Determination Of Carcinoembryonic Antigen Research Articles

A label-free and signal-amplifiable fluorescent biosensor based on aptamer-conjugated gold nanoparticles and hybridization chain reaction for determination of carcinoembryonic antigen.

The sensitive detection of cancer biomarkers is crucial for early accurate diagnostics and therapy of cancer patients. Carcinoembryonic antigen (CEA) is a tumor-associated antigen derived from colon cancer and embryonic tissues. In this study, we have developed a label-free fluorescence biosensing platform for the quantification of CEA with the "turn-on" signal output. This platform employs a label-free strategy that incorporates an aptamer-modified gold nanoparticle (Apt@AuNP) probe for the recognition of CEA, in combination with hybridization chain reaction (HCR) amplification. In the presence of target CEA, Apt@AuNPs selectively capture CEA, resulting in a reduction of subsequent complementary chains (CP) binding on Apt@AuNPs. The remaining CP, acting as the initiator sequence for HCR, triggers the HCR, leading to the formation of abundant G-quadruplex structures. By employing Thioflavin T (ThT) for the formation of G-quadruplex/ThT complexes, the biosensor exhibits a significant enhancement of the fluorescence signal. Under optimized conditions, the biosensor platform demonstrates a limit of detection of 0.03 nM and a linear range from 0.1 to 2.5nM. Additionally, the specificity investigation reveals the high selectivity of this fluorescent biosensor. Finally, the performance of this method has been validated by successfully detecting CEA in real-life samples, highlighting its potential for clinical applications.

A Complex Interplay of Tumor Microenvironment Could Enhance Cholangiocarcinoma Progression Even After Surgery: A Prospective Study.

The current study was conducted to explore the impact of macrophages and programmed cell death protein 1 (PD-1) expression on tumor-infiltrating lymphocytes (TILs) on treatment outcomes and to define the interaction between these factors and the clinicopathologic features of advanced cholangiocarcinoma (CCA) patients. Twenty-five patients with metastatic CCA were recruited for the current study from El-Rajhi Hospital and the Clinical Oncology Department of Assiut University. Additionally, 19 healthy controls were included. Before the flow cytometric detection of immune cells, the diagnosis and staging of CCA were performed based on surgical intervention, imaging, carbohydrate antigen 19-9 (CA19-9), and carcinoembryonic antigen (CEA) determinations. This was followed by flow cytometric detection of CD4+, CD8+, CD4+PD-1+, CD8+PD-1+, and CD11b+CD68+ macrophages in the peripheral blood of both patients and controls. The current results revealed higher levels of CD4+, CD8+, and CD11b+CD68+ macrophages in controls compared to patients. At the same time, PD-1 expression was significantly higher in patients compared to controls. CD4+ was correlated with improved progression-free survival (PFS), while CD8+PD-1 was associated with shorter PFS. In general, CD4+ and CD8+ levels progressively increased with improved response to treatments, differentiation, single organ site metastasis, and surgical interventions. On the contrary, PD-1 expression and macrophages progressively increased with worsening response, dedifferentiation, multiple organ sites, and surgical interventions. The median PFS was 12 months, and the mean ± standard error (SE) was 13.1 ± 1.3. CCA has a desmoplastic microenvironment with complex immunologic topography and tumor-reactive stroma. The immune landscape of the peripheral blood mononuclear cells (PBMCs) in CCA patients before treatment could reflect the state of systemic immune function and response to treatments. Our results revealed that T-lymphocytes correlated with better prognosis while macrophages and PD-1+ expression were associated with poor outcomes.

Aptamer-controlled peroxidase activity of platinum nanoparticles/Fe-MOF nanozyme for highly effective voltammetric detection of carcinoembryonic antigen

