Multimodal CEA-Targeted Image-Guided Colorectal Cancer Surgery using 111In-Labeled SGM-101.

PURPOSE: Intraoperative image guidance may aid in clinical decision-making during surgical treatment of colorectal cancer. We developed the dual-labeled carcinoembryonic antigen-targeting tracer, [111In]In-DTPA-SGM-101, for pre- and intraoperative imaging of colorectal cancer. Subsequently, we investigated the tracer in preclinical biodistribution and multimodal image-guided surgery studies, and assessed the clinical feasibility on patient-derived colorectal cancer samples, paving the way for rapid clinical translation. EXPERIMENTAL DESIGN: SGM-101 was conjugated with p-isothiocyanatobenzyl-diethylenetriaminepentaacetic acid (DTPA) and labeled with Indium-111 (111In). The biodistribution of 3, 10, 30, and 100 µg [111In]In-DTPA-SGM-101 was assessed in a dose escalation study in BALB/c nude mice with subcutaneous LS174T human colonic tumors, followed by a study to determine the optimal timepoint for imaging. Mice with intraperitoneal LS174T tumors underwent micro-SPECT/CT imaging and fluorescence image-guided resection. In a final translational experiment, we incubated freshly resected human tumor specimens with the tracer and assessed the tumor-to-adjacent tissue ratio of both signals. RESULTS: The optimal protein dose of [111In]In-DTPA-SGM-101 was 30 µg (tumor-to-blood ratio, 5.8 ± 1.1) and the optimal timepoint for imaging was 72 hours after injection (tumor-to-blood ratio, 5.1 ± 1.0). In mice with intraperitoneal tumors, [111In]In-DTPA-SGM-101 enabled preoperative SPECT/CT imaging and fluorescence image-guided resection. After incubation of human tumor samples, overall fluorescence and radiosignal intensities were higher in tumor areas compared with adjacent nontumor tissue (P < 0.001). CONCLUSIONS: [111In]In-DTPA-SGM-101 showed specific accumulation in colorectal tumors, and enabled micro-SPECT/CT imaging and fluorescence image-guided tumor resection. Thus, [111In]In-DTPA-SGM-101 could be a valuable tool for preoperative SPECT/CT imaging and intraoperative radio-guided localization and fluorescence image-guided resection of colorectal cancer.

Wrinkled metal based quantum sensor for In vitro cancer diagnosis.

This article presents a unique 3D biocompatible Aluminum-based quantum structure (QS) for in vitro cancer detection using Surface Enhanced Raman Scattering (SERS). The Al-based QSs fabricated using ultrashort pulsed laser are of two distinct surface characters, wrinkled and smooth spherical. The limit of detection for chemical sensing of Crystal Violet and Rhodamine 6G by the Al-QS was driven up to single molecule sensing (femtomolar concentration). Biological sensing of cysteine, a disease biomarker and carcinoembryonic antigen (CEA), a cancer biomarker was also tested by the Al-QS. The ability of in vitro cell detection using Al-QS was analyzed with three cell lines, mammalian fibroblast and pancreatic and lung cancer cells. The Al-QS were up taken by the cells through label-free self-internalization and were sensed by SERS. Further assay was performed to differentiate cancerous and non-cancerous cells by measuring lipid and protein peak intensity within the cells. The result of this research indicated that SERS based Al-QS could be a suitable candidate for the early diagnosis of cancer.

An Optical Microfiber Biosensor for CEACAM5 Detection in Serum: Sensitization by a Nanosphere Interface.

