Development of a one-shot dual aptamer-based fluorescence nanosensor for rapid, sensitive, and label-free detection of periostin.

Periostin is associated with several diseases, including cancers. Therefore, monitoring blood periostin levels is a powerful tool for diagnosing various diseases and identifying their severity. However, conventional detection methods pose several challenges, including high costs. To address these issues, we developed a novel one-shot dual aptamer-based fluorescence nanosensor for detecting periostin. The proposed nanosensor facilitates rapid, label-free, and sensitive detection of periostin using gold nanoprobes constructed by rhodamine-b isothiocyanate, PL2trunc aptamer, and gold nanoparticles and silver nanoprobes fabricated by the PL5trunc aptamer and silver nanoparticles. The two nanoprobes form a core-satellite structure by interacting with periostin, and the nanosensor detects periostin through the fluorescence regenerated by the increased proximity between them. The nanosensor successfully detected periostin with remarkable detection limits of 106.68 pM in buffer and 463.3 pM in serum-spiked conditions within 30 min without additional washing or signal amplification processes. Considering serum periostin levels in various diseases, the proposed nanosensor provides a suitable method for identifying patients with various diseases and determining disease severity. Moreover, the platform can be helpful as a practical method for on-site medical diagnosis because it can be adapted to detect other biomarkers simply by replacing the aptamer with other detection probes.

Bifunctional G-Quadruplex Aptamer Targeting Nucleolin and Topoisomerase 1: Antiproliferative Activity and Synergistic Effect of Conjugated Drugs.

As a counterpart to antibody-drug conjugates (ADCs), aptamer-drug conjugates (ApDCs) have been considered a promising strategy for targeted therapy due to the various benefits of aptamers. However, an aptamer merely serves as a targeting ligand in ApDCs, whereas the antibody enables the unexpected therapeutic efficacy of ADCs through antibody-dependent cellular cytotoxicity (ADCC). In this study, we developed a tumor-specific aptamer with an effector function and used it to confirm the feasibility of more potent ApDCs. First, we designed a nucleolin (NCL)-binding G-quadruplex (GQ) library based on the ability of NCL to bind to telomeric sequences. We then identified a bifunctional GQ aptamer (BGA) inhibiting the catalytic activity of topoisomerase 1 (TOP1) by forming an irreversible cleavage complex. Our BGA specifically targeted NCL-positive MCF-7 cells, exhibiting antiproliferative activity, and this suggested that tumor-specific therapeutic aptamers can be developed by using a biased library to screen aptamer candidates for functional targets. Finally, we utilized DM1, which has a synergistic interaction with TOP1 inhibitors, as a conjugated drug. BGA-DM1 exerted an anticancer effect 20-fold stronger than free DM1 and even 10-fold stronger than AS1411 (NCL aptamer)-DM1, highlighting our approach to develop synergistic ApDCs. Therefore, we anticipate that our library might be utilized for the identification of aptamers with effector functions. Furthermore, by employing such aptamers and appropriate drugs, synergistic ApDCs can be developed for targeted cancer therapy in a manner distinct from how ADCs exhibit additional therapeutic efficacy.

Development of an optical sandwich ELONA using a pair of DNA aptamers for yellow fever virus NS1.

Here, we proposed an enzyme-linked oligonucleotide assay (ELONA) for yellow fever (YF) diagnosis that uses a pair of aptamers, YFns1-4 and YFns1-31. The aptamers were selected to specifically bind to nonstructural protein 1 (NS1), which is secreted at a high concentration after YF infection. We applied the aptamers which did not interfere with each other on binding to the NS1 in a sandwich ELONA. In the assay, the best detection sensitivity was obtained when the combination of YFns1-31 as a capture aptamer and YFns1-4 as a detect aptamer was used. The sensitivity could be attributed to the results of the direct ELONA with each YFns1-4 and YFns1-31; a great absorbance intensity and a broad detectable range of NS1, respectively. The sandwich ELONA achieved a low detection limit of 0.85 nM in buffer and was highly specific to the YFV-NS1 as its detection signals were significantly distinct from those of other flavivirus-derived NS1. In addition, the assay showed a desirable sensitivity in serum-spiked condition. Our developed sandwich ELONA can be a new practical and applicable serological diagnostics in YF endemic regions where other flaviviruses coexist and facilities for complex diagnostic tests are lacking.

