Crewmembers of current and future long duration spaceflights require drugs to overcome the deleterious effects of weightlessness, sickness and injuries. Unfortunately, recent studies have shown that some of the drugs currently used may degrade more rapidly in space, losing their potency well before their expiration dates. To complicate matters, the degradation products of some drugs can be toxic. Consequently there is a need for an analyzer that can determine if a drug is safe at the time of use, as well as to monitor and understand space-induced degradation, so that drug types, formulations, and packaging can be improved. Towards this goal we have been investigating the ability of Raman spectroscopy to monitor and quantify drug degradation. Here we present preliminary data by measuring acetaminophen, and its degradation product, p-aminophenol, as pure samples, and during forced degradation reactions.
One of the greatest dangers of drug use is in combination with driving. According to the most recent National
Highway Traffic Safety Administration (NHTSA) studies, more than 11% of drivers tested positive for illicit drugs,
while 18% of drivers killed in accidents tested positive for illicit, prescription or over-the-counter drugs.
Consequently, there is a need for a rapid, noninvasive, roadside drug testing device, similar to the breathalyzers used
by law enforcement officials to estimate blood alcohol levels of impaired drivers. In an effort to satisfy this need we
have been developing a sampling kit that allows extraction of drugs from 1 mL of saliva and detection by surfaceenhanced
Raman spectroscopy using a portable Raman analyzer. Here we describe the development of the sampling
kit and present measurements of diazepam at sub μg/mL concentrations measured in ~15 minutes.
In 2011 Escherichia, Listeria, and Salmonella species infected over 1.2 million people in the United States, resulting
in over 23,000 hospitalizations and 650 deaths. In January 2013 President Obama signed into law the Food and
Drug Administration (FDA) Food Safety Modernization Act (FSMA), which requires constant microbial testing of
food processing equipment and food to minimize contamination and distribution of food tainted with pathogens.
The challenge to preventing distribution and consumption of contaminated foods lies in the fact that just a few
bacterial cells can rapidly multiply to millions, reaching infectious doses within a few days. Unfortunately, current
methods used to detect these few cells rely on similar growth steps to multiply the cells to the point of detection,
which also takes a few days. Consequently, there is a critical need for an analyzer that can rapidly extract and detect
foodborne pathogens at 1000 colony forming units per gram of food in 1-2 hours (not days), and with a specificity
that differentiates from indigenous microflora, so that false alarms are eliminated. In an effort to meet this need, we
have been developing an assay that extracts such pathogens from food, selectively binds these pathogens, and
produces surface-enhanced Raman spectra (SERS) when read by a Raman analyzer. Here we present SERS
measurements of these pathogens in actual food samples using this assay.
Portable Raman analyzers have emerged during the first part of this century as an important field tool for crime scene
and forensic analysis, primarily for their ability to identify unknown substances. This ability is also important to the US
military, which has been investigating such analyzers for identification of explosive materials that may be used to
produce improvised explosive devices, chemicals that may be used to produce chemical warfare agents, and fuels in
storage tanks that may be used to power US military vehicles. However, the use of such portable analyzers requires that
they meet stringent military standards (specifically MIL-STD 810G). These requirements include among others: 1)
light weight and small size (< 35 pounds, < 3 cu. ft.), 2) vibration and shock resistant (26 four foot drops), 3) operation
from -4 to 110 oF, 4) operation in blowing dust, sand and rain, 5) battery operation, and of course 6) safe operation (no
laser or shock hazards). Here we describe a portable Raman analyzer that meets all of these requirements, and its use to
determine if captured fuels are suitable for use.
Since the distribution of Bacillus anthracis-Ames spores through the US Postal System, there has been a persistent fear that biological warfare agents will be used by terrorists against our military abroad and our civilians at home. While there has been substantial effort since the anthrax attack of 2001 to develop analyzers to detect this and other biological warfare agents, the analyzers remain either too slow, lack sensitivity, produce high false-positive rates, or cannot be fielded. In an effort to overcome these limitations we have been developing a surface-enhanced Raman spectroscopy system. Here we describe the use of silver nanoparticles functionalized with a short peptide to selectively capture Bacillus anthracis spores and produce SER scattering. Specifically, measurements of 100 B. anthracis-Ames spores/mL in ~25 minutes performed at the US Army’s Edgewood Chemical Biological Center are presented. The measurements provide a basis for the development of systems that can detect spores collected from the air or water supplies with the potential of saving lives during a biological warfare attack.