The detection of carcinoembryonic antigen (CEA)-related cell adhesion molecules 5 (CEACAM5) is significant in cancer prewarning. Early diagnosis can effectively alleviate the danger of cancer. Point-of-care testing (POCT) has become a competitive technology for early detection. Fiber optic biosensors have great potential as POCT tools. However, their limits of detection (LODs) are not sufficient to afford ultralow concentration detection at the early stage. Herein, this work presents an optical microfiber sensor functionalized by a polystyrene@gold nanosphere (PS@Au nanosphere) interface for a synergistic sensitization effect to detect the ultralow CEACAM5 concentrations in serum at the early stage. The sensor's LOD achieves 3.54 × 10-17 M in pure solution and 5.27 × 10-16 M in serum, with the sensitization effect coupled with surface area enlargement and electromagnetic enhancement of interface. This LOD is about 6 orders of magnitude lower than that of current methods. It can be employed to detect the biomarkers at ultralow concentrations present in serum in the early stages of cancer. As the interfacial synergistic sensitization strategy is suitable for refractive index (RI)-based optical transducers, this work provides new opportunities to employ fiber optic biosensors as effective POCT tools.

Mulberry-like Au@PtPd porous nanorods composites as signal amplifiers for sensitive detection of CEA.

Effective detection of cancer biomarkers plays a crucial role in the prevention of early cancer. Here, a sandwich-type electrochemical immunosensor was successfully constructed for sensitive detection of carcinoembryonic antigen (CEA) using MoS2/CuS-Au as sensing platform and mulberry-like Au@PtPd porous nanorods (Au@PtPd MPs) as signal amplifiers. The large surface area and good biocompatibility of MoS2/CuS-Au increased the loading of primary antibody. And the good conductivity of MoS2/CuS-Au accelerated the electron transport rate of the electrode surface. Au@PtPd MPs with large specific surface area and a large number of catalytically active sites showed excellent electrocatalytic performance for hydrogen peroxide reduction. The sandwich-type immunosensor prepared by the signal amplification strategy exhibited a wide linear detection range (50 fg/mL to 100 ng/mL) and a low detection limit of 16.7 fg/mL (S/N = 3), featuring good selectivity, stability and reproducibility. Moreover, the satisfactory results in analysis of human serum samples indicated that it possessed a potential application promising in early clinical diagnoses.

Resonance Raman scattering-infrared absorption dual-mode immunosensing for carcinoembryonic antigen based on ZnO@SiO2 nanocomposites.

Detection of cancer biomarkers is crucial for the diagnosis and monitoring of malignant tumors. However, the accuracy and sensitivity still require sufficient improvement for practically clinical application. In this work, a reliable and sensitive dual-mode immunosensing method is described for carcinoembryonic antigen (CEA) detection using a biofunctional ZnO@SiO2 nanocomposite as a resonance Raman scattering (RRS)-infrared (IR) absorption nanoprobe. The multiphonon RRS signal originating from the ZnO and the characteristic IR fingerprint signal of the transverse optical and longitudinal optical phonon modes of the asymmetric stretching of Si-O-Si bonds showed no interference with each other. A CEA antibodies-immobilized substrate was fabricated to capture the analyte/nanoprobe complexes. The RRS intensity at 569 cm‒1 and the IR absorption at 1061 cm‒1 were used for quantitative analysis. Accurate CEA detection was performed as a result of the strong resistance of the dual-mode nanoprobe to surrounding interference. The limit of detection was 98.0 fg mL‒1. The detection range was 500 ng mL‒1 - 50 fg mL‒1, which is wider than those of single-mode RRS or IR absorption immunosensings. High reproducibility, selectivity and specificity were achieved. The assay performance of human serum samples demonstrated the practicability of the method in clinical cancer diagnosis.

Orthogonal dual molecularly imprinted polymer-based plasmonic immunosandwich assay: A double characteristic recognition strategy for specific detection of glycoproteins.

