2 research outputs found
Label-Free and High-Throughput Detection of Biomolecular Interactions Using a Flatbed Scanner Biosensor
Fluorescence based
microarray detection systems provide sensitive
measurements; however, variation of probe immobilization and poor
repeatability negatively affect the final readout, and thus quantification
capability of these systems. Here, we demonstrate a label-free and
high-throughput optical biosensor that can be utilized for calibration
of fluorescence microarrays. The sensor employs a commercial flatbed
scanner, and we demonstrate transformation of this low cost (∼100
USD) system into an Interferometric Reflectance Imaging Sensor through
hardware and software modifications. Using this sensor, we report
detection of DNA hybridization and DNA directed antibody immobilization
on label-free microarrays with a noise floor of ∼30 pg/mm<sup>2</sup>, and a scan speed of 5 s (50 s for 10 frames averaged) for
a 2 mm × 2 mm area. This novel system may be used as a standalone
label-free sensor especially in low-resource settings, as well as
for quality control and calibration of microarrays in existing fluorescence-based
DNA and protein detection platforms
DNA-Directed Antibody Immobilization for Enhanced Detection of Single Viral Pathogens
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