Immunosensor For Detection Of Carcinoembryonic Antigen Research Articles

3D gold dendrite and reduced graphene oxide-chitosan nanocomposite-based immunosensor for carcinoembryonic antigen detection in clinical settings

Electrodeposited metallic nanostructures with tree-like hierarchical morphology, often termed metallic nanodendrites (MNDs), are gradually gaining interest in the development of electrochemical biosensors. Noble metal nanodendrites exhibit exceptional conductive and electrocatalytic activity. In this work, we have reported a robust method of electrodeposition of gold nanodendrites (AuND). In order to achieve this, we first optimized the number of gold nanoparticles (AuNP) as seed molecules on the sensor surface and observed that “less seed” resulted in enhanced growth of AuND. Thereafter, AuNP/AuND was used as an excellent surface in conjugation with reduced graphene oxide (rGO), chitosan (CS), and an Anti-CEA antibody for electrochemical detection of carcinoembryonic antigen (CEA), a clinically established cancer biomarker. The developed immunosensor, glassy carbon electrode/gold nanoparticle/gold nanodendrites/chitosan-reduced graphene oxide/Anti-CEA antibody (GCE/AuNP/AuND/CS-rGO/Anti-CEA), is capable of detecting the biomarker in the linear dynamic range (LDR) of 1 × 10−13 to 1 × 10−8 g/mL, which covers the normal as well as clinical range of CEA in serum with a limit of detection (LOD) of 2.23 (±0.03) x 10−14 g/mL. Real sample analysis was performed in serum with a recovery rate ranging between 90 and 99.20 %, demonstrating the feasibility of the sensors for CEA monitoring.

An ultrasensitive photoelectrochemical immunosensor for carcinoembryonic antigen detection based on cobalt borate nanosheet array and Mn2O3@Au nanocube

Highly sensitive and selective method of determination for carcinoembryonic antigen (CEA) is of important significance for the effective early diagnosis and treatment of cancer. In this work, we report an ultrasensitive sandwich photoelectrochemical (PEC) immunosensor for CEA detection. To be precise, cobalt-borate nanosheet arrays (Co-Bi NSs) with the larger specific surface area are prepared by electrodeposition and used as the basal material to capture the primary antibody (Ab1) for the first time. And the other photoactive material Mn2O3@Au nanocube is exploited for labeling the secondary antibody (Ab2). The coulomb force of Mn2O3@Au nanocube and Co-Bi NSs photoelectrodes as the driving force effectively improves the photoelectric response. Under the light irradiation, charge separation occurs at the same time between AuNPs and Mn2O3, and the energy levels of Mn2O3@Au and Co-Bi NSs are effectively matched, achieving the high PEC performance of the biosensor. The synthesized nanomaterials are physically characterized by a series of characterization techniques. Besides, ascorbic acid (AA) is employed as an excellent electron donor, which can inhibit the recombination process of photogenerated electrons and holes, then obtaining enhanced and stable photocurrent signals. Under the optimal experimental conditions, the immunosensor shows a lower detection limit of 5.0 pg mL−1 (S/N = 3), a wider linear range of 0.1 ng mL−1 ∼ 1000 ng mL−1, as well as excellent specificity, stability and reproducibility. Additionally, as-constructed PEC immunosensor can be applied to detect CEA in human serum, this proposed strategy may afford a promising approach for the biomarker sensing and clinical applications.

