Quantitative Detection Of Carcinoembryonic Antigen Research Articles

Difunctional Magnetic Nanoparticles Employed in Immunochromatographic Assay for Rapid and Quantitative Detection of Carcinoembryonic Antigen.

Immunochromatographic assay (ICA) plays an important role in in vitro diagnostics because of its simpleness, convenience, fastness, sensitivity, accuracy, and low cost. The employment of magnetic nanoparticles (MNPs), possessing both excellent optical properties and magnetic separation functions, can effectively promote the performances of ICA. In this study, an ICA based on MNPs (MNP-ICA) has been successfully developed for the sensitive detection of carcinoembryonic antigen (CEA). The magnetic probes were prepared by covalently conjugating carboxylated MNPs with the specific monoclonal antibody against CEA, which were not only employed to enrich and extract CEA from serum samples under an external magnetic field but also used as a signal output with its inherent optical property. Under the optimal parameters, the limit of detection (LOD) for qualitative detection with naked eyes was 1.0 ng/mL, and the quantitative detection could be realized with the help of a portable optical reader, indicating that the ratio of optical signal intensity correlated well with CEA concentration ranging from 1.0 ng/mL to 64.0 ng/mL (R2 = 0.9997). Additionally, method comparison demonstrated that the magnetic probes were beneficial for sensitivity improvement due to the matrix effect reduction after magnetic separation, and the MNP-ICA is eight times higher sensitive than ICA based on colloidal gold nanoparticles. The developed MNP-ICA will provide sensitive, convenient, and efficient technical support for biomarkers rapid screening in cancer diagnosis and prognosis.

Facile preparation of Ru nanoassemblies for electrochemical immunoassay of carcinoembryonic antigen in clinical serum

Abnormal expression of carcinoembryonic antigen (CEA) can be used for early diagnosis of various cancers (e.g. colorectal cancer, cervical carcinomas, and breast cancer). In this work, using l-cysteine-ferrocene-ruthenium nanocomposites (L-Cys-Fc-Ru) to immobilize secondary antibody (Ab2) and Au nanoparticles (NPs) as the substrate to ensure accurate capture of primary antibody (Ab1), a signal-on sandwich-like biosensor was constructed in the presence of CEA. Specifically, Ru nanoassemblies (NAs) were first prepared by a facile one-step solvothermal approach as signal amplifiers for the electrical signal of Fc. Based on specific immune recognition, as the increase of CEA concentration, the content of L-Cys-Fc-Ru-Ab2 captured on the electrode surface also increased, thus the signal of Fc gradually increased. Therefore, the quantitative detection of CEA can be realized according to the peak current of Fc. After a series of experiments, it was found that the biosensor has a wide detection range from 1.0 pg mL−1 to 100.0 ng mL−1 and a low detection limit down to 0.5 pg mL−1, as well as good selectivity, repeatability and stability. Furthermore, satisfactory results were also obtained for the determination of CEA in serums, which were comparable to commercial electrochemiluminescence (ECL) method. The developed biosensor shows great potential in clinical applications.

Dumbbell-like upconversion nanoparticles synthesized by controlled epitaxial growth for light-heat-color tri-modal sensing of carcinoembryonic antigen

Accurate quantitative analysis of tumor markers in a wide linear range has important practical significance towards complex clinical samples in cancer identification and monitoring of tumor development stages, but remains challenging. Herein, three-layer dumbbell-like upconversion nanoparticles NaErF4:Tm@NaYF4@NaNdF4 (labeled as UCNPs) combined with G-quadruplex (G4) DNAzyme are reported for tri-modal sensing of carcinoembryonic antigen (CEA) in a wide range using upconversion luminescence (UCL), photothermal and catalysis signal readouts. Initially, dumbbell-like UCNPs were controlled synthesized by a three-dimensional epitaxial growth strategy through tuning the concentration of Nd precursors. After surface functionalization, G4zyme-UCNPs-cDNA/Apt-MB was subsequently fabricated by biotin-streptavidin interaction and DNA hybridization. Quantitative detection of CEA was achieved by competitive interaction and magnetic separation, and the intensities of tri-modal signals (light, heat and catalysis-based chrominance) of dissociative probes are linearly related to the concentration of CEA. The results showed that the tri-modal sensing method exhibited a wide linear range (0.005–2000 ng/mL) and low limit of detection (LOD) across three models: the luminescence model (0.005–50 ng/mL, LOD = 0.910 pg/mL), the catalysis model (10–1000 ng/mL, LOD = 0.387 ng/mL), and the temperature model (50–2000 ng/mL, LOD = 1.114 ng/mL). These findings suggest that the tri-modal sensing platform is suitable for use in the analysis of a wide range of complex and diverse clinical samples.

