DNA-Directed Antibody Immobilization for Enhanced
Detection of Single Viral Pathogens
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Abstract
Here, we describe the use of DNA-conjugated
antibodies for rapid
and sensitive detection of whole viruses using a single-particle interferometric
reflectance imaging sensor (SP-IRIS), a simple, label-free biosensor
capable of imaging individual nanoparticles. First, we characterize
the elevation of the antibodies conjugated to a DNA sequence on a
three-dimensional (3-D) polymeric surface using a fluorescence axial
localization technique, spectral self-interference fluorescence microscopy
(SSFM). Our results indicate that using DNA linkers results in significant
elevation of the antibodies on the 3-D polymeric surface. We subsequently
show the specific detection of pseudotyped vesicular stomatitis virus
(VSV) as a model virus on SP-IRIS platform. We demonstrate that DNA-conjugated
antibodies improve the capture efficiency by achieving the maximal
virus capture for an antibody density as low as 0.72 ng/mm<sup>2</sup>, whereas for unmodified antibody, the optimal virus capture requires
six times greater antibody density on the sensor surface. We also
show that using DNA conjugated anti-EBOV GP (Ebola virus glycoprotein)
improves the sensitivity of EBOV-GP carrying VSV detection compared
to directly immobilized antibodies. Furthermore, utilizing a DNA surface
for conversion to an antibody array offers an easier manufacturing
process by replacing the antibody printing step with DNA printing.
The DNA-directed immobilization technique also has the added advantages
of programmable sensor surface generation based on the need and resistance
to high temperatures required for microfluidic device fabrication.
These capabilities improve the existing SP-IRIS technology, resulting
in a more robust and versatile platform, ideal for point-of-care diagnostics
applications