Ultrasensitive immunosensor for multiplex detection of cancer biomarkers carcinoembryonic antigen (CEA) and yamaguchi sarcoma viral oncogene homolog 1 (YES1) based on eco-friendly synthesized gold nanoparticles

Cancer is one of the most extensive diseases with the highest mortality rate, accounting for almost 10 million deaths in 2020. The most common cancers are breast, lung, colon and rectum and prostate cancers. Of these, lung cancer, accounted for about 1.8 million of all cancer deaths (25%) in 2020. Detection of cancer relies on presence of biomarkers such as DNA molecules, proteins and metabolites released by cancerous cells into the circulation. Carcinoembryonic antigen (CEA) is one of the biomarkers that has been used for the detection of lung cancer. However, CEA is not specific to lung cancer since it is also manifested in gastric cancer, pancreatic cancer, colorectal cancer, and breast cancer. Recently, v-YES1 Yamaguchi sarcoma viral oncogene homolog 1 (YES1) was described as a specific biomarker for lung cancer. The detection of both CEA and YES1 would give more precise and authentic information for detecting lung cancer. This is because detection of a single tumor marker usually limits the precision in tumor diagnosis, due to the fact that several cancers have more than one marker linked with their prevalence. Whereas traditional methods have been used for the detection of CEA, electrochemical immunosensors have attracted considerable attention owing to their profound advantages, including fast response, miniaturization, high selectivity, low sample requirements and magnificent sensitivity. The fabrication of a multiplex and simultaneous immunosensor is met with challenge of preparation of distinguishable immunoprobes with different redox activities. This can be addressed by incorporation of electroactive Nano metals into the sensing platform. In this study, gold nanoparticles were used for the fabrication of an ultrasensitive sandwich electrochemical multiplex immunosensor for simultaneous detection of CEA and YES1. Under optimized conditions, the electrochemical immunosensor detection limit for YES1 and CEA was found to be 0.0022 and 0.0034 ng/mL respectively within a linear range of 0.1–50 ng/mL. The proposed immunosensor proved to be stable for up to 2 weeks and had negligible cross reactivity towards various interfering compounds in human plasma. This study reports that gold nanoparticles can be bio synthesized using shade dried Mangifera indica leaves extract. The bio-synthesized gold nanoparticles coupled with thiolated protein G can be used for fabrication of a multiplex immunosensor for detection of CEA and YES1. The proposed immunosensor can provide a new approach for early diagnosis of circulating cancer biomarkers and holds great promise for application in clinical diagnosis.

Sensitive photoelectrochemical immunosensor for carcinoembryonic antigen detection based on copolymer of thiophene and thiophene-3-acetic acid modified phosphate-doped Bi2WO6

In this study, PO43− doped Bi2WO6 (BWO-PO) was prepared by hydrothermal method, and then copolymer of thiophene and thiophene-3-acetic acid (P(Th-T3A)) was chemically deposited on the BWO-PO surface. The introduction of PO43− created point defects, greatly improving the photoelectric catalytic performance of Bi2WO6; the copolymer semiconductor could form heterojunction with Bi2WO6 to promote the separation of photo-generated carriers, due to its proper band gap. Furthermore, the copolymer could enhance the light absorption ability and photo-electronic conversion efficiency. Hence, the composite had good photoelectrochemical properties. When it was combined with carcinoembryonic antibody through the interaction of –COOH groups of the copolymer and the end groups of antibody for constructing ITO-based PEC immunosensor, the resulting sensor exhibited superb response to carcinoembryonic antigen (CEA), with a wide linear range of 1 pg/mL−20 ng/mL, and a relatively low detection limit of 0.41 pg/mL. It also showed high anti-interference ability, stability, and simplicity. The sensor has been successfully applied to monitor the concentration of CEA in serum. The sensing strategy can also be applied to the detection of other markers by changing the recognition elements, hence it has good application potential.

An ultrasensitive electrochemical immunosensor for carcinoembryonic antigen detection based on two-dimensional PtPd/Cu-TCPP(Fe) nanocomposites.

