Researchers from the Wayne State University School of Medicine's Department of Physiology have invented a tiny thermometer for measuring muscle efficiency that could detect metabolic diseases such as cancer, multiple sclerosis and muscular dystrophy earlier than previously thought possible.
The thermometer, dubbed the world's tiniest and most sensitive, is made up of metal alloy nanoparticles that can detect temperatures less than 1/1000th of a centigrade, or 1 mK, said Distinguished Professor of Physiology Bhanu Jena, Ph.D., the study's principal investigator and director of WSU's NanoBioScience Institute. As many as 50,000 of the nano thermometers could fit on one strand of human hair.
"All life processes and every chemical reaction is governed by temperature, hence a precise assessment of temperature is critical. Despite recent advances in thermometry, determination of temperature at the nanometer scale in single molecules to live cells remains a challenge that holds great promise in disease detection among others," Dr. Jena said. "Muscle biopsies could predict muscle disorders much earlier, enabling early intervention and appropriate treatment modalities."
"The nano thermometer has different levels of fluorescence at different temperatures. The higher the temperature, the lower its fluorescence. For example, a car engine is more efficient if it performs more mechanical work and releases less heat. Similarly, muscles use ATP (adenosine triphosphate) as the energy source to perform work. Therefore, if more heat is released, then less of the energy is available for work, hence less efficient," Dr. Jena said.
Similarly, cancer cells release more heat due to a change in their metabolism.
"We could therefore differentiate cancer from normal tissue. Exposure of cells or tissues to the nano thermometer will provide precise temperature readings from their fluorescent intensities, measured both under a fluorescent microscope or using a fluorimeter," he said.
The initial two-year study utilized the direct association of two nanometer quantum dots with cardiac and skeletal muscle myosin, and measured efficiency of the molecular motor. Additional related studies using human cancer biopsies and biopsies of various metabolic disorders are ongoing.
"Once those studies are complete, and the approach works, it can be immediately used since it is not a drug but rather a biosensor for disease detection," he said.
Dr. Jena's study colleagues included Assistant Professor of Physiology Robert Wessells, Ph.D.; postdoctoral fellow Suvra Laha, Ph.D.; and graduate students Akshata Naik, Eric Kuhn, Maysen Alvarez and Alyson Sujkowski.
"In collaboration with Dr. Wessells, we further extended this approach to demonstrate the gain in efficiency of the fruit fly skeletal muscle overexpressing a homolog of a human gene known to be a mediator of improved exercise performance," Dr. Jena said. "We are delighted that, besides major improvement in thermal resolution of live cells and molecules, there is great promise of detecting various metabolic disorders using this approach. We are very pleased, and collaborative work with colleagues is fast progressing using various human tissue biopsies. Harnessing the power of this simple, inexpensive and rapid approach in disease detection is exciting."
Dr. Jena also is the George E. Palade University professor and a professor in the WSU Department of Physics and Anatomy and the WSU Department of Chemical Engineering and Material Sciences.
The work is supported in part by a National Science Foundation grant (CBET1066661), the WSU Vice President for Research Post-Doctoral Fellowship and the WSU Interdisciplinary Biomedical Systems Fellowship.