254
Q. Lv et al.
for anti-cells aptamer immobilization. After the aptamer-cancer cells interaction,
the MSN@PMA@T-primer DNA (mesoporous silica nanoparticles@phorbol 12myristate 13-acetate@telomerase primer DNA) probe was endocytosed into the HL60 cancer cells. The T-primer DNA was removed by intracellular telomerase, and
then PMA was released to induce ROS production. The ROS could interact with
the polyluminol-Pt NPs film to trigger the ECL signal, as well as kill the cancer
cells. The telomerase activity could be detected with the LOD of 15 cells/mL, and
the generated ROS could kill cancer cells with high efficacy. The integration of
sensing and therapy made this approach more beneficial for application [82]. The
PEC cytosensors are also attractive due to several advantages such as low background
and convenient operation. Dai’s group presented a PEC aptasensor based on the Bi
nanocrystal core with N, O-doped carbon shell (Bi@NOC) nanohybrids for tumor
cells detection, along with the intracellular telomerase activity quantification. This
biosensor offered the linear range of 5.0 × 10
2 –5.0 × 10
6 HeLa cells/mL, with the
LOD of 60 cells/mL, and was helpful for the cancer’s early clinical diagnosis [83]
(Fig. 9.6b).
Compared with the signal-on strategy, those signal-off method-based aptasensors
majorly suffer from false-positive signals derived from non-specific adsorption of
unrelated components. According to this inherent flaw, voltammetry techniques,
especially the DPV (differential pulse voltammetry) technique, are employed most
widely due to straightforward-interpret signal [84]. For example, a voltammetric
aptamer-based cytosensors for tumor cells quantification was established utilizing
the nanochannel-ion channel. The aptamers were immobilized on the surface of
ion channel for target cancer cells capture. And the trapped cells would cover the
channel entrance and block the ionic flow, resulting in varied mass-transfer property.
The linear sweep voltammetry (LSV) technique was employed for the signal output
with the LOD of 100 cells/mL [85] (Fig. 9.6c). The signal-off-type ECL and PEC
cytosensors were employed for CTCs sensing. Several novel materials were used
for electrode surface functionalization to improve the electron transfer reaction [86].
Using the hypotoxic ternary AgInS 2 NPs and sgc8c aptamer probe, a novel red
light-driven PEC cytosensor was established for cancer cells sensing. The aminoterminated aptamer was immobilized on the interface of AgInS 2 NPs to capture the
lymphoblast CCRF-CEM cells through binding the overexpressed tyrosine kinase-7
on the surface. With the excellent photon-to-current conversion efficiency provided
by the AgInS2 NPs, this signal-off PEC sensor archived a wide linear range of 1.5
× 10
2 –3.0 × 10
5 cells/mL [87].
The sandwich-type aptasensors are based on the structure as capture probe-target
cells-signaling probe, exhibiting high sensitivity and selectivity. The target cells
were trapped within sandwich-type architecture on the sensing interface via a pair
of binding elements, as the capture probe and the signaling probe. For example, the
sandwich-type electrochemical sensors were established for the detection of Burkitt’s
lymphoma-derived Ramos cell [89] and human cervical cancer HeLa cells [90]. The
performance of the sandwich-type cytosensors depends on the specification of target
cells identification of capture probe, as well as the signal amplification of signal
Q. Lv et al.
for anti-cells aptamer immobilization. After the aptamer-cancer cells interaction,
the MSN@PMA@T-primer DNA (mesoporous silica nanoparticles@phorbol 12myristate 13-acetate@telomerase primer DNA) probe was endocytosed into the HL60 cancer cells. The T-primer DNA was removed by intracellular telomerase, and
then PMA was released to induce ROS production. The ROS could interact with
the polyluminol-Pt NPs film to trigger the ECL signal, as well as kill the cancer
cells. The telomerase activity could be detected with the LOD of 15 cells/mL, and
the generated ROS could kill cancer cells with high efficacy. The integration of
sensing and therapy made this approach more beneficial for application [82]. The
PEC cytosensors are also attractive due to several advantages such as low background
and convenient operation. Dai’s group presented a PEC aptasensor based on the Bi
nanocrystal core with N, O-doped carbon shell (Bi@NOC) nanohybrids for tumor
cells detection, along with the intracellular telomerase activity quantification. This
biosensor offered the linear range of 5.0 × 10
2 –5.0 × 10
6 HeLa cells/mL, with the
LOD of 60 cells/mL, and was helpful for the cancer’s early clinical diagnosis [83]
(Fig. 9.6b).
Compared with the signal-on strategy, those signal-off method-based aptasensors
majorly suffer from false-positive signals derived from non-specific adsorption of
unrelated components. According to this inherent flaw, voltammetry techniques,
especially the DPV (differential pulse voltammetry) technique, are employed most
widely due to straightforward-interpret signal [84]. For example, a voltammetric
aptamer-based cytosensors for tumor cells quantification was established utilizing
the nanochannel-ion channel. The aptamers were immobilized on the surface of
ion channel for target cancer cells capture. And the trapped cells would cover the
channel entrance and block the ionic flow, resulting in varied mass-transfer property.
The linear sweep voltammetry (LSV) technique was employed for the signal output
with the LOD of 100 cells/mL [85] (Fig. 9.6c). The signal-off-type ECL and PEC
cytosensors were employed for CTCs sensing. Several novel materials were used
for electrode surface functionalization to improve the electron transfer reaction [86].
Using the hypotoxic ternary AgInS 2 NPs and sgc8c aptamer probe, a novel red
light-driven PEC cytosensor was established for cancer cells sensing. The aminoterminated aptamer was immobilized on the interface of AgInS 2 NPs to capture the
lymphoblast CCRF-CEM cells through binding the overexpressed tyrosine kinase-7
on the surface. With the excellent photon-to-current conversion efficiency provided
by the AgInS2 NPs, this signal-off PEC sensor archived a wide linear range of 1.5
× 10
2 –3.0 × 10
5 cells/mL [87].
The sandwich-type aptasensors are based on the structure as capture probe-target
cells-signaling probe, exhibiting high sensitivity and selectivity. The target cells
were trapped within sandwich-type architecture on the sensing interface via a pair
of binding elements, as the capture probe and the signaling probe. For example, the
sandwich-type electrochemical sensors were established for the detection of Burkitt’s
lymphoma-derived Ramos cell [89] and human cervical cancer HeLa cells [90]. The
performance of the sandwich-type cytosensors depends on the specification of target
cells identification of capture probe, as well as the signal amplification of signal