Dong Qin - US grants

Along with regional partners, the College is beginning an initiative to develop a Northwest Nanotechnology Node (N3). N3 is dedicated to collaborative efforts among regional institutions of education, local industries, and government laboratories to develop innovative educational and professional programs in nanotechnology, with a biotechnology emphasis, for faculty, secondary teachers, and students in the Northwest.

This work is building on a newly-developed Associate of Applied Science - Transfer (AAS-T) degree program in nanotechnology. N3 is directed at meeting the growing demand for a technically skilled workforce, and provides the framework for development and dissemination of much needed course curricula, class modules, faculty workshops, and other educational resources for community colleges, secondary schools and universities around the region and nation.

Intellectual Merit: In providing conceptual linkages among the biological, chemical, and physical sciences, nanotechnology is highly interdisciplinary and also underlies profound revolutions occurring within the boundaries of the traditional disciplines. This project is exploring the best ways of disseminating the body of knowledge generated from current nanoscale science and technology research to a broad student population in an effective and comprehensive manner.

Broader Impacts: N3 has the potential to strengthen the foundation for a comprehensive nanotechnology program in the state of Washington. N3 can also infuse nanotechnology concepts into existing science, technology, engineering and mathematics (STEM) courses, and thus it can have a broad impact on many institutions and educational programs beyond nanotechnology.

INTELLECTUAL MERIT: In the proposed research patterned surfaces will be created on gold substrates using a solvent-assisted micro-contact molding procedure. These surfaces will have two regions, one displaying indole moieties and the other displaying adamantine moieties. These bind, strongly and selectively, to alpha- and beta-cyclodextrin, respectively. The cyclodextrins (CD) are barrel shaped water soluble cyclic glucans with a hydrophobic interior that binds the respective hydrocarbon species in an aqueous environment. In preliminary work the PI has demonstrated that beta-CD can be conjugated with positively charged polyethyleneimine (PEI) and that these conjugates complex with negatively charged DNA to form nanoparticulate DNA delivery vehicles. Formation of host-guest inclusion complexes between surface-bound adamantine and the beta-CD moiety of these nanoparticulate delivery vehicles then permits immobilization of the nanoparticles on the surface. The goal of the current proposal is to create patterned surfaces with regions that can selectively bind two different delivery vehicles, one by complexing surface bound indole and a second by complexing surface bound adamantine, respectively, with alpha- and beta-CD. The PI intends to pursue the program in the following sequence: First, indole-oligo(ethylene oxide)-thiol adducts will be synthesized and bound to gold surfaces as self-assembled monolayers. Next it will be shown, using surface plasmon resonance spectroscopy and atomic force microscopy, that specific nanoparticle immobilization can be accomplished through host-guest complexation of surface bound indole moieties and nanoparticles bearing alpha-CD moieties. Then she will demonstrate that the two types of guest moieties, adamantine and indole, can be patterned on a surface and that these can organize two different nanoparticles on the surface by self-assembly through selective host-guest complexation. These studies will employ fluorescently-labeled alpha- and beta-CD nanoparticle formulations that can be imaged using fluorescence microscopy. Finally, she will demonstrate spatially-controlled delivery of the nanoparticles to cultured cells. Attachment and viability of cultured fibroblasts will be evaluated using imaging and cell toxicity studies. Spatially-controlled delivery of two different, fluorescently-labeled nanoparticle formulations will be assessed using confocal microscopy imaging, and functionally and spatially controlled delivery of DNA will be evaluated by delivery of nucleic acids coding for green and red fluorescent proteins.

BROADER IMPACTS: Localized display of gene delivery vehicles from solid surfaces has applications ranging from gene therapy to tissue engineering to functional genomics. Spatial control of the display of multiple vehicle formulations can play an important role in therapeutic applications. For example, complex signaling cascades involved in stimulating tissue regeneration can be mimicked in synthetic tissue engineering constructs by immobilizing gene delivery vehicles containing a series of growth factor expression plasmids in spatially defined patterns. This project is developing delivery platforms to meet these needs. In educational outreach the research group supported by this grant participates in various activities at the University of Washington, including a summer Bioscience Experiences program of hands-on laboratory sessions for under represented high school students. The project will develop a lab module on immobilizing and imaging nanoparticles using fluorescence microscopy for this program. They will also be involved in a Bioengineering summer camp that introduces 7th and 8th graders to science and engineering.

