Label-free Electrochemical Aptasensor Research Articles

Hierarchical nickel hydroxide nanosheets grown on hollow nitrogen doped carbon nanoboxes as a high-performance surface substrate for alpha-fetoprotein cancer biomarkers electrochemical aptasensing

During recent decades, we have witnessed a great improvement in the performance of aptamer-based sensors, specifically when aptamers are combined with new nanomaterials; as a platform for biosensors. The design of hollow carbon-based materials has also received a lot of attention due to its excellent properties in various applications. Herein, we aim at designing hierarchical porous Ni(OH)2 nanosheets on hollow N-doped carbon nanoboxes Ni(OH)2@N-C n-box). In this sense, we obtained the hollow N-C n-box skeletons from the Fe2O3 nanocubes template. The development of label-free electrochemical aptasensor was carried out using the covalently immobilizing NH2-functionalized aptamer on Ni(OH)2@N-C n-box as an efficient substrate. The Ni(OH)2@N-C n-box was characterized using scanning fourier transform infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Brunauer, Emmett and Teller (BET), transmission electron microscopes (TEM) and electron microscopy (FESEM). The electrochemical evaluations clarified the fact that a linear relationship exists between the alpha-fetoprotein (AFP) contents and the charge transfer resistance (Rct) (from 1 fg mL−1 to 100 ng mL−1) with a low detection limit of 0.3 fg mL−1. Moreover, regarding the aptasensor, the superior detection recoveries were experienced in real biological samples, illustrating its great detection performance and practical feasibility. Considering the aptasensor application, these studies showed that Ni(OH)2@N-C n-box possesses different enhanced electrochemical features, making it appropriate as an electrode material for aptasensor application.

Monitoring of Aflatoxin M1 in milk using a novel electrochemical aptasensor based on reduced graphene oxide and gold nanoparticles

Accurate and rapid detection of Aflatoxins as one of the most hazardous compounds in foodstuffs is very important. In this study, a label-free electrochemical aptasensor was developed to identify aflatoxin M1 using a reduced graphene oxide (rGO) and gold nanoparticles (AuNPs)-based pencil graphite electrode (PGE). The morphological characteristics of the electrode surface were investigated using SEM and rGO functional groups were confirmed by FTIR. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques were used to characterize various stages of electrode modification. In order to optimize the impedimetric response of the aptasensor, aptamer immobilization time, aptamer concentration, and binding aflatoxin M1 with aptamer time were optimized. Under optimal conditions, the linear concentration range of 0.5–800 ng/L and limit of detection (LOD) of 0.3 ng/L were obtained for aflatoxin M1 by measuring the resistance charge transfer data. Finally, the fabricated aptasensor was successfully used to measure AFM1 compared to HPLC method.

Sensitive electrochemical aptasensor for determination of sulfaquinoxaline based on AuPd NPs@UiO-66-NH2/CoSe2 and RecJf exonuclease-assisted signal amplification

The authors designed a sensitive label-free electrochemical aptasensor for the detection of sulfaquinoxaline (SQX), including the AuPd NPs@UiO-66-NH2/CoSe2 nanocomposites and RecJf exonuclease-assisted target recycle signal amplification strategy. AuPd NPs@UiO-66-NH2/CoSe2 nanocomposite with excellent conductivity and numerous active sites was successfully synthesized to provide a favorable sensing platform and load more double-strand DNA (dsDNA) on the electrode surface. The negatively charged phosphate group of the oligonucleotide and [Fe (CN)6] 3-/4- repel each other electrostatically, resulting in very low electrical signals. In the presence of SQX, its corresponding aptamer will be released from the double-stranded structure and then digested by RecJf exonuclease, which resulted in the SQX being released to initiate the next recycling to help amplify the DPV signal. Under the optimal conditions, the peak current has a linear relationship with the logarithmic of SQX concentration in the range of 1 pg/mL∼100 ng/mL and the obtained detection limit was 0.547 pg/mL. Furthermore, the contrasted aptasensor possess reliable specificity, reproducibility and stability toward SQX, and has been applied to detect SQX in pork samples with a satisfied recovery varied from 94.40% to 95.98%.

