Carcinoembryonic Antigen In Human Serum Research Articles

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.

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.

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.

Homogeneous Electrochemical Aptamer Sensor Based on Two-Dimensional Nanocomposite Probe and Nanochannel Modified Electrode for Sensitive Detection of Carcinoembryonic Antigen.

A rapid and convenient homogeneous aptamer sensor with high sensitivity is highly desirable for the electrochemical detection of tumor biomarkers. In this work, a homogeneous electrochemical aptamer sensor is demonstrated based on a two-dimensional (2D) nanocomposite probe and nanochannel modified electrode, which can realize sensitive detection of carcinoembryonic antigen (CEA). Using π-π stacking and electrostatic interaction, CEA aptamer (Apt) and cationic redox probe (hexaammineruthenium(III), Ru(NH3)63+) are co-loaded on graphite oxide (GO), leading to a 2D nanocomposite probe (Ru(NH3)63+/Apt@GO). Vertically ordered mesoporous silica-nanochannel film (VMSF) is easily grown on the supporting indium tin oxide (ITO) electrode (VMSF/ITO) using the electrochemical assisted self-assembly (EASA) method within 10 s. The ultrasmall nanochannels of VMSF exhibits electrostatic enrichment towards Ru(NH3)63+ and size exclusion towards 2D material. When CEA is added in the Ru(NH3)63+/Apt@GO solution, DNA aptamer recognizes and binds to CEA and Ru(NH3)63+ releases to the solution, which can be enriched and detected by VMSF/ITO electrodes. Based on this mechanism, CEA can be an electrochemical detection ranging from 60 fg/mL to 100 ng/mL with a limit of detection (LOD) of 14 fg/mL. Detection of CEA in human serum is also realized. The constructed homogeneous detection system does not require the fixation of a recognitive aptamer on the electrode surface or magnetic separation before detection, demonstrating potential applications in rapid, convenient and sensitive electrochemical sensing of tumor biomarkers.

Gas-Mediated Immunoassay for the Carcinoembryonic Antigen at Atmospheric Pressure with Smartphone Coupling with the Fluorescence Quenching Length of Perovskite Capillary

By combining the photothermal properties of the 3,3',5,5'-tetramethylbenzidine oxidation product (TMBox) with the sensitive quenching of perovskite fluorescence by ammonia gas, a gas-mediated immunoassay at atmospheric pressure was constructed, which took the fluorescence quenching length of perovskite fluorescent capillary as the signal output. First, a CsPbBr3 perovskite with surface modification of 3-aminopropyl triethoxysilane was synthesized by thermal injection and decorated to the capillary wall by glutaraldehyde cross-linking. In the presence of H2O2 and the tumor marker carcinoembryonic antigen (CEA), TMB was oxidized to TMBox by the horseradish peroxidase (HRP)-labeled CEA antibody. The photothermal effect of TMBox at 808 nm laser irradiation increases the concentration of ammonia gas, and the prepared fluorescent capillary can respond sensitively to ammonia gas. The fluorescence quenching length can be observed by the naked eye for a semiquantitative evaluation of CEA concentration. At the same time, we developed a mobile APP for the first time to measure the fluorescence quenching length. In the range of 0-20 ng mL-1, the quenching length increased linearly with the increase in CEA concentration, and the detection limit was 0.078 ng mL-1. This method has been successfully used for the detection of CEA in human serum with a recovery of 95.8%-106.5%.

