Engineering

Photonics Symposium Showcases Innovations in Point-of-Care Diagnostics

Fri, 20 Nov 2009 00:00:00 EST

To better understand, diagnose and treat specific diseases, scientists are increasingly seeking technologies to investigate biological systems at the cellular and molecular levels. Among the most promising is biophotonics, the study of the interaction of light with biological material. Drawing on research in the life sciences, physical sciences and engineering, emerging biophotonics technology is extending scientists’ ability to image, analyze and manipulate living tissue in minimally invasive ways.

On Nov. 16 at the Photonics Center, the 13th annual Future of Light Symposium, “Biophotonics Sensors and Systems: Point of Care Diagnostics,” showcased leading edge research in biophotonic imaging and biomedical photonics. Chaired by Professor Irving Bigio (BME, ECE), the symposium highlighted the achievements of Photonics Center researchers and collaborators from academic and medical institutions in Greater Boston and across the country.

Contributing to three separate technical sessions of the conference, three College of Engineering faculty members — Professor Selim Ünlü (BME, ECE), Associate Professor Jerome Mertz (BME) and Assistant Professor Satish Singh (BME) — presented new methods that could improve the accuracy, efficiency and cost-effectiveness of point-of-care diagnostic tools.

Mertz described HiLo microscopy, a new imaging technique that could be used in endoscopic microscopes. Rather than requiring researchers and clinicians to extract and bring tissue to the microscope, endomicroscopy enables them to bring the microscope to the tissue. HiLo microscopy produces a three-dimensional image of a tissue sample based on an inexpensive modification to a wide-field fluorescence microscope.

Fusing low-resolution data obtained from a non-uniformly illuminated image — one generated by illuminating the tissue sample with a grid-based or other pattern of light — with high-resolution data from a uniformly illuminated image, the method yields a high-contrast, in-focus image.

“It’s very simple, there are no moving parts, it’s very fast, there are reduced motion artifacts, and it’s very insensitive to the type of structural illumination used,” noted Mertz, whose lab is seeking to implement HiLo microscopy in a clinically useful endoscope to facilitate early cancer detection in the colon and other tissues.

Singh, a staff gastroenterologist at the Veterans Administration Boston Healthcare System, introduced a promising new fiber optic probe that he’s devised that could considerably improve the effectiveness of traditional colonoscopy. Incorporating optical spectroscopic imaging into a conventional colonoscopic forcep, the probe performs an optical biopsy in concert with the physical biopsy of the colon.

“The analysis to date reveals great promise for the system to classify colonic polyps in situ,” said Singh, citing a study that he and colleagues conducted at the Boston VA. “The system has the potential to be a low cost, low maintenance, user-friendly, easily adopted clinical tool.”

Ünlü discussed the development of a simple technique — the Spectral Reflectance Imaging Biosensor (SRIB) — based on the interference of light reflected from a silicon dioxide surface. Measuring optical path length differences caused by biomolecular binding on the surface, the SRIB could be used to detect proteins, DNA and single viruses.

“We can get not only multiplexed, label-free results, but we can also do dynamic measurements,” said Ünlü, who has already commercialized the high-throughput technique and applied it to the study of liver and Alzheimer’s diseases.

New Nano Technique Could Help Detect Disease

Tue, 17 Nov 2009 00:00:00 EST

This article originally appeared in the November 17 issue of BU Today.

GE VP Highlights Firm’s Profitable Clean Energy Solutions

Mon, 09 Nov 2009 00:00:00 EST

In today’s daunting economic and environmental challenges, General Electric sees gold. Green gold. Since launching its “ecomagination” business initiative in 2005, the multinational corporation has developed several profitable technologies and services to reduce environmental impacts around the world.

Ronald Roy Awarded ASA Silver Medal

Fri, 06 Nov 2009 00:00:00 EST

The Acoustical Society of America (ASA) has awarded Professor Ronald A. Roy (ME) the Helmholtz-Rayleigh Interdisciplinary Silver Medal for his for contributions to physical acoustics and biomedical ultrasonics. Roy will receive the award at the 159th meeting of the ASA in Baltimore on April 21, 2010.

Roy is 16th recipient of the Helmholtz-Rayleigh medal, which is awarded annually to a researcher whose contributions encompass multiple technical areas in acoustics. Roy’s research specializes in the application of physical acoustics principles to problems in biomedical acoustics, industrial ultrasonics, opto-acoustics, and acoustical oceanography.

“It’s wonderful to have one’s work recognized in this way,” Roy said. “It is a true honor to be both nominated and selected by your peers. The ASA silver medal is one of the higher recognitions one can achieve in the field of acoustics.”

Roy has served as chairman of the Mechanical Engineering Department since 2007. He joined the College as an associate professor in 1996 and was promoted to full professor in 2002. He spent the 2006-2007 academic year at the University of Oxford, where he served as the 65th George Eastman Distinguished Visiting Professor. His work in academic contract research includes stints as a adjunct assistant professor of physics and research scientist at the National Center for Physical Acoustics of the University of Mississippi, and affiliate associate professor of mechanical engineering, research associate professor of biomedical engineering, and research scientist at the Applied Physics Laboratory ot the University of Washington.

