Group News and Events:
- Kevin Dorney, First place Award for the Oral Presentation of "Routes to Single-Molecule SERRS-based Detection using Concentrated, Unfunctionalized Silver nanoparticles." at the The 6th Annual Cleveland State Interdisciplinary Research Conference (CSIRC), November 3rd, 2012, Cleveland, OH.
- C.B. Anders, J. D. Baker, A. C. Stahler, A. Williams, J. N. Sisco, J. C. Trefry, D. P. Wooley, and I. E. Pavel Sizemore, Tangential Flow Ultrafiltration: A “Green” Method for the Size Selection and Concentration of Colloidal Silver Nanoparticles, Journal of Visualized Experiment, e4167, 2012, 1-9.
- Joshua Baker -Thesis Defense, July 26, 2012, 10:00 AM, 449 Oelman Hall
- Adam Stahler, Wright State University, 2012 Graduate Student Excellence Award
- Catherine Anders Wright State University, College of Science and Mathematics (CoSM), 2012 Outstanding GTA Teaching Award
IOana e. pavel Sizemore, ph.d - research
The National Science Foundation has recently predicted that approximately 1 million jobs will be created in the Unites States nanotechnology sector. Over 80% of these employment opportunities will require training in nanotechnology and nanoscience. Unfortunately, very few schools offer such trainings at the undergraduate level. Our main goal is develop research-inspired nanotechnology and nanoscience laboratories for several laboratory courses including instrumental analysis, physical chemistry and nanotechnology.
The first NANOTECHNOLOGY AND NANOSCIENCE LABORATORY on campus will start in Fall 2012 semester and will be open to both undergraduate and graduate students from the College of Science and Mathematics and the College of Computer Science and Engineering. It will be team-taught by Dr. Ioana (Pavel) Sizemore, Dr. Steven Higgins, Dr. Jason Deibel and Dr. Hong Huang. All laboratory modules will be research-oriented and will make use of cutting-edge technologies and state-of-the-art instrumentation. This unique laboratory will be developed with the help of a grant from the National Science Foundation – Nanotechnology Undergraduate Education Program (NSF-NUE). Students interested in learning more about the course should contact any of the four faculties.
Silver nanomaterials are at the leading edge of the rapidly developing fields of nanotechnology and nanoscience. Due to their unique physical and chemical properties, silver nanomaterials find numerous industrial and research applications. For example, silver nanomaterials are used in biology and medicine for drug delivery, biosensing, imaging, as antimicrobials, cancer therapeutics, and so on. Industrial applications include solar cells, conductive coatings, inks or pastes, batteries, data storage, additive for plastics and waxes, optical devices and filters, etc. In addition, the incorporation of silver nanomaterials into consumer products has experienced a huge increase for the past 10 years. Silver is overwhelmingly the most prevalent nanomaterial in consumer products, i.e., 259 products or 57% of the total products. The incorporation of silver nanomaterials into consumer products exploits the historic and scientifically proven antimicrobial and antiangiogenic properties of silver. Examples of these products include body soap, toothpaste, dietary supplements, laundry detergents, antimicrobial gels, and wall paints. Other product categories include home and garden, food and beverage, appliances, medical applications, etc.
Nowadays, Raman spectroscopy is extensively and routinely used as a sensitive analytical method. Raman spectra are information rich, producing a vibrational "fingerprint" unique to each Raman active molecule. One of the main advantages of this technique is that it can differentiate between molecules that have similar structures and exhibit the same fluorescence emission profiles. The Raman spectra of such molecules will have a different spectral pattern. Furthermore, Raman spectroscopy has the advantage of being compatible with aqueous systems. Surface-enhanced Raman spectroscopy (SERS) is an embodiment of Raman spectroscopy that has all molecular “fingerprint” capabilities of Raman and extremely high sensitivity. The SERS effect occurs when the analyte molecules of interest reside at appropriate sites or near nano-structured systems composed of noble metals (e.g., silver or gold). On average, the SERS enhancement factor ranges between 3 and 6 orders of magnitude. Recently, theory predicted and experiment confirmed that exceptionally large Raman cross-section increases are associated with molecules located in between aggregates of silver nanoparticles (AgNPs). The cross-sections normally measured for Raman (10-30-10-25 cm2 per molecule) can be increased under favorable SERS circumstances by as much as 11 to 14 orders of magnitude. These enhancement factors correspond to single-molecule SERS events and rival those of fluorescence-based detection methods. One of the most exciting and demanding applications of SERS involves the real-time detection of biological and chemical warfare agents at ultralow concentrations. Unfortunately, no analytical technique or traditional detection method is able to simultaneously detect a multitude of hazardous materials at very low concentrations in a rapid, reliable manner or without the use of an extensive infrastructure. For all these reasons, one of the main projects in our group focuses on the development of ultrasensitive SERS-based nanosensors for the detection of specific biological and chemical warfare agents.
