materials science at clemson university

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The Research Interests of the Foulger Group

The Foulger Research Group was formed in 1999 when Dr. Stephen Foulger took a position as an assistant professor in what was then the School of Textiles, Fiber, and Polymer Science Clemson World v. 57 n. 3 (2004) (STFPS) at Clemson University. In those early days, the group was housed in the Sirrine Hall Laboratories on campus, but in 2005, moved out to the Advanced Materials Research Laboratories (AMRL) after their construction. AMRL is a 111,000 square foot laboratory that houses a range of state-of-the-art equipment and is located in the Clemson University Advanced Materials Center, an innovative campus and technology park located in Anderson, SC, approximately eight miles from campus. Around the same period, the Department of Ceramic Engineering and STFPS joined to become the School of Materials Science and Engineering. As of 2008, Dr. Foulger was promoted to the rank of professor and became the Gregg-Graniteville Endowed Chair. In 2012, Professor Foulger received a joint appointment in the Department of Bioengineering in recognition of the multitude of efforts being pursued in his group that focus on bio-related science and technologies.

The unifying point for the relatively disparate research themes within the group is a fascination with colloids and their use to passively or actively control light. As you look through all of our publications you will see this unify point embedded in the research themes which range from self-assembled colloidal crystals, colloidally-based organic light emitting devices, small molecule synthesis of UV/Vis & NIR chromophores, surface chemistry on particles, tunable lasers, biological imaging, roll-to-roll printing of devices, particulate-based cancer therapy, just to name a few. The diversity in research themes is not indicative of a lack of research direction, but is more reflective of the culture of curiosity that is encouraged & rewarded within the group and resulted in our journal covers.

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Journal Cover: Journal Of Materials Chemistry B n.36 v.1 2013

The cover of the journal Journal of Materials Chemistry B recently depicted an effort lead by Ragini Jetty entitled Protein Triggered Fluorescence Switching of Near-Infrared Emitting Nanoparticles for Contrast-Enhanced Imaging . According to this journal:

"Journal of Materials Chemistry B is a weekly journal in the materials field. The journal is interdisciplinary, publishing work of international significance on all aspects of materials chemistry related to biology and medicine..."

Sub-100 nm colloidal particles which are surface-functionalized with multiple environmentally-sensitive moieties have the potential to combine imaging, early detection, and the treatment of cancer with a single type of long-circulating “nanodevice”. Deep tissue imaging is achievable through the development of particles which are surface-modified with fluorophores that operate in the nearinfrared (NIR) spectrum and where the fluorophore's signal can be maximized by “turning-on” the fluorescence only in the targeted tissue. We present a general approach for the synthesis of NIR emitting nanoparticles that exhibit a protein triggered activation/deactivation of the emission. Dispersing the particles into an aqueous solution, such as phosphate buffered saline (PBS), resulted in an aggregation of the hydrophobic fluorophores and a cessation of emission. The emission can be reinstated, or activated, by the conversion of the surface-attached fluorophores from an aggregate to a monomeric species with the addition of an albumin. This activated probe can be deactivated and returned to a quenched state by a simple tryptic digestion of the albumin. The methodology for emission switching offers a path to maximize the signal from the typically weak quantum yield inherent in NIR fluorophores.

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Journal: ACS Nano n.1 v.7 2013

Research lead by Michael A. Daniele was recently published in the journal ACS Nano and was entitled Magnetic Nanoclusters Exhibiting Protein-Activated Near-Infrared Fluorescence. According to this journal:

"ACS Nano is an international forum for the communication of comprehensive articles on nanoscience and nanotechnology research at the interfaces of chemistry, biology, materials science, physics, and engineering. Moreover, the journal helps facilitate communication among scientists from these research communities in developing new research opportunities, advancing the field through new discoveries, and reaching out to scientists at all levels." (2011 ISI Impact Factor: 11.421)

Composite nanoclusters with chemical, magnetic, and biofunctionality offer broad opportunities for targeted cellular imaging. A key challenge is to load a high degree of targeting, imaging, and therapeutic functionality onto stable metal-oxide nanoparticles. Here we report a route for producing magnetic nanoclusters (MNCs) with alkyne surface functionality that can be utilized as multimodal imaging probes. We form MNCs composed of magnetic Fe3 O4 nanoparticles and poly(acrylic acid-co-propargyl acrylate) by the co-precipitation of iron salts in the presence of copolymer stabilizers. The MNCs were surface-modified with near-infrared (NIR) emitting fluorophore used in photodynamic therapy, an azide-modified indocyanine green. The fluorophores engaged and complexed with bovine serum albumin, forming an extended coverage of serum proteins on the MNCs. These proteins isolated indocyanine green fluorophores from the aqueous environment and induced an effective “turn-on” of NIR emission.