Gold nanoparticles anchored onto covalent poly deep eutectic solvent functionalized graphene: An electrochemical aptasensor for the detection of C-reactive protein

An electrochemical aptasensor for specific recognition of CRP biomarker was designed and synthesized with a novel porous and planar structure based on poly deep eutectic solvent modified graphene oxide coated by gold nanoparticles. Different steps of the synthesis of sponge-like aptasensor were characterized by SEM, mapping, EDX, FTIR, XRD, HRTEM, and BET. The designed DNA aptamers were prepared on the Au NPs-modified electrode surface through the gold-sulfur affinity. The presence of the high amount of the AuNPs as a signal amplifier on the surface of the composite afforded a label-free electrochemical aptasensor for the selective and sensitive detection of CRP via electrochemical impedance spectroscopy (EIS). To achieve an efficient sensitivity, optimization of the variables affecting this method was carried out. Under the optimized conditions, the proposed technique provided good linearity in the range of 0.001–50 ng mL−1 as well as a low detection limit of 0.0003 ng mL−1. The sensor moreover was used for the determination of CRP in human serum in which recoveries are between 96.0 and 102.2%, and the relative standard deviations are within 2.09–5.47%. The designed platform provides an efficient pathway for the sensitive detection of various biomolecules in a label-free manner by changing the corresponding particular aptamer recognition strands.

Ultrasensitive and label-free electrochemical aptasensor based on carbon dots-black phosphorus nanohybrid for the detection of Ochratoxins A

In this work, we have synthesized the novel carbon dots-black phosphorus nanohybrid (CDs-BP). And a novel label-free electrochemical aptasensor based on CDs-BP was constructed for ultrasensitive detection of Ochratoxins A (OTA). The morphology and structure of nanocomposite were analyzed by transmission electron microscope, X-ray photoelectron spectroscopy, Zeta potential, et al. The CDs-BP nanohybrid, an excellent carrier for the immobilization of aptamer (Apta), was prepared through C-P bond, resulting in the enhancement of the electrochemical sensing performance for OTA detection. The results showed that the aptasensor had a wide linear range towards OTA (0.1 fg/mL − 10.0 ng/mL) with a low detection limit of 0.03 fg/mL under the optimal conditions. The proposed aptasensor displayed good electrochemical stability and excellent selectivity to OTA detection. Moreover, a satisfactory practical application results were obtained for different actual samples of wheat and grape juice samples. Thus, a new aptasensor was raised based on the CDs-BP nanocompound for the electrochemical detection of contaminants in edible agricultural food.

Highly Sensitive Electrochemical Aptasensor for Detecting the VEGF165 Tumor Marker with PANI/CNT Nanocomposites.

Sensing targeted tumor markers with high sensitivity provides vital information for the fast diagnosis and treatment of cancer patients. A vascular endothelial growth factor (VEGF165) have recently emerged as a promising biomarker of tumor cells. The electrochemical aptasensor is a promising tool for detecting VEGF165 because of its advantages such as a low cost and quantitative analysis. To produce a sensitive and stable sensor electrode, nanocomposites based on polyaniline (PANI) and carbon nanotube (CNT) have potential, as they provide for easy fabrication, simple synthesis, have a large surface area, and are suitable in biological environments. Here, a label-free electrochemical aptasensor based on nanocomposites of CNT and PANI was prepared for detecting VEGF165 as a tumor marker. The nanocomposite was assembled with immobilized VEGF165 aptamer as a highly sensitive VEGF165 sensor. It exhibited stable and wide linear detection ranges from 0.5 pg/mL to 1 μg/mL, with a limit of detection of 0.4 pg/mL because of the complementary effect of PANI/CNT. The fabricated aptasensor also exhibited good stability in biological conditions, selectivity, and reproducibility after several measurement times after the dissociation process. Thus, it could be applied for the non-invasive determination of VEGF, in biological fluid diagnosis kits, or in an aptamer-based biosensor platform in the near future.