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The applicants propose the acquisition of a state-of-the-art, reactive ion etching, inductively coupled plasma (RIE/ICP) system to develop the nanofabrication capabilities at Washington University (WU), which will be extended to researchers in the St. Louis metropolitan area and elsewhere. The capability for high-spatial resolution, site-specific fabrication/modification of nanostructures using electron-beam lithography (eBL) and RIE/ICP is essential for cutting-edge research in integrated nanostructured materials and devices. RIE/ICP provides dry-etch processing that is standard in nanofabrication design work, and allows the creation of sophisticated, three-dimensional, functional devices with nanometer-scale features.

The goal of this Nanotechnology Undergraduate Education (NUE) in Engineering program at Washington University (WU) in St. Louis entitled "NUE: Nanotechnology Minor at Washington University University in St. Louis", under the direction of Dr. Dong Qin, is to attract and engage undergraduate students to the study of nanoscale science, engineering, and technology. A Minor in Nanotechnology for all undergraduate students across the campus will be created and a total of twenty summer research internships will be provided to develop the Process Orientated Guided Inquiry Learning (POGIL) modules related to Nanotechnology for K-12 education outreach.

This new initiative at WU will provide an excellent opportunity to build an interdisciplinary education and research program in nanotechnology for undergraduate students with a focus on the following components: 1) learning that exposes students to a multifaceted, integrated approach to learning about the fundamentals and new developments in nanotechnology, as well as its environmental and societal impacts; 2) training that offers students research experience in the Nano Research Facility (NRF)-a site of the NSF supported National Nanotechnology Infrastructure Network (NNIN) and in the laboratories of participating faculty for exploration of research tools and discovery in the frontiers of nanotechnology; and 3) engaging that connects the students with community and society to impart and promote a basic conceptual understanding of nanotechnology in high school students and teachers.

Dong Qin from the Georgia Institute of Technology is supported by the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry to grow metal nanocrystals on other ("seed") metal nanocrystals with metal combinations that have not previously been possible. A nanocrystal is a crystal whose size is limited to several billionths of a meter, and such small crystals often have unusual properties. Noble-metal nanocrystals have received steadily growing interest in recent years owing to their fascinating properties and widespread use in applications ranging from catalysis to sensing, imaging, and biomedicine. Today, growing them on seed particles has emerged as a prevalent route to the syntheses of nanocrystals from a number of noble metals, such as silver (Ag), gold (Au), palladium (Pd), and platinum (Pt), as well as some of their bimetallic combinations. Despite the remarkable successes, the seed usually has to be the less reactive molecule or it gets eaten away ("galvanic replacement") during the growth process of the second metal. The project is aimed at finding a way to avoid galvanic replacement even when the seed particle is made of the more reactive metal. The new classes of bimetallic nanocrystals being made can be used in a broad range of applications since they may enhance spectroscopy of nearby molecules and catalysis of chemical reactions. The proposed research encompasses disciplines across materials science, chemistry, colloidal science, solid-state physics, optics, and surface chemistry. The project builds an interdisciplinary education program in nanoscale science and engineering for graduate and undergraduate students, with a major focus on the following components: i) learning that exposes students to a multifaceted, integrated approach to understanding the fundamentals of nanomaterials and their unique properties due to nanoscale sizes; ii) training that offers students hands-on experience in the laboratory and the school user facilities in exploring research tools and discoveries and frontiers of nanotechnology; and iii) engaging that connects the students with community and society to impart and promote a conceptual understanding of nanoscale science and technology in high school students and teachers.

This project is to develop a scientific basis for achieving seeded growth with two metals that have been plagued by galvanic replacement reactions. Specifically, the team aims to achieve replacement-free growth of Au on Ag nanocubes using a faster, parallel reduction to kinetically compete with and thus inhibit a galvanic reactions. The proposed research includes the following major thrusts: i) synthesis of Ag nanocubes with edge lengths at 30, 60, and 90 nm as uniform samples, together with different degrees of corner truncation; ii) determination of the kinetic parameters (rate law and activation energy) for the reduction of HAuCl4 by a strong reducing agent, such as ascorbic acid, NH2OH, and NaBH4; iii) measurement of the kinetic parameters for the galvanic reaction between HAuCl4 and Ag nanocubes of different sizes and with different degrees of corner truncation; iv) understanding the role of surface diffusion in controlling the final structure (core-frame vs. core-shell) of the bimetallic nanocrystals; and v) evaluation of the optical properties and chemical stability of the bimetallic nanocrystals. Collectively, a solid understanding of the system involving Ag and Au serves as the foundation for achieving replacement-free growth of a less reactive metal on the seeds made of a more reactive metal. These new classes of Ag-Au nanostructures can find widespread use in optical applications with greatly improved performance in terms of chemical stability and activity, together with their potentials for emerging applications such as sensing, imaging, biomedicine, and photonics, as well as in the conversion of solar light into energy through the field enhancement effect. The principle for the galvanic replacement-free growth of Au on Ag can also be extended to other pairs of noble metals, including Ag-Pd, Ag-Pt, Ag-Rh, and Ag-Ir. The resultant bimetallic nanocrystals with a core-frame or core-shell structure may find immediate use in catalysis and environmental protection.