Carcinoembryonic antigen (CEA) is the most widely adopted biomarker for the early determination of various cancers, thus it is very important to design a simple and highly effective sensing method to detect CEA. Herein, by synthesizing Fe-MOF nanohybrid loaded with platinum nanoparticles (Pt NPs/Fe-MOF) nanozyme and selecting CEA aptamer (Apt) as the specific recognition element, a simple nanozyme-based voltammetric sensor was designed to detect CEA based on Apt-controlled the catalytic activity of Pt NPs/Fe-MOF nanozyme. The as-synthesized Pt NPs/Fe-MOF nanozyme could catalyze effectively 1,2-diaminobenzene oxidation to produce electroactive 2,3-diaminophenazinc (DAP) which can exhibit a strong reduction current. Nonetheless, when Pt NPs/Fe-MOF is covered fully by Apt of CEA, the peroxidase activity of the as-synthesized Pt NPs/Fe-MOF nanozyme is remarkably restricted and the peak current of DAP would disappear nearly. Interestingly, this catalytic activity could be recovered effectively in the presence of CEA owing to the specific identification of Apt toward CEA. Through optimizing several experimental factors, the as-designed nanozyme voltammetric sensor offers superior detective performance for CEA. In addition, the as-designed sensor possesses superior specificity and selectivity, reproducibility and stability as well as practical applications, showing great potentials for achieving simple, sensitive and highly effective determination of CEA.

Dual-potential ratiometric electrochemiluminescence based on single emitter and single coreactant for the sensitive detection of carcinoembryonic antigen

Dual-potential ratiometric electrochemiluminescence (ECL) is in favor of resistance to environmental interference. However, two kinds of emitters or coreactants, and a wide scan potential range (>2 V) are mandatory. This work developed a new dual-potential ratiometric ECL sensor for detection of carcinoembryonic antigen (CEA) using single emitter (luminol) and single coreactant (H2O2) with a mild potential range from −0.1 to 0.6 V. Luminol could produce a strong cathodic ECL (Ec) induced by hydroxyl radicals (HO‧) from the reduction of H2O2, and a relatively weak anodic ECL (Ea). After the ferrocene modified CEA aptamer (Apt-Fc) was attached, Fc could promote Ea by catalyzing the oxidation of H2O2, and reduce Ec by consuming HO‧. With the cycling amplification of the exonuclease I, CEA could substantially reduce the amount of Apt-Fc, resulting in the decrease of Ea and the rise of Ec. So, the ratio of Ec to Ea (Ec/Ea) was used as the detection signal, realizing the sensitive determination of CEA from 0.1 pg mL−1 to 10 ng mL−1 with a LOD of 41.85 fg mL−1 (S/N = 3). The developed sensor demonstrated excellent specificity, stability and reproducibility, with satisfactory results in practical detection.

Advancing CEA quantification: Designing a sensitive electrochemical immunosenor using MWCNT/Ni(OH)2 nanocomposite

An ultra-sensitive immunosensor was designed for the accurate determination of Carcinoembryonic Antigen (CEA). To enhance the performance of immunosensor, an MWCNT/Ni(OH)2 nanocomposite was utilized as the electrochemical interface and modifier of the electrode surface. The simple preparation procedures for MWCNT/Ni(OH)2 composite were provided. Its characteristics and properties were investigated by HRTEM, FESEM, XRD, and FTIR techniques. Leveraging the unique electrochemical characteristics shown by the MWCNT/Ni(OH)2 nanocomposite and its correlation with CEA, high accuracy in CEA detection was achieved. Experimental findings provide evidence that the proposed immunosensor has the ability to detect CEA in laboratory samples. This research contributes towards achieving precise and rapid CEA detection in cancer diagnosis and prognosis. Across a wide concentration range of CEA, the designed immunosensor demonstrated a linear response from 0.0001 ng/mL to 2 ng/mL, and its limit of detection (LOD) was just 0.076 pg/mL. To evaluate the practical applicability of the electrochemical immunosensor, blood serum samples were examined, revealing the immunosensor's remarkable specificity and longevity. Its high accuracy and stability make it a valuable tool in clinical settings and biomedical research, paving the way for improved cancer management and patient outcomes.

Sensitive Electrochemical Detection of Carcinoembryonic Antigen Based on Biofunctionalized Nanochannel Modified Carbonaceous Electrode.

The convenient construction of carbon-based electrochemical immunosensors with high performance is highly desirable for the efficient detection of tumor biomarkers. In this work, an electrochemical immunosensor was fabricated by integrating a biofunctionalized mesoporous silica nanochannel film with a carbon-based electrode, which can enable the sensitive determination of carcinoembryonic antigen (CEA) in serum. The commonly used carbonaceous electrode, glassy carbon electrode (GCE), was employed as the supporting electrode and was pre-treated through electrochemical polarization to achieve the stable binding of a vertically ordered mesoporous silica film with amino groups (NH2-VMSF) without the use of any adhesive layer. To fabricate the immunorecognition interface, antibodies were covalently immobilized after the amino groups on the outer surface of NH2-VMSF was derivatized to aldehyde groups. The presence of amino sites within the high-density nanochannels of NH2-VMSF can facilitate the migration of negatively charged redox probes (Fe(CN)63-/4-) to the supporting electrode through electrostatic adsorption, leading to the generation of electrochemical signals. In the presence of CEA, the formation of immunocomplexes on the recognitive interface can reduce the electrochemical signal of Fe(CN)63-/4- on the supporting electrode. Based on this principle, the sensitive electrochemical detection of CEA was achieved. CEA can be determined to range from 0.01 ng mL-1 to 100 ng mL-1 with a limit of detection of 6.3 pg mL-1. The fabricated immunosensor exhibited high selectivity, and the detection of CEA in fetal bovine serum was achieved.