Aptamer-antibody hybrid ELONA that uses hybridization chain reaction to detect a urinary biomarker EN2 for bladder and prostate cancer.

We report an EN2-specific (Kd = 8.26 nM) aptamer, and a sensitive and specific enzyme-linked oligonucleotide assay (ELONA) for rapid and sensitive colorimetric detection of bladder and prostate cancer biomarker EN2 in urine. The assay relies on an aptamer-mediated hybridization chain reaction (HCR) to generate DNA nanostructures that bind to EN2 and simultaneously amplify signals. The assay can be performed within 2.5 h, and has a limit of detection of 0.34 nM in buffer and 2.69 nM in artificial urine. Moreover, this assay showed high specificity as it did not detect other urinary proteins, including biomarkers of other cancers. The proposed ELONA is inexpensive, highly reproducible, and has great chemical stability, so it may enable development of a simple, sensitive and accurate diagnostic tool to detect bladder and prostate cancers early.

Direct Detection of Low Abundance Genes of Single Point Mutation.

Cell-free DNA (cfDNA) analysis, specifically circulating tumor DNA (ctDNA) analysis, provides enormous opportunities for noninvasive early assessment of cancers. To date, PCR-based methods have led this field. However, the limited sensitivity/specificity of PCR-based methods necessitates the search for new methods. Here, we describe a direct approach to detect KRAS G12D mutated genes in clinical ctDNA samples with the utmost LOD and sensitivity/specificity. In this study, MutS protein was immobilized on the tip of an atomic force microscope (AFM), and the protein sensed the mismatched sites of the duplex formed between the capture probe on the surface and mutated DNA. A noteworthy LOD (3 copies, 0.006% allele frequency) was achieved, along with superb sensitivity/specificity (100%/100%). These observations demonstrate that force-based AFM, in combination with the protein found in nature and properly designed capture probes/blockers, represents an exciting new avenue for ctDNA analysis.

Fast Aptamer Generation Method Based on the Electrodynamic Microfluidic Channel and Evaluation of Aptamer Sensor Performance.

We demonstrate for the first time a fast aptamer generation method based on the screen-printed electrodynamic microfluidic channel device, where a specific aptamer selectively binds to a target protein on channel walls, following recovery and separation. A malaria protein as a model target, Plasmodium vivax lactate dehydrogenase (PvLDH) was covalently bonded to the conductive polymer layer formed on the carbon channel walls to react with the DNA library in a fluid. Then, the AC electric field was symmetrically applied on the channel walls for inducing the specific binding of the target protein to DNA library molecules. In this case, the partitioning efficiency between PvLDH and DNA library in the channel was attained to be 1.67 × 107 with the background of 5.56 × 10-6, which was confirmed using the quantitative polymerase chain reaction (qPCR). The selectively captured DNAs were isolated from the protein and separated in situ to give five aptamers with different sequences by one round cycle. The dissociation constants (Kd) of the selected aptamers were determined employing both electrochemical impedance spectroscopy (EIS) and the fluorescence method. The sensing performance of each aptamer was evaluated for the PvLDH detection after individual immobilization on the screen-printed array electrodes. The most sensitive aptamer revealed a detection limit of 7.8 ± 0.4 fM. The sensor reliability was evaluated by comparing it with other malaria sensors.

Troponin Aptamer on an Atomically Flat Au Nanoplate Platform for Detection of Cardiac Troponin I.

Well-ordered bioreceptors on atomically flat Au surfaces can be a high-performance biosensor. Cardiac troponin I proteins (cTnIs) have been regarded as a specific biomarker for acute myocardial infarction (AMI). Here, we report the accurate detection of cTnIs using an aptamer-immobilized Au nanoplate platform. The single-crystalline and atomically flat Au nanoplate was characterized by atomic force microscopy. For the precise detection of cTnI, we immobilized an aptamer that can strongly bind to cTnI onto an atomically flat Au nanoplate. Using the aptamer-immobilized Au nanoplate, cTnIs were successfully detected at a concentration of 100 aM (2.4 fg/mL) in buffer solution. Furthermore, cTnIs in serum could be identified at a concentration of 100 fM (2.4 pg/mL). The total assay time was ~7 h. Importantly, the aptamer-immobilized Au nanoplate enabled us to diagnose AMI patients accurately, suggesting the potential of the present method in the diagnosis of AMI.

