3 Bio-microelectromechanical Systems (BioMEMS) in Bio-sensing …
83
Fig. 3.1 WFP after
functionalization; inset
shows close-up of nano-rods
after antibody
immobilization (Tiwari et al.
2017)
examples of the paper-based BioMEMS used for fluorescence detection are provided
in this chapter.
Tiwari et al. (2017) investigated the performance of Zinc oxide nanorods functionalized paper (ZnO-NRs-WFP) compared to regular Whatman filter paper (WFP)
in the capture, detection, and release capabilities of the cardiac myoglobin. WFP
was functionalized with nanorods (Fig. 3.1) that increased the surface area available
to bind to the surface primary antibodies. With these paper alterations, the device
showed a threefold improvement when compared to the control (non-functionalized)
WFP. Although enzyme-linked immunosorbent assay (ELISA) protocol was used to
demonstrate sensitivity and performance of the device through fluorescent detection of analyte posterior to exposure to secondary antibody, the results adduced the
capability of molecular trapping, justifying future use as a preconcentration stage
integrated into a multi-stage biosensor.
One of the main challenges of the paper materials for their use in biosensing
is the fact that they commonly require functionalization to better interact with
biomolecules. µPADs can be exposed to the biomolecules without functionalization as well (physical attachment). However, through many washing steps involved
in bio-assays, these molecules may leach out of the fibrous structure of paper which
expectedly results in undesirable detection outcomes. To avoid this, Rosa et al. (2014)
investigated the use of the third family of carbohydrate binding module (CBM) of
the Clostridium Thermocellum. This CBM has a high specificity towards cellulose
and is therefore used as a part of a larger conjugate in order to bind the ZZ-domain
of the staphylococcal protein A to the paper fibers. Once this interaction took place,
the ZZ-domain from its free end can be used to bind to an IgG antibody. The IgG, in
turn, can bind to and detect the presence of biotin. For that reason, if a DNA strand
is biotinylated and fluorescently tagged, the presence of a fluorescent response in the
paper would attest to the device’s effectiveness in detection. The study demonstrated
83
Fig. 3.1 WFP after
functionalization; inset
shows close-up of nano-rods
after antibody
immobilization (Tiwari et al.
2017)
examples of the paper-based BioMEMS used for fluorescence detection are provided
in this chapter.
Tiwari et al. (2017) investigated the performance of Zinc oxide nanorods functionalized paper (ZnO-NRs-WFP) compared to regular Whatman filter paper (WFP)
in the capture, detection, and release capabilities of the cardiac myoglobin. WFP
was functionalized with nanorods (Fig. 3.1) that increased the surface area available
to bind to the surface primary antibodies. With these paper alterations, the device
showed a threefold improvement when compared to the control (non-functionalized)
WFP. Although enzyme-linked immunosorbent assay (ELISA) protocol was used to
demonstrate sensitivity and performance of the device through fluorescent detection of analyte posterior to exposure to secondary antibody, the results adduced the
capability of molecular trapping, justifying future use as a preconcentration stage
integrated into a multi-stage biosensor.
One of the main challenges of the paper materials for their use in biosensing
is the fact that they commonly require functionalization to better interact with
biomolecules. µPADs can be exposed to the biomolecules without functionalization as well (physical attachment). However, through many washing steps involved
in bio-assays, these molecules may leach out of the fibrous structure of paper which
expectedly results in undesirable detection outcomes. To avoid this, Rosa et al. (2014)
investigated the use of the third family of carbohydrate binding module (CBM) of
the Clostridium Thermocellum. This CBM has a high specificity towards cellulose
and is therefore used as a part of a larger conjugate in order to bind the ZZ-domain
of the staphylococcal protein A to the paper fibers. Once this interaction took place,
the ZZ-domain from its free end can be used to bind to an IgG antibody. The IgG, in
turn, can bind to and detect the presence of biotin. For that reason, if a DNA strand
is biotinylated and fluorescently tagged, the presence of a fluorescent response in the
paper would attest to the device’s effectiveness in detection. The study demonstrated