9 Aptamers for the Diagnosis of Malign Tumors
247
simultaneous detection of cytochrome c (CYC)and VEGF 165 . Reduced graphene
oxide poly (amidoamine)/gold nanocomposite (rGO-PAMAM/Au nano ) was used as
the support matrix for flavin adenine dinucleotide (for CYC), thionine (for VEGF),
and their aptamers immobilization of dual working electrode. Differential pulse
voltammetry (DPV) and cyclic voltammetry (CV) were used for tracking the electrochemical behaviors. The biosensors exhibited a linear range from 2.5 to 320.0 pM for
VEGF without the serum interference [41]. Based on aptamer-bridged DNA network
structure and g-C 3 N 4 as photoactive material, Chai’s group established a “sign-off”
photoelectrochemical aptasensor for VEGF 165 detection. The binding of aptamer
and VEGF could destroy the DNA network, resulting in a significant decrease of the
photocurrent. This strategy could offer a good linear range of 100 fM-10 nM, with
the LOD of 30 fM [42].
Carcinoembryonic antigen (CEA) is a glycoprotein naturally derived from the
embryonic digestive tissue, disappearing after birth. An abnormally high level of
CEA in the blood of adults can be a ubiquitous sign of several kinds of cancers
[44]. For example, a novel label-free sandwich-type electrochemical sensor was
constructed for sensitive CEA sensing based on anti-CEA aptamers and concanavalin
A (ConA). Both the CEA and horseradish peroxidase (HRP) bind onto ConA through
sugar-lectin interactions, resulting in signal amplification. This proposed aptasensor
exhibited the detection linear range as 5–40 ng/mL CEA, with the LOD of 3.4 ng/mL
(Fig. 9.3b) [43]. The introduction of a variety of nanomaterials and biomacromolecules has injected unlimited possibilities for the development of electrochemical aptamer sensors. It is believed that the realization of clinical applications will be
realized in the near future.
9.3.2 Aptamer-Based Optical Assays
Several optical-based aptasensors and bioassays are applied to cancer biomarker
detections. Among these techniques, we will discuss the application of surface
plasmon resonance (SPR), surface-enhanced Raman scattering(SERS), fluorescence,
and colorimetry-based platforms.
9.3.2.1 SPR- and SERS-Based Platforms
SPR-based biosensors own many unique advantages, as label-free systems, realtime tracking, as well as the opportunity for kinetic studies. Aptamers are always
immobilized on the surface of matrix and used as the binding elements in aptamerbased SPR biosensors. When an interaction happens between the aptamers and their
corresponding targets on the sensor surface, the refractive index at the surface will
change according to the mass of the targets and the incident resonance [45].
The protein biomarkers exist in low abundance in biological samples, leading
to the increased difficulty in detection with SPR biosensors. To overcome this
247
simultaneous detection of cytochrome c (CYC)and VEGF 165 . Reduced graphene
oxide poly (amidoamine)/gold nanocomposite (rGO-PAMAM/Au nano ) was used as
the support matrix for flavin adenine dinucleotide (for CYC), thionine (for VEGF),
and their aptamers immobilization of dual working electrode. Differential pulse
voltammetry (DPV) and cyclic voltammetry (CV) were used for tracking the electrochemical behaviors. The biosensors exhibited a linear range from 2.5 to 320.0 pM for
VEGF without the serum interference [41]. Based on aptamer-bridged DNA network
structure and g-C 3 N 4 as photoactive material, Chai’s group established a “sign-off”
photoelectrochemical aptasensor for VEGF 165 detection. The binding of aptamer
and VEGF could destroy the DNA network, resulting in a significant decrease of the
photocurrent. This strategy could offer a good linear range of 100 fM-10 nM, with
the LOD of 30 fM [42].
Carcinoembryonic antigen (CEA) is a glycoprotein naturally derived from the
embryonic digestive tissue, disappearing after birth. An abnormally high level of
CEA in the blood of adults can be a ubiquitous sign of several kinds of cancers
[44]. For example, a novel label-free sandwich-type electrochemical sensor was
constructed for sensitive CEA sensing based on anti-CEA aptamers and concanavalin
A (ConA). Both the CEA and horseradish peroxidase (HRP) bind onto ConA through
sugar-lectin interactions, resulting in signal amplification. This proposed aptasensor
exhibited the detection linear range as 5–40 ng/mL CEA, with the LOD of 3.4 ng/mL
(Fig. 9.3b) [43]. The introduction of a variety of nanomaterials and biomacromolecules has injected unlimited possibilities for the development of electrochemical aptamer sensors. It is believed that the realization of clinical applications will be
realized in the near future.
9.3.2 Aptamer-Based Optical Assays
Several optical-based aptasensors and bioassays are applied to cancer biomarker
detections. Among these techniques, we will discuss the application of surface
plasmon resonance (SPR), surface-enhanced Raman scattering(SERS), fluorescence,
and colorimetry-based platforms.
9.3.2.1 SPR- and SERS-Based Platforms
SPR-based biosensors own many unique advantages, as label-free systems, realtime tracking, as well as the opportunity for kinetic studies. Aptamers are always
immobilized on the surface of matrix and used as the binding elements in aptamerbased SPR biosensors. When an interaction happens between the aptamers and their
corresponding targets on the sensor surface, the refractive index at the surface will
change according to the mass of the targets and the incident resonance [45].
The protein biomarkers exist in low abundance in biological samples, leading
to the increased difficulty in detection with SPR biosensors. To overcome this