The use of portable Raman analyzers to identify unknown substances in the field has grown dramatically during the
past decade. Measurements often require the laser beam to exit the confines of the sample compartment, which
increases the potential of eye or skin damage. This is especially true for most commercial analyzers, which use 785
nm laser excitation. To overcome this safety concern, we have built a portable FT-Raman analyzer using a 1550 nm
retina-safe excitation laser. Excitation at 1550 nm falls within the 1400 to 2000 nm retina-safe range, so called
because the least amount of damage to the eye occurs in this spectral region. In contrast to wavelengths below 1400
nm, the retina-safe wavelengths are not focused by the eye, but are absorbed by the cornea, aqueous and vitreous
humor. Here we compare the performance of this system to measurements of explosives at shorter wavelengths, as
well as its ability to measure surface-enhanced Raman spectra of several chemicals, including the food contaminant
Since the distribution of Bacillus anthracis causing spores through the US Postal System, there has been a persistent
fear that biological warfare agents (BWAs) will be used by terrorists against our military abroad and our civilians at
home. Despite the substantial effort to develop BWA analyzers, they remain either too slow, produce high falsealarm
rates, lack sensitivity, or cannot be fielded. Consequently there remains a need for a portable analyzer that
can overcome these limitations as expressed at the 2011 Biological Weapons Convention. To meet this need we
have been developing a sample system that selectively binds BWAs and produce surface-enhanced Raman (SER)
spectra using portable Raman spectrometers. Here we describe the use of a short peptide ligand functionalized on
silver nanoparticles to selectively capture Bacillus cereus spores (a surrogate of B. anthracis) and their subsequent
detection by SER spectroscopy. This technique was used to specifically detect B. cereus spores over closely related
species like B. subtilis belonging to the same genus within 15 minutes. Sensitivity of the method was demonstrated
by detecting 104 B. cereus spores/mL of water. The technology, once developed should prove invaluable for rapid
monitoring of BWAs, which will immensely help first responders and emergency personnel in implementing
appropriate counter measures.
Foodborne diseases resulting from Campylobacter, Escherichia, Listeria, Salmonella, Shigella and Vibrio species
affect as many as 76 million persons in the United States each year, resulting in 325,000 hospitalizations and 5,000
deaths. The challenge to preventing distribution and consumption of contaminated foods lies in the fact that just a
few bacterial cells can rapidly multiply to millions, reaching infectious doses within a few days. Unfortunately,
current methods used to detect these few cells rely on lengthy growth enrichment steps that take a similar amount of
time (1 to 4 days). Consequently, there is a critical need for an analyzer that can rapidly extract and detect
foodborne pathogens in 1-2 hours (not days), at 100 colony forming units per gram of food, and with a specificity
that differentiates from indigenous microflora, so that false alarms are eliminated. In an effort to meet this need, we
have been developing a sample system that extracts such pathogens from food, selectively binds these pathogens,
and produces surface-enhanced Raman spectra (SERS). Here we present preliminary SERS measurements of
Listeria and Salmonella.
US Military forces are dependent on indigenous water supplies, which are considered prime targets to effect a
chemical or biological attack. Consequently, there is a clear need for a portable analyzer capable of evaluating
water supplies prior to use. To this end we have been investigating the use of a portable Raman analyzer with
surface-enhanced Raman spectroscopy (SERS) sampling systems. The superior selectivity and exceptional
sensitivity of SERS has been demonstrated by the detection of single molecules. However, the extreme sensitivity
provided by SERS is attributed to "hot spot" structures, such as particle junctions that can provide as much as 10
orders of magnitude enhancement. Unfortunately, hotspots are not evenly distributed across substrates, which
results in enhancements that cannot be quantitatively reproduced. Here we present analysis of uniformity for a
newly developed substrate and commercial sample vials using benzenethiol and bispyridylethylene, two chemicals
often used to characterize SERS substrates, and methyl phosphonic acid, a major hydrolysis product of the nerve
Ensuring safe water supplies requires continuous monitoring for potential poisons and portable analyzers to map
distribution in the event of an attack. In the case of chemical warfare agents (CWAs) analyzers are needed that have
sufficient sensitivity (part-per-billion), selectivity (differentiate the CWA from its hydrolysis products), and speed (less
than 10 minutes) to be of value. We have been investigating the ability of surface-enhanced Raman spectroscopy
(SERS) to meet these requirements by detecting CWAs and their hydrolysis products in water. The expected success of
SERS is based on reported detection of single molecules, the one-to-one relationship between a chemical and its Raman
spectrum, and the minimal sample preparation requirements. Recently, we have developed a simple sampling device
designed to optimize the interaction of the target molecules with the SERS-active material with the goal of increasing
sensitivity and decreasing sampling times. This sampling device employs a syringe to draw the water sample
containing the analyte into a capillary filled with the SERS-active material. Recently we used such SERS-active
capillaries to measure 1 ppb cyanide in water. Here we extend these measurements to nerve agent hydrolysis products
using a portable Raman analyzer.
