Doctors treating patients with life-threatening injuries or illnesses need to know practically at a moment's notice the presence of certain biomarkers in the blood that can indicate imminent organ failure of the liver, kidneys, or heart. The standard procedure to determine these biomarkers is to draw blood from the patient and perform extensive testing, sometimes taking up to 90 minutes, as reported in a recent article in the MIT Technology Review. Although accurate, the current testing methods do not provide the immediate results needed for patients whose conditions may be rapidly deteriorating.
What's required is a system that can detect multiple biomarkers simultaneously in the blood and provide the results in real time at the patient's bedside. This will enable doctors to quickly implement necessary life-saving procedures and treatments based on the patient's changing conditions. Vista Therapeutics, a startup company in New Mexico with licensing agreements from Nanosys and Harvard University, is actively pursuing such a system based on nanotechnology.
Detecting the biomarkers is accomplished using sensitive biosensors made up of extremely fine nanowires having diameters of less than 10 nanometers. The nanowires can be functionalized or processed to detect any form of bimolecular interaction that involves proteins or nucleic acids, as stated on Vista's website at www.vistatherapeutics.org.
Processing requires the pre-attachment through covalent bonding of capture molecules such as antibodies to the nanowire. Charged target molecules in the fluid are attracted to the capture molecules, producing a change in the electric field around the nanowire. The resultant current flow in the nanowire corresponds to the binding and unbinding of target molecules depending upon their concentration in the fluid. Each nanowire serves as the gate of an FET. Since conductance of the nanowire varies with the number of charged target molecules, monitoring this conductance provides an accurate indication of the level of the specific functionalized biomarker. Target molecules can be detected in the range of tens of proteins/ml.
Sets of nanowires can be processed into microfluidic chips that have input and output ports for the fluid to pass through. The chips are manufactured in much the same way as standard ICs. For bedside use, these chip biosensors will be located in the patient's IV line to allow continuous detection and monitoring of multiple biomarkers.
According to Vista Therapeutics, the market for biosensor technology currently is estimated to be greater than $3B spread over a number of commercial and military applications. Topping the list at $2B is point-of-care clinical settings, followed by clinical research and trials, and military and bioweapons at $500M each. Preclinical safety assessment is pegged at $300M with drug discovery and development at $250M. In terms of hardware, it is estimated that 7B microfluidic chips will be needed for patient monitoring and 1B for academic research. In light of this growing market, combining engineering with biomedicine could well be an exciting field to consider, not only for recent graduates, but seasoned professionals as well.