Selective Electrochemical Aptasensor Research Articles

Development of a highly sensitive and selective electrochemical aptasensor for the detection of Staphylococcus aureus in various samples

Food poisoning caused by toxins produced by Staphylococcus aureus (S. aureus) is a significant global public health concern, impacting both developing and developed countries. One effective method for detecting S. aureus is the use of electrochemical aptasensors. This study introduces a highly sensitive and selective electrochemical aptasensor designed for detecting of S. aureus bacteria. The aptasensor incorporates ferrocene (Fc) as an electrochemical signal tag, which is covalently bonded to a zeolitic imidazolate framework-8 (ZIF-8). To enhance the performance of the working electrode, a nanocomposite of three-dimensional reduced graphene oxide and chitosan is used to create a nanomaterial film with a large surface area and excellent conductivity. The S. aureus-specific aptamer sequence is immobilized as the bio-recognition element, and cDNA-ZIF-8-Fc is hybridized with the immobilized aptamer. Differential pulse voltammograms of the modified electrode are recorded before and after the interaction between the immobilized aptamer and S. aureus. The changes in peak current serve as the analytical signal for the quantitative measurement of S. aureus. The designed aptasensor can detect S. aureus within a linear concentration range of 15.0 to 1.5 × 107 CFU mL−1, with a limit of detection (LOD) of 5.3 CFU mL−1. The results demonstrate that the aptasensor effectively quantifies S. aureus selectively in the presence of other bacterial species. Additionally, satisfactory results are obtained when measuring S. aureus in tap water and milk samples.

Surface‐Based Multimeric Aptamer Generation and Bio‐Functionalization for Electrochemical Biosensing Applications

AbstractMultimeric aptamers have gained more attention than their monomeric counterparts due to providing more binding sites for target analytes, leading to increased affinity. This work attempted to engineer the surface‐based generation of multimeric aptamers by employing the room temperature rolling circle amplification (RCA) technique and chemically modified primers for developing a highly sensitive and selective electrochemical aptasensor. The multimeric aptamers, generated through surface RCA, are hybridized to modified spacer primers, facilitating the positioning of the aptamers in the proximity of sensing surfaces. These multimeric aptamers can be used as bio‐receptors for capturing specific targets. The surface amplification process was fully characterized, and the optimal amplification time for biosensing purposes was determined, using SARS‐CoV‐2 spike protein (SP). Interestingly, multimeric aptasensors produced considerably higher response signals and affinity (more than 10‐fold), as well as higher sensitivity (almost 4‐fold) compared to monomeric aptasensors. Furthermore, the impact of surface structures on the response signals was studied by utilizing both flat working electrodes (WEs) and nano‐/microislands (NMIs) WEs. The NMIs multimeric aptasensors showed significantly higher sensitivity in buffer and saliva media with the limit of detection less than 2 fg/ml. Finally, the developed NMIs multimeric aptasensors were clinically challenged with several saliva patient samples.

Surface-Based Multimeric Aptamer Generation and Bio-Functionalization for Electrochemical Biosensing Applications.

Multimeric aptamers have gained more attention than their monomeric counterparts due to providing more binding sites for target analytes, leading to increased affinity. This work attempted to engineer the surface-based generation of multimeric aptamers by employing the room temperature rolling circle amplification (RCA) technique and chemically modified primers for developing a highly sensitive and selective electrochemical aptasensor. The multimeric aptamers, generated through surface RCA, are hybridized to modified spacer primers, facilitating the positioning of the aptamers in the proximity of sensing surfaces. These multimeric aptamers can be used as bio-receptors for capturing specific targets. The surface amplification process was fully characterized, and the optimal amplification time for biosensing purposes was determined, using SARS-CoV-2 spike protein (SP). Interestingly, multimeric aptasensors produced considerably higher response signals and affinity (more than 10-fold), as well as higher sensitivity (almost 4-fold) compared to monomeric aptasensors. Furthermore, the impact of surface structures on the response signals was studied by utilizing both flat working electrodes (WEs) and nano-/microislands (NMIs) WEs. The NMIs multimeric aptasensors showed significantly higher sensitivity in buffer and saliva media with the limit of detection less than 2 fg/ml. Finally, the developed NMIs multimeric aptasensors were clinically challenged with several saliva patient samples.