A Rapid Colorimetric Sensor for Soluble Interleukin-2 Receptor α, Based on Aptamer-Adsorbed AuNP.

The soluble interleukin-2 receptor α (sIL-2Rα) is a broad indicator of clinical disease activity in various inflammatory diseases. Here we have developed, for the first time, a rapid, washing-free colorimetric aptasensor based on a sIL-2Rα aptamer (Kd =1.33 nm). The aptasensor was fabricated with Au nanoparticles (AuNPs) adsorbing sIL-2Rα aptamers. On addition of sIL-2Rα, the aptamers become desorbed from the AuNPs, and this in turn weakens the absorption corresponding to AuNP-catalyzed oxidation of ortho-phenylenediamine (oPD) with H2 O2 . The aptasensor was characterized by TEM imaging, ζ potential measurements, dynamic light scattering (DLS) analysis, and UV/Vis spectrometry, followed by further optimization. The fabricated sensor exhibited great analytical performance, with a linear range of 1 to 100 nm and a detection limit of 1 nm both in buffer and in spiked human serum within 25 min. Other proteins, such as bovine serum albumin (BSA), IL-17Rα, IL-5Rα, IL-13Rα2 , and CD166, showed negligible effects on the aptasensor. Thanks to the great advantages of the aptamers and AuNPs, this aptasensor provides a rapid, simple, and inexpensive process that might offer insights into various diagnostic applications of sIL-2Rα.

Aptasensor for multiplex detection of antibiotics based on FRET strategy combined with aptamer/graphene oxide complex.

The development of a multiplexed sensing platform is necessary for highly selective, sensitive, and rapid screening of specific antibiotics. In this study, we designed a novel multiplex aptasensor for antibiotics by fluorescence resonance energy transfer (FRET) strategy using DNase I-assisted cyclic enzymatic signal amplification (CESA) method combined with aptamer/graphene oxide complex. The aptamers specific for sulfadimethoxine, kanamycin, and ampicillin were conjugated with Cyanine 3 (Cy3), 6-Carboxyfluorescein (FAM), and Cyanine 5 (Cy5), respectively, and graphene oxide (GO) was adopted to quench the fluorescence of the three different fluorophores with the efficiencies of 94.36%, 93.94%, and 96.97% for Cy3, FAM, and Cy5, respectively. CESA method was used for sensitive detection, resulting in a 2.1-fold increased signal compared to those of unamplified method. The aptasensor rapidly detected antibiotics in solution with limit of detection of 1.997, 2.664, and 2.337 ng/mL for sulfadimethoxine, kanamycin, and ampicillin, respectively. In addition, antibiotics dissolved in milk were efficiently detected with similar sensitivities. Multiplexed detection test proved that the fluorescently modified aptamers could work separately from each other. The results indicate that the aptasensor offers high specificity for each antibiotic and enables simultaneous and multicolor sensing for rapid screening of multiple antibiotics at the same time.

Translational control of phloem development by RNA G-quadruplex-JULGI determines plant sink strength.

The emergence of a plant vascular system was a prerequisite for the colonization of land; however, it is unclear how the photosynthate transporting system was established during plant evolution. Here, we identify a novel translational regulatory module for phloem development involving the zinc-finger protein JULGI (JUL) and its targets, the 5' untranslated regions (UTRs) of the SUPPRESSOR OF MAX2 1-LIKE4/5 (SMXL4/5) mRNAs, which is exclusively conserved in vascular plants. JUL directly binds and induces an RNA G-quadruplex in the 5' UTR of SMXL4/5, which are key promoters of phloem differentiation. We show that RNA G-quadruplex formation suppresses SMXL4/5 translation and restricts phloem differentiation. In turn, JUL deficiency promotes phloem formation and strikingly increases sink strength per seed. We propose that the translational regulation by the JUL/5' UTR G-quadruplex module is a major determinant of phloem establishment, thereby determining carbon allocation to sink tissues, and that this mechanism was a key invention during the emergence of vascular plants.

Comparative lipidomic profiling of the human commensal bacterium Propionibacterium acnes and its extracellular vesicles.

