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1.
In this work, aptamers-modified silver nanoparticles (AgNPs) were prepared as capture substrate, and fluorescent dyes-modified aptamers were synthesized as detection probes. The sandwich assay was based on dual aptamers, which was aimed to accomplish the highly sensitive detection of single protein and multiplex detection of proteins on one-spot. We found that aptamers-modified AgNPs based microarray was much superior to the aptamer based microarray in fluorescence detection of proteins. The result shows that the detection limit of the sandwich assay using AgNPs probes for thrombin or platelet-derived growth factor-BB (PDGF-BB) is 80 or 8 times lower than that of aptamers used directly. For multiplex detection of proteins, the detection limit was 625 pM for PDGF-BB and 21 pM for thrombin respectively. The sandwich assay based on dual aptamers and AgNPs was sensitive and specific. 相似文献
2.
An aptamer-based assay for thrombin with high specificity and sensitivity was presented. In the protocol, the aptamer for thrombin was immobilized on magnetic nanoparticle, and its complementary oligonucleotide was labeled with gold nanoparticles, then the aptamer was hybridized with the complementary oligonucleotide to form the duplex structure as a probe, this probe could be used for the specific recognition for thrombin. In the presence of thrombin, the aptamer prefer to form the G-quarter structure with thrombin, resulting in the dissociation of the duplex of the probe and the release of the gold labeled oligonucleotide. Upon this, we were able to detect thrombin through the detection of the electrochemical signal of gold nanoparticles. The strategy combines with the high specificity of aptamer and the excellent characteristics of nanoparticles. This assay is simple, rapid, sensitive and highly specific, it does not require labeling of thrombin, and it could be applied to detect thrombin in complex real sample. The method shows great potential in other protein analysis and in disease diagnosis. 相似文献
3.
Angel A. Martí Steffen Jockusch Zengmin Li Bindu Raveendra Irina Morozova Daniel L. Akins Nicholas J. Turro 《Tetrahedron》2007,63(17):3591-3600
We report the design, synthesis, and characterization of binary oligonucleotide probes for mRNA detection. The probes were designed to avoid common problems found in standard binary probes such as direct excitation of the acceptor fluorophore and overlap between the donor and acceptor emission spectra. Two different probes were constructed that contained an array of either two or three dyes and were characterized using steady-state fluorescence spectroscopy, time-resolved fluorescence spectroscopy, and fluorescence depolarization measurements. The three-dye binary probe (BP-3d) consists of a Fam fluorophore which acts as a donor, collecting light and transferring it as energy to Tamra, which subsequently transfers energy to Cy5 when the two probes are hybridized to mRNA. This design allows the use of 488 nm excitation, which avoids the direct excitation of Cy5 and at the same time provides a good fluorescence resonance energy transfer (FRET) efficiency. The two-dye binary probe system (BP-2d) was constructed with Alexa488 and Cy5 fluorophores. Although the overlap between the fluorescence of Alexa488 and the absorption of Cy5 is relatively low, FRET still occurs due to their close physical proximity when the probes are hybridized to mRNA. This framework also decreases the direct excitation of Cy5 and reduces the fluorescence overlap between the donor and the acceptor. Picosecond time-resolved spectroscopy showed a reduction in the fluorescence lifetime of donor fluorophores after the formation of the hybrid between the probes and target mRNA. Interestingly, BP-2d in the presence of mRNA shows a slow rise in the fluorescence decay of Cy5 due to a relatively slow FRET rate, which together with the reduction in the Alexa488 lifetime provides a way to improve the signal to background ratio using time-resolved fluorescence spectra (TRES). In addition, fluorescence depolarization measurements showed complete depolarization of the acceptor dyes (Cy5) for both BP-3d (due to sequential FRET steps) and BP-2d (due to the relatively low FRET rate) in the presence of the mRNA target. 相似文献
4.
5.
Electroactive chitosan nanoparticles for the detection of single-nucleotide polymorphisms using peptide nucleic acids 总被引:1,自引:0,他引:1
Here we report an electrochemical biosensor that would allow for simple and rapid analysis of nucleic acids in combination
with nuclease activity on nucleic acids and electroactive bionanoparticles. The detection of single-nucleotide polymorphisms
(SNPs) using PNA probes takes advantage of the significant structural and physicochemical differences between the full hybrids
and SNPs in PNA/DNA and DNA/DNA duplexes. Ferrocene-conjugated chitosan nanoparticles (Chi-Fc) were used as the electroactive
indicator of hybridization. Chi-Fc had no affinity towards the neutral PNA probe immobilized on a gold electrode (AuE) surface.