A label-free electrochemical aptasensor for breast cancer cell detection based on a reduced graphene oxide-chitosan-gold nanoparticle composite

Regarding the cancer fatal consequences, early detection and progression monitoring are the most vital issues in patients’ treatment and mortality reduction. Therefore, there is a great demand for fast, inexpensive, and selective detection methods. Herein, a graphene-based aptasensor was designed for sensitive human breast cancer cell detection. A reduced graphene oxide-chitosan-gold nanoparticles composite was used as a biocompatible substrate for the receptor stabilization. The significant function of the aptamer on this composite is due to the synergistic effects of the components in improving the properties of the composite, including increasing the electrical conductivity and effective surface area. After the aptasensor incubation in MCF-7 cancer cells, the cell membrane proteins interacted specifically with the three dimensional-structure of the AS1411 aptamer, resulting in the cell capture on the aptasensor. The aptasensor fabrication steps were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. The higher cell concentrations concluded to the higher captured cells on the aptasensor which blocked the Ferro/Ferricyanide access to the sensor, causing increases in the charge transfer resistances. This aptasensor shows a linear relationship with the cell concentration logarithm, high selectivity, a wide linear range of 1 × 101–1 × 106 cells/mL, and a low detection limit of 4 cells/mL.

Fabrication of electro-active nano-trans surfaces to design label free electrochemical aptasensor for ochratoxin A detection

The importance of developing multifunctional nanohybrid materials for sensing technologies is rising with the advent of nanotechnology. Herein, we present integration of a novel nanohybrid electro-active material in the construct of electrochemical aptasensor. Electrochemical aptasensor was based on the electroactive composite of fGO/ Fe3O4NP/PPY (functionalized graphene oxide/ iron oxide nanoparticles/ polypyrrole) and analyte specific DNA aptamer. The sensing architecture was relatively less complex, highly sensitive and multi-functional in design. The Pencil electrode was modified with fGO/Fe3O4NP/PPY to work as a multifunctional electrochemical transduction platform. The nano-transducer surface not only served as a conductive and immobilization support, but also functioned as an electrochemical signal generating probe. Ochratoxin A (OTA) was used as target analyte to demonstrate the working principle of the developed aptasensor. The introduction of the target analyte (OTA) on designed probe triggered switching of the aptameric structure resulting in the marked decrement of the redox current. This decrease was proportional to the analyte concentration, thus featuring signal on/off strategy. The aptasensors showed linear range of 10 pg/mL-200 ng/mL, limit of detection (LOD) and limit of quantification (LOQ) of 5 pg/mL and 40 pg/mL, respectively. Real sample analysis was performed in spiked wheat samples to demonstrate the real-life applicability of the designed aptasensor.

Label-Free Electrochemical Aptasensor Based on Stone-like Gold Nanoparticles for Ultrasensitive Detection of Tetracycline

The widespread use of tetracycline (TET) for controlling bacterial infections has led to its residues and accumulation in animal food and the environment, which leads to a serious threat to food sa...

Label-Free DNA Electrochemical Aptasensor for Fumonisin B1 Detection in Maize Based on Graphene and Gold Nanocomposite

Label-Free DNA Electrochemical Aptasensor for Fumonisin B1 Detection in Maize Based on Graphene and Gold Nanocomposite

Encapsulation of hemin in Fe-based metal-organic frameworks and its application for the direct determination of aflatoxin M1

A label-free electrochemical aptasensor was constructed for the sensitive and selective determination of AFM1. For preparation of the aptasensor, the AFM1 aptamer was immobilised on the surface of a glassy carbon electrode modified with hemin encapsulated in Fe-based metal-organic frameworks (hemin@Fe-MIL-101). The morphology and the structure of Fe-MIL-101 and hemin@Fe-MIL-101 were evaluated by scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray powder diffraction and Brunauer-Emmett-Teller-N2 sorption methods. Electrochemical impedance spectroscopy and cyclic voltammetry were performed to monitor the fabrication process of the electrochemical aptasensor. The electrochemical reduction current of hemin encapsulated in Fe-MIL-101 serves as a signal for the quantitative determination of AFM1. Differential pulse voltammetry was done to determine the AFM1 concentration in the linear range of 1.0×10-1-100.0 ng/ml. The detection limit of AFM1 was estimated to be 4.6×10-2 ng/ml. Finally, the fabricated aptasensor was applied to determine AFM1 in raw and boiled milk samples.