Propionibacterium acnes is a lipophilic commensal bacterium mainly found on the skin and in the gastrointestinal tract. Pathophysiological effects of P. acnes have recently been reported not only in acne progression but in various diseases. As an emerging mode of bacterial communication, extracellular vesicles (EVs) have been demonstrated to conduct critical pathophysiological functions. To provide information on P. acnes lipid composition for the first time, we conducted a comparative lipidomic analysis of P. acnes and P. acnes EVs and identified 214 lipids with high confidence using triplicated liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analyses. P. acnes EVs contained substantially more PCs, DGs, PAs, PEs, LPAs, LPCs, and MGs than P. acnes, and contained fewer PSs, SO1Ps, SA1Ps, LPGs, LPIs, and LPSs. Distinctively, P. acnes EVs possessed a markedly reduced amount of TG. These findings will provide useful clues for understanding the biological and pathophysiological mechanisms of P. acnes and for clinical applications such as vaccine development, diagnostics and therapeutics.

Cardioprotective Effect of the SDF-1α/CXCR4 Axis in Ischemic Postconditioning in Isolated Rat Hearts.

BACKGROUND AND OBJECTIVES: Information about the role of the stromal cell-derived factor-1α (SDF-1α)/chemokine receptor type 4 (CXCR4) axis in ischemic postconditioning (IPOC) is currently limited. We hypothesized that the SDF-1α/CXCR4 signaling pathway is directly involved in the cardioprotective effect of IPOC. METHODS: Isolated rat hearts were divided into four groups. The control group was subjected to 30-min of regional ischemia and 2-hour of reperfusion (n=12). The IPOC group was induced with 6 cycles of 10-second reperfusion and 10-second global ischemia (n=8) in each cycle. The CXCR4 antagonist, AMD3100, was applied before reperfusion in the IPOC group (AMD+IPOC group, n=11) and control group (AMD group, n=9). Hemodynamic changes with electrocardiography were monitored and infarct size was measured. The SDF-1α, lactate dehydrogenase (LDH) and creatine kinase (CK) concentrations in perfusate were measured. We also analyzed extracellular signal-regulated kinase 1/2 (ERK1/2) and Akt phosphorylation state expression. RESULTS: IPOC significantly reduced infarct size, but AMD3100 attenuated the infarct reducing effect of IPOC. IPOC significantly decreased LDH and CK, but these effects were reversed by AMD3100. ERK1/2 and Akt phosphorylation increased with IPOC and these effects were blocked by AMD3100. CONCLUSION: Based on the results of this study, SDF-1α/CXCR4 signaling may be involved in IPOC cardioprotection and this signaling pathway couples to the ERK1/2 and Akt pathways.

Highly sensitive amperometric detection of cardiac troponin I using sandwich aptamers and screen-printed carbon electrodes.

In this study, we developed a sandwich aptamer-based screen-printed carbon electrode (SPCE) using chronoamperometry for the detection of cardiac troponin I (cTnI), one of the promising biomarkers for acute myocardial infarction (AMI). Disposable three-electrode SPCEs were manufactured using a screen printer, and various modifications such as electrodeposition of gold nanoparticles and electropolymerization of conductive polymers were performed. From the bare electrode to the aptamer-immobilized SPCE, all processes were monitored and analyzed via various techniques such as cyclic voltammetry, electrochemical impedance spectroscopy, and X-ray photoelectron spectroscopy. The quantification of cTnI was conducted based on amperometric signals from the catalytic reaction between hydrazine and H2O2. The fabricated aptasensor in a buffer, as well as in a serum-added solution, exhibited great analytical performance with a dynamic range of 1-100 pM (0.024-2.4ng/mL) and a detection limit of 1.0 pM (24pg/mL), which is lower than the existing cutoff values (40-700pg/mL). Furthermore, the developed sensor showed high sensitivity to cTnI over other proteins. It is anticipated that this potable SPCE aptasensor for cTnI will become an innovative diagnostic tool for AMI.

Proteomic analysis of extracellular vesicles derived from Propionibacterium acnes.

PURPOSE: Extracellular vesicle (EV) has been reported to conduct critical pathophysiological functions as an emerging mode of communication in bacteria. Recently, Propionibacterium acnes, an anaerobic Gram-positive human commensal found in the skin and gastrointestinal tract, has drawn increasing attention as an underestimated pathogen in a variety of diseases. EXPERIMENTAL DESIGN: For the comprehensive understanding of P. acnes, here we report the isolation of P. acnes EVs for the first time and identification of 252 vesicular proteins with high confidence using triplicate LC-MS/MS analyses. RESULT: Comprehensive proteomic profiling reveals that P. acnes EVs harbor various proteins involved in biochemical processes, antibiotic resistance, bacterial competition, cell adherence, virulence, and immunogenicity. CONCLUSION AND CLINICAL RELEVANCE: We believe that this report will provide valuable information for investigating the biological role of P. acnes EVs and effective targets for developing clinical applications against P. acnes.