Designing an electrochemical aptasensor based on a microstructure porous-covalent organic polymer for the determination of 2,4,6-trinitrotoluen in water and soil samples

A selective electrochemical aptasensor assessment based on a microstructure porous-covalent organic polymer (MP-COP) was introduced and applied for 2,4,6-Trinitrotoluen (TNT) sensing. The synthesis of MP-COP involves the formation of an amide bond by coupling carboxylic acids and amine groups using trimesic acid. The synthesized MP-COP was used to modify the glassy carbon electrode (GCE) due to its ability to enhance electrochemical activity. The GCE is modified with the MP-COP and aptamer to create a sensing substrate, with the goal of improving the aptasensor’s electrochemical performance for TNT detection. Electrochemical impedance spectroscopy, differential pulse voltammetry, and cyclic voltammetry were applied for the evaluation of the introduced aptasensor in [Fe(CN)6]3−/4− probe. Moreover, it was delineated using fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller. The suggested aptasensor for TNT has a limit of detection of 0.0003 pM and the linear range from 0.001 to 100 pM. The usability of the proposed aptasensor for TNT measurement in actual samples was examined with the recovery range from 98.30 to 102.40 %. It seems that the proposed strategy can be expanded to design of electrochemical aptasensors.

A sensitive bimetallic copper/bismuth metal-organic frameworks-based aptasensors for zearalenone detection in foodstuffs

Electrochemical aptasensors have emerged as promising platforms for effectivelydetection of various target analytes. Here, we developed a sensitive and selective electrochemical aptasensor for zearalenone (ZEN) determination based on a bimetallic organic framework (CuBi-BPDC). The results of HR-TEM, FE-SEM, XPS, etc. indicate the CuBi-BPDC possessing mixed nodes of Cu(II) and Bi(III) and multilayered nanosheets bearing nanoparticles. Due to its improved electrochemical activity and strong affinity for aptamers, the CuBi-BPDC-based aptasensor obtains a low limit of detection of 0.19 fg mL−1 (IUPAC S/N = 3) in a wide range of 1 fg mL−1–10 ng mL−1 via EIS and 0.73 fg mL−1 from 0 fg mL−1 to 1 × 107 fg mL−1 via DPV for ZEN detection, respectively. Moreover, the excellent selectivity allows this aptasensor to specifically identify ZEN from other interfering substances in raw milk and rice, indicating the potential applicability of the CuBi-BPDC-based aptasensor in sensitive and selective detection of ZEN.

Defective zirconium/titanium bimetallic metal-organic framework as a highly selective and sensitive electrochemical aptasensor for deoxynivalenol determination in foodstuffs.

Anelectrochemical aptsensor for deoxynivalenol determination was successfully designed and constructed based on a defective bimetallic organic framework (denoted as ZrTi-MOF). The high porosity, large specific surface area, several structural defects, mixed metal clusters, and rich functionality of ZrTi-MOF markedly enhanced its electrochemical activity and facilitated the aptamer immobilization. As a result, the ZrTi-MOF-based aptasensor shows high sensitivity to detect deoxynivalenol via specific recognition between aptamer and deoxynivalenol, as well as the formation of aptamer-deoxynivalenol complex. On this basis, the developed ZrTi-MOF-based impedimetric aptasensor showed a low detection limit of 0.24fgmL-1 for deoxynivalenol determination in the deoxynivalenol concentration range 1fgmL-1-1ngmL-1 under optimized conditions, which also exhibited satisfactory selectivity, stability, reproducibility, and regenerability. Furthermore, determinationof deoxynivalenol was achieved in bread and wheat flour samples via the developed ZrTi-MOF-based deoxynivalenol aptasensor. The result from this study showed that the ZrTi-MOF-based electrochemical aptasensor could become a promising strategy for detecting deoxynivalenol in foodstuffs in the future.

A three-dimensional boron-doped diamond mesh aptasensor for the sensitive determination of cefquinome

Aptamer can specifically identify the target and combine with surface functionalized electrodes to construct highly selective electrochemical aptasensor, so it has a wide range of applications in environmental monitoring, medical diagnosis and other fields. In this study, we designed and fabricated a boron-doped diamond (BDD) electrochemical aptasensor based on three-dimensional mesh structure for the detection of trace cefquinome (CFQ). The low detection limit of 9.29 × 10−16 mol L−1 as well as broad linear relationship ranging from 1.0 × 10−15 to 1.0 × 10−9 mol L−1 were achieved through a modification to the surface of BDD mesh using gold nanoparticle (Au-NPs), aptamers and 6-mercapto-1-ethanol (MCH). The experimental findings demonstrate that the aptasensor is of significant sensitivity, specificity and stability, and it has broad application prospects in the field of trace detection.

