Biomedical Engineering Reference
In-Depth Information
(2)
Incubate for 2 h at hybridization temperature based on the length of the
ONT-C6QD620.
(3)
Wash with 0.3 M PBS, pH 7, two times to remove the unbound target
ONT-C6QD620.
(4)
Dehybridize by incubating in NaOH at a final concentration of 50 mM at a
pH of 11-12 for 4 h.
(5)
Neutralize the solution with 1 M HCl.
(6)
Centrifuge to separate the AuNP-thiolONT-dylight550 which precipitates
leaving the ONT-C6QD620 in the supernatant solution.
(7)
Take the absorbance of the ONT-C6QD620 at 610 nm.
(8)
Establish the concentration of the ONT-C6QD620 by extrapolating from
the calibration curve.
(9)
Prepare standard solutions of the original ONT-C6QD620. Generate the
calibration curve by taking the absorbance of solutions of the original
ONT-C6QD620.
4.7 TRANSDUCTION DETECTION SYSTEMS
FOR NP BIOSENSORS
Different types of NMs of various sizes and compositions that are used in opti-
cal
21,92
and electrochemical
93,94
biosensors such as enzyme-based sensors,
immunosensors, and DNA sensors are currently available in the market. These
NMs are coated with polymer or biological coating materials that serves as
bioactive and selective interface for functionalization prior to their application
in biosensing systems. As discussed in the previous sections, physical adsorp-
tion, electrostatic interaction, covalent linkage, or self-assembly are the vari-
ous strategies for the attachment of functional groups. Since the NMs and the
functional groups are both in the nanoscale, when used in biosensors, they are
appropriately termed nanobiosensors, biomolecular nanotechnology, or nano-
biotechnology.
72
Aside from the physical, chemical, and biological modifica-
tions (with antibodies, DNA, RNA, peptides, cells, parts of cells, etc.), the
modified NMs characterization and quantification are crucial for the biosens-
ing application.
The size-dependent optical and electrochemical properties of NMs offer var-
ious signal transduction modes, including simultaneous approaches (optical and
electrochemical) that are not available with other materials.
13,14,92,95
The range
of potential applications of nanobiosensors depends on the NMs properties, the
biomolecules to detect as well as the type of sample to be analyzed. Nano-
biosensors can be used for the detection of DNA, protein, bacteria, virus, and
cell analysis using optical and electrical biosensing systems. Aside from optical
and electrochemical detection principles
13,14,21,92,95
involving nanobiosensors,
NMs are also used in fluorescence quenching, magnetoelastic, and lateral flow
assays.