Label-free electrochemical biosensor based on Ng-PCL polymer signal amplification for the detection of carcinoembryonic antigen

Carcinoembryonic antigen (CEA) is the related antigen first extracted from embryonic tissue and is an acidic glycoprotein with human embryonic antigenic properties. It is an important biomarker for the detection of many malignancies. In this paper, we have developed a signal amplified sandwich-type electrochemical impedance biosensor based on naringin initiated poly(ε-caprolactone) (Ng-PCL) polymer for highly sensitive and rapid determination of CEA. The polymer Ng-PCL is a macromolecular polymer that can increase the sensitivity of biosensor. First, SH-functionalized CEA-aptamer 1 (Apt1) was attached to the electrode surface as a recognition probe by Au-S bonds in order to form a self-assembly monolayer (SAM). Then, the one end of CEA antigen could recognize the Apt1 modified on the electrode surface, the other end could recognize the COOH-functionalized CEA-aptamer 2 (Apt2) forming a sandwich structure. Finally, polymer Ng-PCL as a signal amplification unit, which was connected to Apt2 by ester bonds. As a result, the electron transfer in the electrode interface was hindered effectively and a label-free electrochemical impedance sensor was constructed successfully. The high sensitivity and selectivity of biosensor relied on the SAM, polymer Ng-PCL, and specific recognition of CEA. Under the optimum experimental conditions, we proposed electrochemical impedance biosensor had wide detection range between 5 pg/mL and 200 ng/mL, and the sensitivity can reach 0.675 pg/mL. Moreover, the electrochemical impedance biosensor performed high specificity, good stability and satisfactory reproducibility as well. Thus, this strategy will provide new path for the detection of other biomarkers in early clinical diagnosis.

A biosensor based on graphene oxide nanocomposite for determination of carcinoembryonic antigen in colorectal cancer biomarker

Colorectal cancer is still a major global health concern, and early detection and accurate biomarker analyses are critical to its successful management. This paper describes the design and testing of a new biosensor based on a graphene oxide (GO) nanocomposite for the exact measurement of carcinoembryonic antigen (CEA), a well-known biomarker for colorectal cancer. The current study attempted to create a highly sensitive immunosensor for sensitive measurement of CEA based on a polypropylene-imine-dendrimer (PPI) and GO nanocomposite on GCE (PPI/GO/GCE). The PPI/GO nanocomposite served as an appropriate biocompatible nanostructure with a large surface area for immobilizing carcinoembryonic antigen (anti-CEA) and bovine serum albumin (BSA) molecules (BSA/anti-CEA/PPI/GO/GCE), thereby promoting the selectivity of electrochemical immunosensors, according to structural and electrochemical studies. Results showed that the BSA/anti-CEA/PPI/GO/GCE as a selective, sensitive, and stable immunosensor revealed a wide linear response from 0.001 to 2000 ng/mL, and a limit of detection of 0.3 pg/mL, which indicated comparable or better performance towards the CEA immunosensors in recent reports in the literature. This was due to the synergetic effect of the GO nanosheets and PPI with porous structure and more conductivity. Analytical results showed values of RSD (4.49%–5.04%) and recovery (90.00%–99.98%) are suitable for effective and accurate practical assessments in CEA in clinical samples. The capacity of the BSA/anti-CEA/PPI/GO/GCE to determine CEA in human blood was studied.