Electrochemical detection of carcinoembryonic antigen in human serum based on designed anti-fouling and anti-enzymolysis peptides conjugated with silk sericine-inspired beta-homoserine

Zwitterionic peptides with strong water binding ability have drawn much attention in the biomedical diagnosis field as antifouling materials. However, the proteolytic susceptibility of natural peptides in human serum or blood greatly limited their practical application. Herein, inspired by the strong stability and biocompatibility of sericin, an extended zwitterionic peptide containing unnatural β-homoserine (pβ-peptide) was designed to construct antifouling biosensors with enhance stability in complex biological fluids. The molecular dynamic simulation illustrated the strong water binding capability of the pβ-peptide owing to the formation of a large quantity of hydrogen bonds with water. Compared with the electrodes modified with normal peptide, ones modified with the designed peptide demonstrated much stronger antifouling capability and significantly enhanced stability when evaluated in human serum and blood. Furthermore, the constructed biosensor integrating the designed antifouling peptide with carcinoembryonic antigen (CEA) aptamer exhibited a great sensitivity for detecting CEA protein, with a broad linear range of 1.0 fg·mL−1-1.0 ng·mL−1 and a low detection limit of 0.33 fg·mL−1. The biosensor was competent to accurately assay CEA in clinical serum samples when compared with the commonly adopted ELISA method, which indicates a promising potential for practical applications.

Electrochemical stripping chemiluminescence coupled with recycling amplification strategy for sensitive detection of carcinoembryonic antigen

As a new generation of electrochemiluminescence (ECL) technology, the electrochemical stripping chemiluminescence (ESCL), which combines the advantages of chemiluminescence and stripping voltammetry, has attracted increasing attention in the biosensor field. Here, Ag nanoclusters (NCs) were prepared using DNA double strands as a template and explored to construct an ESCL aptamer sensor (aptasensor) for the detection of a carcinoembryonic antigen (CEA). During the detection process, Ag NCs and the Ag+ cations stripped out from Ag NCs were found to respectively catalyze the electrochemical reduction and oxidation of H2O2, accelerating the decomposition of H2O2 to generate reactive oxygen species (ROSs) and thus effectively enhancing the ECL intensity of luminol. Coupled with the exonuclease I-assisted recycling amplification technology, the developed ESCL aptasensor enabled the sensitive detection of CEA, exhibiting a broad linear response from 100 ag/mL to 10 ng/mL with a low detection limit of 38.86 ag/mL (S/N = 3). In addition, the aptasensor showed good performance in the determination of CEA in human serum with a relative standard deviation (RSD) below 5 %. This work provides an effective method for constructing simple, fast, and sensitive biosensors.

Ti3C2-MXene-assisted signal amplification for sensitive and selective surface plasmon resonance biosensing of biomarker

Surface plasmon resonance (SPR) technology has become one of the powerful tools for real-time bioassay of various targets without needing labels. However, SPR biosensing faces great challenge with the extension of application fields due to the limited sensitivity. Herein, we report an ultrasensitive SPR biosensing strategy for detecting carcinoembryonic antigen (CEA) with the introduction of amino-functionalized Ti3C2-MXene (N-Ti3C2-MXene) nanosheets. The ultrathin Ti3C2-MXene nanosheets were prepared by hydrochloric acid (HF) etching and further modified by (3-aminopropyl) triethoxysilane (APTES) to obtain amino terminals for conjugating polyclonal anti-CEA antibody (Ab2) via covalent bonding. Staphylococcal protein A (SPA) decorated Au film was utilized as sensing platform to orientedly immobilize monoclonal anti-CEA antibody (Ab1) via its Fc region. The N-Ti3C2-MXene-Ab2 nanoconjugates were introduced to the sensing system after capture of CEA, forming sandwiched immunocomplexes on the SPR chip. A signal amplification strategy of Ti3C2-MXene-induced spontaneous gold reductive deposition on Ti3C2-MXene nanosheets was employed to further enhance sensitivity. The proposed biosensor exhibits a wide linear range for CEA determination of 10−11 to 10−6 g mL−1 with a detection limit of 1.7 pg mL−1 (S/N=3). Moreover, good reproducibility and high specificity were demonstrated by serum samples analysis, which indicates the present method holds potential in evaluating CEA in human serum for early diagnosis and monitoring of cancer.