Proximity hybridization triggered hybridization chain reaction for label-free electrochemical homogeneous aptasensors

A label-free homogeneous electrochemical aptasensor was developed for detection of thrombin based on proximity hybridization triggered hybridization chain reaction induced G-quadruplex formation. Thrombin promoted the formation of a complex via the proximity hybridization of the aptamer DNA strands, which unfolded the molecular beacon, the stem part of molecular beacon as a primer to initiate the hybridization chain reaction process. Thus, with the electrochemical indicator hemin selectively intercalated into the multiple G-quadruplexes, a significant electrochemical signal drop is observed, which is dependent on the concentration of the target thrombin. Thus, using this“signal-off” mode, label-free homogeneous electrochemical strategy for sensitive thrombin assay with a detection limit of 44 fM is realized. Furthermore, this method also exhibits additional advantages of simplicity and low cost, since both expensive labeling and sophisticated probe immobilization processes are avoided. Its high sensitivity, acceptable accuracy, and satisfactory versatility of analytes led to various applications in bioanalysis.

A label-free electrochemical aptasensor based on the core-shell Cu-MOF@TpBD hybrid nanoarchitecture for the sensitive detection of PDGF-BB.

As one of the significant serum cytokines, platelet-derived growth factor-BB (PDGF-BB) is a crucial protein biomarker overexpressed in human life-threatening tumors, the sensitive identification and quantification of which are urgently desired but challenging. Herein we report a novel core-shell nanoarchitecture consisting of Cu-based metal-organic frameworks (Cu-MOFs) and covalent organic frameworks (denoted as TpBD-COFs), which was used to prepare an aptasensor for the detection of platelet-derived growth factor-BB (PDGF-BB). The central Cu-MOFs function as signal labels with no need for extra redox media, whereas the porous TpBD serves as the shell to immobilize the PDGF-BB-targeted aptamer strands in abundance via strong interactions involving π-π stacking, electrostatic, and hydrogen bonding interactions. The proposed aptasensor based on Cu-MOF@TpBD can achieve a detection limit as low as 0.034 pg mL-1 within the dynamic detection range from 0.0001 to 60 ng mL-1. The hybridization of MOFs and COFs, together with the immobilization with the specific analyte targeted aptamer, provides a promising and propagable approach to prepare an aptasensor for the simple, sensitive, and selective detection of a specific biomarker in clinical diagnosis.

Label-free electrochemical aptasensor based on reduced graphene oxide–hemin–chitosan nanocomposite for the determination of glypican-3

A GPC3 electrochemical aptasensor was constructed using an RGO–H–CS-modified SPE as a biosensing platform and GPC3 aptamer as the recognition element.

A label-free enrofloxacin electrochemical aptasensor constructed by a semiconducting CoNi-based metal–organic framework (MOF)

A semiconducting CoNi-based metal–organic framework (MOF), CoxNi3-x(HITP)2, was designed and synthesized using 2,3,6,7,10,11-hexaaminotriphenylene (HATP) as organic linker. Compared with Co3(HITP)2 and Ni3(HITP)2, CoxNi3-x(HITP)2 possesses mixed metal valences of Co2+/Co3+/Ni2+/Ni3+ and more defects within the MOF skeleton, which also shows amino-rich functionality, biocompatibility, and the intrinsic features of semiconducting MOFs, such as two-dimensional graphene-like nanostructure, high stability in water solution, and good electrochemical activity. As a consequence, the CoxNi3-x(HITP)2-based electrochemical aptasensor demonstrates superior sensing performances for enrofloxacin, with an extremely low detection limit of 0.2 fg•mL−1 and a linear range of 0.001−1 pg•mL−1, as well as high selectivity, excellent reproducibility, good stability, and wide applicability. The developed sensing strategy provides new insights into the fabrication of MOFs-based sensors for food safety, environment protection, and medical diagnosis.