Determination of carcinoembryonic antigen (CEA) by surface plasmon resonance-enhanced total internal reflection ellipsometry (SPRe-TIRE)

A surface plasmon resonance-enhanced total internal reflection ellipsometric (SPRe-TIRE) aptasensor is reported for the determination of the carcinoembryonic antigen (CEA). A gold nanofilm-coated SF10 glass slide was modified with electrochemical diazonium salt reduction and gold nanoparticles (AuNPs) to form a sensor. Next, a specific aptamer for CEA was immobilized on the AuNPs via self-assembly. The platform was characterized by X-ray photoelectron spectroscopy, ellipsometry, and cyclic voltammetry for each step of the preparation of the sensor. CEA aptamers with different affinities were used. SPRe-TIRE employed total internal reflection geometry and AuNPs to enhance plasmon resonance for the sensitive and selective determination of CEA in human serum. The working range of the aptasensor was from 0.01 to 500 ng/mL with an optimum detection limit of 0.1 pg/mL.

An electrochemiluminescence immunosensor based on functionalized metal organic layers as emitters for sensitive detection of carcinoembryonic antigen

The concentration of carcinoembryonic antigen (CEA) is an important indicator for clinical monitoring and diagnosis of tumor. Early sensitive detection of CEA is significant for cancer diagnosis and therapy. In this study, a sensitive electrochemiluminescence (ECL) immunosensor was fabricated based on functionalized metal organic layers (MOLs) for the determination of CEA. In this immunosensor, Au nanoparticles (AuNPs) were grown on ultrathin two-dimensional MOLs via in situ reduction. AuNPs not only can accelerate the electron transfer but also can be used as the labels to conjugate with antibody. The as-prepared AuNPs@Ir-Zr-MOL nanocomposite showed high ECL efficiency and can be used as an ECL emitter owing to the great ECL property of Ir-Zr-MOL. The ECL intensity of AuNPs@Ir-Zr-MOL decreased linearly with the logarithm of CEA concentration in the range from 1.00 pg mL−1 to 100 ng mL−1. And the detection limit was 0.200 pg mL−1 (S/N = 3). What’s more, the as-prepared immunosensor worked well in human blood samples, showing its potential for real analysis.

Construction of Magnetic Core-Large Mesoporous Satellite Immunosensor for Long-Lasting Chemiluminescence and Highly Sensitive Tumor Marker Determination.

Chemiluminescence immunoassay exhibits high sensitivity and signal-to-noise ratio, thus attracting great attention in the early diagnosis and dynamic monitoring of diseases. However, the collection of conventional flash-type chemiluminescence signal (<5s) relies heavily on automatic sampling and reading instrument. Herein, a novel core-satellite multifunctional chemiluminescence immunosensor is designed for the efficient enrichment and highly sensitive determination of cancer biomarker carcinoembryonic antigen (CEA) with enhanced and long-lasting output signal that can be conveniently recorded by a simple microplate plate reading instrument. Anti-CEA monoclonal antibody 2 (Ab2) modified Fe3 O4 @SiO2 microspheres (Fe3 O4 @SiO2 -Ab2, 370nm in diameter) are synthesized as the core for selectively capturing and enriching target CEA in solution, and anti-human CEA monoclonal antibody 1 (Ab1) and horseradish peroxidase (HRP) co-immobilized dendritic large-mesoporous silica nanospheres (MSNs-HRP/Ab1, 80nm in diameter, pore size: 17nm) are synthesized as the satellite for efficient immunological recognition and signal amplification. The as-designed core-satellite magnetic chemiluminescence immunosensors exhibit a broad linear range of 0.01-20ngmL-1 and a low detection limit of 3.0pgmL-1 for the convenient, highly specific, and sensitive determination of CEA in human serum. Such core-satellite chemiluminescence immunosensors are expected to act as a powerful tool for in vitro detection of various biomarkers, overcome the defect of conventional chemiluminescence relying heavily on expensive and bulky automatic instruments and popularize chemiluminescence analysis to primary medical institutions and remote areas.

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.

Fiber Laser-Based Lasso-Shaped Biosensor for High Precision Detection of Cancer Biomarker-CEACAM5 in Serum.