Crystal structure of a DNA aptamer bound to PvLDH elucidates novel single-stranded DNA structural elements for folding and recognition.

Structural elements are key elements for understanding single-stranded nucleic acid folding. Although various RNA structural elements have been documented, structural elements of single-stranded DNA (ssDNA) have rarely been reported. Herein, we determined a crystal structure of PvLDH in complex with a DNA aptamer called pL1. This aptamer folds into a hairpin-bulge contact by adopting three novel structural elements, viz, DNA T-loop-like motif, base-phosphate zipper, and DNA G·G metal ion zipper. Moreover, the pL1:PvLDH complex shows unique properties compared with other protein:nucleic acid complexes. Generally, extensive intermolecular hydrogen bonds occur between unpaired nucleotides and proteins for specific recognitions. Although most protein-interacting nucleotides of pL1 are unpaired nucleotides, pL1 recognizes PvLDH by predominant shape complementarity with many bridging water molecules owing to the combination of three novel structural elements making protein-binding unpaired nucleotides stable. Moreover, the additional set of Plasmodium LDH residues which were shown to form extensive hydrogen bonds with unpaired nucleotides of 2008s does not participate in the recognition of pL1. Superimposition of the pL1:PvLDH complex with hLDH reveals steric clashes between pL1 and hLDH in contrast with no steric clashes between 2008s and hLDH. Therefore, specific protein recognition mode of pL1 is totally different from that of 2008s.

Enhanced electrochemical sensing of leukemia cells using drug/lipid co-immobilized on the conducting polymer layer.

Electrochemical biosensors using five anticancer drug and lipid molecules attached on the conducting polymer layer to obtain the orientation of drug molecules toward cancer cells, were evaluated as sensing materials and their performances were compared. Conjugation of the drug molecules with a lipid, phosphatidylcholine (PC) has enhanced the sensitivity towards leukemia cells and differentiates cancer cells from normal cells. The composition of each layer of sensor probe was confirmed by electrochemical and surface characterization experiments. Both impedance spectroscopy and voltammetry show the enhanced interaction of leukemia cells using the drug/lipid modified sensor probe. As the number of leukemia cells increased, the charge transfer resistance (Rct) in impedance spectra increased and the amine oxidation peak current of drug molecules in voltammograms decreased at around 0.7-1.0V. Of test drug molecules, raltitrexed (Rtx) showed the best performance for the cancer cells detection. Cancer and normal cell lines from different origins were examined to evaluate the degree of expression of folate receptors (FR) on cells surface, where cervical HeLa cell line was found to be shown the highest expression of the receptor. Impedance and chronoamperometric experiments for leukemia cell line (Jurkat E6-1) showed linear dynamic ranges of 1.0×10(3)-2.5×10(5) cells/mL and 1.0×10(3)-8.0×10(3) cells/mL with detection limits of 68±5 cells/mL and 21±3 cells/mL, respectively.

Aptamer-nanoparticle complexes as powerful diagnostic and therapeutic tools.

Correct diagnosis and successful therapy are extremely important to enjoy a healthy life when suffering from a disease. To achieve these aims, various cutting-edge technologies have been designed and fabricated to diagnose and treat specific diseases. Among these technologies, aptamer-nanomaterial hybrids have received considerable attention from scientists and doctors because they have numerous advantages over other methods, such as good biocompatibility, low immunogenicity and controllable selectivity. In particular, aptamers, oligonucleic acids or peptides that bind to a specific target molecule, are regarded as outstanding biomolecules. In this review, several screening techniques for aptamers, also called systematic evolution of ligands by exponential enrichment (SELEX) methods, are introduced, and diagnostic and therapeutic aptamer applications are also presented. Furthermore, we describe diverse aptamer-nanomaterial conjugate designs and their applications for diagnosis and therapy.

Overexpression of angiotensin II type 1 receptor in breast cancer cells induces epithelial-mesenchymal transition and promotes tumor growth and angiogenesis.