Establishing an effective signal amplification strategy is the key to achieving sensitive detection of analytes by electrochemical immunoassay. In this work, a novel sandwich-type electrochemical immunosensor with dual-signal amplification was successfully constructed using PtPd/Cu-TCPP(Fe) as the sensing platform and mesoporous silicon dioxide as the signal amplifier. Firstly, two-dimensional wrinkled Cu-TCPP(Fe) nanomaterials loaded with PtPd nanoparticles have strong affinity for the immobilization of capture antibodies and can generate excellent electrochemical signals. Meanwhile, the mesoporous silicon dioxide with large steric hindrance was used as signal label to further improve the sensitivity of the immunosensor by increasing the difference of the current response signal. Under optimal experimental conditions, the electrochemical immunosensor exhibited a wide linear detection range from 0.1pg/mL to 1.0μg/mL, with a detection limit as low as 0.166fg/mL. The experimental results showed that the constructed immunosensor has a great application prospect in clinical biomarker detection.

Ultrasensitive photoelectrochemical immunosensor for carcinoembryonic antigen detection based on pillar[5]arene-functionalized Au nanoparticles and hollow PANI hybrid BiOBr heterojunction

In this study, an ultrasensitive and specific photoelectrochemical (PEC) immunosensor was designed for carcinoembryonic antigen (CEA) detection. Benefitting from the ascorbic acid (AA) used as an electron donor that led to a notable change in the photocurrent density, pillar[5]arene functionalized Au and Polyaniline-Bismuth oxybromide heterojunction (Au@WP5/PANI-BiOBr) displayed superior PEC performance for CEA sensing. In detail, the localized surface plasmon resonance (LSPR) of the Au NPs and host-guest complexation between WP5 and AA increased the photocurrent signal, the photogenerated holes on BiOBr accelerated the oxidation of AA, and the fast electron transfer of the hollow PANI tubes benefited an increase in the photocurrent. The antibody effectively bound with CEA when bovine serum albumin blocked the residual sites on the Au@WP5/PANI-BiOBr electrode, generating a clear decrease in photocurrent density in AA solution. Under the optimum condition, the developed PEC immunosensor exhibited a sensitive response to CEA which was linear in the range of 0.01 ng mL-1 to 50 ng mL-1 with a detection limit of 3 pg mL-1. The proposed PEC immunosensor displayed high specificity, good stability, and excellent reproducibility, paving a new way to construct sensitive and specific photoactive heterojunction materials for biomarker immunosensing.

First use of inorganic copper silicate-transduced enzyme-free electrochemical immunosensor for carcinoembryonic antigen detection

Reducing the background signal and interference is an effective method for improving the sensitivity of an electrochemical immunosensor, which is greatly important for detecting tumour markers. In this study, a novel hybrid, nanoflower-like immunosensor probe was synthesised using graded copper silicate hollow spheres (CSH). A ‘close and open’ strategy was used in the immunosensor to magnify response signal. When the reaction conditions were 0.1 M PBS (pH = 7), the silicate and molybdate reaction produced a smaller signal, at which point the signal was off. When the reaction conditions were changed to 0.1 M PBS solution (containing 0.2 M HCl), MoS2 dissolved to form molybdate, while CSH-generated silicates reacted to form molybdate silicates to produce strong oxidation currents and the signal was turned on. This was the first enzyme-free electrochemical reading experiment conducted using inorganic silicate ion transduction. It had the following advantages: (1) CSH spheres with a three-dimensional hierarchical structure had a high specific surface area that allowed them to connect with more antibodies, which improved sensitivity; (2) the method was simple, the detection was fast and the background signal and interference were reduced. The immunosensor had a wide linear range from 0.1 pg mL−1 to 80 ng mL−1 and a minimum detection limit of 0.03 pg·mL−1 (S/N = 3) when detecting carcinoembryonic antigen.

Sandwich-type electrochemical immunosensor for carcinoembryonic antigen detection based on the cooperation of a gold-vertical graphene electrode and gold@silica-methylene blue.