Detection of trace tumor markers in blood/serum is essential for the early screening and prognosis of cancer diseases, which requires high sensitivity and specificity of the assays and biosensors. A variety of label-free optical fiber-based biosensors has been developed and yielded great opportunities for Point-of-Care Testing (POCT) of cancer biomarkers. The fiber biosensor, however, suffers from a compromise between the responsivity and stability of the sensing signal, which would deteriorate the sensing performance. In addition, the sophistication of sensor preparation hinders the reproduction and scale-up fabrication. To address these issues, in this study, a straightforward lasso-shaped fiber laser biosensor was proposed for the specific determination of carcinoembryonic antigen (CEA)-related cell adhesion molecules 5 (CEACAM5) protein in serum. Due to the ultra-narrow linewidth of the laser, a very small variation of lasing signal caused by biomolecular bonding can be clearly distinguished via high-resolution spectral analysis. The limit of detection (LOD) of the proposed biosensor could reach 9.6 ng/mL according to the buffer test. The sensing capability was further validated by a human serum-based cancer diagnosis trial, enabling great potential for clinical use. The high reproduction of fabrication allowed the mass production of the sensor and extended its utility to a broader biosensing field.

Novel rapid coordination of ascorbic acid 2-phosphate and iron(III) as chromogenic substrate system based on Fe2O3 nanoparticle and application in immunoassay for the colorimetric detection of carcinoembryonic antigen

This work for the first time reports on a simple and rapid colorimetric immunoassay with rapid coordination of ascorbic acid 2-phosphate (AAP) and iron (III) for determination of carcinoembryonic antigen (CEA, used as a model) by using Fe2O3 nanoparticle based-chromogenic substrate system. The signal was produced rapidly (1 min) from the coordination of AAP and iron (III) with color development of colorless to brown. TD-DFT calculation methods were employed to simulate the UV–Vis spectra of AAP-Fe2+ and AAP-Fe3+ complexes. Moreover, Fe2O3 nanoparticle could be dissolved with the aid of acid, thereby releasing free iron (III). Herein, a sandwich-type immunoassay was established based on Fe2O3 nanoparticle as labels. As target CEA concentration increased, the number of Fe2O3 labelled-antibodies (bound specifically) increased, resulting in loading more Fe2O3 nanoparticle on platform. The absorbance increased as the number of free iron (III), derived from Fe2O3 nanoparticle, increased. So, the absorbance of reaction solution is positively correlated with antigen concentration. Under optimal conditions, the current results showed good performance for CEA detection in the range 0.02–10.0 ng/mL with a detection limit of 11 pg/mL. Moreover, the repeatability, stability, and selectivity of the colorimetric immunoassay were also acceptable.

Pt Nanodot Inlaid Mesoporous NaBiOF Nanoblackberry for Remarkable Signal Amplification Toward Biomarker Detection.

Anew ultrasensitive sandwich-type electrochemical immunosensor has been successfully constructedto quantitatively detect carcinoembryonic antigen (CEA) using blackberry-like mesoporous bismuth-based nanospheres NaBiOF (NBOF NSs) inlaid with Pt nanodots (NDs) (BiPt NSs) as the antibody capture and signal-amplifying probe. The growth of Pt NDs inside the holes of NBOF NSs formed the nanozyme inlay outside NBOF NSs, greatly increasing the specific surface area and exposure of the catalytic active sites by minimizing the particle size of the Pt to nanodot scale. Such a blackberry-shaped heterojunction structure of BiPt NSs was well-suited to antibody capture and improvedthe catalytic performance of BiPt NSs in reducing H2O2, amplifying the signal, and yielding highly sensitive detection of CEA. Theuse of Au nanoparticle-modified multi-walled carbon nanotubes (Au@MWCNTs) as the electrode substrates significantly enhanced the electron transfer behavior over the electrode surface, further increasing the conductivity and sensitivity of the immunosensor. Remarkably, good compatibility with human body fluid was achieved using the newly developed BiPt-based immunosensor resulting from the favorable biocompatibility and stability of both BiPt NSs and Au@MWCNTs. Benefiting from the double signal amplification strategy and the high biocompatibility, the immunosensor responded linearly to CEA in a wide range from 50 fg/mL to 100 ng/ml with an extremely low detection limit of 3.52 fg/mL (S/N = 3). The excellent detection properties of this new immunosensor were evidenced by the satisfactory selectivity, reproducibility, and stability obtained, as well as the reliable and precise determination of CEA in actual human blood samples. This work provides a new strategy for the earlyclinical diagnosis of cancer. Novel blackberry-like mesoporous NaBiOF nanospheres with Pt nanodot inlay were successfully usedto construct a sandwich-type electrochemical immunosensor for the ultra-sensitive detection ofcarcinoembryonic antigen in human blood plasma based on a remarkable signal amplification strategy.

A Chemiluminescence Sensor for the Detection of α-Fetoprotein and Carcinoembryonic Antigen Based on Dual-Aptamer Functionalized Magnetic Silicon Composite.