Sensitive and specific detection methods are critical to the detection of glycoproteins. Immunoassay has been a powerful tool for this purpose, in which antibodies or their mimics particularly molecularly imprinted polymers (MIPs) are used for specific recognition. Epitope and glycan are two structure features of a glycoprotein. However, immunoassays based on simultaneous recognition towards the two characteristics have been scarcely explored so far. Herein we present a new strategy called orthogonal dual molecularly imprinted polymer-based plasmonic immunosandwich assay (odMIP-PISA). It relies on double recognition towards a target glycoprotein by two different types of MIPs, using epitope-imprinted gold nanoparticles (AuNPs)-coated slide as capturing substrate to recognize the peptide epitope and glycans-imprinted Raman-active silver nanoparticles as labeling nanotags to recognize the glycans. Carcinoembryonic antigen (CEA), a routinely used marker for colon cancer, was used as a test glycoprotein. The orthogonal double recognition apparently improved the specificity, reducing the maximum cross-reactivity from 14.4% for epitope recognition and 15.2% for glycan recognition to 8.2% for double recognition. Meanwhile, the plasmonic nanostructure-based Raman detection provided ultrahigh sensitivity, yielding a limit of detection of 5.56 × 10-14 M (S/N = 10). Through measuring the CEA level in human serum, this method permitted differentiation of colon cancer patient from healthy individual. Compared with the traditional immunoassay, odMIP-PISA exhibited multiple advantages, including simplified procedure (6 steps), speed (30 min), reduced cost, and so on. Therefore, this new approach holds great promise in many applications particularly clinical diagnosis.

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.

Photovoltaics, plasmonics, plastic antibodies and electrochromism combined for a novel generation of self-powered and self-signalled electrochemical biomimetic sensors.

This work describes further developments into the self-powered and self-signalled biosensing system that merges photovoltaic cells, plastic antibodies and electrochromic cells into a single target. Herein, the plasmonic effect is introduced to improve the photoanode features of the photovoltaic cell, a dye sensitized solar cell (DSSC), and better electrocatalytic features are introduced in the electrode containing the sensing element. In brief, the DSSC had a counter-electrode of poly(3,4-ethylenedioxythiophene) on an FTO glass modified by a plastic antibody of 3,4-ethylenedioxythiophene and pyrrol. The photoanode had dye sensitized TiO2 modified with gold nanoparticles (AuNPs) to increase the cell efficiency, aiming to improve the sensitivity of the response of hybrid device for the target biomarker. The target biomarker was carcinoembryonic antigen (CEA). The response of the hybrid device evidenced a linear trend from 0.1 ng/mL to 10 µg/mL, with an anionic slope of 0.1431 per decade concentration. The response of the plastic antibody for CEA revealed great selectivity against other tumour markers (CA 15-3 or CA 125). The colour response of the electrochromic cell was also CEA concentration dependent and more sensitive when the hybrid device was set-up with a photoanode with AuNPs. A more intense blue colour was obtained when higher concentrations of CEA were present. Overall, this improved version of the self-powered and self-signalled set-up has zero-requirements and is particularly suitable for point-of-care analysis (POC). It is capable of screening CEA in real samples and differentiating clinical levels of interest. This concept opens new horizons into the current cancer screening approaches.

A label-free and double recognition-amplification novel strategy for sensitive and accurate carcinoembryonic antigen assay.

Herein, a label-free and double recognition-amplification (LDRA) strategy for carcinoembryonic antigen (CEA) detection was developed, based on a new designed dual-function messenger probe (DMP) coalescing with DNA tetrahedron probes (DTPs) and hybridization chain reaction (HCR). The DMP possess dual-function to replace CEA for specific interface hybridization and initiate hybridization chain reaction. The interfacial hybridization event was quantitatively converted to an electrochemical signal by using hemin/G-quadruplex (h-Gx) formed after the hybridization chain reaction. Self-assembled DNA tetrahedron probes, which were readily decorated on an electrode surface as a scaffold with rigid support and ordered orientation, enabled the highly efficient strands hybridization and greatly increased target accessibility as well as significantly decreased noise. The proposed assay integrated dual recognition processes and HCR signal amplification processes, achieving the identification of low concentration of CEA as detection limit of 18.2 fg mL-1 (S/N = 3) and wider linearity range of 0.0001 ng mL-1-50 ng mL-1. A new electrochemical sensing method was proposed for CEA detection and used in real clinical samples. The obtained results were good consistency with those of clinical diagnosis.

Porous hollow carbon nanobubbles@ZnCdS multi-shelled dodecahedral cages with enhanced visible-light harvesting for ultrasensitive photoelectrochemical biosensors.