Electrochemical Detection of Carcinoembryonic Antigen in Human Serum Based on Designed Anti-Fouling and Anti-Enzymolysis Peptides Conjugated with Silk Sericine-Inspired Beta-Homoserine

Electrochemical Detection of Carcinoembryonic Antigen in Human Serum Based on Designed Anti-Fouling and Anti-Enzymolysis Peptides Conjugated with Silk Sericine-Inspired Beta-Homoserine

A label-free fluorescent aptasensor based on the AIE effect and CoOOH for ultrasensitive determination of carcinoembryonic antigen.

Highly sensitive and specific detection of cancer markers (such as carcinoembryonic antigen) is very important for early diagnosis and treatment of cancer. Herein, we developed a label-free fluorescent aptamer biosensor based on the aggregation-induced emission (AIE) effect and hydroxycobalt oxide (CoOOH) platform, and used it to detect carcinoembryonic antigen (CEA) with high sensitivity and specificity. Fluorescent ionic liquid Compound B can combine with a CEA aptamer (CEA-Apt) through electrostatic attraction and hydrophobic interaction to form an ionic liquid/aptamer (CEA-Apt/B) complex and produce the AIE effect, thereby enhancing the fluorescence intensity of B. CEA-Apt/B was adsorbed on the surface of CoOOH when CoOOH was added to the buffer solution, and the fluorescence of B was quenched. After adding CEA to the solution, CEA-Apt/B bound to CEA and separated from the surface of CoOOH because CEA-Apt had stronger affinity for CEA, resulting in fluorescence recovery of B. In the level range of 0.67-10000 pg mL-1, the fluorescence recovery intensity of the sensor had an excellent linear relationship with the level of CEA, and its LOD was 0.2 pg mL-1 (S/N = 3). In addition, the sensor had good selectivity and can be directly used to detect CEA in human serum with high accuracy.

An electrochemical aptasensor for highly sensitive detection of CEA based on exonuclease III and hybrid chain reaction dual signal amplification

At present, carcinoembryonic antigen (CEA) is considered a broad-spectrum cancer biomarker, and its accurate analysis in clinical samples can assist early cancer diagnosis and treatment. Herein, a novel electrochemical aptasensor has been proposed for CEA detection based on exonuclease III and hybrid chain reaction. The target CEA specifically binds to the aptamer region in hairpin probe 1 (defined as H1) by strong attraction, which leads the rest of the H1 triggering catalytic hairpin assembly to form a high quantity of H1 and hairpin probe 2 (defined as H2) double chain complex (denoted as H1@H2). Subsequently, the exonuclease III digests the complex of H1@H2 and liberates H1 to induce the first signal amplification. Simultaneously, a large number of generated trigger chains initiate a hybrid chain reaction and produce a second signal amplification. This proposed sensor exhibited excellent analytical performance for the detection of CEA, with wide linear range from 10 pg.mL−1 to 100 ng.mL−1 and low limit of detection of 0.84 pg.mL−1. Additionally, the biosensing strategy was successfully verified for direct measurement of CEA in human serum. Therefore, this elaborated sensor provides a new simple method for detecting CEA and exhibits great promise in the early screening of cancer.

A DNAzyme-catalyzed label-free aptasensor based on multifunctional dendrimer-like DNA assembly for sensitive detection of carcinoembryonic antigen

Carcinoembryonic antigen (CEA) is an important malign tumor marker. In this study, a simple, label-free and antibody-free aptasensor was fabricated based on a multifunctional dendrimer-like DNA nanoassembly. The DNA nanoassembly was embedded with multiple G-quadruplex DNAzyme motifs and a hanging CEA aptamer motif. It was prepared from short DNA sequences by autonomous-assembly. The aptasensor was prepared simply by self-assembly of a capture DNA (cpDNA) on a gold electrode, followed by hybridization with a CEA aptamer (AptGAC-P). CEA as a model target was detected through competitive binding of CEA with AptGAC-P, exposing cpDNA to bind with the DNA nanoassembly. The detection process only contains 2 incubation steps. The high load of G-quadruplex DNAzyme motifs and their catalytic activity resulted in an amplified and label-free differential pulse voltammetry (DPV) electrochemical signal. The peak current correlated linearly with the CEA concentration, with a linear range of 2–45 ng mL−1, and an LOD value of 0.24 ng mL−1. The aptasensor showed high specificity and reproducibility, and retained 96.5% of detection signal intensities after 31 days of storage. The recovery rates for spiked CEA in human serum were within 100 ± 5%, and the coincidence rates for clinical human serum samples with ELISA kits were 80.7–111%. Conceivably, possessing simplicity, sensitivity, reproducibility, storage stability, and accuracy, the aptasensor should be a very prominent and applicable tool for clinical CEA detection and cancer diagnosis, and is promisingly applicable as a platform for detecting other targets of interests.