In this work, a dual-aptamer functionalized magnetic silicon composite was prepared and used to construct a chemiluminescence (CL) sensor for the detection of α-fetoprotein (AFP) and carcinoembryonic antigen (CEA). First, SiO2@Fe3O4 was prepared, and polydiallyl dimethylammonium chloride (PDDA) and AuNPs were sequentially loaded on SiO2@Fe3O4. Subsequently, the complementary strand of CEA aptamer (cDNA2) and the aptamer of AFP (Apt1) were attached to AuNPs/PDDA-SiO2@Fe3O4. Then, the aptamer of CEA (Apt2) and G quadruplex peroxide-mimicking enzyme (G-DNAzyme) were sequentially connected to cDNA2, leading to the final composite. Then, the composite was used to construct a CL sensor. When AFP is present, it will combine with Apt1 on the composite to hinder the catalytic ability of AuNPs to luminol-H2O2, achieving AFP detection. When CEA is present, it will recognize and bind with Apt2, so G-DNAzyme is released to solution and catalyzes the reaction of luminol-H2O2 to achieve CEA determination. After the application of the prepared composite, AFP and CEA were detected in the magnetic medium and supernatant, respectively, after simple magnetic separation. Therefore, the detection of multiple liver cancer markers is realized through the CL technology without additional instruments or technology, which broadens the application range of CL technology. The sensor for detecting AFP and CEA shows wide linear ranges of 1.0 × 10-4 to 1.0 ng·mL-1 and 0.0001-0.5 ng·mL-1 and low detection limits of 6.7 × 10-5 ng·mL-1 and 3.2 × 10-5 ng·mL-1, respectively. Finally, the sensor was successfully used to detect CEA and AFP in serum samples and provides great potential for detection of multiple liver cancer markers in early clinical diagnosis.

Reliable capillary sampling of carcinoembryonic antigen at home: the CASA feasibility study.

Follow-up after colorectal cancer requires frequent surveillance of the tumour marker carcinoembryonic antigen (CEA). Home-based blood sampling could be beneficial in terms of patients' well-being and societal cost-effectiveness. Blood sampling by venepuncture is unsuitable for home-based sampling. The aim of this feasibility study is to evaluate the long-term whole-blood stability of CEA. In this prospective feasibility study capillary blood withdrawal was collected in a Hem-Col® microtube containing a patented stabilization buffer using an internal lithium standard to correct for dilution. Long-term whole-blood stability was considered adequate if the relative bias in CEA concentration between delayed analysis of capillary samples and directly processed venepuncture is within the total error margin of CEA. Twenty two colorectal cancer patients were included to determine the stability of CEA in capillary sampling compared with directly processed (i.e. within 2h) venepuncture sampling. The median time between venous sampling and CEA analysis and capillary sampling and CEA analysis was 2h (interquartile range 1-4h) and 76 h (interquartile range 74-95 h), respectively. A Bland-Altman difference plot excluding outliers showed an overall relative bias of -1.23%. The two capillary samples in our outlier analysis also showed the highest lithium concentrations. Home-based capillary sampling with the use of the Hem-Col® buffer is a feasible method for CEA determination when analysed within 4 days after blood withdrawal, allowing monitoring for colorectal cancer patients from home. High lithium concentrations due to insufficient filling of the Hem-Col® tube suggest less reliable CEA measurements.

Probe-integrated electrochemical immunosensor based on electrostatic nanocage array for reagentless and sensitive detection of tumor biomarker.

