Faster diagnostics through cheap, ultra-portable blood testing

New sensor described in Biomedical Optics Express combines state-of-the-art performance and accuracy for widespread use

2011-09-02

(Press-News.org) WASHINGTON, Sept. 1—Blood tests are important diagnostic tools. They accurately tease-out vanishingly small concentrations of proteins and other molecules that help give a picture of overall health or signal the presence of specific diseases. Current testing procedures, however, are expensive and time-consuming, while sophisticated test equipment is bulky and difficult to transport.

Now, a team of researchers from the University of Toledo in Ohio has addressed all these drawbacks by developing a low-cost, portable technique that is able to quickly and reliably detect specific proteins in a sample of human blood. This innovative technique, described in the Sept. 1 issue of the Optical Society's (OSA) open-access journal, Biomedical Optics Express, could help in a wide range of medical sensing applications, including diagnosing diseases like cancer and diabetes long before clinical symptoms arise.

"The detection and measurement of specific blood proteins can have a huge impact on numerous applications in medical diagnostic sensing," says Brent D. Cameron with the department of bioengineering at the University of Toledo, one of the paper's authors. "This method has the potential to provide similar functionality of large and costly clinical instrumentation currently used to identify and quantify blood proteins for a fraction of current costs."

Human blood contains literally thousands of different proteins. Many are essential for the day-to-day mechanics of life. Others are formed only in response to certain diseases. Knowing which protein is the hallmark of an illness and singling it out of a blood sample leads to earlier diagnosis and more effective treatment. An example of this is the prostate-specific antigen (PSA), which is now routinely tested for to help detect prostate cancer and other prostate abnormalities in men.

In this new system, the researchers borrowed a trick from nature, using artificially created molecules called aptamers to latch on to free-floating proteins in the blood. Aptamers are custom-made and commercially available short strands of nucleic acid. In some ways, they mimic the natural behavior of antibodies found in the body because they connect to one type of molecule, and only one type. Specific aptamers can be used to search for target compounds ranging from small molecules – such as drugs and dyes – to complex biological molecules such as enzymes, peptides, and proteins.

Aptamers, however, have advantages over antibodies in clinical testing. They are able to tolerate a wide range of pH (acid and base environments) and salt concentrations. They have high heat stability, are easily synthesized, and cost efficient.

For their demonstration, the researchers chose thrombin and thrombin-binding aptamers. Thrombin is a naturally occurring protein in humans that plays a role in clotting.

The researchers affixed the aptamers to a sensor surface, in this case a glass slide coated with a nanoscale layer of gold. As the blood sample is applied to the testing surface, the aptamer and their corresponding proteins latched together.

The next step is to actually determine if the couples pairing was successful. To make this detection, the researchers used a real-time optical sensing technique known as Surface Plasmon Resonance (SPR). A surface plasmon is a "virtual particle," created by the wave-motion of electrons on the surface of the sensor. If the protein is present and has bound to the aptamer, conditions for which resonance will occur at the gold layer will change. This resonance change is detected through a simple reflectance technique that is coupled to a linear detector.

"By monitoring these conditions, we can quantify the amount of the target protein that is present; even at very low concentrations," says Cameron. "This approach is very robust in that unique aptamers for almost any given protein can be identified. This makes the technique very specific and adaptable for any given application." The approach also requires less-bulky optics, which is the key to the portability aspect of the design.

Aptamer sensors, according to the researchers, are also capable of being reversibly denatured, meaning they can easily release their target molecules, which makes them perfect receptors for biosensing applications.

"The advantage of this surface plasmon sensor," says Cameron, "is that it enabled us to demonstrate low sample consumption, high sensitivity, and fast response time." The direct detection of blood proteins in this manner can benefit a number of scientific and clinical applications, such as monitoring diabetes, drug research, environmental monitoring, and cancer diagnosis.

For commercial use in medical diagnostics, according to Cameron, the technology is three to five years away, pending FDA procedures and filings. "The time frame is very dependent on the target application area. We are currently in the procedure of determining suitable aptamers for a range of target proteins for both diabetic and cancer-related applications," he says.

INFORMATION:

Paper: "Development of a highly specific amine-terminated aptamer functionalized surface plasmon resonance biosensor for selective blood protein detection," Biomedical Optics Express, Volume 2, Issue 9, pp. 2731-2740. http://www.opticsinfobase.org/boe/abstract.cfm?uri=boe-2-9-2731

EDITOR'S NOTE: Illustrations of the Surface Plasmon Resonance system are available to members of the media. Please contact astark@osa.org.

About Biomedical Optics Express

Biomedical Optics Express is OSA's principal outlet for serving the biomedical optics community with rapid, open-access, peer-reviewed papers related to optics, photonics and imaging in the life sciences. The journal scope encompasses theoretical modeling and simulations, technology development, and biomedical studies and clinical applications. It is published by the Optical Society and edited by Joseph A. Izatt of Duke University. Biomedical Optics Express is an open-access journal and is available at no cost to readers online at http://www.OpticsInfoBase.org/BOE.

About OSA

Uniting more than 106,000 professionals from 134 countries, the Optical Society (OSA) brings together the global optics community through its programs and initiatives. Since 1916 OSA has worked to advance the common interests of the field, providing educational resources to the scientists, engineers and business leaders who work in the field by promoting the science of light and the advanced technologies made possible by optics and photonics. OSA publications, events, technical groups and programs foster optics knowledge and scientific collaboration among all those with an interest in optics and photonics. For more information, visit www.osa.org.