Metal nanocrystals with controlled shapes are essential to a variety of applications, including energy conversion, environmental protection, and chemical/pharmaceutical manufacturing. Despite recent progress in their synthesis, there still exists a major gap in transitioning the nanocrystals from academic studies to industrial applications, primarily due to the lack of ability to manufacture them at an industrially relevant scale without compromising quality. Recent demonstrations indicate that continuous-flow droplet reactors offer a practical platform for the scalable and cost-effective production of metal nanocrystals with uniform sizes and controlled shapes. The droplet-based platform offers a linearly scalable technology that can be operated at both small and large quantities under essentially identical conditions for the purposes of protocol optimization and manufacturing, respectively. In addition to the scientific and technological advances, this award will help forge links between different disciplines that include nonmanufacturing, materials science, catalysis, colloidal science, and energy technology. It also has immediate impacts on the society in the following two aspects: manufacturing of nanocatalysts for fuel cells, a truly zero-emission technology critical to environmental protection; and promotion of diversity in higher education by engaging women, minorities, and other underrepresented groups into this project.

In working with its collaborators at Nissan, the team aims to develop a new technology for the scalable manufacturing of octahedral platinum-nickel nanocrystals. Such bimetallic nanocrystals have been produced in batch reactors and demonstrated with the highest activity toward oxygen reduction, a key reaction occurring on the cathodes of polymer electrolyte membrane fuel cells (PEMFCs). However, due to the poor batch-to-batch reproducibility and inevitable variations between syntheses, it has proven challenging to obtain an adequate amount of uniform nanocrystals for device testing. Through this award, an optimal combination of metal precursors and reductant will be identified based on kinetic measurements to ensure that the reduction will not occur prematurely, and instead only when the droplet reactors pass through a reaction zone held at an elevated temperature. A similar protocol will also be developed to conformally coat the surfaces of platinum-nickel octahedra with platinum shells of 1-2 atomic layers thick to greatly enhance their catalytic activity. The catalysts will be tested by engineers at Nissan and evaluated for commercial use in vehicles powered by PEMFCs. This research will pave the way for future deployment of industrial catalysts based on nanocrystals with controlled shapes.

Nanocrystals are geometrically well-ordered solids with diameters on the order of 0.00000005 inches. Bimetallic nanocrystals, made of two different metal species, have properties that are often superior to their single-metal counterparts. The arrangement of the two different metals relative to each other in the nanocrystal is very important in determining the nanocrystal properties, and considerable effort has been made to deposit one metal atop the nanocrystal surface of another metal with precision in location. It remains a grand challenge to detect and quantify the metal being deposited, particularly when the nanocrystals are still suspended in the reaction medium undergoing growth. Dr. Dong Qin addresses this challenge by developing a class of molecules, the isocyanides (molecules containing the -NC chemical group), as probes for in situ characterization with detection of the isocyanides by a spectroscopic technique, surface-enhanced Raman scattering (SERS). The ultimate goal is to establish a scientific basis for enabling the rational synthesis of bimetallic nanocrystals with well-controlled compositions and shapes, which have broader societal impact through their need in a variety of applications. This research project encompasses multiple disciplines such as materials science, chemistry, colloidal science, solid-state physics, photonics, and surface science, with a focus on the following components for student development: i) active learning in interdisciplinary areas involved in understanding the structure and property relationships of nanomaterials; ii) training that provides hands-on experience in the synthesis of nanomaterials in the Qin laboratory, and on the characterization of nanomaterials in the state-of-the-art facilities at Georgia Tech and national laboratories; and iii) exposing the community and society, including high school students and teachers, to nanoscale science and technology concepts.

