Office: BSF 312
Phone: (813) 974-3397
Lab: BSF 357,359
B.A., Mercyhurst College, 1971
M.S., Duquesne University, 1973
Ph.D., University of Rochester, 1983
Our research philosophy centers on the premise that applied research is most effective when it is basic in nature. In past years scientists often distinguished between basic and applied research. A more current line of thinking stresses the point that scientists are accountable to society to interface with industry in an effort to focus their basic understanding of scientific principles on the pertinent needs of society.
We have several exciting areas of research in our laboratories, including: high performance polymer composites with increased resistance to different types of radiation, optically transparent polymer/carbon nanotube composites with enhanced mechanical properties, polymer composites with high thermal conductivity, polymer nanocomposites that exhibit magnetic properties and new biocompatible composites based on hydrophilic polymers.
Our group has made important advances in carbon nanotube composite research. The goal of this research is to use carbon nanotubes as radiation sinks, dissipating energy and decreasing the frequency of radiolysis events. Most recently, progress has been made in solubilizing carbon nanotubes in polymer matrices. Optically transparent polymer composites with increased radiation resistance have been designed and tested and analyzed. This research resulted in two patent applications:
Harmon, J. P., Clayton, L., and Muisener, P., USF Invention Disclosure, "Transparent Polymer Nanotube Composites, "USF Ref No: 01B100, December 2001. Patent pending.
Harmon, J. P., Muisener, P., Clayton, L., and D'Angelo, J., USF Invention Disclosure, "Ionizing Radiation Resistant Carbon Nanotube/Polymer Composites", USF Ref. No. 01B090, December, 2001. Patent pending.
Another area of research in our group focuses on interaction of polymeric materials and highly energetic heavy atoms that are known to be part of Galactic Cosmic Radiation (GCR). A biological effectiveness (amount of damage) of the heavy ions consists of two major parts: a) energy transferred by a heavy particle along its trajectory, b) secondary radiation effects due to the nuclear interactions of incoming particles with shield material. Shield materials composed of atoms with small atomic mass (small number of inner shell electrons) have lower possibility of induced X-ray radiation as well as fewer neutrons to release during the nuclear interactions. Polymers consisting of only small atomic weight atoms (carbon, hydrogen) are considered to be promising materials for the production of GCR shields. Our group is in the process of developing new polymer nanocomposites that will show an enhanced resistance to GCR.
A new area of research is concerned with formulation, modification and characterization of biocompatible coatings. Certain hydrogels, due to their high biocompatibility, have been used in biomedical field as contact lens materials, bioadhesives, artificial tissue and implantable devices. The group is now engaged in synthesis and characterization of novel block-copolymer based hydrogel systems.
An important area of research in our group deals with optical fiber materials. This includes developing fiber core and cladding materials with controlled refractive indexes. One project focuses on designing polymeric core materials that are transparent in the near IR region of the electromagnetic spectrum. Another project involves the design in transparent, low refractive index cladding materials. In addition to stringent optical and mechanical criterion, the effect of ionizing radiation on optical and mechanical properties of these materials is also characterized. This work is applicable to space environments and to particle accelerators where scintillating optical fibers are used. Research involves collaborations with Optical Polymer Research Inc. and Honeywell Space Systems Group.
We have developed expertise in structure-property relations of dendrimers. Dendritic structures currently dominate the field of macromolecular chemistry in hopes that they will meet the need of the 21st century. Applications are found in drug therapy, polymer rheology modification and in nonlinear optical devices. Surprisingly, very little work has been done on characterizing these molecules by dielectric analysis. Our group has performed one of the first known dielectric analyses on neat, dendrimer molecules. These molecules exhibit relaxation phenomenon similar to those of linear macromolecules, exhibiting WLF behavior for the glass transition region and Arrhenius behavior for secondary relaxations. This is an area of expanding interest for our group.
View our currently funded projects here.
Synthetic Polymer/Matrix Crystallization
Inductively Based Fluidic (IBF) Sample Preparation for MALDI
Matrix-assisted laser desorption/ionization time of flight mass
spectrometry (MALDI-TOF-MS) is a powerful tool for the
characterization of biomarkers. Extensive, much needed research
is being devoted to improving the reproducibility and sensitivity
of MALDI signals by optimizing sample preparation techniques. We
are one of two universities worldwide to obtain an experimental
sample deposition device based inductively based fluidics (IBF)
that has the potential of greatly increasing signal to noise ratios
and will, hopefully, lead to the standardization of quantitative
MALDI techniques. IBF employs an electric field to kinetically
energize, direct and transport liquids to targets in a highly
parallel manner. It is well known that a plethora of sample
preparation problems currently hinder researchers. There is a lack
of fundamental understanding on how to formulate and deposit MALDI
targets to quantitatively interpret the observed mass spectrum.
The work that we are currently conducting shows that for the same
spot size, the signal to noise ratio for IBF samples is enhanced as
compared to the dry droplet method samples. This is prompting us to
focus more on sample morphology and crystallinity. We are interested
in how the electric field influences uniformity. We are also interested
in how spot sizes effect the signal to noise ratio. It is well known that
methods that concentrate sample spots on targets improve detection. The
IBF unit deposits denser sample with smaller radii than those obtained when
the same volume is deposited via the dry drop method. The nL samples are
enriched. In addition, the delivery is so precise that several depositions
can be made atop one another in layers, affording the opportunity for greater
MALDI samples consist of analytes mixed with a matrix and ion source in a solvent
which are deposited on the MALDI target. The matrix is, in reality, a laser dye.
That is, the spotted target is pulsed via a laser that emits light that is
absorbed by the matrix dye. The matrix is volatilized and pick up the analyte with
it. The analyte is ionized in the process and travels into the mass spectrometer for
analysis. This is a soft ionization technique; the analyte is not fragmented and the
mass can be determined. A vast number of compounds have been tested for use as MALDI
matrices using solvent formulations containing analytes and layering analytes on top
of matrix surfaces. We have selected well studied, high performance, formulations for
this research. Yet, using current deposition techniques, these solid matrices
crystallize during solvent desorption and produce regions of varying analyte
concentrations. For example, when the solutions are deposited by the dry drop method
via a micropipettor, non-uniform sample are produced. When the laser hits the MALDI
target the analyte concentration varies with position. When multiple analytes are used
it is impossible to quantify the concentrations. Matrix non-uniformity has plagued MALDI
operators since the onset of the instrumentation.
We have found that IBF depositions yield samples with distinctively different morphologies.
The series of movies and poster which are linked below illustrate the difference between
sample prepared by IBF and the micropipette. Notice the morphology development versus time
as the samples dry.
The MALDI recipe consists of 5.0 mg/ml Poly (methyl methacrylate) (Mn=10,600 Da)/ 40.0 mg/ml
2,5-dihydroxy benzoic acid/ 5 mg/ml NaTFA/ THF solvent. The components were mixed in a 1:10:1 ratio.
The IBF device was custom designed for us by Nanoliter LLC in Henderson, NV.
- MALDI-TOF-MS Sample Preparation for Synthetic Polymers via Nanoliter Induction Based Fluidic
Link to Poster (PDF) or
- Synthetic Polymer Crystallization Morphology Study for the preparation of samples for MALDI
Video File (Windows Media)
Garrett Craft, Tamalia Julien, Imalka Marasinghe Arachchilage, Alejandro Rivera Nicholls