[Attachments] See images for this press release:

ELSE PRESS RELEASES FROM THIS DATE:

Dangers on Missouri Highways: Unsecured Truck Loads

2011-09-02

It might seem like an accident that could only happen in a horror movie, but the reality of unsecured cargo is much more serious and more prevalent than most people assume. AAA reported that around 25,000 vehicle accidents and 80-90 deaths occur as a direct result of unsecured cargo per year. Unsecured cargo is essentially insufficient stability of the materials a trucker is transporting. Typically, materials transported by 18-wheelers include steel coils, lumber, auto parts and various construction supplies, but the list can also extends to liquid or hazardous materials ...

Getting the Lead Out: Protecting Children From Dangerous Toys

2011-09-02

How do you protect your child's safety when there are 30,000 tons of potentially dangerous toys pouring into the United States from foreign countries every year? These boatloads of foreign toys account for 95 percent of the toys sold in the U.S. every year -- and many of them cause serious injuries to children. Of course, American-made toys can cause children's injuries too. Regardless of their origin, toys should not put children at undue risk of injury. Trouble in Toyland Report That's why a leading consumer advocacy group, U.S. PIRG, tries to educate the public ...

Lung cancer ALK rearrangement may predict pemetrexed efficacy, study shows

2011-09-02

Patients with ALK-rearranged non-small cell lung cancer (NSCLC) responded significantly better to pemetrexed (brand name: Alimta) than patients whose cancer did not show ALK translocation, according to research published in the September issue of the Journal of Thoracic Oncology, the official publication of the International Association for the Study of Lung Cancer (IASLC). Lung adenocarcinoma can display genetic mutations, including anaplastic lymphoma kinase (ALK) rearrangement and epidermal growth factor receptor (EGFR) mutations. Knowing whether the tumor displays ...

The quantum tunneling effect leads electron transport in porphyrins

2011-09-02

Porphyrins are organic molecules that appear in the central region of macromolecules such as chlorophyll and hemoglobin, and have a metal atom at their center that determines their specific function. The importance of these molecules in the field of molecular electronics lies in their "ease of transfer electrons from one region to another" explains the responsible of the work at the Nanomaterials and Nanotechnology Research Center (a joint research center of the CSIC, the University of Oviedo and the Government of the Principality of Asturias) Víctor Manuel García. ...

Federal Study Determines Causes of Trucking Accidents

2011-09-02

Commercial tractor-trailers are involved in an increasing number of serious, and often fatal, accidents. To learn why, the Federal Motor Carrier Safety Administration (FMCSA) and the National Highway Traffic Safety Administration (NHTSA) conducted the Large Truck Crash Causation Study (LTCCS). This study provided vital information, including the reasons behind serious crashes involving large trucks. Researchers reviewed 120,000 crashes that occurred between April 2001 and December 2003 and selected a nationally representative sample of 963 accidents. These accidents, ...

Decrease in smoking reduces death rates within months

2011-09-02

A study by the University of Liverpool has found that a decrease in smoking rapidly reduces mortality rates in individuals and entire populations within six months. Research by Professor Simon Capewell and Dr Martin O'Flaherty at the Institute of Psychology, Health and Well-being, examined evidence from clinical trials and natural experiments. They found that a reduction in smoking has a positive impact on mortality rates in both individuals and populations within six months. Likewise, dietary improvements get very positive results within one to three years. Professor ...

Sight fails when defective eye cells cripple renewal

2011-09-02

In a rare eye disease, the retina degenerates because light-receiving cells fail to regenerate, research led by a student at Case Western Reserve University School of Medicine shows. The researchers include Dr. Samuel G. Jacobson's group at the University of Pennsylvania and Dr. Andreas Engel's group at University of Basel, Switzerland. They found that when the natural renewal process fails, metabolites are locked in, build up and turn toxic, killing cells over time in Enhanced S-Cone Syndrome. A description of their work is online and will be published in print in ...

Hubble movies reveal solar-system-sized traffic jams

2011-09-02

When it comes to big-budget action movies, Rice University astronomer Patrick Hartigan prefers Hubble to Hollywood. Using Hubble Space Telescope images collected over 14 years, Hartigan has created time-lapse movies that offer astronomers their first glimpse of the dynamic behavior of stellar jets, huge torrents of gas and particles that spew from the poles of newborn stars. An analysis of the movies that was published in The Astrophysical Journal is forcing astronomers to rethink some of the processes that occur during the latter stages of star birth. And in an effort ...

Distracted Driving Still a Problem Despite Cell Phone Ban

2011-09-02

With more than 22 million drivers on its roads, California became the largest state to enact formal distracted driving laws in 2008. Sections 23123 and 23124 of the California Vehicle Code prohibited use of cell phones without a hands-free device, which enables drivers to dial phone numbers or complete calls without taking their hands from the steering wheel. The law also prohibited all drivers under age 18 from using cell phones behind the wheel. Proponents of the new law suggested that hands-free devices provided the safety and convenience drivers needed to make calls ...

Living with parents in adult life can prolong family conflict

2011-09-02

"We have worked with young people, in this case, in the family environment, to see what happens during the 'full nest syndrome', i.e., when children reach 18 years of age and they continue living at home," explained Beatriz Rodríguez, researcher from the University of La Laguna and co-author of the study. Researchers classified adolescents into three stages: early teens (12 and 13 years), mid-teens (14 and 15), and late teens (16-18). Those 18-25 were called 'emerging adults'. In Spain, given the country's social, economic and cultural characteristics, children leave ...