The objective of this project is to develop a rapid and accurate lab-on-a-chip device for characterization of nano-size vesicles based on their unique and intrinsic biophysical properties. The immediate focus of this project is to characterize small cell-secreted vesicles (exosomes) which are classified as circulating biomarkers associated with many types of disease including cancer, diabetes, cardiovascular, infectious, and neurodegenerative diseases. This research also has the potential to be expanded beyond exosomes to detect and study other small membrane bound vesicles including viruses. Thus, this high throughput detection tool can be utilized in a wide range of medical diagnosis and biomedical research which could potentially reduce the cost of healthcare by providing frequent, affordable, and early testing to patients. Furthermore this multidisciplinary project crosses the traditional boundaries between engineering, physics, and biomedical sciences which will provide students with a unique educational experience during their academic training. The undergraduate students will be trained and exposed to the field of micro- nanotechnology and biomedical sciences by closely working with the graduate students and being mentored by the principal investigator. The proposed project will also educate public about the importance of the field of micro-nanotechnologies for medicine through YouTube channel and “ThinkTV†program which will be broadcasting in Southwest Ohio.
Exosomes are extracellular vesicles with diameters of ~30-120 nm, released from many cell types into the extracellular space. They are composed of a lipid bilayer membrane containing various receptors and tetraspanin proteins. They also encapsulate nucleic acids, proteins, and lipids in their lumen. Exosomes are promising biomarkers for several reasons: 1) they are highly abundant in all bodily fluids and therefore easily accessible; 2) their composition reflects their cellular origins and can therefore serve as indicators of pathology; and 3) they are stable. Also, it has been shown that exosomes secreted from different cellular origins, in particular pathogenic exosomes, undergo compositional changes and could have additional membrane receptors and/or elevated or suppressed levels of nucleic acids which can be associated with their total electric charges and dipoles. However, use of exosomes as biomarkers has been hampered by the lack of workable technologies to reliably isolate and rigorously characterize their unique properties in a timely manner. Although, some of the biophysical properties of exosomes such as size, density and morphology have been characterized before, their dielectric property which is associated with their unique compositional charges has not yet been investigated. The proposed label-free lab-on-a-chip device will utilize controllable electrokinetic forces across an array of borosilicate micropipettes to rapidly entrap exosomes at the tip of the pipettes and characterize the vesicles based on their unique dielectric properties by measuring their impedance. The impedance measurement will be conducted across an array of microelectrodes embedded in close proximity to the pipettes’ tips as an alternative current (AC) is applied at a wide range of frequency spectrum (500 KHz to 50 MHz). The AC field at a wide frequency range will polarize the bound and unbound charges associate with exosomes’ structure. The difference in impedance measurements will be linked to exosomes’ unique dielectric properties which includes their membrane capacitance and cytosolic conductance. Additionally, the impedance of exosomes secreted from different cellular origins and size distribution will be measured and their uniqueness in dielectric properties will be investigated. This rapid and label-free electrokinetic device can be further evolved as a diagnostic tool for initial non-invasive detection of pathogenic exosomes while keeping their compositions intact for further downstream analysis
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