Optical biosensor based on SERS with signal calibration function for quantitative detection of carcinoembryonic antigen.

Monitoring the levels of cancer biomarkers is essential for cancer diagnosis and evaluation. In this study, a novel sandwich type sensing platform based on surface-enhanced Raman scattering (SERS) technology was developed for the detection of carcinoembryonic antigen (CEA), with a limit of detection (LOD) of 0.258 ng/mL. In order to achieve sensitive detection of CEA in complex samples, gold nanoparticle monolayer modified with CEA antibodies and with aptamer-functionalized probes was fabricated to target CEA. Two gold layers were integrated into the SERS platform, which greatly enhanced the signal of the probe by generating tremendous "hot spots". Meanwhile, the intensity ratio of Raman probes and the second-order peak of the silicon wafer was used to achieve dynamic calibration of the Raman probe signal. Excitingly, this sensing platform was capable of distinguishing cancer patients from healthy individuals via CEA concentrations in blood samples with the accuracy of 100%. This sandwich structure SERS sensing platform presented promising potential to be an alternative tool for clinical biomarker detection in the field of cancer diagnosis.

Enzyme-free sandwich-type electrochemical immunosensor for CEA detection based on the cooperation of an Ag/g-C3N4-modified electrode and Au@SiO2/Cu2O with core-shell structure

Effective signal amplification is a prerequisite for electrochemical immunosensors to achieve ultra-sensitive detection. In this work, we prepared a sandwich-type electrochemical immunosensor for the quantitative detection of carcinoembryonic antigen (CEA). As a base platform, Ag NPs modified aminated two-dimensional nitrogen carbide nanosheets (Ag/g-C3N4) have good biocompatibility and conductivity. In addition, with the layered structure of Au@SiO2/Cu2O as the signal label, the response current value of H2O2 was monitored by the Amperometric i-t Curve (i-t), so as to realize the accurate measurement of CEA. The presence of SiO2 nanoframes not only reduces the agglomeration of Au NPs and Cu2O but also provides good biocompatibility to facilitate the connection of secondary antibodies. Finally, we also verified the signal amplification mechanism of the immunosensor through XPS and other means, and calculated the kinetic parameters of the signal tag, which proved the good peroxidase-like activity of Au@SiO2/Cu2O. Under the best test conditions, the prepared immunosensor has a detection range from 0.01 pg/mL to 80 ng/mL, and the detection limit is as low as 0.0038 pg/mL. The results show that the immunosensor has good analytical performance and it can provide a new method for the clinical diagnosis of CEA.

A smartphone-based enzyme-linked immunochromatographic sensor for rapid quantitative detection of carcinoembryonic antigen

The development and application of portable, cost-effective, and user-friendly biosensing technology to enable real-time disease diagnosis on the spot are alway a top priority in the in vitro diagnostic (IVD). Here, a smartphone based enzyme-linked immunochromatographic sensor (ELICS) system was developed as required. This hand-held sensing system utilizes built-in ambient light sensor in smartphone and integrated with a specially designed disposable chromatography device. Immunoassay and enzyme coloration are performed on the chromatography device to form a biosensor channel, and the results are read directly by the smartphone ambient light sensor. To demonstrate this platform, the commonly used cancer biomarker carcinoembryonic antigen (CEA) was chosen as a proof-of-concept test. This method was 100-folds more sensitive than conventional used immunochromatographic assay, and whole detection and analysis process was completed within 25 min. For detection of CEA in clinical serum samples, the ELICS results were well correlated with those from chemiluminescence immunoassay (CLIA). With the advantages of high sensitivity, rapid, user-friendly, low cost and portability, ELICS would have wide applicability in family and community medical institution, especially in the areas of poor medical resources.

Design and application of terahertz metamaterial sensor based on DSRRs in clinical quantitative detection of carcinoembryonic antigen.

The terahertz (THz) metamaterial biosensor has great potential for label-free and rapid specificity testing. Here, we designed two highly sensitive structures to detect the carcinoembryonic antigen (CEA) of the cancer biomarker in early stages. There was about 29 GHz (500 ng/ml) resonance shift for CEA with an insert grate metamaterial, which was consistent with simulation results. Moreover, the concentration of CEA was gained through the relationship between the cancer marker concentration and frequency shift (Δƒ). Our design and detection methods may provide a potential route for the early warning stages of cancer.