When the PNA probe on the electrode surface hybridized with a full-complementary target DNA, Chi-Fc electrostatically attached
to the negatively-charged phosphate backbone of DNA on the surface and gave rise to a high electrochemical oxidation signal
from ferrocene at ∼0.30 V. Exposing the surface to a single-stranded DNA specific nuclease, Nuclease S1, was found to be very
effective for removing the nonspecifically adsorbed SNP DNA. An SNP in the target DNA to PNA made it susceptible to the enzymatic
digestion. After the enzymatic digestion and subsequent exposure to Chi-Fc, the presence of SNPs was determined by monitoring
the changes in the electrical current response of Chi-Fc. The method provided a detection limit of 1 fM (S/N = 3) for the
target DNA oligonucleotide. Additionally, asymmetric PCR was employed to detect the presence of genetically modified organism
(GMO) in standard Roundup Ready soybean samples. PNA-mediated PCR amplification of real DNA samples was performed to detect
SNPs related to alcolohol dehydrogenase (ALDH). Chitosan nanoparticles are promising biometarials for various analytical and
pharmaceutical applications.
Figure The electrochemical method for SNP detection using PNA probes and chitosan nanoparticles takes advantage of the significant
structural and physicochemical differences between PNA/DNA and DNA/DNA duplexes. Single-stranded DNA specific enzymes selectively
choose these SNP sites and hydrolyze the DNA molecules on gold electrode (AuE) surface.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
6.
Aptamer-based microarrays for the quantitation of multiple protein analytes have been developed. A multiplex aptamer microarray was generated by printing two RNA aptamers (anti-lysozyme and anti-ricin) and two DNA aptamers (anti-IgE and anti-thrombin) on to either streptavidin (SA) or neutravidin (NA)-coated glass slides. However, substantial optimization was required in order to ensure the simultaneous function of the aptamer:analyte pairs. The effects of protein labeling, assay buffer, surface coating, and immobilization chemistry and orientation were investigated. A single buffer (PBS buffer containing 5 mM MgCl2 and 0.1% Tween 20) was found to work well with all the aptamers, even though this was not the buffer originally used in their selection, while neutravidin-coated slides yielded a lower detection limit, wider detection range, and more uniform background than streptavidin-coated slides. Incubation with Cy3-labeled proteins yielded sensitive, target-specific, and dose-dependent responses to each protein. Target protein concentrations as low as 72 pg/mL (5 pM, lysozyme), 15 ng/mL (0.5 nM, ricin), 1.9 ng/mL (0.01 nM, IgE), and 170 ng/mL (5 nM, thrombin) could be detected. These results show that aptamer arrays can potentially be used with numerous proteins in parallel, furthering the notion that aptamer arrays may be useful in proteomics. 相似文献
7.
Aptasensor for ampicillin using gold nanoparticle based dual fluorescence–colorimetric methods 总被引:1,自引:0,他引:1
A gold nanoparticle based dual fluorescence–colorimetric method was developed as an aptasensor to detect ampicillin using
its single-stranded DNA (ssDNA) aptamer, which was discovered by a magnetic bead-based SELEX technique. The selected aptamers,
AMP4 (5′-CACGGCATGGTGGGCGTCGTG-3′), AMP17 (5′-GCGGGCGGTTGTATAGCGG-3′), and AMP18 (5′-TTAGTTGGGGTTCAGTTGG-3′), were confirmed
to have high sensitivity and specificity to ampicillin (K
d, AMP7 = 9.4 nM, AMP17 = 13.4 nM, and AMP18 = 9.8 nM, respectively). The 5′-fluorescein amidite (FAM)-modified aptamer was
used as a dual probe for observing fluorescence differences and color changes simultaneously. The lower limits of detection
for this dual method were a 2 ng/mL by fluorescence and a 10 ng/mL by colorimetry for ampicillin in the milk as well as in
distilled water. Because these detection limits were below the maximum residue limit of ampicillin, this aptasensor was sensitive
enough to detect antibiotics in food products, such as milk and animal tissues. In addition, this dual aptasensor will be
a more accurate method for antibiotics in food products as it concurrently uses two detection methods: fluorescence and colorimetry. 相似文献
8.