The angiotensin II type I receptor (AGTR1) has been implicated in diverse aspects of human disease, from the regulation of blood pressure and cardiovascular homeostasis to cancer progression. We sought to investigate the role of AGTR1 in cell proliferation, epithelial-mesenchymal transition (EMT), migration, invasion, angiogenesis and tumor growth in the breast cancer cell line MCF7. Stable overexpression of AGTR1 was associated with accelerated cell proliferation, concomitant with increased expression of survival factors including poly(ADP-ribose) polymerase (PARP) and X-linked inhibitor of apoptosis (XIAP), as well as extracellular signal-regulated kinase (ERK) activation. AGTR1-overexpressing MCF7 cells were more aggressive than their parent line, with significantly increased activity in migration and invasion assays. These observations were associated with changes in EMT markers, including reduced E-cadherin expression and increased p-Smad3, Smad4 and Snail levels. Treatment with the AGTR1 antagonist losartan attenuated these effects. AGTR1 overexpression also accelerated tumor growth and increased Ki-67 expression in a xenograft model. This was associated with increased tumor angiogenesis, as evidenced by a significant increase in microvessels in the intratumoral and peritumoral areas, and enhanced tumor invasion, with the latter response associated with increased EMT marker expression and matrix metallopeptidase 9 (MMP-9) upregulation. In vivo administration of losartan significantly reduced both tumor growth and angiogenesis. Our findings suggest that AGTR1 plays a significant role in tumor aggressiveness, and its inhibition may have therapeutic implications.

A highly sensitive and selective impedimetric aptasensor for interleukin-17 receptor A.

Interleukin-17 receptor A (IL-17RA) has been recognized as a valuable biomarker for diverse diseases, including autoimmune diseases. In this work, an electrochemical biosensor with great sensitivity and selectivity toward IL-17RA was fabricated using an IL-17RA aptamer (Kd=14.00nM) for the first time. The aptasensor was manufactured using electrodeposition of gold nanoparticles, and then quantitative detection of IL-17RA was performed based on impedimetry. The developed sensor exhibited a superior analytical performance for IL-17RA with a wide dynamic range of 10-10,000pg/mL in buffer and a detection limit of 2.13pg/mL, which is lower than that of commercially available ELISA kits. In addition, we validated the high specificity of the designed aptasensor to only IL-17RA, which showed good sensitivity even in human serum solution. Furthermore, the detection of the differentiated HL-60 cells expressing IL-17RA was successfully performed. Clinical applicability of the sensor was also demonstrated utilizing neutrophils separated from asthma patients. It is expected that the fabricated aptasensor will become an excellent diagnostic platform for IL-17RA-mediated diseases.

Electrochemical aptasensor of cardiac troponin I for the early diagnosis of acute myocardial infarction.

Cardiac troponin I (cTnI) is well-known as a promising biomarker for the early diagnosis of acute myocardial infarction (AMI). In this work, single-stranded DNA aptamers against cTnI were identified by the Systematic Evolution of Ligands by Exponential enrichment (SELEX) method. The aptamer candidates exhibited a high selectivity and sensitivity toward both cTnI and the cardiac Troponin complex. The binding affinities of each aptamer were evaluated based on their dissociation constants (Kd) by surface plasma resonance. The Tro4 aptamer that had the highest binding capacity to cTnI showed a very low Kd value (270 pM) compared with that of a cTnI antibody (20.8 nM). Furthermore, we designed a new electrochemical aptasensor based on square wave voltammetry using ferrocene-modified silica nanoparticles. The developed aptasensor demonstrated an excellent analytical performance for cTnI with a wide linear range of 1-10 000 pM in a buffer and a detection limit of 1.0 pM (24 pg/mL; S/N = 3), which was noticeably lower than the cutoff values (70-400 pg/mL). The specificity of the aptamers was also examined using nontarget proteins, demonstrating that the proposed sensor responded to only cTnI. In addition, cTnI was successfully detected in a human serum albumin solution. On the basis of the calibration curve that was constructed, the concentrations of cTnI in a solution supplemented with human serum were effectively measured. The calculated values correlated well with the actual concentrations of cTnI. It is anticipated that the highly sensitive and selective aptasensor for cTnI could be readily applicable for the accurate diagnosis of AMI.