3 Aptamer-Based Point of Care Testing Schemes
69
aptamer (LBApt) was immobilized on the polymer p(AGE-DIPAMA) modified MNP
(pMNP), which was synthesized through the easy operated free radical polymerization method to develop the adsorbent LBApt-pMNP. It was successfully applied to
the recognition of foodborne disease allergen lysozyme in egg white samples. The
adsorbent immobilized with cytochrome C (Cyt C) binding aptamer (CBApt-pMNP)
also displayed Cyt C adsorption capacity and recognition selectivity. The controllable adsorption and desorption of protein giving a sensitive and efficient aptamerbased and pH-responsive polymer assisted adsorbents for protein recognition in real
biological samples [84].
Tang et al. utilized the semiconductor QDs for fabrication of aptamer-conjugated
nanosensors for the determination of EGFR variant III expressed glioma tissues and
suggested that the sensor can be used for pre- and postoperative examination in
glioma tissues [85]. A CdTe quantum dots-single walled carbon nanohorns (CdTeSWCNHs) nanocomposite was synthesized by Xu et al., via a one-pot method
for photo-electrochemical (PEC) aptasensing of streptomycin (STR). The CdTeSWCNHs nanocomposite showed 3.2 times enhanced PEC activity in comparison
with CdTe quantum dots (QDs). By using aptamers as recognition element and CdTeSWCNHs as photoactive species, a PEC aptasensor was synthesized for the detection
of STR [86].
Xia et al. developed a visible and simple method for the detection of exosomes
by integrating single-walled carbon nanotubes bearing excellent water solubility (sSWCNTs) and aptamers. Aptamers, specific to exosomes transmembrane protein
CD63, were absorbed onto the surface of s-SWCNTs and improved the peroxidase
activity of s-SWCNTs, which can efficiently catalyze H 2 O 2 -mediated oxidation of
3, 3
, 5, 5
-tetramethylbenzidine (TMB) and lead to a change from colorless to blue.
After adding exosomes, the aptamers bound with CD63, leaving from the surface
of s-SWCNTs through structural changes, which resulted in the color from deep to
moderate, and this could be observed by the naked eye and monitored by UV–vis
spectrometry [87]. In addition, Ming et al., synthesized a nanoassembly consisting
of amine-functionalized single-walled carbon nanotube/new methylene blue/gold
nanoparticles (AuNPs) and modified the working electrode with this nanoassembly
to detect estradiol in serum with LOD of 5 pg.mL
−1 [88].
3.3.8 Multiple Aptasensing Platforms
In recent years, aptamers have been used in various multiplex detection systems to
independently detect more than one analyte in a single assay at the same time. Li
et al. proposed a multiplex electrochemical aptasensor based on a screen-printed
carbon electrode (SPCE), modified by carbon nanofibers (CNFs) and mesoporous
carbon-gold nanoparticles (OMC-AuNPs) for the ultrasensitive detection of foodborne disease pathogen kanamycin (KAN) and streptomycin (STR) from milk. In
the absence of KAN and STR, the aptamers bound to their complementary strands.
69
aptamer (LBApt) was immobilized on the polymer p(AGE-DIPAMA) modified MNP
(pMNP), which was synthesized through the easy operated free radical polymerization method to develop the adsorbent LBApt-pMNP. It was successfully applied to
the recognition of foodborne disease allergen lysozyme in egg white samples. The
adsorbent immobilized with cytochrome C (Cyt C) binding aptamer (CBApt-pMNP)
also displayed Cyt C adsorption capacity and recognition selectivity. The controllable adsorption and desorption of protein giving a sensitive and efficient aptamerbased and pH-responsive polymer assisted adsorbents for protein recognition in real
biological samples [84].
Tang et al. utilized the semiconductor QDs for fabrication of aptamer-conjugated
nanosensors for the determination of EGFR variant III expressed glioma tissues and
suggested that the sensor can be used for pre- and postoperative examination in
glioma tissues [85]. A CdTe quantum dots-single walled carbon nanohorns (CdTeSWCNHs) nanocomposite was synthesized by Xu et al., via a one-pot method
for photo-electrochemical (PEC) aptasensing of streptomycin (STR). The CdTeSWCNHs nanocomposite showed 3.2 times enhanced PEC activity in comparison
with CdTe quantum dots (QDs). By using aptamers as recognition element and CdTeSWCNHs as photoactive species, a PEC aptasensor was synthesized for the detection
of STR [86].
Xia et al. developed a visible and simple method for the detection of exosomes
by integrating single-walled carbon nanotubes bearing excellent water solubility (sSWCNTs) and aptamers. Aptamers, specific to exosomes transmembrane protein
CD63, were absorbed onto the surface of s-SWCNTs and improved the peroxidase
activity of s-SWCNTs, which can efficiently catalyze H 2 O 2 -mediated oxidation of
3, 3
, 5, 5
-tetramethylbenzidine (TMB) and lead to a change from colorless to blue.
After adding exosomes, the aptamers bound with CD63, leaving from the surface
of s-SWCNTs through structural changes, which resulted in the color from deep to
moderate, and this could be observed by the naked eye and monitored by UV–vis
spectrometry [87]. In addition, Ming et al., synthesized a nanoassembly consisting
of amine-functionalized single-walled carbon nanotube/new methylene blue/gold
nanoparticles (AuNPs) and modified the working electrode with this nanoassembly
to detect estradiol in serum with LOD of 5 pg.mL
−1 [88].
3.3.8 Multiple Aptasensing Platforms
In recent years, aptamers have been used in various multiplex detection systems to
independently detect more than one analyte in a single assay at the same time. Li
et al. proposed a multiplex electrochemical aptasensor based on a screen-printed
carbon electrode (SPCE), modified by carbon nanofibers (CNFs) and mesoporous
carbon-gold nanoparticles (OMC-AuNPs) for the ultrasensitive detection of foodborne disease pathogen kanamycin (KAN) and streptomycin (STR) from milk. In
the absence of KAN and STR, the aptamers bound to their complementary strands.