Herein, novel photoactive materials, MOF-derived porous hollow carbon nanobubbles@ZnCdS multi-shelled dodecahedral cages (C@ZnCdS MSDCs)， were synthesized via continuous chemical etching, sulfurization, cation-exchange and calcination strategies. Due to the synergistic effect between the porous shells and the carbon-layer coating， C@ZnCdS MSDCs displayed superior photoelectrochemical (PEC) performance. The synthesized C@ZnCdS MSDCs were assembled onto TiO2 modified ITO electrodes to form a type-II heterostructures. Then, Au nanoparticles (NPs) were deposited on the surface of ITO/TiO2/C@ZnCdS MSDCs. Benefiting from the unique structure and performance merits of photoactive materials, a label-free PEC sensing platform based on ITO/TiO2/C@ZnCdS MSDCs/Au was successfully constructed for CEA detection. Under optimal conditions, the PEC biosensor exhibited a wide linear range (0.00005-500 ng mL-1) and low detection limit (2.28 fg mL-1). The proposed PEC biosensor also showed good stability, specificity, reproducibility and acceptability in human serum. The prepared C@ZnCdS MSDCs would be a promising photoactive material for PEC biosensors. Most importantly, this work opens up new horizons for the application of MOFs-derived hollow carbon materials in sensing.

Target-inspired Zn2+-dependent DNAzyme for ultrasensitive impedimetric aptasensor based on polyacrylic acid nanogel as amplifier.

In general, the traditional impedimetric aptasensor for detecting protein is based on its high molecular weight and low dielectric constant. Yet, the efficiency of these aptasensors is hindered by the slight resistance change in the trace concentration range because of the high initial resistance (the electrostatic repulsion between the compact negatively charged DNA on the electrode and [Fe(CN)6]3-/4-). To effectively and simply circumvent this issue and improve the detection sensitivity, we design an impedimetric aptasensor by reducing the substrate DNA's density on the electrode through the target-inspired recycling DNA cleavage. In order to enlarge the differences in resistance, the polyacrylic acid (PAA) nanogel is implemented as amplifier due to its poor conduction and negative charge that can hinder electron transfer and repulse the mediator [Fe(CN)6]3-/4-, respectively. Based on the target-inspired DNAzyme and PAA nanogel as amplifier, the ultrasensitive impedimetric aptasensor of carcinoembryonic antigen (CEA) in the buffer solution possesses a wide dynamic range of 10 fg mL-1 to 10 ng mL-1 and ultra-low detection limit of 7.9 fg mL-1 (10-fold relative to equivalent aptasensors). When tested in human serum, the proposed aptasensor exhibits good performance with an ultra-low detection limit of 1.4 fg mL-1, which is slightly higher than that in buffer solution.

Sandwich-type electrochemical immunosensor for sensitive detection of CEA based on the enhanced effects of Ag NPs@CS spaced Hemin/rGO.

An ultrasensitive sandwich-type electrochemical immunosensor was designed by using gold nanoparticles (Au NPs) as the substrate material and microporous carbon spheres (CS) loading silver nanoparticles (Ag NPs) spaced Hemin/reduced graphene oxide (Hemin/rGO) porous composite materials (Ag NPs@CS-Hemin/rGO) as the detection antibodies (Ab2) label for detecting carcinoembryonic antigen (CEA). The Au NPs with good electrical conductivity and biocompatibility could accelerate the electron transfer on the electrode interface and enhance the load capacity of capture antibodies (Ab1). Hemin is peroxidase-like substance which has excellent catalytic ability for H2O2 reduction but easy to molecular aggregation and oxidative self-destruction. Reduced graphene oxide (rGO) is a good supporting material for Hemin to mitigate this disadvantage. CS loading Ag NPs (Ag NPs@CS) as the spacer inserts into Hemin/rGO sheet can overcome the irreversible stacking of rGO, and form complex porous structure which exposes more active sites of Hemin. Moreover, Ag NPs loaded on CS also has catalytic ability for H2O2 reduction. Thus the Ag NPs@CS-Hemin/rGO used as the Ab2 label has a large working surface area and high utilization rate, which heightens the catalytic ability for H2O2 reduction to amplify the current signal effectually. The current signal and the logarithm of CEA concentration presented a wide linear response range of 20 fg/mL to 200 ng/mL, and the detection limit of CEA was 6.7 fg/mL. Furthermore, the designed immunosensor exhibited a good reproducibility, selectivity and stability, which confirms a broad development prospect when applying it in early clinical detection.