A Simple, sensitive, and selective electrochemical aptasensor for cortisol based on rGO‐AuNPs

AbstractCortisol is a steroid hormone naturally produced by the adrenal glands. It participates in and controls several processes in the body and is considered an important physiological biomarker. Due to its very low concentrations in body fluids, its detection requires high sensitivity and specificity. Here, we present a simple electrochemical biosensor based on reduced graphene oxide (rGO) modified with gold nanoparticles (AuNPs) for the immobilization of the cortisol‐specific aptamer (Ap) (MCH‐Ap‐AurGO/GCE). Important analytical parameters for identifying the target analyte were optimized, such as conditions and amount of immobilized Ap, the influence of the concentration and nature of the supporting electrolyte, pH of the medium, and incubation time. The optimized conditions for the aptasensor were: concentration of Ap 1.0 × 10−6 mol L−1, support electrolyte Tris/HCl 50 mmol L−1, MgCl2 10 mmol L−1, and NaCl 10 mmol L−1, at pH 5.0 and incubation time of 15 min. A linear response range was obtained from 1 × 10−18 up to 1 × 10−11 mol L−1 of cortisol with a detection limit (LOD) of 1.0 × 10−18 mol L−1. A curve adjusted for operational purposes in the saliva sample was fitted for the concentration range between 0.5 × 10−14 and 1 × 10−11 mol L−1, with a linear regression equation ΔRtc/Rtc1 = 2.70 + 0.17 × log([Cortisol]). The aptasensor demonstrated a great potential for detecting cortisol in a simple, fast, and highly sensitive way, opening its path for application in real samples, which present levels below the concentration in which cortisol is commonly found in body fluids.

Highly sensitive and selective electrochemical aptasensor with gold-aspartic acid, glycine acid-functionalized and boron-doped graphene quantum dot nanohybrid for detection of α-amanitin in blood

Poisonous mushroom may cause fatal harm to human and animal, but its rapid detection still faces a great challenge. The paper reports synthesis of gold-aspartic acid, glycine acid-functionalized and boron-doped graphene quantum dot nanohybrid (AGB-GQD@Au) for the electrochemical detection of α-amanitin. AGB-GQD was prepared by pyrolysis and then reacted with chloroauric acid to produce gold nanoparticles. AGB-GQD@Au offers 12.5 nm-sized particles and Schottky heterojunction, improving the catalytic activity. AGB-GQD@Au connected with hairpin DNA and thionine by Au–S bonds was used as redox probe for electrochemical detection of α-amanitin coupled with one target-induced DNA cycle amplification strategy. α-Amanitin specifically hybridizes with aptamer in duplex DNA to release auxiliary strand DNA. The released DNA triggers one DNA cycle process and brings one redox probe to the electrode surface. By the DNA cycle, one target brings many redox probes to the electrode surface, producing a significant signal amplification. The detection signal was further enhanced by the catalysis of AGB-GQD@Au towards redox of thionine. Differential pulse voltammetric current increases linearly with the increasing α-amanitin in the range from 4 to 4 × 105 fM with the detection limit of 1.2 fΜ (S/N = 3). The analytical method provides advantages of sensitivity, selectivity and repeatability. It has been successfully applied in electrochemical detection of α-amanitin in blood.

A label-free and selective electrochemical aptasensor for ultrasensitive detection of Di(2-ethylhexyl) phthalate based on self-assembled DNA nanostructure amplification

• An electrochemical aptasensor was constructed to detect Di(2-ethylhexyl) phthalate. • The aptasensor has the advantages of easy operation, label-free and low cost. • Utilizing self-assembly of DNA nanostructures for amplifying detection signal. • The aptasensor shows wide linear range and low detection limit of 0.04 ng mL −1 . • The aptasensor shows good reproducibility and high selectivity for DEHP assay. Di(2-ethylhexyl) phthalate (DEHP) is an endocrine disrupting compound that is often used as a plasticizer and tends to migrate in the environment and accumulates in the human body causing harm to humans. Thus, a simple, label-free, enzyme-free, high selective and ultrasensitive electrochemical aptasensor has been constructed for detection of DEHP based on the self-assembly of DNA nanostructure signal amplification strategy in this paper. The DNA-junction nanostructure is made of hairpin 1 (HP1), hairpin 2 (HP2), hairpin 3 (HP3) and quarter sequence (QS). Without DEHP, the electrochemical detection response is very low. Only when the aptamer binds to the target and detaches from the electrode surface, the DNA-junction is trapped on the electrode surface, enhancing the electrochemical signal. This is because the DNA-junction nanostructure is rich in guanine, which is able to adsorb more methylene blue (MB) for the purpose of enhancing the detection signal. The linear detection range of the obtained aptasensor is 0.1 ng mL −1 to 5000 ng mL −1 and the limit detection is 0.04 ng mL −1 . Finally, the proposed aptasensor has been applied to analyze DEHP in real samples, laying the foundation for its utilization in environmental water samples and food safety.