Self-Polymerized Dopamine-Decorated Au NPs and Coordinated with Fe-MOF as a Dual Binding Sites and Dual Signal-Amplifying Electrochemical Aptasensor for the Detection of CEA.

Fabrication of functional electrochemical biosensor is a hot topic; however, precise and sensitive cancer detection in early clinical diagnosis is still a great challenge. Continuous efforts have been devoted to explore functional materials for this issue. In this work, we developed a dual binding sites and dual signal-amplifying electrochemical aptasensor of self-polymerized dopamine-decorated Au and coordinated with Fe-MOF (Au@PDA@Fe-MOF) for the detection of carcinoembryonic antigen (CEA). Remarkably, Au@PDA@Fe-MOF features high sensitivity, multiple active sites, good biocompatibility, and excellent selectivity, which is attributed to abundant -COOH in porous Fe-MOF and unsaturated Fe3+ sites on the surface of Fe-MOF as the active binding sites grafting more NH2-functionalized CEA-specific aptamer and redox PDA and Fe-MOF accelerating the movement of electrons for dual signal amplifying. Meanwhile, the electrochemical aptasensor shows favorable repeatability with 1.82% relative standard deviation (RSD) under five independent aptasensors and strong stability with only 3.3% degradation after 12 days of storage. In addition, the aptasensor has wide CEA detection range from 1 fg mL-1 to 1 μg mL-1 with a low detection limit of 0.33 fg mL-1 (S/N = 3). Furthermore, the aptasensor is feasible for accurate and quantitative detection of CEA in serum samples with RSD below 2.32%. The satisfying results demonstrate promising applications of the CEA aptasensor in practical sample analysis and lay an important foundation for other biomarker detection in early clinical diagnosis.

Interference-free and high precision biosensor based on surface enhanced Raman spectroscopy integrated with surface molecularly imprinted polymer technology for tumor biomarker detection in human blood

The reliable quantitative analysis of tumor biomarkers in circulating blood is crucial for cancer early screening, therapy monitoring and prognostic prediction. Herein, a novel biosensor combing surface-enhanced Raman spectroscopy (SERS) and surface molecularly imprinted polymer (SMIP) technology was developed for quantitative detection of carcinoembryonic antigen (CEA) that is closely related to several common cancers. Owing to the use of SMIP, recognition sites with high affinity to the target of interest can be well imprinted on the surface of SERS substrate, leading to a more stable and specific capture ability. In addition, two layers of core-shell nanoparticles were integrated to this SERS substrate to form highly efficient electromagnetic enhancement for SERS measurement via the generation of lots of “hot spot”. Besides, a unique Raman reporter (CC) with silent Raman signals at 2024 cm−1 was capsulated in the nanoparticles to avoid the optical noises originating from endogenous molecules at fingerprint region (300-1800 cm−1). Meanwhile, we employed an internal standard molecular (CN) to real time correct the fluctuating signals of Raman reporter when performing the quantitative analysis. Due to these features, a limit of detection (LOD) of 0.064 pg mL−1 with the detection range of 0.1 pg mL−1 - 10 μg mL−1 can be achieved by this assay. Excitingly, this technology even showed wonderful performances for CEA detection in real blood from cancer patients, demonstrating great potential for biomarker-based cancer screening.

Graphene Quantum Dots Decorated Gold-Polyaniline Nanowire for Impedimetric Detection of Carcinoembryonic Antigen

A label-free impedimetric immunosensor based on N, S-graphene quantum dots@Au-polyaniline (N, S-GQDs@Au-PANI) nanowires was fabricated for the quantitative detection of carcinoembryonic antigen (CEA). The N, S-GQDs and Au-PANI were synthesized by a simple hydrothermal pyrolysis and interfacial polymerization, respectively. Subsequently, 2–9 nm N, S-GQDs are successfully decorated onto 30–50 nm Au-PANI nanowires by Au-thiol linkage to serve as the bifunctional probe for amplifying the electrochemical activity as well as anchoring anti-CEA. The N, S-GQDs@Au-PANI nanowires are excellent conducting materials to accelerate the electron transfer, while the formation of CEA antibody-antigen bioconjugates after the addition of CEA significantly increase the charge transfer resistance, and subsequently provides a highly stable and label-free immunoassay platform for the impedimetric detection of CEA. The label-free immunosensor exhibits a wide linear range from 0.5 to 1000 ng mL−1 with a low detection limit of 0.01 ng mL−1. The N, S-GQDs@Au-PANI based immunosensor also shows high selectivity and stability over other cancer makers and amino acids. Moreover, this promising platform is successfully applied to the detection of CEA in human serum samples with excellent recovery of (96.0 ± 2.6)–(103 ± 3.8)%. These results clearly demonstrate a newly developed highly efficient and label-free impedimetric immunosensor for the detection of CEA using N, S-GQDs@Au-PANI nanowires as the biosensing probe, which can pave the gateway for the fabrication of high performance and robust impedimetric immunosensor to detect cancer makers in early stage of cancer diagnosis and therapy.

