The researchers haven’t tried this out on blood, saliva, or urine yet but this July 21, 2012 news item by Gary Thomas on Azonano hints that will be the next step,
Researchers at the University of Georgia have devised a single-step, quick and accurate technique using nanomaterials to detect pathogens and contaminants. The team demonstrated the capability of the new technique in detecting compounds like protein albumin and lactic acid in extremely diluted mixtures that comprised of dyes and chemicals.
The researchers conclude that the same method can be employed on biological mixtures like blood, saliva, food and urine to detect contaminants and pathogens.
The originating July 19, 2012 news release by Sam Fahmy for the University of Georgia provides more detail,
“The results are unambiguous and quickly give you a high degree of specificity,” said senior author Yiping Zhao, professor of physics in the UGA [University of Georgia] Franklin College of Arts and Sciences and director of the university’s Nanoscale Science and Engineering Center.
Zhao and his co-authors—doctoral students Jing Chen and Justin Abell and professor Yao-wen Huang of the UGA College of Agricultural and Environmental Sciences—used nanotechnology to combine two well-known techniques and create their new diagnostic test. …
The first component of their two-in-one system uses a technique known as surface enhanced Raman spectroscopy, or SERS, which measures the change in frequency of a laser as it scatters off a compound. Every compound displays a series of distinctive changes in frequency, or Raman shifts, that are as unique as a fingerprint. The signal produced by Raman scattering is inherently weak, but Zhao and his colleagues have arrayed silver nanorods 1,000 times finer than the width of a human hair at a precise angle to significantly amplify the signal. In previous studies with Ralph Tripp in the UGA College of Veterinary Medicine and chemist Richard Dluhy in the Franklin College, they demonstrated that the use of SERS with silver nanorods could identify viruses such as HIV and RSV isolated from infected cells.
Here’s why they needed a second technique and how it fits into the picture (from the news release),
“In a clinical setting, the sample that you obtain from patients typically contains bacteria or viruses as well as a lot of fluid—as in blood, urine or saliva—that contains biological agents that interfere with the signal you’re trying to detect,” Zhao said. “To develop a diagnostic that could be used at the point of care, we needed a way to separate those agents.”
Once again, the scientists turned to nanotechnology to create a next-generation diagnostic test. Using traditional thin layer chromatography, or TLC, scientists blot a drop of sample onto a porous surface. They then apply a solvent such as methanol to the sample, and the sample components separate based on how strongly they’re attracted to the solvent and the surface.
Study co-author Justin Abell, a doctoral student in the UGA College of Engineering, explained that TLC typically requires a large sample volume because the compound of interest soaks into the surface in addition to moving along it, like a stain on a rug. The silver nanorod surface that the researchers use, in contrast, allows them to use a miniscule amount of sample in a technique known as ultra-thin layer chromatography.
“In our case, the nanorods are acting as the detection medium but also as the separation medium,” Abell said, “so it’s a two-in-one system.”
To test their method, the researchers used mixtures of dyes, the organic chemical melamine, lactic acid and the protein albumin. In each case, they were able to directly identify the compounds of interest, even in samples diluted to concentrations below 182 nanograms per milliliter-roughly 200 billionths of a gram in a fifth of a teaspoon. And while the detection of viruses using techniques such as polymerase chain reaction can take days or even weeks and requires fluorescent labels, the on-chip method developed by the UGA researchers yields results in less than an hour without the use of molecular labels.
As for future plans to develop this application (from the news release),
The researchers are currently testing their technique with biological samples from Tripp’s lab that contain viruses, and Zhao said preliminary results are promising. He adds that while his team is focused on health and food safety applications, SERS and ultra-thin layer chromatography can be used to detect compounds of all types—everything from forensic materials at a crime scene to environmental pollutants. His team also is working with colleagues across campus to create an online encyclopedia that would allow technicians to identify viruses, bacteria, biomarkers and pharmaceuticals based on their distinctive Raman shifts.
“Every compound has a unique SERS spectrum,” Zhao said, “so this is a very robust technology whose applications are practically endless.”