A sensitive aflatoxin B1 electrochemical aptasensor based on ferrocene-functionalized hollow porous carbon spheres as signal amplifier

Due to the high toxicity and carcinogenicity of Aflatoxin B1 (AFB1), a sensitive, low-cost and simple method to accurately detect AFB1 in foodstuffs is highly desirable. Herein, a sensitive and selective AFB1 electrochemical aptasensor was developed by using ferrocene immobilized hollow porous carbon spheres (HPCS-Fc) as the electrochemical signal tag. Attributed to the large surface and high conductivity of HPCS, the prepared Fc-HPCS showed the high load amount of Fc and HPCS-Fc labelled GC electrode displayed large oxidation peak current. To further improve the biosensing ability, tetrahedral DNA nanostructures (TDNs) was attached on the biosensing interface to control the orientation of HPCS-Fc-cDNA. Based on the above advantages, the HPCS-Fc labelled electrochemical aptasensor exhibited high sensitivity towards AFB1 in a wide linear range from 1.0 × 10−2 pg mL−1 to 100.0 μg mL−1 and a low detection limit down to 3.3 × 10−5 ng mL−1. Furthermore, the developed aptasensor was applied to detect AFB1 in wheat powder samples with satisfactory recoveries of 91.7%∼107.7%, demonstrating its potential application in testing AFB1 in food samples.

Highly Sensitive and Selective Electrochemical Aptasensor with Gold-Aspartic Acid, Glycine Acid-Functionalized and Boron-Doped Graphene Quantum Dot Nanohybrid for Detection of Α-Amanitin in Blood

Highly Sensitive and Selective Electrochemical Aptasensor with Gold-Aspartic Acid, Glycine Acid-Functionalized and Boron-Doped Graphene Quantum Dot Nanohybrid for Detection of Α-Amanitin in Blood

Cellulose acetate-MoS2 nanopetal hybrid: A highly sensitive and selective electrochemical aptasensor of Troponin I for the early diagnosis of Acute Myocardial Infarction

In this work, a novel aptamer-based CA-MoS2 hybrid biosensor was developed for diagnosis of Acute Myocardial Infraction (AMI). Specifically, a novel petal-like MoS2 nanoflower was used as the active material on the Screen-Printed Electrode (SPE) for AMI biomarker determination. The aptamer-based CA-MoS2–24 hybrid was able to attain a low limit of detection (LOD) and sensitivity to 10 fM at a linear range from 10 fM to 1 nM with good reproducibility based on an electrochemical impedance spectroscopy and a ~4 folds higher selectivity of troponin I compared to the signal from other biomolecules in human serum, retaining a 91% stability after 6 weeks. This novel CA-MoS2 aptamer-based biosensor with a 2.3% RSD value has the potential to revolutionize medical diagnosis by conducting multiple biomolecule detection on a single sensing platform.

Highly sensitive label-free electrochemical aptasensors based on photoresist derived carbon for cancer biomarker detection

-Label-free electrochemical aptasensors for cancer biomarker detection can be a promising means for early detection of cancer due to their high sensitivity, selectivity, and stability, and low cost. In this study, a highly sensitive and selective label-free electrochemical aptasensor based on carbon microelectromechanical systems (C-MEMS) was developed for the detection of platelet-derived growth factor-BB (PDGF-BB). The active electrodes of the aptasensors were synthesized via carbonization of SU-8 derived electrodes at high temperatures in an oxygen-free furnace. An oxygen-plasma oxidation treatment was used to functionalize the C-MEMS electrodes, which provided efficient covalent immobilization of amino terminated affinity aptamers. The turn-off and turn-on detection strategies–based on capacitance and resistance measurement, respectively—were employed. The capacitance detection strategies exhibited a wide linear response range of 0.01–50 nM, with a high sensitivity of 3.33 mF cm-2 Logc-1 (unit of c, nM) and a low limit of detection of 7 pM (S/N = 3). The resistance detection strategies exhibited an even wider linear response range of 0.005–50 nM, and a lower limit of detection of 1.9 pM (S/N = 3), with a high sensitivity of 1.65 × 103 Ω Logc-1 (unit of c, nM). Both detection strategies provided high selectivity for PDGF-BB and high stability of 90.34% after 10 days. This research demonstrates that the developed label-free electrochemical C-MEMS based PDGF-BB aptasensor is highly sensitive, selective, and robust. This aptasensor is a promising prospect for the highly demanding task of early detection of cancer biomarkers.