A novel method for the future development of label-free DNA sensors is proposed here. The approach is based on the displacement
of a labelled suboptimum mutated oligonucleotide hybridised with the immobilised biotin-capture probe. The target fully complementary
to the biotin-capture probe can displace the labelled oligonucleotide causing a subsequent decrease of the signal that verifies
the presence of the target. The decrease of signal was demonstrated to be proportional to the target concentration. A study
of the hybridisation of mutated and complementary labelled oligonucleotides with an immobilised biotin-capture probe was carried
out. Different kinetic and thermodynamic behaviour was observed for heterogeneous hybridisation of biotin-capture probe with
complementary or suboptimum oligonucleotides. The displacement method evaluated colourimetrically achieved the objective of
decreasing the response time from 1 h for direct hybridisation of 19-mer oligonucleotides in the direct enzyme-linked oligonucleotide
assay (ELONA) to 5 min in the case of displacement detection in the micromolar concentration range.
Figure The detection system is based on the displacement of suboptimum HRP-labelled mutated oligonucleotide by the fully complementary
target 相似文献
9.
Chen Z Li G Zhang L Jiang J Li Z Peng Z Deng L 《Analytical and bioanalytical chemistry》2008,392(6):1185-1188
Fluorescence resonance energy transfer (FRET) between a quantum dot as donor and an organic fluorophore as acceptor has been
widely used for detection of nucleic acids and proteins. In this paper, we developed a new method, characterized by 605-nm
quantum dot (605QD) fluorescence intensity increase and corresponding Cy5 fluorescence intensity decrease, to detect adenosine
triphosphate (ATP). The new method involved the use of three different oligonucleotides: 3′-biotin-modified DNA that binds
to streptavidin-conjugated 605QD; 3′-Cy5-labelled DNA; and a capture DNA consisting of an ATP aptamer and a sequence which
could hybridize with both 3′-biotin-modified DNA and 3′-Cy5-labelled DNA. In the absence of the target ATP, the capture DNA
binds to 3′-biotin-modified DNA and 3′-Cy5-labelled DNA, bringing quantum dot and Cy5 into close proximity for greater FRET
efficiency. When ATP is introduced, the release of the 3′-Cy5-labelled DNA from the hybridization complex took place, triggering
605QD fluorescence intensity increase and corresponding Cy5 fluorescence intensity decrease. Taken together, the virtue of
FRET pair 605QD/Cy5 and the property of aptamer-specific conformation change caused by aptamer–ATP interaction, combined with
the fluorescence intensity change of both 605QD and Cy5, provide prerequisites for simple and convenient ATP detection.
Zhang Chen and Guang Li contributed equally to this work. 相似文献
10.
Zhouping Wang Nuo Duan Xu Hun Shijia Wu 《Analytical and bioanalytical chemistry》2010,398(5):2125-2132
A highly selective electrochemiluminescent biosensor for the detection of target nephrotoxic toxin, ochratoxin A (OTA), was
developed using a DNA aptamer as the recognition element and N-(4-aminobutyl)-N-ethylisoluminol (ABEI) as the signal-producing compound. The electrochemiluminescent aptamer biosensor was fabricated by
immobilizing aptamer complementary DNA 1 sequence onto the surface of a gold-nanoparticle (AuNP)-modified gold electrode.
ABEI-labeled aptamer DNA 2 sequence hybridized to DNA 1 and was utilized as an electrochemiluminescent probe. A decreased
electrochemiluminescence (ECL) signal was generated upon aptamer recognition of the target OTA, which induced the dissociation
of DNA 2 (ABEI-labeled aptamer electrochemiluminescent probe) from DNA 1 and moved it far away from the electrode surface.
Under the optimal conditions, the decreased ECL intensity was proportional to an OTA concentration ranging from 0.02 to 3.0 ng mL-1, with a detection limit of 0.007 ng mL-1. The relative standard deviation was 3.8% at 0.2 ng mL-1 (n = 7). The proposed method has been applied to measure OTA in naturally contaminated wheat samples and validated by an official
method. This work demonstrates the combination of a highly binding aptamer with a highly sensitive ECL technique to design
an electrochemiluminescent biosensor, which is a very promising approach for the determination of small-molecule toxins. 相似文献
11.
