Immunomagnetic bead-assisted nanomechanical biosensor
Abstract
Detecting biomolecules such as cancer markers, proteins, DNA, RNA, antibodies, and monitoring their activity in low concentrations is crucial for early detection of diseases. The ultimate goal of biomolecular detection is a portable, inexpensive, fast biosensor that is also highly sensitive. Smaller biosensors generally offer higher sensitivity along with array capability i.e., the capability of detecting many molecules simultaneously. However, they have less surface area for capturing the target and hence, smaller probability to “find” the target molecule. A biomolecular sensing platform that is: (1) small (capable of becoming an array); (2) sensitive; and (3) that does not suffer from reduced transport of target molecules is extremely desirable, and constitutes the aim of this study. Our approach is to combine a well-known nanobiosensor, the cantilever-based biosensor, with immunomagnetic bead-bead separation. Detection in cantilever-based sensors depends on mechanical motion – the cantilever’s deflection – which can be increased using magnetic beads deposited on the cantilever surface by means of a biomolecular recognition in conjunction with an external magnetic field. We show that signal-to-noise ratio can be greatly enhanced by excitation at a high frequency where the noise is low and by a careful design of the overall system. We demonstrate that the immunomagnetically-assisted system can easily resolve subangstrom-level motions. Most importantly, the system is able to separate biomolecules from complex mixtures and to concentrate them into smaller volumes via immunomagnetic separation. This not only helps transport of target molecules to the sensor surface but also avoids exposing the sensor to complex mixtures which can often interfere with its operation. The developed system is versatile and generic so that it can be applied to a wide variety of biological targets.
Degree
Ph.D.
Advisors
Savran, Purdue University.
Subject Area
Biomedical engineering
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