Project 5: Nanotechnology-based environmental sensing
WORK ON THIS PROJECT COMPLETED IN 2014
Remediation of highly contaminated Superfund sites requires monitoring and evaluation of the contaminants themselves and their byproducts. Superfund sites have diverse and complex toxic species that contaminate soils, water and the surrounding air; determining what is there, and then determining the extent and effectiveness of remediation continue to present challenges. The rapid development of nanotechnology has offered significant opportunities to produce new sensors for the characterization and monitoring needs of Superfund, not only in the gas phase, but in the different environments where toxic and/or hazardous materials are produced or where they accumulate. We will take advantage of the unique properties of nanoscale materials to detect and measure species such as heavy metals. We plan to develop a collection of sensing protocols for the detection of arsenic, mercury and flame retardant compounds with high sensitivity and specificity. We will develop and apply small-molecule chemical indicators for fluorescence detection of mercury, lead, cadmium, and other toxic heavy metals in environmental laboratory and field samples, with specific interest in seafood and soil specimens. Parallel with this effort, plasmon absorption spectroscopy based on metal nanocrystals will be used for low-cost, rapid detection of mercury in air and aqueous environmental samples. We will continue to develop silver nanocrystal based substrates for ultra-sensitive arsenic detection using surface enhanced Raman spectroscopy. We will extend this sensing platform towards detecting chemical fingerprint for the analytes, distinguishing between the two most common oxidation states of arsenic: arsenate (AsV) and arsenite (AsIII) both in ground water and some other complex media. Similarly this sensing scheme will be applied towards detection of methylated arsenic species with high sensitivity using small sample volume. In addition, we will also develop a sensitive and selective miniaturized electronic sensor for environmental toxicants molecules such as polybrominated diphenylethers (PBDE) using specific molecular recognition elements. These studies should provide new methods to detect and measure chemical and biological species at Superfund sites. The new methods will also be useful for assessing remediation efforts and the reduction of hazardous species at known sources.
This is relevant because novel sensing methods based on nanoscale materials could be deployed to gather more information about the extent of contamination as well as for verifying that cleanup methods are effective. Our proposal seeks to further explore the unique properties of materials on the nanoscale, and to exploit that knowledge to develop new sensing elements embodied in small molecules, nanoparticles and their ensembles. Our work focuses on the detection and quantification of heavy metals such as arsenic and mercury, and certain flame retardant compounds; these methods have the potential to be extended to other targets of interest.
Catherine P. Koshland, PhD
Professor, Engineering and Environmental Health Sciences
Vice Provost for Teaching, Learning, Academic Planning & Facilities, UC Berkeley
Environmental Health Sciences,
School of Public Health
University of California, Berkeley
Donald Lucas, PhD
Environmental Health Sciences,
School of Public Health
University of California, Berkeley
Environmental Energy Technologies Division
Lawrence Berkeley National Laboratory
Based on previous research in Project 5, we received an Administrative Supplement to develop and manufacture a cheap and effective sensor of environmental mercury contamination. We looked at peaks in absorbance caused by localized surface Plasmon resonance (LSPR). Mercury causes changes in the composition and refractive index of nanoparticles, causing a shift in observable peak absorbance.
Our research lead to the development, design, construction, and testing of a robust mercury-sensing prototype. With this device, we were able to measure ng/m3 concentrations of mercury in samples we obtained. We tested the prototype for interferences from possible co-existing contaminants. On a heated stage the nanoparticle film shows no response to water vapor, carbon dioxide (20%), sulfur dioxide (2000 ppm), and NOx (501 ppm). This is a key advantage of the technology compared to other spectrometry techniques for mercury measurement that show interferences from all of these contaminants. The levels tested were based on the high levels found in untreated coal exhaust. We manufactured films using the Langmuir-Blodgett method because it allows control over the packing density and produces uniform batches. Regenerating the films is easily done by heating them above 212 degrees farenheit, which vaporizes the mercury and frees space on the surface for repeated measurement.
The optical response of the sensor is directly proportional to the absorbed mercury mass, which is the intrgral of the vapor concentration. To return a value of concentration, we track the time derivative of the response. The tested dynamic range spans 4 orders of magnitude. By controlling the sample flow rate, we can provide equivalent time resolutions across a range of concentrations. We adapted EPA method 1631 for use with our plasmonic sensor. After oxidation/reduction, the elemental mercury vapor is collected and measured by the nanoparticle film. We showed the feasibility of aqueous detection with gold nanopartyicle plasmonic transducer and directly detected mercury in ranges below the EPA limit. The mass limit of detection is ~5 pg, with only 2 atoms of absorbed mercury needed per particle for a measurable change in absorbance.
The cost of gold needed is miniscule, $0.0001 of gold per sensor chip. Operational costs are pennies per hour with low power requirements. The sensor can be built with off-the-shelf components. The advantages of our sensor are:
- Mercury vapor is collected and measured in a single step using a regenerating film of gold nanpoarticles, reducing contamination and measurement errors,
- Oxygen does not interfer with the measurement, so no inert gas is required,
- Uses solid state components and has a small footprint,
- Measures ambient mercury without sample preconcentration.
The sensor can also be regenerated by heat for reuse.
Heavy metals such as mercury and arsenic continue to pose significant human and environmental health risks. They are found in many Superfund sites, as well as throughout the world. We development an inexpensive, simple, and robust sensor for ultra-sensitive, continuous mercury detection would allow more measurements of these species in the environment, and could reduce the exposure of humans and animals. Sensors such as ours that can be used in remote locations and developing countries will help policy makers fill gaps in emission monitoring of mercury identified by the European Commission’s Global Mercury Observation System.