In this research, Dr. Dong Qin from the Georgia Institute of Technology is supported by the Macromolecular, Supramolecular and Nanochemistry (MSN) Program to study the fundamentals involved in the heterogeneous nucleation and overgrowth of bimetallic nanocrystals. Specifically, a novel class of isocyanide-based molecular probes (R-NC) are developed for in situ detection and analysis of the overgrowth of a second noble metal (M: Pd, Pt, Ir, Rh, or Ru) on Ag nanocrystals suspended in the original growth solution by surface-enhanced Raman scattering (SERS). Because the binding of the isocyanide group to a metal surface is similar to that of carbon monoxide, it is anticipated that the stretching frequency of the NC bond differs when the isocyanide group binds to the Ag and M atoms, respectively. Therefore, it is feasible to monitor the M atoms being deposited onto Ag nanocrystals by following the stretching frequencies and intensities of NC vibration in real time. On the other hand, the SERS hot spots on the Ag nanocrystals can be designed to coincide with the sites favored by M atoms for heterogeneous nucleation, allowing for unprecedented sensitivity with a detection limit below one monolayer. By leveraging their consummate sensitivity toward metal atoms, the novel SERS probes open up new opportunities to elucidate the mechanistic details involved in the seeded overgrowth of a second noble metal on the surface of Ag nanocrystals. The mechanistic insights support the rational design and knowledge-based synthesis of bi- and multi-metallic nanocrystals for a variety of applications. This research project encompasses multiple disciplines such as materials science, chemistry, colloidal science, solid-state physics, photonics, and surface science, with a focus on the following components for student development: i) active learning in interdisciplinary areas involved in understanding the structure and property relationships of nanomaterials; ii) training that provides hands-on experience in the synthesis of nanomaterials in the Qin laboratory, and on the characterization of nanomaterials in the state-of-the-art facilities at Georgia Tech and national laboratories; and iii) exposing the community and society, including high school students and teachers, to nanoscale science and technology concepts.

The Macromolecular, Supramolecular, and Nanochemistry Program in the Chemistry Division supports Professor Dong Qin and her group at the Georgia Institute of Technology to develop tiny crystals called bimetallic nanocrystals. Their bimetallic nanocrystals contain two metals whose chemical function and spatial position within the nanocrystals are precisely controlled. Metal nanocrystals play a vital role in enabling catalysis for energy conversion, environmental protection, and organic synthesis. Despite some success, it remains a daunting challenge to monitor the catalytic reactions in real time by spatially confining the reactants to the catalytic sites while detecting the final and intermediate products in situ. The research team addresses this challenge by developing bimetallic nanocrystals in which one of the metals can serve as a catalyst while the other can report the ?chemical fingerprint? (signals associated with the reaction). The concepts, materials, and methods developed during this research may find use in a broad range of applications related to solid-state chemistry, catalysis, sensing, and photonics. This team recruits women and minority students as well as those from community colleges and minority institutions for summer research. This effort is carried out in collaboration with the National Nanotechnology Coordinated Infrastructure called the Southeastern Nanotechnology Infrastructure Corridor.

In this research supported by the Macromolecular, Supramolecular and Nanochemistry (MSN) Program, Professor Qin?s team develops new design principles and methods to fabricate a novel class of bifunctional nanoreactors from Ag@M (M: Pt, Pd, and Rh) core-frame nanocubes via metal-selective surface functionalization and self-assembly. Specifically, molecules bearing isocyanide groups at the two ends are used to selectively bind to the M atoms on the edges of the core-frame nanocubes, serving as ?clips? to bring two nanocubes face to face for the generation of a dimer. The gap region between the two nanocubes naturally presents a well-controlled nanoreactor, in which the side faces can be orthogonally functionalized with the reactants while the M atoms not coordinated by isocyanide will serve as the catalyst. Due to a strong plasmonic coupling between the two Ag nanocubes separated by a gap of only a few nanometers, the nanoreactor offers a unique capability to monitor various types of important catalytic reactions by in situ SERS. The model reactions include the hydrogenation of nitroaromatics for the production of thermodynamically unfavorable products such as hydroxylamine and azo compounds, as well as the bond-selective hydrogenation of cinnamaldehyde, a catalytic reaction pivotal to the production of fragrance, agrochemical, and pharmaceutical compounds. This research not only enables real-time characterization of heterogeneous catalytic reactions but also sheds light on the rational design of new or improved catalyst materials.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.