Research in the Institute of Fluorescence is concerned with the development of new leading-edge and existing fluorescence and plasmonic based phenomenon for resolving clinically, biologically and industrially important questions, as well as addressing areas of immense national and international importance. These include the development of clinical devices for health care safeguard and continuous monitoring, the development of technologies to facilitate the early and rapid detection of bio-warfare agents; as well as developing fundamental scientific principles, which are themselves likely to find a global impact and use.
Under the leadership of Dr Chris D. Geddes, Professor and Director of the Institute of Fluorescence, the research group has earned a well-deserved international reputation for its advances in Fluorescence Spectroscopy. Approaches and concepts developed by the group are well-recognized and used in laboratories around the world.

Dr Chris D. Geddes

Dr Chris D. Geddes is Professor and Director of the Institute of Fluorescence at the Medical Biotechnology Center, University of Maryland Biotechnology Institute. He has a B.Sc. from Lancaster University, UK and a Ph.D. in physical chemistry (fluorescence spectroscopy) from the University of Wales Swansea, UK. He is the Editor-in-chief of the Journal of Fluorescence, Plasmonics, Who's Who in Fluorescence, Reviews in Plasmonics, Reviews in Fluorescence, Co-Editor of the popular series Topics in Fluorescence Spectroscopy, as well as Executive Director of the Society of Fluorescence. Dr Geddes has published over 110 scientific articles, papers, review articles and book chapters, as well as 10 books on the principles and applications of fluorescence.

Research Description

Current research in Dr Geddes' Institute of Fluorescence can be categorized into 3 main areas; Clinical Diagnostics and Health Care; Rapid and Ultra-sensitive Sensing platforms and the Principles of Plasmonics and Plasmon Scatter. Research in these areas is undertaken in the Institute of Fluorescence's two main laboratories: 1) The Laboratory for Advanced Fluorescence Spectroscopy (LAFS) and 2) The Laboratory for Advanced Medical Plasmonics (LAMP).

Over the last few years, Dr Geddes has competitively secured both Federal, State, Military, Industrial and Big Pharma monies in excess of several million dollars in support of his research aspirations and laboratories.

Clinical Diagnostics and Health Care

There are fewer conditions in the world today that influence as many lives as compared to that of diabetes. It is estimated that 18.2 million Americans suffer from diabetes with many more not even knowing they have the condition. Over the last several years, we have been developing a range of glucose sensing contact lenses for use by diabetics. The contact lenses feature fluorescent sensor spots which change color in response to tear glucose levels, which track blood levels with a 30 minute lag time. By simply looking in a mirror and comparing the color change against a color chart, a patient can colorimetrically determine their tear and therefore blood glucose levels.

This leading-edge technology is a significant step forward for the non-invasive monitoring of physiological glucose by diabetics and is particularly attractive to parents of young diabetic children and care workers of the elderly, where self-monitoring and insulin / diet compliance is problematic. This technology has recently received much international press, being featured on the Discovery Channel, on radio broadcasts, in many press releases as well as published in numerous peer-reviewed journals.

At present Dr Geddes's research group is developing the second generation of contact lenses which can monitor other physiological analytes in addition to glucose, such as cholesterol, sodium, potassium, lithium and body core temperature. A range of contact lenses for military applications are also being developed for the detection of different bio-agents. Similar to a car heads-up display, the wearer (soldier) can see sensor spots changing color in response to exposure to different warfare / bio-terrorism agents.

In addition to developing contact lenses for physiological analyte monitoring, the group has recently developed a rapid and sensitive detection method for the clinical assessment of a myocardial infarction. Even if a patient can arrive at hospital soon after the onset of chest pains, current cardiac marker assays still take up to one hour to complete to make an assessment. Current technology in the Institute of Fluorescence enables cardiac marker assays to be kinetically complete in less than 10 seconds, which could significantly go some ways to safeguard human life. In addition, the compactness of our technology may allow the future development of small hand held devices, no bigger than a pregnancy test stick, for heart-attack risk assessment.

Rapid and Ultra-Sensitive Sensing Platforms

Dr Geddes's research group has recently developed a platform technology for ultra fast and ultra sensitive clinical and bio-agent sensing. The new technology combines the use of Metal-Enhanced Fluorescence (MEF) to amplify fluorescence signatures up to a million fold, with the use of low power microwaves. The resultant technology, Microwave-Accelerated Metal-Enhanced Fluorescence (MAMEF), when applied to bio-agent detection, allows for their fast and sensitive detection. This technology may allow first responders to assess on-site, both the nature and concentration of a reagent, without the need for time consuming laboratory processing and amplification, such as by real-time PCR.

For clinical settings, Dr Geddes and his team are assessing the use of MAMEF for the early detection of Staphylococcus Aureous. It may be possible that infections after an operation, can be quickly detected and therefore treated.

Principles of Plasmonics and Fluorescence

Over the past 5 or so years the Institute of Fluorescence has described new plasmonic-based technologies which promise to fundamentally change the way we both use and employ fluorescence and other sensing technologies today.

Although fluorescence is a highly sensitive technique, where single molecules can even be detected, there is still a drive for reduced detection limits. The detection limit is usually limited by the quantum yield of the fluorophore, the autofluorescence of the samples and the photostability of the fluorophores. However, there has been a recent explosion in the use of metallic nanostructures to favorably modify the spectral properties of fluorophores and to alleviate some of their photophysical constraints. The use of fluorophore-metal interactions has been termed both Radiative decay engineering and also metal-enhanced fluorescence (MEF) by Dr Geddes and his colleagues. The uses of MEF have included the increased detectability and photostability of fluorophores, improved DNA detection, the release of self-quenched fluorescence of over labeled proteins, enhanced wavelength-ratiometric sensing and the application of metallic surfaces to amplified assay detection, to name but just a very few. In addition, our laboratories have developed many surfaces for metal-enhanced fluorescence such as those comprised of silver islands, silver colloids, silver nano triangles, silver nanorods, and even fractal-like silvered surfaces. Several modes of silver deposition have also been developed, such as silver deposition by light and electrochemically, on glass, plastics and even electrodes.

