Compound Specific Imprinted Nanospheres for Optical SensingEPA Grant Number: R830911
Title: Compound Specific Imprinted Nanospheres for Optical Sensing
Investigators: Lavine, Barry K. , Fendler, Janos , Seitz, William Rudolf
Institution: Clarkson University , University of New Hampshire - Main Campus
Current Institution: Oklahoma State University - Main Campus , Clarkson University , University of New Hampshire - Main Campus
EPA Project Officer: Carleton, James N
Project Period: August 24, 2003 through August 23, 2006 (Extended to August 31, 2010)
Project Amount: $323,000
RFA: Environmental Futures Research in Nanoscale Science Engineering and Technology (2002) RFA Text | Recipients Lists
Research Category: Nanotechnology , Safer Chemicals
The objective of the proposed research is to investigate the use of molecularly imprinted polymers as the basis of a sensitive and selective sensing method for the detection of pharmaceutical and other emerging organic contaminants at parts per billion (ppb) levels in aquatic environments. The effects of polymerization conditions including formulation, temperature, and solvent on the size, selectivity, and sensitivity of the molecularly imprinted polymers employed will be determined. Both the sensitivity and selectivity of prototype sensors developed from the molecularly imprinted polymers will be evaluated in a realistic milieu using samples of known buffering capacity, ionic strength and bivalent metal content.
The research will involve the preparation of moderately crosslinked, molecularly imprinted polymeric microspheres and nanospheres that are designed to swell and shrink as a function of analyte concentration in aqueous media. These spheres will be incorporated into hydrogel membranes. Chemical sensing is based on changes in the optical properties of the membrane that accompany swelling of the molecularly imprinted nanospheres. Two effects contribute to this change. One is an increase in the size of the microspheres, and the other is a change in the refractive index. Because swelling leads to an increase in the percentage of water in the polymer, the refractive index of the nanospheres will decrease as they swell. This brings them closer to the refractive index of the hydrogel membrane, leading to a decrease in the amount of light scattered/reflected by the microspheres. For the systems that we will be studying, the change in refractive index will be the dominant effect. This change will be measured by surface plasmon resonance spectroscopy (SPR). The prototype SPR sensor will be capable of detecting pollutants and hazardous materials selectively at ppb levels.
The U.S. Geological Survey reported in the March 2002 issue of Environmental Science and Technology that steroids, hormones, antibiotics, and numerous other prescription and nonprescription drugs, e.g., caffeine and ibuprofen, are present in streams throughout the U.S. at parts per billion levels. The continual input of organic contaminants and pharmaceutical compounds such as reproductive hormones, steroids, antibiotics, prescription and nonprescription drugs, and products used in everyday life such as detergents, disinfectants, and plasticizers, into the environment affords these substances a persistence quality. Unfortunately, little is known about the toxicity of these compounds so it is difficult to predict what health effects they may have on humans or aquatic organisms as a result of their persistence in the environment. In addition, monitoring data are lacking, largely due to the paucity of field based inexpensive rapid methods of analysis for the determination of the concentrations of these contaminants in aquatic systems. As a first step towards investigating the transport of these contaminants in the nation's waterways, it will be necessary to develop inexpensive field-based methods that can monitor the concentration of these organic contaminants in a variety of aquatic environments. The work described in this proposal, the development of field based inexpensive, and rapid sensors for the detection and determination of emerging organic and pharmaceutical compounds in water, will have an impact on how the nation will approach the monitoring, regulation, clean-up, and ultimate removal of these contaminants from U.S. waters.