A sandwich-type amperometric immunosensor fabricated by Au@Pd NDs/Fe2+-CS/PPy NTs and Au NPs/NH2-GS to detect CEA sensitively via two detection methods

The quantitative detection of carcinoembryonic antigen (CEA) is significant to assess tumor status and therapeutic efficiency. In this study, a sandwich-type amperometric immunosensor for CEA detection sensitively was fabricated by novel signal amplification system. The signal amplification system was formed by gold nanoparticles loaded on amino functionalized graphene sheet (Au NPs/NH2-GS) and gold@palladium nanodendrites loaded on ferrous-chitosan functionalized polypyrrole nanotubes (Au@Pd NDs/Fe2+-CS/PPy NTs). Au NPs/NH2-GS as platform enhanced the electron transfer proven by apparent electron transfer rate constant. Au@Pd NDs/Fe2+-CS/PPy NTs nanocomposite as label appeared high catalytic activity to hydrogen peroxide reduction. Thus, the immunosensor showed wide linear concentration range (50 fg/mL to 50 ng/mL) and low detection limit of 17 fg/mL via amperometric i-t curve (i-t). Significantly, the nanocomposite can act as electroactive substance, which provided a good method to detect CEA without additional electroactive substance via square wave voltammetry (SWV). An overlapping linear concentration range (500 fg/mL to 5.0 ng/mL) was obtained compared i-t with SWV.The good reliability was verified mutually by i-t and SWV in actual sample analysis under overlapping linear concentration range. The detection method of without additional electroactive substance has vast potential for future development, due to simple testing condition.

Immune fluorescence test strips based on quantum dots for rapid and quantitative detection of carcino-embryonic antigen

At present, many researchers focused on the point-of-care testing (POCT), a method of disease markers detection without large-scale instruments and specialized persons. However, most POCT diagnostic methods were suffered from poor detection sensitivity or inefficiency in quantitative detection. Herein, we developed a newly QD-immune fluorescence test strips (QD-IFTS) based on quantum dots (QDs) as the fluorescence nanocarrier to prepare the immune fluorescence probes in the classical immunochromatography detection system for sensing carcino-embryonic antigen (CEA), a kind of glycoprotein produced by intestinal tissue and a broad spectrum of tumor marker for cancer diagnosis. And we designed a homemade strips fluorescence reader for detection of fluorescence intensity of QDs on the QD-IFTS. Under the optimized reaction conditions, chromatographic time of the newly QD-IFTS was only 25min, sample volume of the newly QD-IFTS was only 40μL and the LOD of the newly QD-IFTS was 0.72ng/mL. In addition, the efficiency and robustness of the newly QD-IFTS were confirmed by successfully application in 300 clinical serum samples, and the results revealed great potential in clinical POCT of other biomarkers.

Label-free electrochemical immunosensor based on flower-like Ag/MoS2/rGO nanocomposites for ultrasensitive detection of carcinoembryonic antigen

In this work, a label-free electrochemical immunosensor was developed for the quantitative detection of carcinoembryonic antigen (CEA). Flower-like Ag/MoS2/rGO nanocomposites were employed as the signal amplification platform of the designed immunosensor for the first time. Due to the synergistic effect between molybdenum disulfide (MoS2), reduced graphene oxide (rGO) and Ag nanoparticles (NPs), Ag/MoS2/rGO nanocomposites could provide a high sensitivity for the label-free electrochemical immunosensor. The detection mechanism was based on the monitoring of the electrocatalytic current response change towards the reduction of hydrogen peroxide (H2O2) when immunoreaction occurred on the surface of the electrode modified with Ag/MoS2/rGO nanocomposites. Using amperometric i-t curve to record the electrocatalytic process, the proposed immunosensor achieved an ultrasensitive and specific detection of CEA with a low detection limit of 1.6 fg/mL. Under optimal conditions, the fabricated immunosensor exhibited acceptable reproducibility, selectivity and excellent stability. This designed immunosensor could provide an effective method in the clinical diagnosis of other tumor markers.