Label-Free Electrochemical Aptasensors Based on Photoresist Derived Carbon for Cancer Biomarker Detection

Cancer biomarkers are substances found in the human fluid, tissue, and bone marrow that can indicate the presence of cancer diseases in the human body. In the past decades, various cancer biomarkers have been discovered for early detection of cancers and risk assessment of reoccurring cancers. Among the discovered cancer biomarkers, platelet-derived growth factor-BB (PDGF-BB) is an essential biomarker for early detection of cancer diseases. This biomarker plays a significant role in the development of multiple solid malignant tumors (e.g., breast, brain, pancreatic, prostate, and ovarian) and lymphatic metastasis. A feasible means for early detection of cancers is developing point-of-care biosensors based on synthetic DNA or RNA bio-recognizers (i.e., aptamers), which are referred to as aptasensors. Various advanced technologies have been investigated for developing cancer biomarker aptasensors, including optical, piezoelectric, and electrochemical based techniques. Among the developed technologies, label-free electrochemical aptasensors are highly potent means for this purpose since they can reduce the cost and complications of sample preparation, and the electrochemical cells can be efficiently miniaturized and integrated with available lab-on-chips and MEMS technologies. However, the sensing performance of the label-free electrochemical cancer aptasensors, including the limit of detection, selectivity, and dynamic range requires further enhancements to be at similar levels to benchtop testing. In the light of the importance of PDGF-BB detection and demanded enhancements for label-free electrochemical aptasensors, we have developed label-free electrochemical aptasensors based on photoresist derived carbon microelectrodes. The active electrode of this aptasensor was synthesized via well-established C-MEMS (carbon microelectromechanical systems) fabrication technology. C-MEMS platforms have distinguishing features such as low background capacitance, high stability when they exposed to different physical/chemical treatments, biocompatibility, and good electrical conductivity. Furthermore, the surface of C-MEMS can be modified effectively via electrochemical processes as well as depositing nanomaterials. The applied C-MEMS fabrication in this study includes photopatterning of SU-8 25 negative photoresist-based microelectrodes and carbonization of the developed microelectrodes at high temperatures and oxygen-free tube furnaces. The carbonized microelectrodes were functionalized utilizing oxygen plasma oxidation pretreatment to introduce carboxyl groups to the surfaces of the carbon microelectrodes. The PDGF-BB affinity aptamers were covalently immobilized via amid binding of amino-tag terminated aptamers and carboxyl groups covered carbon surfaces. The Fourier-transform infrared spectroscopy (FTIR) confirmed the successful carboxyl group functionalization of the C-MEMS microelectrodes and covalent immobilization of affinity aptamers via amide biding. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used for characterizing the C-MEMS based aptasensors in different stages of development and sensing performances. The turn-on sensing strategy was deployed via measuring the charge transfer resistance (RCT) from EIS Nyquist plots, which yielded to wide sensing linear range of 0.005 – 50 nM with a high sensitivity of 14.82 × 103 Ω.(Log (M))-1 and low limit of detection of 1.9 pM (S/N=3). The turn-off sensing strategy was applied via measuring capacitance from CV curves, which conceded to wide linear response range of 0.01 – 50 nM with a high sensitivity of 29.97 mF.cm-2.(Log (M))-1 and low limit of detection of 7 pM (S/N=3) toward the PDGF-BB. The developed label-free electrochemical aptasensor exhibited good selectivity, stability, and repeatability, which is highly promising for future lab-on-chip and point-of-care cancer diagnosis technologies.

