Fiber science aspects of an interdisciplinary project aiming to combine the high surface area and liquid transport capabilities of non-woven fabrics with the selectivity and sensitivity of nano-biosensor systems will be described.  Biotin has been incorporated into Poly lactic acid (PLA) electrospun fibers by either suspending biotin in the spinning dope or dissolving biotin in the spinning dope.  Significant loading of biotin (10-18% w/w PLA) was achieved by both methods.  Suspension of the biotin in the resulting fibers was mapped by Electron Probe Microanalysis (EPMA) via detection of the sulfur atom in the biotin molecule.  Any crystallization of biotin in the fibers was measured with differential scanning calorimetry (DSC) and X-ray diffraction (XRD).  Biotin incorporated via suspension in the spinning dope aggregated and to some extent crystallized in the resulting fibers.  Biotin incorporated via dissolution in the spinning dope was well dispersed in the PLA fibers and did not form measurable crystals.  In both cases, biotin incorporated in the PLA fibers was accessible for subsequent binding with protein molecules.  When biotin is dissolved in the spinning solution, significant segregation towards the exterior of the fiber occurs.  Biotin incorporated in fibers is available for streptavidin binding and subsequent activation with biorecognition agents.  Initial estimates for sensitivity of the system confirm detection of fluorescence labeled analytes in femptomolar concentrations.

Margaret Frey received her Ph.D. in Fiber and Polymer Science from the College of Textiles at North Carolina State University and then spent 6 years in industry working on Monofilament melt extrusion, reactive polymer blending and electron beam crosslinking. Her appointment as Assistant Professor in Textiles and Apparel offered the opportunity to return to her alma matter.  Dr. Frey is an alumna of both the School of Chemical Engineering and the Department of Textiles and Apparel.

Research Interests

Electrospun sensor assemblies

In collaboration with researchers from Biological and Environmental Engineering and Chemical and Biomolecular Engineering, sensor materials capable of detecting biohazards are being incorporated into electrospun fibers. The small diameter of electrospun fibers collected as a non-woven fabric results in a high surface area available for detection. The porous structure of the non-woven acts as a sponge to pull analytes contained in liquids to the sensor sites.

Cellulose dissolution and fiber formation

Using the ethylene diamine/salt solvent system for cellulose, analytical work is in progress to determine the mechanism of cellulose dissolution. NMR, FTIR, dynamic rheology, and microscopy are used to determine the role of each solution component and the phases formed in the system. Cellulose solutions are then used to form fibers and films via wet spinning, dry-jet wet spinning and electrospinning techniques.

Electrospun controlled absorption, timed-release fabrics

Non-woven fabrics comprised of electrospun fibers are being developed for controlled absorption and release of chemicals. The high surface area, high porosity and small pore size of the fabrics all contribute to absorption and release performance. Surface chemistry of the non-woven fabrics can be further tailored by combining hydrophilic and hydrophobic fibers. The first target application uses biodegradable, renewable resource polymers to create controlled release agricultural chemical delivery systems.