Sandwich-type amperometric immunosensor using functionalized magnetic graphene loaded gold and silver core-shell nanocomposites for the detection of Carcinoembryonic antigen

Herein, a novel and sensitive sandwich-type electrochemical immunosensor was fabricated for quantitative detection of carcinoembryonic antigen (CEA). In order to construct the base of the immunosensor, the gold nanoparticles (Au NPs) were immobilized on the surface of bare glassy carbon electrode (GCE) through electrochemical reduction of HAuCl4 solution. The electrodeposited gold nanoparticles (D-Au NPs) not only effective improve immobilization of primary anti-CEA antibody (Ab1) but also accelerate the electron transfer on the electrode interface due to the high specific surface area, good biocompatibility and superior electrical conductivity. Moreover, the amino functionalized magnetic graphene loaded gold and silver core-shell nanoparticles to adsorb nickel ion (GS-Fe3O4/Au@Ag/Ni2+), which were used as a novel label to load the secondary anti-CEA antibody (Ab2). The resultant nanocomposites possess high specific surface area, excellent electrochemical property, good biocompatibility and superior auxiliary catalytic activity due to the synergetic effect. The signal amplification strategy, using the synergetic effect present in Au@Ag/Fe3O4-GS/Ni2+ to improve immobilization of Ab2 and increase the reduction ability of the nanocomposites towards H2O2, improved the sensitivity of the immunosensor. Under the optimal conditions, a linear relationship between current signals and the concentrations of CEA was obtained in the range from 0.1pg/mL to 100ng/mL and the detection limit of CEA was 0.0697pg/mL (signal-to-noise ratio of 3). Furthermore, the as-proposed immunosensor showed excellent performance in detection of human serum samples. The results suggest that the proposed immunosensor will be promising in the diagnostics application for accurately quantitative detection of CEA.

A novel label-free electrochemical immunosensor based on functionalized nitrogen-doped graphene quantum dots for carcinoembryonic antigen detection

A novel and ultrasensitive label-free electrochemical immunosensor was fabricated for quantitative detection of carcino-embryonic antigen (CEA). The nitrogen-doped graphene quantum dots (N-GQDs) supported PtPd bimetallic nanoparticles (PtPd/N-GQDs) were synthesized by a simple and green hydrothermal procedure. Subsequently, PtPd/N-GQDs functionalized Au nanoparticles (PtPd/N-GQDs@Au) were prepared successfully via a self-assembly approach. Because of the synergetic effect present in PtPd/N-GQDs@Au, this novel nanocomposites has shown excellent electrocatalytic activity towards hydrogen peroxide (H2O2) reduction. Featuring good biocompatibility, excellent conductivity and large surface area, PtPd/N-GQDs@Au was applied as transducing materials to efficiently conjugate capture antibodies and amplify electrochemical signal. Under the optimal conditions, the proposed immunosensor was used for the detection of CEA with wide dynamic range in the range from 5 fg/mL to 50ng/mL with a low detection limit of 2fg/mL (S/N=3). Furthermore, this label-free immunosensor possesses high sensitivity, special selectivity and long-term stability, which shows promising application in bioassay analysis.

Highly sensitive and selective lateral flow immunoassay based on magnetic nanoparticles for quantitative detection of carcinoembryonic antigen

Carcinoembryonic antigen (CEA) is an important biomarker in cancer diagnosis. Here, we present an efficient, selective lateral-flow immunoassay (LFIA) based on magnetic nanoparticles (MNPs) for in situ sensitive and accurate point-of-care detection of CEA. Signal amplification mechanism involved linking of detection MNPs with signal MNPs through biotin-modified single-stranded DNA (ssDNA) and streptavidin. To verify the effectiveness of this modified LFIA system, the sensitivity and specificity were evaluated. Sensitivity evaluation showed a broad detection range of 0.25–1000ng/ml for CEA protein by the modified LFIA, and the limit of detection (LOD) of the modified LFIA was 0.25ng/ml, thus producing significant increase in detection threshold compared with the traditional LFIA. The modified LFIA could selectively recognize CEA in presence of several interfering proteins. In addition, this newly developed assay was applied for quantitative detection of CEA in human serum specimens collected from 10 randomly selected patients. The modified LFIA system detected minimum 0.27ng/ml of CEA concentration in serum samples. The results were consistent with the clinical data obtained using commercial electrochemiluminescence immunoassay (ECLIA) (p<0.01). In conclusion, the MNPs based LFIA system not only demonstrated enhanced signal to noise ratio, it also detected CEA with higher sensitivity and selectivity, and thus has great potential to be commercially applied as a sensitive tumor marker filtration system.