In this study, a sandwich-type electrochemical (EC) immunosensor was proposed to detect a carcinoembryonic antigen (CEA) based on Au-graphene and Au@SiO2-methylene blue (MB). The Au nanoparticles (NPs)-vertical graphene (VG) electrode efficiently amplifies the response signal by immobilizing a large amount of the coating antibody (Ab) and is characterized by excellent electrocatalytic activity. The MB nanodot-loaded Au@SiO2 carriers with core-shell nanostructure and detection Ab were used to construct the Ab-Au@SiO2-MB label, which improved the sensitivity due to the high EC signal of MB nanodots and the high labeling effect between the detection Ab and MB probe. A novel double-Ab sandwich strategy was developed to further improve the sensitivity and stability based on the same specificity of the coating and detection Abs for the recognition of CEA. Under optimal conditions, the developed EC sensor exhibited a wide linear range from 1 fg mL-1 to 100 ng mL-1, with an ultralow detection limit of 0.8 fg mL-1 (S/N = 3). The feasibility in the clinical application of the EC sensor was verified by the in vitro detection of CEA in human serum.

Perylene diimide as a cathodic electrochemiluminescence luminophore for immunoassays at low potentials.

In the cathodic electrochemiluminescence (ECL) field, most reported luminophores produced ECL emission at high potentials (more than -1.3 V vs. Ag/AgCl), which was adverse for both fundamental studies and practical application. It was important to screen novel ECL luminophores and coreactants for the development of ECL. In this work, N,N'-dimethyl-3,4,9,10-perylenedicarboximide (PDI-CH3) is reported to produce ECL at -0.47 V using K2S2O8 as a coreactant in an aqueous system. In addition, the ECL wavelength was 689 nm, which was interpreted with the emission of excited PDI-CH3 dimers. Finally, this low-triggering-potential ECL system was used to construct sandwiched immunosensors to detect carcinoembryonic antigen (CEA) with the potential range from 0 to -0.8 V. In this immunosensor, PDI-CH3 and gold nanoparticles (AuNPs) reduced by citrate were grafted onto graphite oxide (GO) to label secondary antibodies (Ab2). This immunosensor could sensitively detect CEA with the linear response range between 1 fg mL-1 and 1 μg mL-1 and detection limit 0.29 fg mL-1. In addition, this immunosensor showed good feasibility in various cancer serum samples.

Self-enhanced PEI-Ru(II) complex with polyamino acid as booster to construct ultrasensitive electrochemiluminescence immunosensor for carcinoembryonic antigen detection

In this work, the luminophor tris (4,4′-dicarboxylicacid-2,2′-bipyridyl) ruthenium (II) dichloride (Ru(dcbpy)32+) was linked to coreactant polyethylenimine (PEI) with effectively shorted distance, forming a novel self-enhanced PEI-Ru(II) complex to fabricate ultrasensitive electrochemiluminescence immunosensor for carcinoembryonic antigen (CEA) detection by using polyamino acid l-cysteine (pL-Cys) as booster for further signal amplification. The light-emitting species (PEI-Ru(II)*) based on intramolecular electron transfer between PEI• and Ru(III) could efficiently amplify the ECL signal of Ru(dcbpy)32+ owing to its benefit for electron transmission. Secondly, the pL-Cys film was fabricated on the glassy carbon electrode by cyclic voltammogram. After that, the pL-Cys acted as a strongly reducing radical could react with PEI-Ru(III) to generate the excited state PEI-Ru(II)*, which further amplify the ECL signal. With the signal amplification factors, the prepared ECL immunosensor exhibited great advantages in simplification, rapidity, stability and selectivity. Furthermore, the linear range for the determination of CEA was from 0.10 pg/mL to 80 ng/mL with a correlation coefficient of 0.9942 and a detection limit of 0.045 pg/mL (S/N = 3).