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Journal Cover: Advanced Functional Materials n.6 v.23 2013

The cover of the journal Advanced Functional Materials recently depicted an effort lead by Michael A. Daniele entitled Rapid and Continuous Hydrodynamically Controlled Fabrication of Biohybrid Microfibers . According to this journal:

"In its second decade as a top-tier materials science journal, Advanced Functional Materials reports breakthrough research in all aspects of materials science, including nanotechnology, chemistry, physics, and biology. Advanced Functional Materials is known for its rapid and fair peer review, quality content, and high impact (2011 ISI Impact Factor: 10.179), making it the first choice of the international materials science community."

Cell encapsulation is critical for many biotechnology applications including environmental remediation, bioreactors, and regenerative medicine. Here, the development of biohybrid microfibers comprised of encapsulated bacteria in hydrogel matrices produced on-chip using microfluidics is reported. The fiber production process utilizes hydrodynamic shaping of a cell-laden core fluid by a miscible sheath fluid. Production of the fibers containing viable bacteria was continuous in contrast to the more typical methods in which cells infiltrated or were attached to prepared fibers. The biohybrid fibers were composed of poly (ethylene glycol dimethacrylate) matrices and individually both E. coli and B. cereus were explored as model cellular payloads. Post processing growth curves (24 h) of bacteria within fibers were in excellent agreement with that of controls suggesting minimal impact. Finally, the biohybrid fibers showed even distribution of encapsulated cells and >90% cell viability.

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Sonoco Institute / COMSET Join Forces for 2D Manufacturing

A Joint Sonoco Institute / Center for Optical Materials Science and Engineering Technologies (COMSET) Research and Educational Studio is being created to exploit Clemson’s unique cross-disciplinary capacity and leading-edge technological infrastructure in printed electronics. The studio is located at the Sonoco Institute at the Harris A. Smith building on the Clemson University campus (cf. image). The mission of the studio is to quickly capitalize on its existing advanced materials expertise within COMSET to understand and develop foundational devices (e.g., memory, batteries, sensors, organic light emitting devices, photovoltaics) through printing technologies that are at the core of the Sonoco Institute. Producing examples of technology that testify to the potential of printed electronics is critical to the further development of meaningful innovative products and applications. The mission of this studio is also in-line with Clemson University’s 2020 Plan calling for research and innovation aligned with broad-scale economic growth and will support collaboration among top programs across the university and service key emphasis areas such as Advanced Materials, Sustainable Environment, Transportation Technology, and Biotechnology / Biomedical Sciences. Specific research areas include:

  • Printed photovoltaics and batteries servicing the energy and power industries
  • Solid-state lighting
  • Printed sensors for environmental detection, food packaging, and biomedical uses
  • Radio frequency and near field communications (RF and NFC) technologies for smart cards and other personal security devices
  • Pharmaceutical delivery methods and user compliance through printed medicines, sensors and circuitry.

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Journal Cover: Small n.13 v.8 2012

The cover of the journal Small recently depicted an effort within the group and lead by Michael A. Daniele entitled Substrate-Baited Nanoparticles: A Catch and Release Strategy for Enzyme Recognition & Harvesting . According to this journal:

"Science at the nano- and microscale is currently receiving enormous wordwide interest. Small provides the very best forum for experimental and theoretical studies of fundamental and applied interdisciplinary research at these dimensions. Read an attractive mix of peer-reviewed Communications, Reviews, Concepts, Highlights, Essays, and Full Papers. With an 2010 ISI Impact Factor of 7.333, Small continues to be among the top multidisciplinary journals covering a broad spectrum of topics at the nano- and microscale at the interface of materials science, chemistry, physics, engineering, medicine, and biology."

The isolation of a single type of protein from a complex mixture is vital for the characterization of the function, structure, and interactions of the protein of interest and is typically the most laborious aspect of the protein purification process. In this work, a model system is utilized to show the efficacy of synthesizing a “baited” nanoparticle to capture and recycle enzymes (proteins that catalyze chemical reactions) from crude cell lysate. Enzyme trapping and recycling is illustrated with the carbazole 1,9a-dioxygenase (CARDO) system, an enzyme important in bioremediation and natural product synthesis. The enzymes are baited with azide-modified carbazolyl moieties attached to poly(propargyl acrylate) nanoparticles through a click transformation. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF) and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis indicates the single-step procedure to immobilize the enzymes on the particles is capable of significantly concentrating the protein from raw lysate and sequestering all required components of the protein to maintain bioactivity. These results establish a universal model applicable to concentrating and extracting known substrate–protein pairs, but it can be an invaluable tool in recognizing unknown protein–ligand affinities.

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Journal Cover: Macromolecular Bioscience n.7 v.11 2011

The cover of the journal Macromolecular Bioscience recently depicted an effort within the group and lead by Dr. Parul Rungta entitled Selective imaging and killing of cancer cells with protein-activated near-infrared fluorescing nanoparticles . According to this journal:

"Macromolecular Bioscience is a leading journal at the intersection of polymer and materials sciences with life science and medicine. In its second decade the journal is currently ranked among the top 5 biomaterials journals and is listed among the top 10 polymer journals, with a 2009 ISI Impact Factor of 3.108."