Sensitive and selective electrochemical aptasensor via diazonium-coupling reaction for label-free determination of oxytetracycline in milk samples

As one kind of tetracycline antibiotics, oxytetracycline (OTC) residues in animal-derived foods can do serious harm to human health. Though aptasensors for the detection of OTC are widely reported, label-free electrochemical aptasensor with low cost, simple preparation and good applicability should be further explored to meet the current urgent needs. In this study, a label-free electrochemical aptasensor for OTC determination was designed. The detection was based on specific recognition by the aptamer covalently-bound on the sensing interface via diazonium coupling reaction, which was verified by computer simulation. Experiment results showed that the differential pulse voltammetry (DPV) current response of the constructed electrochemical aptasensor was linear with the logarithm of OTC concentration in the range of 1.0 × 10−9 g mL−1–1.0 × 10−4 g mL−1 (R2 = 0.9897) with the limit of detection of 2.29 × 10−10 g mL−1. The proposed aptasensor indicated good selectivity, reproducibility and stability, which could be attributed to the stable modification of aptamer on the sensing interface. The OTC in the milk sample was detected by the spiked recovery method, and good results were obtained, with the recovery rate being 87.0%-99.3%. The proposed label-free electrochemical aptasensor can provide methods for low-cost, accurate and rapid detection of antibiotic residues.

Ultrasensitive voltammetric and impedimetric aptasensor for diazinon pesticide detection by VS2 quantum dots-graphene nanoplatelets/carboxylated multiwalled carbon nanotubes as a new group nanocomposite for signal enrichment

Polluted water and groundwater resources contaminated by pesticides are among the most important environmental distresses. Therefore, a simple, ultrasensitive, and selective electrochemical aptasensor is proposed for diazinon (DZN) determination as an organophosphorus compound. The vanadium disulfide quantum dots (VS2QDs) were synthesized by a facile hydrothermal method and doped on the graphene nanoplatelets/carboxylated multiwalled carbon nanotubes (GNP/CMWCNTs) as a new group of nanocomposite. The prepared nanocomposite (VS2QDs-GNP/CMWCNTs) on a glassy carbon electrode (GCE) was incubated with the DZN binding aptamer (DZBA) through electrostatic interaction (GCE/VS2QDs-GNP/CMWCNTs/DZBA). The modified electrode was used for the low detection of DZN by monitoring the oxidation of [Fe(CN)6]3−/4− as the redox probe. The characterizations of the modified electrode were performed by several electrochemical methods include: cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). Also, the prepared nanocomposite was characterized with field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), UV–Vis absorption spectroscopy, fourier transform infrared (FT-IR), fluorescence emission spectroscopy, dynamic light scattering (DLS), elemental mapping, and energy dispersive spectroscopy (EDS). The DZBA selectively adsorbs DZN on the modified electrode, leading to a decrease and increase in the current of DPV and charge transfer resistance (RCT) of EIS, respectively, as analytical signals. The developed electrochemical aptasensor at the optimal conditions have low limits of detection (LOD) equal to 1.1 × 10−14 and 2.0 × 10−15 mol L−1 with wide dynamic ranges of 5.0 × 10−14-1.0 × 10−8 mol L−1 and 1.0 × 10−14-1.0 × 10−8 mol L−1 for DPV and EIS calibration curves, respectively. Finally, this aptasensor had good selectivity, stability, reproducibility, and feasibility for the DZN detection in various real samples.

Detection of Cytochrome C Using a Selective and Sensitive Methylene Blue-Based Electrochemical Aptasensor

The present research aimed to detect the cytochrome C using methylene blue (MB)-anchored ultrasensitive electrochemical aptamer conjugated with Au nanoparticles (NPs), as a new electrochemical sandwich immunoassay. Aptamer-Au NPs could act as sandwich amplification element and MB accumulation reagent. According to the results, the interaction of MB and guanine occurred strongly on aptamer probe. After switching the aptamer structure by the cytochrome C, the MB- labeled aptamer probe was forced to detach from the sensing interface. Moreover, the cytochrome C concentrations (0.05-10.0 µM) with 5.0 nM detection limit reduced linearly the peak current of MB. In conclusion, an acceptable selectivity was observed for the constructed aptasensor in detecting the cytochrome C.

