A novel approach to synthesizing nanowires (NWs) allows their direct integration with microelectronic systems for the first time, as well as their ability to act as highly sensitive biomolecule detectors that could revolutionize biological diagnostic applications, according to a report in Nature.
"We electronically plugged into the biochemical system of cells," said senior author Mark Reed, Harold Hodgkinson Professor of Engineering & Applied Science. "These developments have profound implications both for application of nanoscience technologies and for the speed and sensitivity they bring to the future of diagnostics."
An interdisciplinary team of engineers in the Yale Institute for Nanoscience and Quantum Engineering has overcome hurdles in NW synthesis by using a tried-and-true process of wet-etch lithography on commercially available silicon-on-insulator wafers. These NWs are structurally stable and demonstrate an unprecedented sensitivity as sensors for detection of antibodies and other biologically important molecules.
According to Reed, not only can the NWs detect extremely minute concentrations (as few as 1000 individual molecules in a cubic millimeter), they can do it without the hazard or inconvenience of any added fluorescent or radioactive detection probes.
The study demonstrated ability of the NWs to monitor antibody binding, and to sense real-time live cellular immune response using T-lymphocyte activation as a model. Within approximately 10 seconds, the NW could register T-cell activation as the release acid to the device. The basis for the sensors is the detection of hydrogen ions or acidity, within the physiological range of reactions in the body. Traditional assays for detection of immune system cells such as T cells or for antibodies usually take hours to complete.
"The ability to differentiate between immune system cells based on their function and with label-free reagents is key for rapid and reliable diagnostics as well as for advancing basic science," said co-author Tarek Fahmy, assistant professor of biomedical engineering. "These nanosensors can replace current technology with a solid-state device and the results promise to radically change the way we assay for these cells."
"The sensor is essentially on the size scale of the molecules it is designed to sense," said lead author Eric Stern, a graduate student whose thesis work has focused on designing and building nanoscale chemical and biological sensors. His project was funded by the Department of Defense and placed high importance on the capability of detecting multiple molecules, including pathogens.