A graphene quantum dots based electrochemiluminescence immunosensor for carcinoembryonic antigen detection using poly(5-formylindole)/reduced graphene oxide nanocomposite

A novel electrochemiluminescence (ECL) immunosensor for ultrasensitive detection of carcinoembryonic antigen (CEA) was developed using signal amplification strategy based on poly(5-formylindole)/reduced graphene oxide nanocomposite (P5FIn/erGO) and Au nanoparticle (AuNP) decorated graphene quantum dots (GQDs) (GQDs@AuNP). As an effective matrix for immobilization of primary antibody (Ab1), P5FIn/erGO nanocomposite facilitated the ion transport during the redox reactions and provided larger surface areas for the immobilization of Ab1. GQDs@AuNP was used as labels to conjugate with secondary antibody (Ab2), which improved electron transfer capability with stable ECL intensity. The multiple amplification of P5FIn/erGO and GQDs@AuNP made the ECL immunosensor have a broad linear range from 0.1pgmL−1 to 10ngmL−1 and a low detection limit with 3.78fgmL−1. In addition, this ECL immunosensor performed with admirable stability and good selectivity and reproducibility as well. When this immunosensor was used for the analysis of CEA in human serum, good recoveries were obtained. Thus, there will be a promising future in the early diagnosis of cancer to detect CEA.

Label-free photoelectrochemical immunosensor for carcinoembryonic antigen detection based on g-C3N4 nanosheets hybridized with Zn0.1Cd0.9S nanocrystals

A label-free photoelectrochemical (PEC) immunosensor for carcinoembryonic antigen (CEA) detection was developed using two-dimensional (2D) ultrathin graphitic carbon nitride (g-C3N4) nanosheets hybridized with Zn0.1Cd0.9S nanocrystals as the photoactive matrix. The g-C3N4 ultrathin nanosheets, which are 2D conjugated polymers, were synthesized through a thermal polymerization-exfoliation method that can generate a high specific surface area. Next, the Zn0.1Cd0.9S nanocrystals was successfully grown on the g-C3N4 ultrathin nanosheets (Zn0.1Cd0.9S/g-C3N4), forming a well-matched band structure where the presence of Zn0.1Cd0.9S/g-C3N4 accelerated the separation and transfer of photogenerated electron-hole pairs. The as-synthesized Zn0.1Cd0.9S/g-C3N4 composites showed excellent photoelectrochemical activity, considerably higher than that of pure Zn0.1Cd0.9S and g-C3N4. It was worth noting that the heterojunction with strong interfacial interaction formed between Zn0.1Cd0.9S and g-C3N4 was adopted in the construction of an immunosensor for the first time. CEA antibody (anti-CEA) was immobilized on the surface of a modified electrode using a chemical bonding effect, with mercaptoacetic acid (MPA) and EDC/NHS being used as bridging media. The highly specific introduction of CEA resulted in increased steric hindrance via the antigen-antibody specific immunoreaction; Thus, the concentrations of CEA could be detected by observing the decrease in photocurrent. Under optimal conditions, the linear range for the immunosensor was from 0.005ngmL−1 to 20ngmL−1. The detection limit was 1.4pgmL−1.

A label-free electrochemical immunosensor for carcinoembryonic antigen detection on a graphene platform doped with poly(3,4-ethylenedioxythiophene)/Au nanoparticles

In this work, a two-step method was developed for the fabrication of a graphene sensing platform doped with poly(3,4-ethylenedioxythiophene)/Au nanoparticles (AuNPs/PEDOT/GR).

Large-scale synthesis of ultrathin Au-Pt nanowires assembled on thionine/graphene with high conductivity and sensitivity for electrochemical immunosensor