Sensitive detection of tumor biomarkers is crucial for early diagnosis and prognosis evaluation of cancer. Owing to no need of labelled antibody, formation of sandwich immunocomplexes and additional solution-based probe, probe-integrated electrochemical immunosensor for reagentless detection of tumor biomarkers is highly desirable. In this work, sensitive and reagentless detection of a tumor biomarker is realized based on fabrication of a probe-integrated immunosensor by confining redox probe in electrostatic nanocage array modified electrode. Indium tin oxide (ITO) electrode is employed as the supporting electrode because it is cheap and easily available. The silica nanochannel array consisted of two layers with opposite charges or different pore diameters was designated as bipolar films (bp-SNA). In this work, Electrostatic nanocage array is equipped on ITO electrode by growth of bp-SNA with two layered nanochannel array having different charge properties including a negatively charged silica nanochannel array (n-SNA) and a positively charged amino-modified SNA (p-SNA). Each SNA can be easily grown with 15s using electrochemical assisted self-assembly method (EASA). Methylene blue (MB) is applied as the model electrochemical probe with positive charge to be confined in electrostatic nanocage array with stirring. The combination of the electrostatic attraction from n-SNA and the electrostatic repulsion from p-SNA endows MB with highly stable electrochemical signal during continuous scanning. When the amino groups of p-SNA are modified using the bifunctional glutaraldehyde (GA) to introduce aldehydes, the recognitive antibody (Ab) of the most commonly used tumor biomarker, carcinoembryonic antigen (CEA), can be covalently immobilized. After the non-specific sites are blocked, the immunosensor is successfully fabricated. As the formation of antigen-antibody complex decreases electrochemical signal, the immunosensor can achieve reagentless detection of CEA ranged from 10pg/mL to 100ng/mL with a low limit of detection (LOD, 4pg/mL). Determination of CEA in human serum samples is realized with high accuracy.

Electrochemical ratiometric dual-signal immunoassay for accurate detection of carcinoembryonic antigen in clinical serum based on rGO-Pd@Au-Thi and Chi-Fc-Au

For prevention and early diagnosis of carcinoembryonic antigen (CEA), it is necessary to develop more accurate approaches for its detection. In this work, a new sensitive electrochemical ratiometric immunosensor for the determination of CEA was constructed on account of chitosan-ferrocenecarboxaldehyde-gold nanospheres (Chi-Fc-Au) and reduced graphene oxide-Pd@Au nanocomposits-thionine (rGO-Pd@Au-Thi) with dual-signal output. The immunosensor utilized Chi-Fc-Au as the substrate to anchor the primary antibody (Ab1) and rGO-Pd@Au-Thi as the secondary antibody (Ab2) label probe, generating two electrical signals (IFc and IThi) derived from Fc and Thi in the presence of CEA, respectively. With the increase of CEA concentration, the IFc and IThi showed opposite changes, so the peak current ratio of IThi/IFc was positively correlated with CEA concentration. In comparison with other immunosensors especially single-signal mode, the proposed immunosensor exhibited a wider linear range (10–4−200 ng mL−1) and a lower detection limit (14.9 fg mL−1), which could be applied in human serum samples for CEA measurement, and was comparable to commercial electrochemiluminescence (ECL) immunoassay. Given the significantly improved accuracy of the constructed sensor, it is expected to be applied in clinical diagnosis for other protein biomarkers determination.

Diagnostic accuracy of pleural fluid to serum carcinoembryonic antigen ratio and delta value for malignant pleural effusion: findings from two cohorts.

Pleural fluid (PF) carcinoembryonic antigen (CEA) is a widely used diagnostic marker for malignant pleural effusion (MPE). Recent studies revealed that PF to serum CEA was also a promising diagnostic parameter for MPE. We aimed to investigate whether PF to serum CEA ratio and delta CEA (PF minus serum CEA) provided added value to PF CEA in diagnosing MPE. Patients with pleural effusion in a retrospective cohort (BUFF) and a prospective cohort (SIMPLE) were included. The clinical characteristics of the patients were extracted from their medical records. The diagnostic value of CEA ratio and delta CEA was estimated by a receiver operating characteristics (ROC) curve, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). A total of 148 patients in the BUFF cohort and 164 patients in the SIMPLE cohort were enrolled. The BUFF cohort had 46 MPE patients and 102 benign pleural effusion (BPE) patients, and the SIMPLE cohort had 85 MPE patients and 79 BPE patients. In both cohorts, MPE patients had significantly higher PF CEA, serum CEA, CEA ratio, and delta CEA. The area under ROC curves (AUCs) of PF CEA, CEA ratio, and delta CEA were 0.78 (95% CI: 0.67-0.88), 0.80 (95% CI: 0.72-0.89) and 0.83 (95% CI: 0.75-0.91) in the BUFF cohort, and 0.89 (95% CI: 0.83-0.94), 0.86 (95% CI: 0.80-0.92), and 0.84 (95% CI: 0.78-0.91) in the SIMPLE cohort. The differences between the AUCs of PF CEA, CEA ratio, and delta CEA did not reach statistical significance. The continuous NRI and IDI of CEA ratio and delta CEA were <0. CEA ratio and delta value cannot provide added diagnostic value to PF CEA. The simultaneous determination of serum and PF CEA should not be adopted in clinical practice.