A novel dual signal and label-free electrochemical aptasensor for mucin 1 based on hemin/graphene@PdPtNPs

A dual signal and label-free electrochemical aptasensor for mucin 1 was constructed based on hemin/graphene@PdPtNPs nanocomposite (H-Gr@PdPtNPs). Hemin attached on the graphene surface not only improves the solubility of graphene and acts as an in-situ electrochemical probe but also exhibits excellent peroxidase-like properties to electrocatalyze the reduction of H2O2. PdPtNPs also show outstanding catalytic capacity to the reduction of H2O2 and provide numerous binding sites for loading dDNA (mucin 1 aptamer and cDNA) to form the sensing interface. In the presence of mucin 1, due to the specific affinity between aptamer and mucin 1, double helix would be induced dissociation and the aptamer would be pulled off from the electrode. As a result, the electrochemical signals of hemin and H2O2 were recovered. Based on these properties, the label-free and sensitive dual signal electrochemical biosensor for mucin 1 detection has been developed. The one is differential pulse voltammetry (DPV) signal of hemin and the other is chronoamperometry signal arisen from the catalytic reduction of H2O2. The linear ranges for mucin 1 were 8.0 pg mL−1 to 80 ng mL−1 and 0.8 pg mL−1 to 80 ng mL−1 with the limit of detection 2.5 pg mL−1 and 0.25 pg mL−1 by DPV and chronoamperometry, respectively. The recovery of mucin 1 in human blood serum samples was from 95.0% to 104.2%. The detection platform does not need signal labeling which greatly reduced the sophisticated and expensive procedures. The aptasensor provide a promising strategy for the determination of mucin 1 in clinical diagnostics.

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.

Development of a label-free electrochemical aptasensor based on diazonium electrodeposition: Application to cadmium detection in water

In this study we have developed a new aptasensor for cadmium (Cd2+) detection in water. Gold electrode surface has been chemically modified by electrochemical reduction of diazonium salt (CMA) with carboxylic acid outward from the surface. This was used for amino-modified cadmium aptamer immobilization through carbodiimide reaction. Chemical surface modification was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). This latter was also used for Cd2+ detection. The aptasensor has exhibited a good linear relationship between the logarithm of the Cd2+ concentration and the impedance changes in the range from 10−3 to 10−9 M with a correlation R2 of 0.9954. A high sensitivity was obtained with a low limit of detection (LOD) of 2.75*10−10 M. Moreover, the developed aptasensor showed a high selectivity towards Cd2+ when compared to other interferences such as Hg2+, Pb2+ and Zn2+. The developed aptasensor presents a simple and sensitive approach for Cd2+detection in aqueous solutions with application for trace Cd2+ detection in spring water samples.

Aptamer-based electrochemical biosensing strategy toward human non-small cell lung cancer using polyacrylonitrile/polypyrrole nanofibers.

In the present study, a sensitive electrochemical aptamer-based biosensing strategy for human non-small cell lung cancer (NSCLC) detection was proposed using nanofiber-modified disposable pencil graphite electrodes (PGEs). The composite nanofiber was comprised of polyacrylonitrile (PAN) and polypyrrole (PPy) polymers, and fabrication of the nanofibers was accomplished using electrospinning process onto PGEs. Development of the nanofibers was confirmed using scanning electron microscopy (SEM). The high-affinity 5'-aminohexyl-linked aptamer was immobilized onto a PAN/PPy composite nanofiber-modified sensor surface via covalent bonding strategy. After incubation with NSCLC living cells (A549 cell line) at 37.5°C, the recognition between aptamer and target cells was monitored by electrochemical impedance spectroscopy (EIS). The selectivity of the aptasensor was evaluated using nonspecific human cervical cancer cells (HeLa) and a nonspecific aptamer sequence. The proposed electrochemical aptasensor showed high sensitivity toward A549 cells with a detection limit of 1.2 × 103 cells/mL. The results indicate that our label-free electrochemical aptasensor has great potential in the design of aptasensors for the diagnostics of other types of cancer cells with broad detection capability in clinical analysis. Graphical abstract.