In this article, for the first time, a novel, label-free and inherent electroactive redox biosensor based on ultrathin Au-Pt nanowire-decorated thionine/reduced graphene oxide (AuPtNWs/THI/rGO) is developed for carcinoembryonic antigen (CEA) detection. Ultrathin AuPtNWs are prepared by a one-pot synthesis method without the use of any stabilizer or template. The AuPtNWs/THI/rGO composites are obtained by the THI/rGO composites surface functionalized with -NH2 group employed as a support for loading ultrathin AuPtNWs by coordination. The AuPtNWs/THI/rGO composites not only favor the immobilization of antibody but also facilitate the electron transfer. It is found that the resultant AuPtNWs/THI/rGO composites can be designed to act as a sensitive label-free electrochemical immunosensor for CEA determination. Under the optimized conditions, the linear range of the proposed immunosensor is estimated to be from 50 fg·mL−1 to 100 ng·mL−1 (R= 0.998) and the detection limit is estimated to be 6 fg·mL−1 at a signal-to-noise ratio of 3, respectively. The prepared immunosensor for detection of CEA shows high sensitivity, reproducibility and stability. Our study demonstrates that the proposed immunosensor has also been used to determine CEA successfully in diluted blood samples.

An ultrasensitive electrochemical immunosensor for carcinoembryonic antigen detection based on staphylococcal protein A—Au nanoparticle modified gold electrode

The fabrication of staphylococcal protein A (SPA) film on Au nanoparticle (AuNPs)-modified electrode was done for the construction of electrochemical immunosensor. In this work, a highly sensitive electrochemical immunosensor for the detection of a tumor biomarker, carcinoembryonic antigen (CEA) was developed by absorption of anti-CEA antibodies on the SPA-AuNPs modified gold electrode. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques were employed in the determination of electrode responses and applicability. Under the optimized condition, the immunosensor displays a good linear response to CEA with a range from 1pg/ml to 100ng/ml and a detection limit of 0.1pg/ml. Furthermore, samples of 1–50ng/ml CEA in rat serum was detected using the immunosensor and the immunosensor showed acceptable recoveries when the CEA value is within the scope of clinical detection. It can be concluded that the immunosensor provides a promising ultrasensitive immunology strategy for clinical diagnosis.

A novel label-free amperometric immunosensor for carcinoembryonic antigen based on Ag nanoparticle decorated infinite coordination polymer fibres

In this article, for the first time, a novel, high-yield and template-free method for the synthesis of Ag nanoparticle decorated thionine/infinite coordination polymer (AgNP/THI/ICP) fibres is proposed. The thionine can be adsorbed to the AgNP/THI/ICP fibres by π-conjugation and act as the redox probe. The AgNP/THI/ICP fibres not only favor the immobilization of antibody but also facilitate the electron transfer. It is found that the AgNP/THI/ICP fibres can be designed to act as a sensitive label-free electrochemical immunosensor for carcinoembryonic antigen (CEA) determination. Under the optimized conditions, the linear range of the proposed immunosensor is estimated to be from 50fg/mL to 100ng/mL and the detection limit is estimated to be 0.5fg/mL at a signal-to-noise ratio of 3, respectively. The prepared immunosensor for detection of CEA shows high sensitivity, reproducibility and stability. Our study demonstrates that the proposed immunosensor has also been used to determine CEA successfully in diluted blood samples.

Biomolecule-based formaldehyde resin microspheres loaded with Au nanoparticles: A novel immunoassay for detection of tumor markers in human serum

A surfactant-free and template-free method for the high-yield synthesis of biomolecule (serotonin)-based formaldehyde resin (BFR) microspheres is proposed for the first time. The colloidal microspheres loaded with Au nanoparticles (AuNPs) prepared by a convenient in-situ synthesis of AuNPs on BFR (AuNPs/BFR) microsphere surface show good stability. AuNPs/BFR microspheres not only favor the immobilization of antibody but also facilitate the electron transfer. It is found that the resultant AuNPs/BFR microspheres can be designed to act as a sensitive label-free electrochemical immunosensor for carcinoembryonic antigen (CEA) determination. The immunosensor is prepared by immobilizing capture anti-CEA on AuNPs/BFR microspheres assembled on thionine (TH) modified glassy carbon electrode (GCE). TH acts as the redox probe. Under the optimized conditions, the linear range of the proposed immunosensor is estimated to be from 25pg/mL to 2000pg/mL (R=0.998) and the detection limit is estimated to be 3.5pg/mL at a signal-to-noise ratio of 3. The prepared immunosensor for detection of CEA shows high sensitivity, reproducibility and stability. Our study demonstrates that the immunosensor can be used for the CEA detection in humans serum.