We plan commercial production and distribution of our sensor.
- Our design was awarded U.S. Application Nos. 61/585,542 and 61/587,546. January 10, 2013 (filed). The International Patent Application has been accorded serial number PCT/US2013/021066.
James JZ, Lucas D, Koshland CP (2013). Elemental mercury vapor interaction with individual gold nanorods. Analyst. 138(8):2323-8. PMID: 23446550. [PMCID Journal – In Process].
James JZ, Lucas D, Koshland CP (2012) Gold nanoparticle films as sensitive and reusable elemental mercury sensors. Environ Sci Technol. 46(17):9557-62. PMCID: PMC3446241.
James JZ, Lucas D, Koshland CP (2012) Gold nanoparticle films as sensitive and reusable elemental mercury sensors. Environ Sci Technol. Sep 4;46(17):9557-62. PMCID: PMC3446241. [PDF]
Holder AL, Carter, BJ, Goth-Goldstein, Lucas D, Koshland CP (2012) Increased Cytotoxicity of Oxidized Flame Soot. Atmos. Pollution Res. Jan;3(1):25-31. doi: 10.5094/APR.2012.001. (PMC Journal – In Process). [PDF]
Babrauskas V, Lucas D, et al. (2012) Flame retardants in building insulation: a case for re-evaluating building codes. Building Research and Information. 40(6):738-755. doi: 1080/09613218.2012.744533. (PMC Journal – In Process). [PDF]
Shick SF, Farraro KF, Fang J, Nasir S, Kim J, Lucas D, Wong H, Balmes J, Giles DK, Jenkins B (2012). An Apparatus for Generating Aged Cigarette Smoke for Controlled Human Exposure Studies. Aerosol Science and Technology. 2012;46 (11):1246-1255 doi: 10.1080/02786826.2012.708947. (PMC Journal – In Process). [PDF]
Mulvihill M, Ling X, Heinzie J, Yang P (2010) Anisotropic etching of silver nanoparticles for plasmonic structures capable of single-particle SERS. J Am Chem Soc. Jan 13;132(1):268-74. PMID: 20000421. [PDF]
Holder AL, Lucas D, Goth-Goldstein R, Koshland CP (2008) Cellular response to diesel exhaust particles strongly depends on the exposure method. Toxicol Sci. May; 103(1):108-15. PMID: 18227103. [PDF]
Mulvihill M, Tao A, Benjauthrit K, Arnold J, Yang P (2008) Surface-Enhanced Raman Spectroscopy for Trace Arsenic Detection in Contaminated Water. Angewandte Chemie International Edition. 47(34):6456-60. PMID: 18618882. [PDF]
Holder AL, Lucas D, Goth-Goldstein R, Koshland CP (2007) Inflammatory response of lung cells exposed to whole, filtered, and hydrocarbon denuded diesel exhaust. Chemosphere. Nov; 70(1):13-9. PMID: 17767946. [PDF]
Choi JH, Koshland CP, Lucas D (2007) Laser Ablation of Nanoscale Particles with 193 nm Light. J. Physics: Conference Series. 59:54-59. doi:10.1088/1742-6596/59/1/012. [PDF]
Scallan K, Koshland CP, Lucas D (2007) Optical Characterization of the Interaction of Mercury with Nanoparticulate Gold Suspended in Solution. Sensors & Transducers Journal. 85(11):1687-98. [PDF]
Das R, Dimitrova N, Xuan Z, Rollins RA, Haghighi F, Edwards JR, Ju J, Bestor TH, Zhang MQ (2006) Computational prediction of methylation status in human genomic sequences. Proc Natl Acad Sci U S A. Jul 11; 103(28):10713-6. PMID: 16818882. PMCID: PMC1502297. [PDF]
Choi JH, Stipe CB, Koshland CP, Lucas D, Choi JH (2006) In situ, real-time detection of soot particles coated with NaCl using 193 nm light. Applied Physics B-Lasers and Optics. 84(3):385-8. [PDF]
Choi JH, Lucas D, Koshland CP, Sawyer RF (2005) Photochemical interaction of polystyrene nanospheres with 193 nm pulsed laser light. J Phys Chem B. Dec 22; 109(50):23905-10. PMID: 16375376. [PDF]
Stipe CB, Lucas D, Koshland CP, Sawyer RF (2005) Soot particle disintegration and detection by two-laser excimer laser fragmentation fluorescence spectroscopy. Appl Opt. Nov 1; 44(31):6537-44. PMID: 16270542. [PDF]
Choi JH, Koshland CP, Sawyer RF, Lucas D (2005) Measurement of polystyrene nanospheres using excimer laser fragmentation fluorescence spectroscopy. Appl Spectrosc. Oct; 59(10):1203-8. PMID: 16274531. [PDF]
Choi JH, Damm CJ, O’Donovan NJ, Sawyer RF, Koshland CP, Lucas D (2005) Detection of lead in soil with excimer laser fragmentation fluorescence spectroscopy. Appl Spectrosc. Feb; 59(2):258-61. PMID: 15720768. [PDF]
Choi JH, Stipe CB, Koshland CP, Sawyer, RF, Lucas D (2005) NaCl particle interaction with 193nm light: UV photofragmentation and nanoparticle production. J. App.Phys. 97(12):124312. [PDF]
Fischer S, Koshland CP, Young J (2005) Social, Economic, and Environmental Impacts Assessment of a Village-Scale Modern Biomass Energy Project in Jilin Province, China: Local Outcomes and Lessons Learned. Energy for Sustainable Development. Vol IX(4):50-9.