Polymer Based Lanthanide Luminescent Sensors for the Detection of Organophosphorous Compounds
A number of organophosphorus compounds are used in nerve agents, including the chemically similar organo-fluorophosphorus compounds found in nerve gasses such as Sarin and Soman. Detection and quantification of these highly toxic compounds by remote sensors at very low levels are critical. Although a variety of physical, chemical and biological techniques have been investigated, few sensors are small and inexpensive enough to be used in military or environmental situations.
Methods for the unambiguous detection and quantification of specific gasses usually involves separate sampling and analysis steps using complex and expensive items such as gas chromatography with detection by either flame ionization or mass spectrometry. Devices based on this technology are not portable and are expensive and/or require extensive analysis procedures making them undesirable for real-time field analysis. Optical sensors generally rely on detecting small changes in indices of refraction. Testing can take up to 24 hours to perform, and frequently lacks specificity, simplicity, rapid detection and portability. Surface acoustic wave (SAW) devices offer many advances over these technologies, but typically lack selectivity, especially with respect to chemically similar organophosphorus compounds, e.g., pesticides and insecticides, making false positive readings a major concern.
The Johns Hopkins Applied Physics Lab has developed molecularly imprinted polymers (MIP), a class of synthetic polymers that may be tailored to selectively detect a particular substance. The molecular imprinting technique involves a polymer, which has been synthesized in the presence of a target molecule, being used to separate a target molecule from other species. The polymers are constructed with ligands to contain cavities which closely match the shapes of various analyte molecules. The analyte molecules are incorporated into a pre-polymeric mixture and allowed to form bonds with the pre-polymer. The mixture is then polymerized with the analyte molecules in place. Once the polymer has formed, the analyte molecules are removed, leaving behind cavities with the analyte molecule's shape. In this way, a particular molecule can be identified since the shape of the cavity is specific to the molecule modeled. This method of identifying a particular molecule is attractive because of the simplicity of the preparation of the polymer and the simplicity and specificity of the identification of a target molecule.
APL has developed this invention to provide a sensor probe/transducer having a MIP containing a lanthanide-complex capable of exhibiting very narrow emission bands at wavelengths above 500 nm for detecting organophosphorus compounds in the parts per billion (ppb) to parts per quadrillion (ppq) levels. This MIP nerve gas sensing technology has many potential embodiments, from being bound to a suitable substrate (i.e., a badge worn by a person), to being used for extraction and preconcentration purposes, to be used as part of a directed fiber optic sensor device, and/or as part of a surface acoustic wave sensor to provide the selectivity they currently lack. This invention is expected to produce a field portable device that will potentially be comparable in size to a pH meter.
Patent Status: U.S. patent(s) 7416703; 6749811 issued.
*US and International patents pending. APL is seeking an exclusive license partner.CONTACT:
Dr. G. R. Jacobovitz
Phone: (443) 778-9899