The Helmholtz-Rayleigh Silver Medal is one of 12 medals awarded by the ASA for contributions to the advancement of science, engineering, or human welfare through the application of acoustic principles or through research accomplishments in acoustics. The first silver medal was awarded in 1974, and Roy said he was honored to be included in the same categories as many of his acoustic research predecessors.

“My most valued mentors won these medals,” he said. “My two thesis advisors – Robert Apfel of Yale and Lawrence Crum of the University of Mississippi – both won Silver Medals from the Acoustical Society, and it amazes me to think that I might be viewed in the same light.”

A Fellow of the ASA, Roy is also a member of the American Society of Mechanical Engineers and the International Society of Therapeutic Ultrasound, and a past member of the European Society of Sonochemistry and the American Institute of Physics.

Roy is the third ME faculty to be awarded in ASA medal in recent years. In 2007, Professor William M. Carey was awarded the “Pioneer of Underwater Acoustics” Silver Medal for his contributions to understanding ocean ambient noise and defining the limits of acoustic array performance in the ocean and Professor Allan D. Pierce recieved the Stanley Ehrlich Gold Medal for his contributions to physical, environmental and structural acoustics and acoustics education.

Nanophotonics Advance Could Boost Biomolecular Studies and Sensor Capabilities

Fri, 30 Oct 2009 00:00:00 EDT

An interdisciplinary team of researchers led by Assistant Professor Hatice Altug (ECE) has created a highly sensitive, infrared (IR) absorption spectroscopy technique that can identify specific proteins and other molecules using far less sample material than what conventional spectrometers require. Exploiting recent advances in nanophotonics, the technique constitutes a powerful new tool for biomolecular studies and drug discovery, and could considerably enhance biological and chemical sensor detection capabilities.

Infrared absorption spectroscopy uses infrared light to excite the bonds that connect atoms within molecules, causing them to vibrate at a specific resonant frequency. By examining what frequencies of light are absorbed by a material, scientists can determine what kind of bonds it contains, and thus identify the material.

Because absorption signals are often weak, conventional IR spectroscopy requires large samples of target molecules in many layers. To overcome this limitation, the research team used tiny gold nanoparticles as highly efficient “nanoplasmonic” antennas that greatly amplify the signal received from an individual protein molecule.

“Our technique enhances the signal by a factor of up to 100,000,” said Altug. “Because our technique is ultra-sensitive, we don’t need a large number of molecules from which to obtain signals. In fact, we can obtain signals from even a single-molecule-layer thick protein film.”

Altug and her collaborators — Professor Shyamsunder Erramilli (BME, Physics); Research Professor Mi Hong (Physics); graduate student Ronen Adato and post-doctoral fellow Ahmet Ali Yanik in Altug’s lab; and Tufts University bioengineers David Kaplan, Fiorenzo Omenetto and Jason Amsden — report on this unprecedented achievement in this week’s online edition of Proceedings of the National Academy of Sciences.

Nanoantennas Dramatically Improve Detection Capability
To obtain the high sensitivity needed to detect vibrations from an extremely small sample of silk protein molecules, the team designed a 50-by-50 array of gold, rod-shaped nanoantennas and tuned their resonant frequency to match that of the bonds within the sampled molecules.

The 2,500 strategically configured antennas focus infrared light on nearly 145 silk protein molecules deployed at the tip of each nanoantenna. The light, in turn, excites the bonds within the molecules to vibrate at their signature 6.6 micron wavelength. After absorbing a significant fraction of the incoming IR light, the silk protein molecules reflect the rest back through the nanoantennas. Upon receipt of the reflected signal, the spectrometer deduces the vibrational signature of the silk protein molecules.

Combining theoretical calculations and advanced nanofabrication techniques, Yanik and Adato obtained up to a 100,000-fold enhancement of the molecules’ vibrational signatures and whittled the sample thickness down to a single layer of protein.

Drawing on seed funding from an ENG Dean’s Catalyst Award and ongoing support from the National Science Foundation, Massachusetts Life Science Center and Department of Defense, Altug and her co-investigators are now applying their novel IR spectroscopy technique to other kinds of molecules.

“Our plasmonic method is quite general and can be adapted to enhance the infrared fingerprints of other biomolecules, such as nucleic acids and lipids,” said Altug. “It therefore provides a general purpose toolkit for ultra-sensitive vibrational spectroscopy of biomolecular systems.”

Drug Discovery Implications
Because the technique requires only one-layer, two-nanometer-thick samples, it may ultimately enable scientists to obtain much more accurate and useful data.

“The sensitivity of our technique can be high enough to provide spectroscopy at the single-molecule scale,” said Altug, “and a single-molecule response can be very different from that of an ensemble of molecules.”

Studying protein molecules in one layer offers yet another advantage.

“Conventional IR spectroscopy requires a large number of proteins, usually 5,000 to 10,000 layers of them in one stack that resembles a baklava,” said Erramilli. “With our single-layer substrate we can capture proteins in their native environment.”

As a result, the new technique could be used to improve our understanding of how protein molecules interact and how external forces alter their shape and behavior — questions of fundamental importance in biochemistry and drug discovery.

The method may also help amplify biological and chemical sensing capabilities in defense and other applications.

“Chemical sensors detect the presence of specific molecules via molecular fingerprints, telltale vibrational frequencies of the molecules’ bonds,” Altug explained. “Our technique’s ultra-sensitivity enables us to pick up clear, identifiable response signals even from a trace amount of a chemical.”