L-selectin is a protein with potential importance for numerous diseases and clinical disorders. In this paper, we present a new aptamer-based luminescent assay developed to detect L-selectin. The sensing system working principle is based on Förster Resonance Energy Transfer (FRET) from a donor terbium complex (TbC) to an acceptor cyanine dye (Cy5). In the present approach, the biotinylated aptamer is combined with Cy5-labelled streptavidin (Cy5-Strep) to yield an aptamer-based acceptor construct (Apta-Cy5-Strep), while L-selectin is conjugated using luminescent TbC. Upon aptamer binding to the TbC-labelled L-selectin (L-selectin-TbC), permanent donor-acceptor proximity is established which allows for radiationless energy transfer to occur. However, when unlabelled L-selectin is added, it competes with the L-selectin-TbC and the FRET signal decreases as the L-selectin concentration increases. FRET from the TbC to Cy5 was observed with time-gated time-resolved luminescence spectroscopy. A significant change in the corrected luminescence signal was observed in the dynamic range of 10–500 ng/mL L-selectin, the concentration range relevant for accelerated cognitive decline of Alzheimer's disease, with a limit of detection (LOD) equal to 10 ng/mL. The aptasensor-based assay is homogeneous and can be realized within one hour. Therefore, this method has the potential to become an alternative to tedious heterogeneous analytical methods, e.g. based on enzyme-linked immunosorbent assay (ELISA). 相似文献
12.
《Analytical letters》2012,45(7):1301-1309
A simple competitive fluorescence quenching assay based on aptamer was developed for IgE detection. Two DNA probes were used. One is 5′-end fluorescein-labeled IgE aptamer; the other is 3′-end DABCYL-labeled short DNA, which would hybridize with IgE aptamer to quench the fluorescence. In the presence of IgE, the aptamer-IgE complex formed is strong enough to prevent the short DNA probes hybridizing with the bounded aptamer probes, which results in the less decrease of fluorescence intensity. The signal change was found to be proportional to the concentration of IgE from 0.35 to 35 nM with a detection limit of 0.17 nM. 相似文献
13.
Different Strategies of Covalent Attachment of Oligonucleotide Probe onto Glass Beads and the Hybridization Properties 总被引:1,自引:0,他引:1
The glass bead is a new biochip support material for immobilization biomolecules, due to its independence and convenient rearrangement.
In order to optimize the immobilization efficiency of oligonucleotides onto glass beads and obtain the highest hybridization
efficiency, three commonly used coupling strategies have been studied for covalently attaching oligonucleotides onto large
glass beads. Glass beads with 250 μm diameter were amino-silaned with 2% 3-aminopropyltrimethoxysilane (APTMS) and then reacted
separately with glutaraldehyde, succinic anhydride and 1,4-phenylene diisothiocyanate (PDITC) to derive CHO beads, COOH beads
and isothiocyanate-modified beads (NCS-Beads) accordingly. Afterwards, amino-terminal oligonucleotides were covalently attached
onto the surface of beads achieved by three strategies mentioned above. The immobilization efficiency were studied to compare
the three strategies, which turned out 2.55 × 1013 probes/cm2 for CHO-Beads, 3.21 × 1013 probes/cm2 for COOH beads and 6.68 × 1013 probes/cm2 for NCS beads. It meant that the immobilization efficiency based on NCS beads was most acceptable. And the method, developed
by attaching amino-terminal oligonucleotides onto these cyanate active beads, could be regarded as an efficient one for immobilizing
oligonucleotides onto a solid surface. Moreover, in this paper, the hybridization properties of NCS bead-based oligonucleotides
have been studied by employing Cy5-tagged complementary oligonucleotides. It was found that the high probe density NCS beads
led to low hybridization efficiency possibly due to the existence of steric crowding. In addition, the equilibrium binding
constant K
A was determined by employing Langmuir isotherm model, which was 7.0 × 106 M−1 for NCS beads with the density of 6.7 × 1013 probes/cm2. Furthermore, it only took 60 min to reach hybridization equilibrium. These large microspheres (>100 μm) can be employed
in the mesofluidic systems for automated heterogeneous assays. 相似文献
14.