Label-free and highly selective electrochemical aptasensor for detection of PCBs based on nickel hexacyanoferrate nanoparticles/reduced graphene oxides hybrids

In consideration of the urgent need to determine polychlorinated biphenyls (PCBs) in the environment, a label-free and highly selective electrochemical aptasensor was constructed for determining PCBs based on nickel hexacyanoferrate nanoparticles (NiHCF NPs)/reduced graphene oxides (rGO) hybrids. NiHCF NPs/rGO hybrids with small size of about 5 nm NiHCF NPs were synthesized for the first time by in situ co-deposition of NiHCF NPs on rGO surface. In the hybrids, rGO with large area and good conductivity can supply more space for loading NiHCF NPs and improve the conductivity of the hybrids. NiHCF NPs that can be used to be act as a signal probe exhibit a couple of well-defined peaks with highly reversible redox ability and good stability. Here, PCB77 as a model molecule, the anti-PCB77 aptamer was anchored on the NiHCF NPs/rGO hybrids by covalent bonding reaction. The design aptasensor for detecting PCB77 exhibits a favorable linear response from 1.0 to 100.0 ng/L with a low detection limit of 0.22 ng/L. Meanwhile, it displays good selectivity for PCB77 detection due to the specificity and high affinity of aptamer to PCB77. Additionally, the application of the aptasensor was evaluated in real environmental samples.

Electrochemical aptasensor for activated protein C using a gold nanoparticle – Chitosan/graphene paste modified carbon paste electrode

In this work, a selective and simple electrochemical aptasensor was developed for the detection of activated protein C by employing methylene blue (MB) as a redox indicator. An activated protein C aptamer (APC-apt) was covalently immobilized on the surface of a carbon paste electrode modified with gold nanoparticle – chitosan /graphene paste (AuNPs-Chi/Gr). The AuNPs-Chi/Gr paste increased electrochemical peak current and immobilized the aptamer on the electrode surface. The process of aptasensor construction and successful immobilization of the aptamer on the electrode surface was confirmed by electrochemical cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Differential pulse voltammetry (DPV) was used to determine the methylene blue peak current. By replacing APC instead of MB at the electrode surface, the cathodic current of the MB decreases, and this decrease corresponds to the APC concentration. Under optimum conditions, the APC concentration was detected in the range from of 0.1 ng·mL−1 to 40 μg·mL−1 with a relatively low detection limit of 0.073 ng·mL−1. This method was then applied to the determination of APC in human serum samples. The results revealed that this strategy can be used to measure other proteins in biological samples.

Fabrication of an ultrasensitive and selective electrochemical aptasensor to detect carcinoembryonic antigen by using a new nanocomposite

A lable-free electrochemical aptasensor was successfully developed for the sensitive detection of carcinoembryonic antigen as a tumor biomarker. To do this, a ternary nanocomposite of hemin, graphene oxide and multi-walled carbon nanotubes was used. The aptamer can be attached to the surface of a hemin, graphene oxide and multi-walled carbon nanotubes glassy carbon electrode through –NHCO- covalent bonds to form a sensing surface. Through fourier transform infrared spectroscopy and scanning electron microscopy, it was indicated that hemin can be successfully incorporated into hemin, graphene oxide and multi-walled carbon nanotubes. Hemin, which protects graphene nanosheets, also serves as an in-situ probe owing to its well-defined redox properties. Multi-walled carbon nanotubes in the modifier enhance conductivity and facilitate the electron transfer between hemin and the glassy carbon electrode. In this study, carcinoembryonic antigen got specifically bound to the aptamer, and the current changes were used for selective and specific detection of that antigen. The devised aptasensor proved to have excellent performance with a wide linear range of 1.0 × 10–15 – 1.0 × 10−8 gmL−1 and a detection limit of 0.82 fg mL−1. The inter-day and intra-day values of RSD% were obtained in the range of 0.10–2.91 and 2.21–4.56 respectively. According to the experiments conducted on real samples, it may be claimed that the proposed label-free electrochemical aptasensor is capable enough of determining carcinoembryonic antigen in clinical diagnostics.