Electrochemical immunosensor based on binary nanoparticles decorated rGO-TEPA as magnetic capture and Au@PtNPs as probe for CEA detection.

Using gold and magnetic nanoparticles co-decorated reduced graphene oxide-tetraethylenepentamine (rGO-TEPA/Au-MNPs) as the magnetic platform for capturing the primary antibody (Ab1), separation and preconcentration of immunocomplex, a novel homogeneous electrochemical immunosensor was successfully developed. The newly prepared magnetic rGO-TEPA/Au-MNPs, compared with MNPs, exhibited better stability and enhanced electrical conductivity attributed to rGO-TEPA, and showed higher biorecognition efficiency due to AuNPs. In addition,Au@PtNPs were prepared and modified with secondary antibody (Ab2) as an efficient signal probe for signal readout. Using carcinoembryonic antigen (CEA) as a model analyte, the prepared immunosensor demonstrated satisfactory properties like high stability, good repeatability and selectivity, wide linear range (5.0pgmL-1~200.0ngmL-1) as well as low detection limit (1.42pgmL-1). Thehomogenous electrochemical immunosensor was applied tothe detection of CEA in human serum and was found to exhibit good correlation with thereference method. Thus, the proposed rGO-TEPA/Au-MNPs-based homogenous immunoassay platform might open up a new way for biomarker diagnosis. Graphical Abstract.

Ratiometric electrogenerated chemiluminescence sensor based on a designed anti-fouling peptide for the detection of carcinoembryonic antigen

In this paper, an effective and accurate ratiometric electrochemiluminescence (ECL) system based on Au-luminol and CdS quantum dots (CdS QDs) as signal probes was constructed for detecting carcinoembryonic antigen (CEA). Polyaniline (PANI) and gold nanoparticles (AuNPs) strongly enhanced the electronic transfer efficiency and the specific area of the modified sensing surface, and improved the detection sensitivity. CdS QDs functionalized DNA strands functioned as cathode ECL emitters, and the aptamer of CEA modified with Au-luminol and quencher cyanine dye (Cy5) fluorophore functioned as anode ECL emitters. After the DNA capture probe combined with CEA aptamer, the negative potential ECL response of the CdS QDs was quenched because of electrochemiluminescence resonance energy transfer (ERET) between the Cy5 fluorophore and CdS QDs. However, the positive potential ECL response of Au-luminol can still be detected. The negative potential ECL response of CdS QDs was recovered, and the positive potential ECL response of Au-luminol decreased after CEA combined with its aptamer to take Cy5 and Au-luminol off the sensing interface. Additionally, the peptide provided effective anti-fouling performance in the detection of complex samples. The ratiometric ECL sensor with anti-fouling ability can sensitively determine the concentration of CEA in human serum.

Background signal-free and highly sensitive electrochemical aptasensor for rapid detecting tumor markers with Pb-MOF functionalized dendritic DNA probes