Label-free aptamer-based colorimetric detection of mercury ions in aqueous media using unmodified gold nanoparticles as colorimetric probe 总被引:2,自引:0,他引:2
We report a simple and sensitive aptamer-based colorimetric detection of mercury ions (Hg2+) using unmodified gold nanoparticles as colorimetric probe. It is based on the fact that bare gold nanoparticles interact
differently with short single-strand DNA and double-stranded DNA. The anti-Hg2+ aptamer is rich in thymine (T) and readily forms T–Hg2+–T configuration in the presence of Hg2+. By measuring color change or adsorption ratio, the bare gold nanoparticles can effectively differentiate the Hg2+-induced conformational change of the aptamer in the presence of a given salt with high concentration. The assay shows a linear
response toward Hg2+ concentration through a five-decade range of 1 × 10−4 mol L−1 to 1 × 10−9 mol L−1. Even with the naked eye, we could identify micromolar Hg2+ concentrations within minutes. By using the spectrometric method, the detection limit was improved to the nanomolar range
(0.6 nM). The assay shows excellent selectivity for Hg2+ over other metal cations including K+, Ba2+, Ni2+, Pb2+, Cu2+, Cd2+, Mg2+, Ca2+, Zn2+, Al3+, and Fe3+. The major advantages of this Hg2+ assay are its water-solubility, simplicity, low cost, visual colorimetry, and high sensitivity. This method provides a potentially
useful tool for the Hg2+ detection. 相似文献
15.
Aptamers, which are nucleic acid oligonucleotides that can bind targets with high affinity and specificity, have been widely applied as affinity probes in capillary electrophoresis (CE). Due to relative weak interaction between aptamers and small molecules, the application of aptamer-based CE is still limited in certain compounds. A new strategy that is based on the aptamer structure-switch concept was designed for small molecule detection by a novel CE method. A carboxyfluorescein (fluorescein amidite, FAM) label DNA aptamer was first incubated with partial complementary strand (CS), and then the free aptamer and the aptamer-CS duplex were well separated and determined by metal cation mediated CE/laser-induced fluorescence. When the target was introduced into the incubated sample, the hybridized form was destabilized, resulting in the changes of the fluorescence intensities of the free aptamer and the aptamer-CS duplex. The length of CS was investigated and 12 mer CS showed the best sensitivity for the detection of cocaine. The presented CE-LIF method, which combines the separation power of CE with the specificity of interactions occurring between target, aptamer, and CS, could be a universal detection strategy for other aptamer-specified small molecules. 相似文献
16.
April K.Y. Wong Denys O. Marushchak Claudiu C. Gradinaru Ulrich J. Krull 《Analytica chimica acta》2010,661(1):103-10
Preliminary studies of mixed films composed of oligonucleotides and poly(2-hydroxyethyl methacrylate) (PHEMA) have recently been shown to enhance the selectivity for detection of 3 base-pair mismatched (3 bpm) oligonucleotide targets. Evaluation of selectivity for detection of single nucleotide polymorphisms (SNP) using such mixed films has now been completed. The selectivity was quantitatively determined by considering the sharpness of melt curves and melting temperature differences (ΔTm) for fully complementary targets and SNPs. Stringency conditions were investigated, and it was determined that the selectivity was maximized when a moderate ionic strength was used (0.1-0.6 M). Increases of ΔTm when using mixed films were up to 3-fold larger compared to surfaces containing only immobilized oligonucleotide probes. Concurrently, increases in sharpness of melt curves for 1 bpm targets were observed to be up to 2-fold greater for mixed films. The co-immobilization of PHEMA resulted in a more homogeneous distribution of oligonucleotide probes on surfaces. Lifetime measurements of fluorescence emission from immobilized oligonucleotide probes labeled with Cy3 dye indicated the difference in microenvironment of immobilized oligonucleotides in the presence of PHEMA. 相似文献
17.
Pablo Lores Lareo Michael W. Linscheid Oliver Seitz 《Journal of mass spectrometry : JMS》2019,54(8):676-683
Detection of nucleic acids and single nucleotide polymorphisms (SNPs) is of pivotal importance in biology and medicine. Given that the biological effect of SNPs often is enhanced in combination with other SNPs, multiplexed SNP detection is desirable. We show proof of concept of the multiplexed detection of SNPs based on the template‐directed native chemical ligation (NCL) of PNA‐probes carrying a metal tag allowing detection using ICP‐MS. For the detection of ssDNA oligonucleotides (30 bases), two probes, one carrying the metal tag and a second one carrying biotin for purification, are covalently ligated. The methodological limit of detection is of 29 pM with RSD of 6.7% at 50 pM (n = 5). Detection of SNPs is performed with the combination of two sets of reporter probes. The first probe set targets the SNP, and its yield is compared with a second set of probes targeting a neighboring sequence. The assay was used to simultaneously differentiate between alleles of three SNPs at 5‐nM concentration. 相似文献
18.