Amperometric immunosensor for carcinoembryonic antigen detection with carbon nanotube-based film decorated with gold nanoclusters

A new amperometric immunosensor for the determination of carcinoembryonic antigen (CEA) was constructed. First, the uniform nanomultilayer film was fabricated via layer-by-layer (LBL) assembly of positively charged carbon nanotubes wrapped by poly(diallyldimethylammonium chloride) and negatively charged poly(sodium- p-styrene-sulfonate), which could provide a high accessible surface area and a biocompatible microenvironment. Subsequently, gold nanoclusters were electrodeposited on the electrode to immobilize anti-CEA. The fabricated process and electrochemical behaviors of the immunosensor were characterized by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). Under optimal conditions, the proposed immunosensor could detect CEA in two linear ranges from 0.1 to 2.0 ng mL −1 and from 2.0 to 160.0 ng mL −1, with a detection limit of 0.06 ng mL −1.

A novel label-free electrochemical immunosensor for carcinoembryonic antigen detection based on the [Ag–Ag 2O]/SiO 2 nanocomposite material as a redox probe

In this work, a new [Ag–Ag 2O]/SiO 2 nanocomposite material was prepared using 3-aminopropyltrimethoxysilane (AMPTS) as a connected material to absorb Ag–Ag 2O nanoparticles on SiO 2 surface. The [Ag–Ag 2O]/SiO 2 nanocomposite material had large surface, excellent conductivity and well redox activity. Then, a label-free immunosensor was prepared by the employment of the novel [Ag–Ag 2O]/SiO 2 nanocomposite material for determination of carcinoembryonic antigen (CEA). And the fabrication process of immunosensor was investigated by scanning electron microscopy (SEM) and cyclic voltammetry (CV). The [Ag–Ag 2O]/SiO 2 nanocomposite material could not only construct a desirable nano-sized surface with large surface-to-volume ratio to immobilize anti-CEA with the cooperation of nano-Au but also act as redox probe for the determination of CEA. By optimization of assay conditions on the pH of HAc–NaAc buffer, temperature and incubation time, the proposed electrode was proven to be sensitive and specific to detect CEA in the range of 0.5 to 160 ng/mL with a detection limit of 0.14 ng/mL, which was well within the normal physiological range. Additionally, the capability of the proposed immunosensor for direct CEA quantification in human blood serum was also discussed here.

A sensitive amperometric immunosensor for carcinoembryonic antigen detection with porous nanogold film and nano-Au/chitosan composite as immobilization matrix

A sensitive amperometric immunosensor for carcinoembryonic antigen (CEA) was prepared. Firstly, a porous nano-structure gold (NG) film was formed on glassy carbon electrode (GCE) by electrochemical reduction of HAuCl 4 solution, then nano-Au/Chit composite was immobilized onto the electrode because of its excellent membrane-forming ability, and finally the anti-CEA was adsorbed onto the surface of the bilayer gold nanoparticles to construct an anti-CEA/nano-Au/Chit/NG/GCE immunosensor. The characteristics of the modified electrode at different stages of modification were studied by cyclic voltammetry (CV). The gold colloid, chitosan and nano-Au/Chit were characterized by transmission electron microscopy and UV–vis spectroscopy. In addition, the performances of the immunosensor were studied in detail. The resulting immunosensor offers a high-sensitivity (1310 nA/ng/ml) for the detection of CEA and has good correlation for detection of CEA in the range of 0.2 to 120.0 ng/ml with a detection limit of 0.06 ng/ml estimated at a signal-to-noise ratio of 3. The proposed method can detect the CEA through one-step immunoassay and would be valuable for clinical immunoassay.