Aadvance in rapid cancer detection and monitoring

Date:
October 12, 2021
Source:
University of Houston
Summary:
An engineer is reporting fast screening of the surface proteins
of exosomes for cancer diagnostics and biomarker discovery.



FULL STORY ==========================================================================
When it comes to cancer detection, size matters. Traditional diagnostic
imaging cannot detect tumors smaller than a certain size, causing
missed opportunities for early detection and treatment. Circulating
tumor exosomes are especially small cancer biomarkers and easy to
miss. These nanovesicles are composed of molecules that reflect the
parental cells. But, because they are tiny (~30- 150nm in diameter)
and complex, the precise detection of exosome-carried biomarkers with
molecular specificity is elusive.


========================================================================== Until now, reports Wei-Chuan Shih, professor of electrical and computer engineering at the University of Houston Cullen College of Engineering,
in IEEE Sensors journal.

"This work demonstrates, for the first time, that the strong synergy
of arrayed radiative coupling and substrate undercut can enable high-performance biosensing in the visible light spectrum where
high-quality, low-cost silicon detectors are readily available for point-of-care application," said Shih. "The result is a remarkable
sensitivity improvement, with a refractive index sensitivity increase from
207 nm/RIU to 578 nm/RIU." Technically speaking, Shih has restored the electric field around nanodisks, providing accessibility to an otherwise
buried enhanced electric field.

Nanodisks are antibody-functionalized artificial nanostructures which
help capture exosomes with molecular specificity.

"We report radiatively coupled arrayed gold nanodisks on invisible
substrate (AGNIS) as a label-free (no need for fluorescent labels), cost-effective, and high-performance platform for molecularly specific
exosome biosensing. The AGNIS substrate has been fabricated by wafer-scale nanosphere lithography without the need for costly lithography,"
said Shih.

This allows fast screening of the surface proteins of exosomes for
diagnostics and biomarker discovery. As an example, Shih has shown that multiple surface antigens (CD9, CD63 & CD81) were more plentiful in cancer-derived exosomes than those from normal cells.

Current exosome profiling relies primarily on DNA sequencing technology, fluorescent techniques such as flow cytometry, or enzyme-linked
immunosorbent assay (ELISA), which involves sophisticated sample
preparation procedures and requires labeling and amplification, all
processes that are labor-intensive and costly. Shih's goal is to amplify
the signal by developing the label-free technique.

"By decorating the gold nanodisks surface with different antibodies (e.g.,
CD9, CD63, and CD81), label-free exosome profiling has shown increased expression of all three surface proteins in cancer-derived exosomes,"
said Shih. "The sensitivity for detecting exosomes is within 112-600 (exosomes/?L), which would be sufficient in many clinical applications." ========================================================================== Story Source: Materials provided by University_of_Houston. Original
written by Laurie Fickman. Note: Content may be edited for style and
length.


========================================================================== Journal Reference:
1. Ibrahim Misbah, Nareg Ohannesian, Yawei Qiao, Steven H Lin,
Wei-Chuan
Shih. Exploring the synergy of radiative coupling and substrate
undercut in arrayed gold nanodisks for economical, ultra-sensitive
label-free biosensing. IEEE Sensors Journal, 2021; 1 DOI:
10.1109/JSEN.2021.3111125 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211012095048.htm

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