; Ma, Y.; Park, O. O. and Xia, Y. Angewandte Chemie International Edition 2011, 50, 6328-6331.
(11) The effect of sedimentation and diffusion on cellular uptake of gold nanoparticles
Cho, E. C.; Zhang, Q. and Xia, Y. Nature Nanotechnology 2011, 6, 385-391 (it was highlighted in an editorial article entitled “The dose makes the poison”).
(12) Mixing an aqueous suspension of palladium or gold nanocrystals with a less polar solvent can cause changes to size, morphology, or both
Lim, B.; Yu, T.; Park, J.; Zheng, Y. and Xia, Y. Angewandte Chemie International Edition 2011, 50, 6068-6071.
(13) Generation of hot spots with silver nanocubes for single-molecule detection by surface-enhanced Raman scattering
Rycenga, M.; Xia, X.; Moran, C.; Zhou, F.; Qin, D.; Li, Z.-Y. and Xia, Y. Angewandte Chemie International Edition 2011, 50, 5473-5477 (hot paper).
(14) Synthesis of Pd-Pt bimetallic nanocrystals with a concave structure through a bromide-induced galvanic replacement reactionZhang, H.; Jin, M.; Wang, J.; Li, W.; Camargo, P. H. C.; Kim, M.; Yang, D.; Xie, Z. and Xia, Y. Journal of the American Chemical Society 2011, 133, 6078-6089.
(15) Gold nanocages: From synthesis to theranostic applications
Xia, Y.; Li, W.; Cobley, C. M.; Chen, J.; Xia, X.; Zhang, Q.; Yang, M.; Cho, E. C. and Brown, P. K. Accounts of Chemical Research 2011, 44, 914-924 (invited review article, this work was highlighted in C&EN News, 2011, September 26, p. 30)
(16) A new theranostic system based on gold nanocages and phase-change materials with unique features for photoacoustic imaging and controlled release
Moon, G. D.; Choi, S.-W.; Cai, X.; Li, W.; Cho, E. C.; Jeong, U.; Wang, L. V.; and Xia, Y. Journal of the American Chemical Society 2011, 133, 4762-4765.
(17) Platinum concave nanocubes with high-index facets and their enhanced activity for oxygen reduction reaction
Yu, T.; Kim, D. Y.; Zhang, H. and Xia, Y. Angewandte Chemie International Edition 2011, 50, 2773-2777 (hot paper).
(18) Controlling the morphology of rhodium nanocrystals by manipulating the growth kinetics with a syringe pump
Zhang, H.; Li, W.; Jin, M.; Zeng, J.; Yu, T.; Yang, D. and Xia, Y. Nano Letters 2011, 11, 898-903.
(19) An enzyme-sensitive probe for photoacoustic imaging and fluorescence detection of protease activity
Xia, X.; Yang, M.; Oetjen, L. K.; Zhang, Y.; Li, Q.; Chen. J. and Xia, Y. Nanoscale 2011, 3, 950-953 (it was highlighted as a hot paper on the website of Nanoscale).
(20) Controlling the synthesis and assembly of silver nanostructures for plasmonic applications
Rycenga, M.; Cobley, C. M.; Zeng, J.; Li, W.; Moran, C.; Zhang, Q.; Qin, D. and Xia, Y. Chemical Reviews 2011, 111, 3669-3712 (invited review article).
(21) Strain-controlled release of molecules from arrayed microcapsules supported on an elastomer substrate
Hyun, D. C.; Moon, G. D.; Park, C. J.; Kim, B. S.; Xia, Y. and Jeong, U. Angewandte Chemie International Edition 2011, 50, 50, 724-727 (it was featured on the inside cover).
(22) Successive deposition of silver on silver nanoplates: Lateral vs. vertical growth
Zeng, J.; Xia, X.; Rycenga, M.; Henneghan, P.; Li, Q. and Xia, Y. Angewandte Chemie International Edition 2011, 50, 244-249 (VIP, it was highlighted on the frontispieces and in an accompanying article published in the same journal, 2011, 50, 992-993).
(23) Metal nanocrystals with highly branched morphologies
Lim, B. and Xia, Y. Angewandte Chemie International Edition 2011, 50, 76-85 (invited mini review article).
(24) Gold nanostructures: A class of multifunctional materials for biomedical applications
Cobley, C. M.; Chen, J.; Cho, E. C.; Wang, L. V. and Xia, Y. Chemical Society Reviews 2011, 40, 44-56 (invited tutorial review).
(25) Nanofiber membranes with controllable microwells and structural cues and their use in forming cell microarrays and neuronal networks
Xie, J.; Liu, W.; MacEwan, M. R.; Yeh, Y.-C.; Thomopoulos, S. and Xia, Y. Small 2011, 7, 293-297 (it was highlighted on the cover).