One of the most exciting applications of SERS is intracellular molecular imaging. SERS-based imaging of living cells is still in its infancy and continuously experiences new challenges. To date, the SERS-based sensing method was reported to facilitate the intracellular detection of a) exogenous chemicals including drug molecules (e.g., monitoring the interaction of doxorubicin with cancerous cells) and b) specific analyte molecules attached to the nanoparticles’ surface (e.g., nanoparticles are functionalized with 4-mercaptobenzoic acid and used for intracellular pH measurements). Most of the SERS studies in living cells used noble metal nanoparticles as SERS-substrates. Any biological molecule that is located within several nanometers of the nanoparticle(s) may be detected and may contribute to the overall SERS signal. These nanoparticles should be benign to the cellular environment and small enough to penetrate the cellular matrix (i.e., to be up taken by the cell) but large enough to give a strong SERS enhancement (the SERS effect is highly dependent on the nanoparticle size). Many biological molecules have strong Raman signatures (i.e., good Raman cross-sections). Two other major challenges result from difficulties with a) controlling the cellular uptake and transport of nanoparticles, and b) identifying specific bioanalyte molecules from the complex SERS spectral patterns. Our group focuses on overcoming some of these challenges.
TNowadays, the majority of new cars sold worldwide are equipped with catalytic converters that transform toxic automobile exhaust emissions into less harmful substances using platinum group metals (PGMs). Palladium (Pd) and rhodium (Rh) are primarily used for automobile catalysis, whereas platinum (Pt) is also utilized as a catalyst in the control of industrial plant emissions. Although these processes successfully improved urban air quality, the deterioration of the PGM catalysts has increased the deposition of PGM particulates alongside highly trafficked roadways and in the environment. As plant materials along roadways uptake and accumulate PGMs, the metals may increasingly enter the food chain of humans and animals raise major concerns about the environmental impact and toxicity of these elements. Our preliminary studies on developing chick embryos indicate the presence of histological changes in the brain tissue and severe skeleton deformities as a result of PGM exposure levels higher than 0.5 ppm. The undeveloped blood-brain barrier was found to permeable to PGMs and to lead to the formation of anomalous calcific inclusions in the brain neurons of embryos. An unknown mechanism is triggered when the developing chick embryos are injected with controlled amounts of PGMs. Our main research goals are to demonstrate that PGMs accumulate in the bone tissue of developing chick embryos and to establish the PGM threshold levels at which abnormal changes in the Ca content and distribution occur within the bone tissue. To achieve these goals, various analytical techniques will be employed (e.g., FAAS, ICP-OES, XRF, and micro-Raman spectroscopy). In particular, Raman spectroscopy will be used to map the chemical composition and morphology of the bone tissue at the nano and microscopic scale.
This is a collaborative project with Prof. Mark N. Goltz at the Air Force Institute of Technology (AFIT) of Wright Patterson Air Force Base and Dr. Sushil R. Kanel, a National Research Council Visiting Scholar working with Dr. Goltz.
Nanosilver is the largest and fastest growing category of nanomaterials, with applications ranging from electronics, medicine, cosmetics, to textiles. A growing number of studies show that nanosilver may pose significant adverse human and environmental effects. Given the ubiquity of nanosilver and its potential toxicity, it is incumbent upon us to understand its environmental fate and transport. Due to the importance of groundwater as a pathway from contamination sources to human and environmental receptors, this study will look at how colloidal silver nanoparticles (AgNPs) are transported in saturated porous media. The transport of various AgNPs in saturated porous media (glass bead-packed column) will be investigated and compared with the transport of a nonreactive tracer. The tracer and AgNPs will be injected into a background solution flowing through columns packed with water-saturated glass beads to obtain outlet concentration versus time breakthrough curves. AgNP breakthrough data will then be simulated using a modified advection-dispersion model. The modified model will incorporate both irreversible and reversible attachment of the AgNPs to the porous media. Our results will be useful in assessing the risk of AgNPs that are released into groundwater.