Current research in the Institute of Fluorescence is focused on further understanding this near-field plasmonics effect, with the vision of developing better clinical sensing and molecular imaging platforms.

Plasmon Scatter: Theory and Application

Surface plasmons are collective oscillations of free electrons at metallic surfaces. These oscillations can give rise to the intense colors of solutions of plasmon resonance nanoparticles and/or very intense scattering. While the use of plasmonic particle absorption based bioaffinity sensing is now widespread throughout biological research, the use of their scattering properties is relatively ill explored. We refer to the use, utility and control of surface plasmons as Plasmonics, an expression coined by Dr Geddes and his co-workers.

In this institute of fluorescence new plasmon scattering theory and applications are being developed. These include the use of plasmon scatter for long-range immunosensing and macromolecular conformation studies, as well as the ability to image cell surface receptors for cancer imaging.
Perhaps one of the most profound future applications of plasmon scatter, is likely to be in the measurement of distances in the range 10-300 nm for biological systems. Today, optical distance measurements less than 10 nm are undertaken using FRET between a fluorescent donor and an acceptor. Distances ranging from macroscopic to about /2, typically about 300 nm, can be measured using confocal, multiphoton and/or laser scanning methods. While atomic force microscopy and scanning tunneling microscopy can measure these distances, these approaches are not readily compatible with biological species, such as with live cells. However we are currently investigating the possible use of long-range plasmon coupling between particles to measure such distances, where the coupling occurs to a minimum value at about 2.5 times the diameter of the colloids. Subsequently, we predict that long-range FRET based on plasmonics will be possible, based on the changes in the scattering, absorption and polarization properties of suitably sized colloids. Interestingly, the coupling distance (transfer distance in FRET) will be dependent on the wavelength of light and the initial choice of colloid size. This approach may be of significant importance for studying macromolecular dynamics and particularly in immunoassays, which typically have dimensions far too large for classical FRET. While the theory for distance measurements using plasmonics has yet to be realized, the lack of a discrete physical dipole may prove simpler than fluorophore dipole-dipole coupling. Theory in this regard is currently underway in the Institute of Fluorescence and is likely to find immense importance in the biological and clinical sciences.

Editorialships

Dr Chris D. Geddes is the editor-in-chief of the Journal of Fluorescence, an international forum for the publication of peer-reviewed original articles that advance the practice of this established spectroscopic technique. Topics covered include advances in theory/and or data analysis, studies of the photophysics of aromatic molecules, solvent, and environmental effects, development of stationary or time-resolved measurements, advances in fluorescence microscopy, imaging, photobleaching/recovery measurements, and/or phosphorescence for studies of cell biology, chemical biology and the advanced uses of fluorescence in flow cytometry/analysis, immunology, high throughput screening/drug discovery, DNA sequencing/arrays, genomics and proteomics. Typical applications might include studies of macromolecular dynamics and conformation, intracellular chemistry, photon migration in tissues and gene expression. See us at http://www.kluweronline.com/issn/1053-0509

Dr Chris D. Geddes is also the founding editor and editor-in-chief of Plasmonics, a new Springer Journal. Plasmonics is an international forum for the publication of peer-reviewed leading-edge original articles that both advance and report our knowledge base and practice of the interactions of free-metal electrons, plasmons. Topics covered include notable advances in the theory, physics, and applications of surface plasmons in metals, to the rapidly emerging areas of nanotechnology, biophotonics, sensing, biochemistry and medicine. Topics, include the theory, synthesis and optical properties of noble metal nanostructures, patterned surfaces or materials, continuous or grated surfaces, devices, or wires for their multifarious applications. Plasmonics publishes papers that describe new plasmonic based devices, new synthetic procedures for the preparation of nanostructures and their optical properties, as well their applications in analytical sensing.

Dr Geddes is also the founding editor and editor-in-chief of both the Reviews in Fluorescence (RIF), and Reviews in Plasmonics (RiP), both annual hard bound book serials. The RIF and RIP serve as comprehensive collections of trends and emerging hot topics in the fields of both Fluorescence and Plasmonics respectively. Both volumes summarize the year's progress in the respective fields, with authoritative analytical reviews, specialized enough to be attractive to professional researchers, yet also appealing to the wider audience of scientists in related disciplines of Fluorescence and Plasmonics.

Dr Geddes is both the Founding Editor and Editor-in-chief of Who's Who in Fluorescence annual volume(WWIF). With over 20,000 copies both sold and disseminated around the world to date, the WWIF serves as a comprehensive archive of fluorescence scientists' interests, contact details and specialty keywords. In addition, Dr Geddes recently introduced a new personal publication statistic in the volume. Similar to ISI journal impact numbers, Dr Geddes's AIM number (Author Impact Measure) calculates author's individual publication statistics for any given year.

Dr Geddes is the Co-editor, with Dr Joseph R. Lakowicz, of the popular book series Topics in Fluorescence Spectroscopy. To date 10 books have been published in this edited volume series by many authors from around the world. The latest volume, Volume 11, "Glucose Sensing", is due to be published in early February 2006.