How to eliminate the background signal of the electrochemical aptasensor and improve its signal amplification efficiency is one of the key factors to build a highly sensitive and selective sensor. Herein, we developed a multi-signal amplified, zero background electrochemical aptasensor for rapid detection of tumor markers, with carcinoembryonic antigen (CEA) as a model analyte. A type of dendritic DNA scaffold labeled with a lead-based metal organic framework (HCR-Pb-MOF) was prepared by hybrid chain reaction as signal tags. After one-step replacement of the signal tags into the supernatant by the target, the inner Pb2+ ions in the replaced tags were detected by square-wave voltammetry (SWV) for qualification. The assay has some distinct advantages. Firstly, one HCR-Pb-MOF can load many Pb-MOFs, with each Pb-MOF containing large amounts of Pb2+; thus, multi-amplified signals from Pb2+ can be obtained after one-step replacement of the target. Secondly, Pb-MOF can also completely avoid the leakage of Pb2+, which is usually observed in the MOF probes electrostatically adsorbing metal ions, to achieve zero background. Thus, the aptasensor with a one-step replacement detection strategy can greatly improve sensitivity, with the detection limit of CEA being 0.333 pg mL−1. Finally, the stirring bar was employed after introducing the target into the system. Therefore, the whole sample detection time can be reduced to within 10 min. This aptasensor was successfully applied to rapidly and accurately analyze CEA in human serum, with results consistent to those of ELISA. All of these findings prove that this multi-signal amplified, rapid, zero background electrochemical aptasensor can meet the requirements for rapid and highly sensitive detection of tumor markers in human serum.

A 2D transition metal carbide MXene-based SPR biosensor for ultrasensitive carcinoembryonic antigen detection

Surface plasmon resonance (SPR) has become a leading technique for in situ bioaffinity assay of diverse targets without need of fluorescent or enzymatic labeling. Nanomaterials-enhanced SPR sensors have developed rapidly and widened the application scope of SPR sensing technology. In this report we describe an ultrasensitive SPR biosensor for detecting carcinoembryonic antigen (CEA). Our SPR biosensor utilizes a Ti3C2-MXene-based sensing platform and multi-walled carbon nanotube (MWCNTs)-polydopamine (PDA)-Ag nanoparticle (AgNPs) signal enhancer. Ti3C2-MXene, a new class of two-dimensional (2D) transition metal carbides, offers a large hydrophilic-biocompatible surface ideal for SPR biosensing. Ti3C2-MXene/AuNPs composites after synthesis are then decorated with staphylococcal protein A (SPA) to orient and immobilize monoclonal anti-CEA antibody (Ab1) through its Fc region. By introducing MWCNTs-PDA-AgNPs-polyclonal anti-CEA antibody (MWPAg-Ab2) conjugate combined with a sandwich format, the present method provides a dynamic range for CEA determination of 2×10-16 to 2×10-8 M and a detection limit of 0.07 fM. This biosensing approach demonstrates good reproducibility and high specificity for CEA in real serum samples providing a promising method to evaluate CEA in human serum for early diagnosis and monitoring of cancer.

Bifunctional bioplatform based on NiCo Prussian blue analogue: Label-free impedimetric aptasensor for the early detection of carcino-embryonic antigen and living cancer cells

A novel bifunctional electrochemical aptasensor based on bimetallic NiCo Prussian blue analogue (NiCoPBA) nanocubes has been constructed for detecting carcino-embryonic antigen (CEA) and corresponding living cancer cells. The NiCoPBA exhibits a regular cubic shape of 100 nm size, with fluorescence and excellent biocompatibility. In view of the intrinsic cavities, metallic coordination centers, rich CN groups, and π-π* interactions of NiCoPBA, the CEA-targeted aptamer strands can be strongly anchored on the surface of nanocubes. Given that the CEA cancer marker is overexpressed on the H460 cell surface of carcinomas, the developed NiCoPBA-based aptasensor not only can be employed to determine CEA in human serum via the formation of stable G-quadruplex between aptamer strands and CEA, but also can be utilized to directly detect cancer cells due to the strong binding force between CEA aptamer and cancer cell. The fabricated sensor shows superior sensing performance toward CEA compared with other reported CEA aptasensors, providing an extremely low limit of detection (LOD) of 0.74 fg mL−1 (1.62 fM) (S/N = 3) in a wide linear range of 1.0 fg mL−1 to 5.0 ng mL−1, as well as an LOD of 47 cells mL–1 for H460 cells. Thereby, the proposed aptasensor may be further used as a promising platform for detecting other cancer markers when anchoring different kinds of aptamers, with potential bifunctional applications in early diagnosis of tumor markers and cancer cells.