Extended weightlessness causes numerous deleterious changes in human physiology, including space motion sickness,
cephalad fluid shifts, reduced immune response, and breakdown of muscle tissue with subsequent loss of bone mass and
formation of renal stones. Furthermore, these physiological changes also influence the metabolism of drugs used by
astronauts to minimize these deleterious effects. Unfortunately, the changes in human physiology in space are also
reflected in drug metabolism, and current pre-flight analyses designed to set dosage are inadequate. Furthermore,
current earth-based analytical laboratory methods that employ liquid or gas chromatography for separation and
fluorescence or mass spectrometry for trace detection are labor intensive, slow, massive, and not cost-effective for
operation in space. In an effort to overcome these instrument limitations we have been developing a sampling device to
both separate these drugs and metabolites from urine, and generate surface-enhanced Raman (SER) spectra. The
detailed molecular vibrational information afforded by Raman scattering allows chemical identification, while the
surface-enhancement increases sensitivity by six or more orders of magnitude and allows detection of nanogram per
milliliter concentrations. Generally no more than 1 milliliter of sample is required and complete analysis can be
performed in 5 minutes using a portable, light-weight Raman spectrometer. Here we present the SER analysis of
several drugs used by astronauts measured in synthetic urine and reconstituted urine.
In recent years a paradigm in chemical manufacturing has emerged, numbering-up production instead of the traditional
scaling-up. This new approach employs nanoliter to milliliter reactors that increase control of reaction pathways,
product choice and yield. These small-scale reactors virtually eliminate mixing and heat transfer problems associated
with large-scale reactors that often limit yield. The value of small-scale reactors is being recognized by the
pharmaceutical industry where only small-scale synthesis is required until clinical trials are complete, at which time fullscale
production needs to be accomplished in the shortest possible time. One of the most often used reaction steps
during the synthesis of pharmaceuticals is protecting carboxylic acid groups by esterification. We have been developing
Raman spectroscopy as a process analytical tool to monitor and control chemistry in such small-scale reactors. Here we
present Raman spectra of the esterification of benzoic acid performed in a 5-mL batch reactor.
Cancer treatment often includes chemotherapy drugs that prevent cancer cell growth through a variety of biochemical
mechanisms, but are not target specific and kill other cells. Consequently, the dosage has a narrow range of safe and
effective use. Furthermore, because of the dangerous side-effects of these drugs, clinical trials are not performed, and
dosage is based on the limited statistics of the response of previously treated patients and administered according to body
surface area. Monitoring dosage during administration would clearly improve patient outcome. Unfortunately current
practices require 10-20 milliliters of blood per analysis, and multiple samples to profile pharmacokinetics may further jeopardize the patient's health. Saliva analysis has long been considered an attractive alternative, but the large sample
volumes are difficult to obtain. In an effort to overcome this limitation we have been investigating metal-doped sol-gels
to both separate drugs and their metabolites from saliva and generate surface-enhanced Raman spectra. We have
incorporated the sol-gel in a disposable pipette format, and generally no more than two drops (100 microL) of sample are
required to perform analysis. The detailed molecular vibrational information allows chemical identification, while the
increase in Raman scattering by six orders of magnitude or more allows detection of nanomolar concentrations.
Measurements of chemotherapy drugs at relevant concentration are presented.