Ultrasensitive sandwich-type electrochemical immunosensor based on trimetallic nanocomposite signal amplification strategy for the ultrasensitive detection of CEA.

A novel and ultrasensitive sandwich-type electrochemical immunosensor was designed for the quantitative detection of carcino-embryonic antigen (CEA). This immunosensor was developed by using the trimetallic NiAuPt nanoparticles on graphene nanosheets (NGs) nanosheets (NiAuPt-NGs) as excellent labels and β-cyclodextrin functionalized reduced graphene oxide nanosheets (CD-NGs) as the platform. The CD-NGs with high specific surface area good biocompatibility and the ideal dispersibility was used to capture the primary antibodies (Ab1) efficiently. The trimetallic NiAuPt-NGs nanocomposites were used as the labels for signal amplification, showing better electrocatalytic activity towards the reduction of hydrogen peroxide (H2O2), which is much better than that the monometallic Pt-NGs, bimetallic NiPt-NGs and AuPt-NGs due to the synergetic effect presented in NiAuPt-NGs. The NiAuPt-NGs nanocomposites consist of tightly coupled nanostructures of Au, Ni and Pt, which have neither an alloy nor a core-shell structure. Under the optimal conditions, a linear range from 0.001–100 ng/mL and a low detection limit of 0.27 pg/mL were obtained for CEA. The proposed electrochemical sandwich-type immunosensor may have a promising application in bioassay and it enriches the electrochemical immunoassays.

Simple synthesis of silver nanoparticles functionalized cuprous oxide nanowires nanocomposites and its application in electrochemical immunosensor

In this work, silver nanoparticles functionalized cuprous oxide nanowires (Ag@Cu2O) nanocomposites were synthesized by a simple method. The nanostructure of it could be well confirmed by a scanning electron microscope (SEM) image. Due to the good synergistic effect between silver nanoparticles (Ag NPs) and cuprous oxide nanowires (Cu2O NWs), Ag@Cu2O nanocomposites displayed a good electrocatalytic performance towards the reduction of hydrogen peroxide (H2O2). Cyclic voltammograms (CVs) were employed to investigate electrocatalytic mechanism of it. Using Ag@Cu2O nanocomposites as the labels, a novel and ultrasensitive sandwich-type electrochemical immunosensor was developed for the quantitative detection of carcinoembryonic antigen (CEA). Due to the special electrochemical performance of Ag@Cu2O nanocomposites, the facile and sensitive fabrication of the designed immunosensor was achieved. Under optimal conditions, the designed immunosensor exhibited a wide linear range with a low detection limit. It also displayed an electrochemical performance with good reproducibility, selectivity and stability, which would provide potential applications in the clinical diagnosis of other tumor markers.

SERS tags-based novel monodispersed hollow gold nanospheres for highly sensitive immunoassay of CEA

Here, a highly specific, sensitive, and reliable immunoassay has been developed based on surface-enhanced Raman scattering for quantitative detection of carcinoembryonic antigen (CEA). A novel hollow gold nanospheres (HGNs) was firstly fabricated by seed-mediated methods instead of the one-step methods with high homogeneity and then, the monodispersed HGNs were embedded with 4-mercaptobenzonic acid to form surface-enhanced Raman scattering (SERS) tags and magnetic microspheres were synthesized as enrichment substrates. Based on this sandwich immunoassay strategy, CEA monoclonal antibody -conjugated HGNs-based SERS tags and CEA polyclonal antibodies -conjugated magnetic microspheres were used to detect CEA up to 100 ng/mL with a detection limit of 10 pg/mL, which were two orders of magnitudes lower than that of GNSs-based SERS tags. The monodispersed HGNs were desirable SERS tags for quantitative sandwich immunoassay assay, showing strong potential for the clinical diagnosis of cancer biomarkers.

A label-free amperometric immunosensor for the detection of carcinoembryonic antigen based on novel magnetic carbon and gold nanocomposites

In this work, a novel label-free electrochemical immunosensor was developed for the quantitative detection of carcinoembryonic antigen (CEA).