Highly sensitive chemiluminescence enzyme immunoassay for the quantification of carcinoembryonic antigen in the presence of an enhancer and a stabilizer

Using the advantages of phenol red, a signal enhancer, and bovine serum albumin (BSA), a stabilizer of horseradish peroxidase (HRP), added in HRP enzyme reaction of Amplex Red and H2O2, highly sensitive 1,1′-oxalyldiimidazole chemiluminescence enzyme immunoassay (ODI-CLEIA) was developed to rapidly quantify trace levels of carcinoembryonic antigen (CEA) in human serum. Phenol red acts as an enhancer in ODI-CLEIA while BSA supported rapid and stable activation of HRP. The CL emission of resorufin formed from the HRP enzyme reaction in the presence of BSA and phenol red was about 70-fold brighter than that in the absence of both materials. ODI-CLEIA in the presence of BSA (1.5 mg/ml).and phenol red (1 mM) was able to rapidly analyze CEA in human serum with the wide linear calibration curve (2.5–100 ng/ml). The limit of detection (LOD = 3σ/slope) of ODI-CLEIA was as low as 0.19 ng/ml. Additionally, it was confirmed that the accuracy, precision, and reproducibility of ODI-CLEIA in the presence of BSA and phenol red were good with the statistically acceptable error range.

Graphene quantum dots-NaYF4:Yb,Er hybrid with significant enhancement of upconversion emission for fluorescent detection of carcinoembryonic antigen with exonuclease III-aided target recycling amplification

Graphene quantum dot-NaYF4:Yb,Er was made via hydrothermal synthesis. The resulting hybrid shows good water-solubility, small particle size of 11.5 nm and significant enhancement of upconversion emission. Further, the hybrid was designed as an upconversion biosensing nanoplatform for detection of carcinoembryonic antigen based on the exonuclease III-aided target recycling amplification. Firstly, the linker DNA (LDNA) is covalently attached to the hybrid surface. Then, the upconversion emission of LDNA-modified hybrid is effectively quenched through the hybridization of gold nanoparticles with hairpin DNA (Hp) via the fluorescence resonance energy transfer. Finally, the Hp on the nanoassembly is specially opened by signal DNA (SDNA) and leads to rapid recovery of the quenched upconversion emission. In addition, the exonuclease III-aided target cycling amplification strategy is introduced to generate the SDNA and release the carcinoembryonic antigen. The released carcinoembryonic antigen is circularly used to produce more SDNA, resulting in a significant signal amplification. The as-proposed biosensor displays good analytical performance in the detection of carcinoembryonic antigen with a wide linear range of 5.0 × 10−17–1.0 × 10-8 g ml−1 giving a low detection limit of 2.4 × 10−17 g ml−1 (S/N = 3) along with a high specificity. Its practicality has been verified by the analysis results of carcinoembryonic antigen in human serum.

Validation of Assaying Carcinoembryonic Antigen in Human Serum by Using Immunomagnetic Reduction

Immunomagnetic reduction (IMR) is a method to assay biomolecules by utilizing antibody functionalized magnetic nanoparticles. For clinical validation, important analytic performances of assaying carcinoembryonic antigen (CEA) using IMR are characterized. Furthermore, IMR is applied to assay carcinoembryonic antigen (CEA) in human serum for clinical validation. A total of 118 healthy controls and 79 patients with colorectal cancer (CRC) are recruited in this study. For comparison, assays using chemiluminometric immunoassay (CLIA) are also done for quantizing CEA in these serum samples. The results reveal a high correlation in terms of serum CEA concentration detected via IMR and CLIA is found (r = 0.963). However, IMR shows higher clinical sensitivity and specificity than those of CLIA. Moreover, the rate of false positives for smoking subjects is clearly reduced through the use of IMR. All the results demonstrate IMR is a promising alternative assay for serum CEA to diagnose CRC.