Rapid analysis of drugs in emergency room overdose patients is critical to selecting appropriate medical care. Saliva analysis has long been considered an attractive alternative to blood plasma analysis for this application. However, current clinical laboratory analysis methods involve extensive sample extraction followed by gas chromatography and mass spectrometry, and typically require as much as one hour to perform. In an effort to overcome this limitation we
have been investigating metal-doped sol-gels to both separate drugs and their metabolites from saliva and generate surface-enhanced Raman spectra. We have incorporated the sol-gel in a disposable lab-on-a-chip format, and generally no more than a drop of sample is required. The detailed molecular vibrational information allows chemical
identification, while the increase in Raman scattering by six orders of magnitude or more allows detection of microg/mL concentrations. Measurements of cocaine, its metabolite benzoylecgonine, and several barbiturates are presented.
Chemotherapy drug dosage is based on the limited statistics of the response of previously treated patients and administered according to body surface area. Considerably better dose regulation could be performed if the drug metabolism of each patient could be monitored. Unfortunately, current technologies require multiple withdrawals of blood to determine metabolism, a precious fluid in limited supply. Saliva analysis has long been considered an attractive alternative, but unfortunately standard techniques require large quantities that are difficult to obtain. In an effort to overcome this limitation we have been investigating the ability of metal-doped sol-gels to both separate drugs and their metabolites from saliva and generate surface-enhanced Raman spectra. Surface-enhanced Raman spectroscopy has the potential to perform this analysis with just a few drops of sample due to its extreme sensitivity. Preliminary measurements are presented for the chemotherapy drug, 5-fluorouracil, and its two metabolites 5-fluorouridine and 5-fluoro-2'-deoxyuridine, and the potential of determining metabolism on a patient-by-patient basis.
Pesticides are a key component in protecting crops and producing the quantity of food required by today's world population. However, since excessive concentrations pose a threat to human health, the USA sets strict tolerance levels to ensure public safety. Unfortunately, many other countries ignore these regulations and imported food exceeding these levels or contaminated with banned pesticides is a common occurrence. Furthermore, rapid chemical analysis of pesticide residues is unavailable, and only a very small fraction of foods are inspected. The greatest concern is fruit, for which an estimated 12 million tons were imported in 2003. In an effort to address this need, we have been developing a simple and rapid procedure to analyze for pesticides on fruit surfaces or in the juice of fruits. The procedure employs metal-doped sol-gel filled capillaries that both chemically extracts the pesticide and generates surface-enhanced Raman spectra when irradiated. The SERS-active capillaries, sensitivity, and preliminary fruit analyses are presented.
Modern agriculture depends on pesticides to curb infestations, increase crop yield and to produce the quantity and
quality of food demanded by today's society. However, potential pesticide residue contamination of food is of critical
concern to the food industry and the regulators responsible for health and safety. For example, many pesticides kill
insects by attacking the central nervous system, and the use of these pesticides above the EPA set tolerance levels (from
0.1 to 50 ppm) could pose a threat to humans, in particular infants. Unfortunately, rapid, chemical analysis of pesticide
residues is unavailable, and only a very small fraction of foods are inspected. The greatest concern is food imported
from nations that simply ignore US regulations. In an effort to address this need, we have been developing a simple
device to collect residues from food surfaces, perform a rapid chemical separation, and detect and identify pesticides by
surface-enhanced Raman spectroscopy (SERS). Capillaries are coated with a metal-doped sol-gel that both separates
chemicals and generates SER spectra when irradiated. SERS of pesticides at ppm concentrations, and a preliminary
product to aid inspectors is presented.
Traditional cancer treatment, surgical removal and gamma- or x-ray irradiation, is often augmented by the use of chemotherapy drugs. Theses drugs prevent cancer cell growth through a variety of biochemical mechanisms, but are not target specific and kill other cells. Consequently, the amount administered has a narrow range of safe and effective use. Furthermore, because of the dangerous side-effects of these drugs, clinical trials can not be performed, and a statistical basis for dosage is not available. Instead, the concentration of the drugs and their metabolites are monitored during treatment of cancer patients, Unfortunately current practices require 10-20 mL of blood per analysis, and multiple samples to profile pharmacokinetics may further jeopardize the patient's health. Saliva analysis has long been considered an attractive alternative, but the large sample volumes are difficult to obtain. In an effort to overcome this limitation we have been investigating metal-doped sol-gels to both separate drugs and their metabolites from saliva and generate surface-enhanced Raman spectra. We have incorporated the sol-gel in a disposable pipette format, and generally no more than two drops (100 μL) of sample are required. The detailed molecular vibrational information allows chemical identification, while the increase in Raman scattering by four to six orders of magnitude allows detection of nanomolar concentrations. Preliminary measurements will be presented.