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Microfluidic Platform for Aptamer based Fluorimetric Analysis of
Analytes
Tanu Bhardwaj and Sandeep Kumar Jha*
Centre for Biomedical Engineering, Indian Institute of Technology Delhi, New Delhi-110016, India
Keywords: PMMA, Microfluidics, Aptamer, Biosensing, FAM, Fluorescence.
Abstract: In this work, we are reporting fabrication of a simple and low cost setup for fluorescence detection based on
aptamer probes. For this reason, we fabricated a PMMA-PMMA microfluidic chip using easily available
laboratory techniques and combined the chip with a simple fluorescence detection setup using optical fiber,
filter, detector and a commercial spectroscopy software. In this new approach, we used two different
strategies to use aptamers as probe. In first strategy, detection of any nucleic acid could be targeted using
simple DNA hybridization with aptamer probe. Such strategy can be used in analysis of samples with
specific nucleic acid sequence, such as pathogen. We proved this using known sequence of ssDNA aptamer
probe immobilized on detection zone on microchip and its FAM labeled complementary strand was passed
over it using microfluidic condition. In other strategy, we attempted detection of any protein or biomarker
using sandwich fluorimetric technique with primary and labeled secondary aptamer immobilized on sensing
region. For this, we used thrombin as model target to validate our setup. Both the strategies proved
satisfactory on our setup. Even more, LOD was also impressive. In future, this setup could further be
miniaturized by using a small on-chip CCD array detector, microcontroller based electronics and LabVIEW
software based control.
1 INTRODUCTION
Aptamers are single stranded nucleic acids, DNA or
RNA, which selectively and specifically bind to a
target molecule such as nucleic acids, proteins, cells,
microorganisms, etc. interacting via weak molecular
forces. They often complement antibodies in terms
of binding efficiency and specificity, yet are more
stable and cheaper to produce. Aptamers are picked
for a particular target from a process called SELEX
(Systematic evolution of ligands by exponential
enrichment) which is comparatively simple process
compared to typical antibody production using
hybridoma technique. In addition, host animal is also
not required for the production of aptamers. Extra
resistance against denaturation and ease of chemical
modifications make aptamers friendlier to use in
biosensing (Tennico, 2010; Song, 2012).
Meanwhile, microfluidics has replaced many
analytical and biomedical techniques due to its
reduced size, cost and reagents utilization. Aptamers
and their application in microfluidics are inspiring
researchers to create a bridge between two
drastically different fields of biological and
analytical techniques. Aptamers with microfluidics
have already been used for analysis of biological
targets/analytes like thrombin, VEG-165, peptides,
cancer cells, C-reactive protein, viruses, microbes
and various other proteins or biomarkers (Xu, 2010).
Out of which, viruses, pathogens or microbes are
identified by these aptamers due to their specific
microbial proteins, lipopolysaccharides or nucleic
acids. On the other hand, biomarkers (proteins)
originating in the case of cancer allow their detection
using aptamers (Viscidi, 1987; Su, 2015).
Detection of various diseases associated with
microbes was made possible by simple hybridization
of aptamer probe labelled with dye to the
complementary nucleic acid strand from the microbe
(Tennico, 2010). Besides, aptamers and
hybridization principle has been used for DNA
microarrays, single nucleotide polymorphism
detection, gene expression studies and nucleic acid
diagnostic applications (Wang, 2011; Abu-Salah,
2015). Furthermore, various proteins and biomarkers
have been identified using primary and dye labeled
secondary aptamers sandwich assay like ELISA
technique. The use of fluorescent dyes in such
218
Bhardwaj, T. and Jha, S.
Microfluidic Platform for Aptamer based Fluorimetric Analysis of Analytes.
DOI: 10.5220/0006645002180223
In Proceedings of the 11th International Joint Conference on Biomedical Engineering Systems and Technologies (BIOSTEC 2018) - Volume 1: BIODEVICES, pages 218-223
ISBN: 978-989-758-277-6
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