In this effort a general approach for the selective imaging and killing of cancer cells using protein-activated near-infrared emitting and cytotoxic oxygen generating nanoparticles is presented. Poly(propargyl acrylate) (PA) particles were surface modified through the copper-catalyzed azide/alkyne cycloaddition of azide-terminated indocyanine green (azICG), a near-infrared emitter, and poly(ethylene glycol) (azPEG) chains of various molecular weights. The placement of azICG onto the surface of the particles allowed for the chromophores to complex with bovine serum albumin when dispersed in PBS that resulted in an enhancement of the dye emission. In addition, the inclusion of azPEG with the chromophores onto the particle surface resulted in a synergistic ninefold enhancement of the fluorescence intensity, with azPEGs of increasing molecular weight amplifying the response. Human liver carcinoma cells (HepG2) overexpress albumin proteins and could be employed to activate the fluorescence of the nanoparticles. Preliminary PDT studies with HepG2 cells combined with the modified particles indicated that a minor exposure of 780 nm radiation resulted in a statistically significant reduction in cell growth.

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Journal Cover: Soft Matter n.6 v.24 2010

The cover of the journal Soft Matter recently depicted an effort within the group and lead by Dr. Parul Rungta entitled Designing fluoroprobes through Forster resonance energy transfer: surface modification of nanoparticles through ‘‘click’’ chemistry . According to this journal:

"Soft Matter remains at the top of its field with an impact factor of 4.70, according to newly-released ISI citation data (2008). This impressive impact factor represents a rise of more than 7% over the 2006 value and clearly reinforces Soft Matter's position as the best journal where biologists, colloid scientists, physicists, polymer scientists, chemical engineers, chemists, and materials scientists can present work for interdisciplinary inspiration."

In this effort, aqueous-phase 83 nm poly(propargyl acrylate) (PA) nanoparticles were surface-functionalized with sparingly water soluble fluorescent moieties through a copper(I)-catalyzed azide–alkyne cycloaddition (CuAAC) (i.e., ‘‘click’’ transformation) to produce fluoroprobes with a large Stokes shift. For moieties which could not achieve extensive surface coverage on the particles utilizing a standard click transformation procedure, the presence of b-cyclodextrin (b-CD) during the transformation enhanced the grafting density onto the particles. Moieties containing oxadiazolyl groups exhibited an 84% increase in grafting density when the transformation was performed in the presence of the oligosaccharide, going from 1.04 oxadiazolyl groups/nm2 to 1.91 oxadiazolyl groups/nm2. Similarly, an azide-modified coumarin 6 (AD1) underwent a 17% enhancement in grafting density from 1.56 AD1 groups/nm2 to 1.82 AD1 groups/nm2 when the transformation was done in the presence of b-CD. A polyethylene glycol modified naphthalimide-based emitter (AD2) was less sensitive to the presence of b-CD due to its elevated water solubility and exhibited a 5% increase in grafting density.

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Journal Cover: Journal of Materials Chemistry n.14 v.17 2007

The cover of the journal Journal of Materials Chemistry recently depicted an effort within the group and lead by Dr. Moon Gyu Han entitled Polyaniline coated poly(butyl methacrylate) core–shell particles: roll-to-roll printing of templated electrically conductive structures. According to this journal:

"Journal of Materials Chemistry wishes to publish original research that demonstrates novelty and advance, either in the chemistry used to produce materials or in the properties/applications of the materials produced. Work submitted that is outside of these criteria will not usually be considered for publication. ISI Impact Factor of 5.099."

Polyaniline coated poly(butyl methacrylate) core–shell particles were synthesized and formulated into electrically conductive colloidal inks appropriate for use in roll-to-roll printing. Since the first demonstration of an organic field-effect transistor, a specific interest in fabricating low-cost, large area organic electronics through the exploitation of conventional ink-jet, screen, or roll-to-roll printing technologies has developed.

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Journal Cover: Advanced Materials n.21 v.19 2007

The cover of the journal Advanced Materials depicted an effort within the group and lead by Dr. David Evanoff entitled Functionalization of Crystalline Colloidal Arrays through Click Chemistry. According to this journal:

"Advanced Materials has been bringing you the latest progress in materials science for more than 20 years. Read carefully selected, top-quality reviews, communications, and research news at the cutting edge of the chemistry and physics of functional materials. The ISI 2010 Impact Factor of Advanced Materials is 10.857, increased from 2009 (+ 30%) and emphasizing its status as one of the leading journals in materials science. Articles in Advanced Materials continue to be heavily cited after they are published, with a 5-Year Impact Factor over 11."

This article was one of the first applications of click chemistry in the surface functionalization of colloidal particles for an optical application. The preparation of well-defined and regioselectively functionalized ordered colloidal particles through the exploitation of ‘click' transformations was presented; specifically, the copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition between azides and terminal alkynes to form 1,2,3-triazoles was utilized. This approach was demonstrated through the attachment of 9-azidomethylanthracene to post-hydrogel stabilized, ordered poly(propargyl acrylate) colloidal particles.