A homogeneous hemin/G-quadruplex DNAzyme (HGDNAzyme) based turn-on chemiluminescence aptasensor for interferon-gamma (IFN-γ) detection is developed, via dynamic in-situ assembly of luminol functionalized gold nanoparticles (lum-AuNPs), DNA, IFN-γ and hemin. The G-quadruplex oligomer of the HGDNAzyme was split into two halves, which was connected with the complementary sequence of P1 (IFN-γ-binding aptamer) to form the oligonucleotide P2. P2 hybridized with IFN-γ-binding aptamer and meanwhile assembled onto lum-AuNPs through biotin–streptavidin specific interaction. When IFN-γ was recognized by aptamer, P2 was released into the solution. The two lateral portions of P2 combined with hemin to yield the catalytic hemin/G-quadruplex DNAzyme, which amplified the luminol oxidation for a turn-on chemiluminescence signaling. Based on this strategy, the homogeneous aptasensor enables the facile detection of IFN-γ in a range of 0.5–100 nM. Moreover, the aptasensor showed high sensitivity (0.4 nM) and satisfactory specificity, pointing to great potential applications in clinical analysis. 相似文献
19.
Katie A. Edwards Yang Wang Antje J. Baeumner 《Analytical and bioanalytical chemistry》2010,398(6):2645-2654
Fluorescent dye-encapsulating liposomes tagged with aptamers were developed and used as reporting signals in an aptamer-based
sandwich assay. α-Thrombin was utilized as a prototypical analyte as two well-studied aptamers binding distinct epitopes are
available to form a sandwich complex. Cholesteryl–TEG-modified aptamers were embedded into the liposomal lipid bilayer while
the interior cavity of the liposomes encapsulated fluorescent sulforhodamine B dye. Such liposomes successfully formed a sandwich
complex with α-thrombin and a microtiter plate immobilized aptamer, proving that aptamers retain their ability to fold when
anchored to the liposome surface. Parameters studied included liposomal aptamer coverage, sandwich aptamer orientation, aptamer
label orientation, aptamer spacer length and type, incubation buffer, and aptamer concentration. The optimized conditions
found here in the fluorescence assay led to a limit of detection of 64 pM or 2.35 ng/mL, corresponding to 6.4 fmol or 235 pg,
respectively, in a 100 μL volume. This is an order of magnitude lower than previous sandwich aptamer assays using the same
sequences with lowest reported limits of detection of 0.45 nM. In addition, the assay was applied successfully to the detection
of α-thrombin in human plasma. The success of this method in a standard microtiter plate format and the relatively facile
functionalization of liposomes with aptamers suggest that this approach provides a versatile option for routine analytical
applications. 相似文献
20.
Engineered nucleic acid probes containing recognition and signaling functions find growing interest in biosensor design. In this paper, we developed a novel electrochemical biosensor for sensitive and selective detecting of Hg2+ based on a bifunctional oligonucleotide signal probe combining a mercury-specific sequence and a G-quadruplex (G4) sequence. For constructing the electrochemical Hg2+ biosensor, a thiolated, mercury-specific oligonucleotide capture probe was first immobilized on gold electrode surface. In the presence of Hg2+, a bifunctional oligonucleotide signal probe was hybridized with the immobilized capture probe through thymine–mercury(II)–thymine interaction-mediated surface hybridization. The further interaction between G4 sequence of the signal probe and hemin generated a G4–hemin complex, which catalyzed the electrochemical reduction of hydrogen peroxide, producing amplified readout signals for Hg2+ interaction events. This electrochemical Hg2+ biosensor was highly sensitive and selective to Hg2+ in the concentration of 1.0 nM to 1 μM with a detection limit of 0.5 nM. The new design of bifunctional oligonucleotide signal probes also provides a potential alternative for developing simple and effective electrochemical biosensors capable of detecting other metal ions specific to natural or artificial bases. 相似文献