8 Aptamers for the Diagnosis of Infectious Diseases
225
during a blood meal and their spreading to the liver through bloodstream. Once inside
into the liver, the sporozoites divide repeatedly and differentiate into merozoites,
which can infect red blood cells (RBCs) and start the intraerythrocytic cycle as long
as they are released in the bloodstream.
Such drugs are available for malaria treatment as chloroquine, sulfadoxine/pyrimethamine (SP), and quinine. Specially, the artemisinin-based combination therapies (ACTs) have been used to malaria treatment globally, with desired
results in malaria diagnosis. Unfortunately, the artemisinin-resistant parasite was
found in the blood of patients after being cured [82]. Therefore, in consideration
of the resistance of parasites, an anti-adhesive drug therapy should be developed.
Aptamer technology can be explored as a potential anti-adhesive therapy for malaria.
8.4.1.1 Different Aptasensors Platforms
Aptasensors based on fluorometric [84, 87, 88], electrochemical [83, 89] and
colorimetric [90, 91] assay have been developed for malaria detection.
Plasmodium falciparum lactate dehydrogenase (Pf LDH) was selected as the
target recognized by DNA aptamer. All kinds of aptamer-based assays were developed for Pf LDH detection. Figueroa-Miranda et al. [83] devised an electrochemical
aptasensor for highly sensitive and selective malaria detection. Due to the isoelectric
point (pI) of Pf LDH, the aptasensor response showed an adjustable detection range
according to the different protein net-charge at variable pH environments. The electrochemical aptasensor responded with a low LOD of 0.84 pM and a linear dynamic
range of 0.01–100 pM Pf LDH concentrations (Fig. 8.8a). The aptasensor can be
applied for detecting the target Pf LDH in human serum as a promising candidate
for malaria point-of-care diagnostic systems.
Tanner group [92] reported an aptamer-tethered enzyme capture (APTEC) method
for rapid malaria diagnostic test. In the test, Pf LDH was captured by its aptamer
specifically, and the result was measured calorimetrically. Pf LDH could catalyze
L-lactate to pyruvate, which would be coupled with the reduction of a tetracycline
dye for a colorimetric response. Pf LDH activity was not inhibited after combining
with its aptamer [93]. Actually, the APTEC assay had no need of additional enzymes
and dyes reducing the operational costs. In addition, the test achieved a LOD at
4.9 ng/mL Pf LDH concentrations in serum samples, which is lower than many
existing experiments results showing extremely high sensitivity.
8.4.1.2 Nanomaterial-Involved Aptasensors
Over the past few years, gold nanoparticles nanoclusters have acquired tremendous
interest due to their attractive physicochemical properties and super biocompatibility,
particularly in malaria biosensor [84, 87, 90, 94]. In 2017, Wu group [84] designed
a AgNCs-dsDNA-based aptasensors. The interaction between Pf LDH and AgNCsdsDNA could induce dramatic fluorescence enhancement, which was adopted to
225
during a blood meal and their spreading to the liver through bloodstream. Once inside
into the liver, the sporozoites divide repeatedly and differentiate into merozoites,
which can infect red blood cells (RBCs) and start the intraerythrocytic cycle as long
as they are released in the bloodstream.
Such drugs are available for malaria treatment as chloroquine, sulfadoxine/pyrimethamine (SP), and quinine. Specially, the artemisinin-based combination therapies (ACTs) have been used to malaria treatment globally, with desired
results in malaria diagnosis. Unfortunately, the artemisinin-resistant parasite was
found in the blood of patients after being cured [82]. Therefore, in consideration
of the resistance of parasites, an anti-adhesive drug therapy should be developed.
Aptamer technology can be explored as a potential anti-adhesive therapy for malaria.
8.4.1.1 Different Aptasensors Platforms
Aptasensors based on fluorometric [84, 87, 88], electrochemical [83, 89] and
colorimetric [90, 91] assay have been developed for malaria detection.
Plasmodium falciparum lactate dehydrogenase (Pf LDH) was selected as the
target recognized by DNA aptamer. All kinds of aptamer-based assays were developed for Pf LDH detection. Figueroa-Miranda et al. [83] devised an electrochemical
aptasensor for highly sensitive and selective malaria detection. Due to the isoelectric
point (pI) of Pf LDH, the aptasensor response showed an adjustable detection range
according to the different protein net-charge at variable pH environments. The electrochemical aptasensor responded with a low LOD of 0.84 pM and a linear dynamic
range of 0.01–100 pM Pf LDH concentrations (Fig. 8.8a). The aptasensor can be
applied for detecting the target Pf LDH in human serum as a promising candidate
for malaria point-of-care diagnostic systems.
Tanner group [92] reported an aptamer-tethered enzyme capture (APTEC) method
for rapid malaria diagnostic test. In the test, Pf LDH was captured by its aptamer
specifically, and the result was measured calorimetrically. Pf LDH could catalyze
L-lactate to pyruvate, which would be coupled with the reduction of a tetracycline
dye for a colorimetric response. Pf LDH activity was not inhibited after combining
with its aptamer [93]. Actually, the APTEC assay had no need of additional enzymes
and dyes reducing the operational costs. In addition, the test achieved a LOD at
4.9 ng/mL Pf LDH concentrations in serum samples, which is lower than many
existing experiments results showing extremely high sensitivity.
8.4.1.2 Nanomaterial-Involved Aptasensors
Over the past few years, gold nanoparticles nanoclusters have acquired tremendous
interest due to their attractive physicochemical properties and super biocompatibility,
particularly in malaria biosensor [84, 87, 90, 94]. In 2017, Wu group [84] designed
a AgNCs-dsDNA-based aptasensors. The interaction between Pf LDH and AgNCsdsDNA could induce dramatic fluorescence enhancement, which was adopted to