Summary: Researchers have developed an innovative device to diagnose glioblastoma, an aggressive brain cancer, in less than an hour using a new biochip. The chip uses electrokinetic technology to detect active epidermal growth factor receptors (EGFR) in extracellular vesicles from a small blood sample.
This method offers high sensitivity and selectivity, which minimizes interference and potentially improves early detection. The technology could be adapted to the diagnosis of other diseases, thus improving its clinical impact.
Key facts:
- New device can diagnose glioblastoma in less than 60 minutes.
- Uses an electrokinetic biochip to detect active EGFRs in blood samples.
- Potential for adaptation to diagnose other diseases beyond glioblastoma.
Source: University of Notre Dame
Researchers at the University of Notre Dame have developed a new automated device that can diagnose glioblastoma, a fast-growing and incurable brain cancer, in less than an hour. The average glioblastoma patient survives 12 to 18 months after diagnosis.
The heart of the diagnostic is a biochip that uses electrokinetic technology to detect biomarkers, or active epidermal growth factor receptors (EGFRs), which are overexpressed in some cancers such as glioblastoma and found in extracellular vesicles.
“Extracellular vesicles, or exosomes, are unique nanoparticles secreted by cells. They are large—10 to 50 times larger than a molecule—and have a low charge. Our technology was specifically designed for these nanoparticles, using their characteristics to our advantage,” said Hsueh-Chia Chang, Bayer Professor of Chemical and Biomolecular Engineering at Notre Dame and lead author of the diagnostic study published in Biology of communications.
The challenge for the researchers was twofold: to develop a process capable of distinguishing between active and non-active EGFRs, and to create a diagnostic technology that is sensitive but selective in detecting active EGFRs on extracellular vesicles from blood samples.
To do this, the researchers created a biochip that uses an inexpensive electrokinetic sensor about the size of a ballpoint pen. Due to the size of the extracellular vesicles, antibodies on the sensor can form multiple bonds with the same extracellular vesicle. This method significantly improves the sensitivity and selectivity of the diagnosis.
Then, synthetic silica nanoparticles “signal” the presence of active EGFRs on the captured extracellular vesicles, while providing a high negative charge. When extracellular vesicles with active EGFRs are present, a voltage shift can be observed, indicating the presence of glioblastoma in the patient.
This charge sensing strategy minimizes interferences common in current sensor technologies that use electrochemical reactions or fluorescence.
“Our electrokinetic sensor allows us to do things that other diagnostics can’t do,” said Satyajyoti Senapati, associate research professor of chemical and biomolecular engineering at Notre Dame and co-author of the study.
“We can directly load blood without any pretreatment to isolate extracellular vesicles because our sensor is not affected by other particles or molecules. It has low noise and makes our sensor more sensitive to disease detection than other technologies.”
In total, the device consists of three parts: an automation interface, a portable prototype machine that administers the materials to perform the test, and the biochip. Each test requires a new biochip, but the automation interface and prototype are reusable.
A test takes less than an hour and requires only 100 microliters of blood. Each biochip costs less than $2 in materials to manufacture.
Although this diagnostic device was developed for glioblastoma, the researchers say it can be adapted to other types of biological nanoparticles. This opens up the possibility for this technology to detect a number of different biomarkers for other diseases.
Chang said the team is exploring the technology to diagnose pancreatic cancer and potentially other disorders such as cardiovascular disease, dementia and epilepsy.
“Our technique is not specific to glioblastoma, but it was particularly relevant to start with it because of its mortality and the lack of available early detection tests,” Chang said. “We hope that if early detection is easier, the chances of survival will be higher.”
Blood samples to test the device were provided by the Brain Cancer Research Centre at the Olivia Newton-John Cancer Research Institute in Melbourne, Australia.
In addition to Chang and Senapati, other collaborators include former Notre Dame postdocs Nalin Maniya and Sonu Kumar; Jeffrey Franklin, James Higginbotham and Robert Coffey of Vanderbilt University; and Andrew Scott and Hui Gan of the Olivia Newton-John Cancer Research Institute and La Trobe University.
Funding:
The study was funded by the National Institutes of Health Joint Fund.
About this brain cancer research news
Author: Brandi Wampler
Source: University of Notre Dame
Contact: Brandi Wampler – University of Notre Dame
Picture: Image credited to Neuroscience News
Original research: Free access.
“An anion-exchange membrane sensor detects EGFR and its activity state in CD63 plasma extracellular vesicles from glioblastoma patients” by Hsueh-Chia Chang et al. Biology of communications
Abstract
An anion-exchange membrane sensor detects EGFR and its activity state in CD63 plasma extracellular vesicles from glioblastoma patients
We present a quantitative sandwich immunoassay for CD63 extracellular vesicles (EVs) and a constitutive surface cargo, EGFR and its activity state, which provides a sensitive, selective, fluorophore-free and rapid alternative to current EV-based diagnostic methods.
Our sensing design uses a charge sensing strategy, with a hydrophilic anion exchange membrane functionalized with capture antibodies and a charged silica nanoparticle reporter functionalized with detection antibodies.
With enhanced sensitivity and robustness through the ionic depletion action of the membrane, this hydrophilic design with charged reporters minimizes interference from dispersed proteins, enabling direct plasma analysis without the need for EV isolation or sensor blocking.
With a LOD of 30 EVs/μL and a high relative sensitivity of 0.01% for targeted proteomic subfractions, our assay enables accurate quantification of the EV marker, CD63, with colocalized EGFR by a universal standardized operator/sample insensitive calibration. We analyzed untreated clinical glioblastoma samples to demonstrate this novel platform.
Notably, we target both total and “active” EGFR on EVs; with a monoclonal antibody mAb806 that recognizes an epitope normally hidden on overexpressed or mutant EGFR variant III.
Analysis of the samples yielded an area under the curve (AUC) value of 0.99 and a low p-value of 0.000033, outperforming the performance of existing tests and markers.