Enhanced peroxidase-like properties of Au@Pt DNs/NG/Cu2+ and application of sandwich-type electrochemical immunosensor for highly sensitive detection of CEA.

Effective treatment of cancer depends upon the early detection of the tumor marker. Here, we report on the development of a new immunosensor for early detection of carcinoembryonic antigen (CEA). Cubic Au@Pt dendritic nanomaterials functionalized nitrogen-doped graphene loaded with copper ion (Au@Pt DNs/NG/Cu2+) with enhanced peroxidase-like properties was synthesized as labels to effectively capture and immobilize secondary anti-CEA. The Au@Pt DNs with more active surface area could efficiently enhance electrocatalysis for reduction of hydrogen peroxide (H2O2). Meanwhile, with good conductivity and large specific surface area, NG can immobilize a large amount of Au@Pt DNs. Furthermore, after adsorbed Cu2+ can further promote the redox of H2O2 and amplify the signal of the immunosensor. For the immobilization of primary antibodies, Au nanoparticles functionalized polydopamine (Au@PDA) were used as transducing materials to modify glassy carbon electrodes and enhance the electron transfer efficiently. Under optimal conditions, the immunosensor exhibited a satisfactory response to CEA with a limit detection of 0.167 pg/mL and linear detection range from 0.5 pg/mL to 50 ng/mL. Based on the high sensitivity and specificity of the immunosensor, we propose this multiple amplified biosensor for early detection of CEA.

Shell-encoded Au nanoparticles with tunable electroactivity for specific dual disease biomarkers detection.

The exploration of electroactive labelling with tailorable and strong differential pulse voltammetry (DPV) responses is of great importance in accurate and sensitive screening of a panel of biomarkers related to cancer. Herein, shell-encoded gold nanoparticles (Au NPs) are fabricated and give rise to shell species-dominated DPV peak potentials. Two independent DPV peaks appear at -0.08V for Au@Cu2O core-shell NPs and 0.26V for Au@Ag core-shell NPs. Shell-encoded Au NPs drastically exhibit shell thickness-tunable amplified peak currents. The non-interfering and amplified DPV responses enable shell-encoded Au NPs to be an alternative electrochemical signal amplifier for dual screening of carcinoembryonic antigen (CEA) and alpha-fetoprotein (AFP). The limits of detection (LODs) are calculated to be 1.8pg/mL for CEA and 0.3pg/mL for AFP. In comparison to the parallel single-analyte assays, shell-encoded Au NPs engineered electrochemical aptasensors offer multiplexing capability and show significant prospects in biomedical research and early diagnosis of diseases.

Label-free photoelectrochemical immunoassay for CEA detection based on CdS sensitized WO3@BiOI heterostructure nanocomposite.

In this work, a label-free photoelectrochemical (PEC) immunosensor for the detection of carcino embryonic antigen (CEA) was developed based on CdS nanowires (NWs) sensitized WO3@BiOI heterostructure. The construction procedure of ITO/WO3@BiOI@CdS electrode was done by dipping the WO3@BiOI modified indium-tin oxide (ITO) electrode interchangeably into [Cd(NH3)4]2+ and S2- solution for several times. Then the ITO/WO3@BiOI@CdS electrode was used as a matrix for the subsequent immobilization of CEA antibody (Ab). The obtained label-free PEC immunosensor showed an excellent PEC performance toward CEA detection. Under optimal conditions, the PEC immunosensor have a sensitive response to CEA in a liner range of 0.01ng/mL to 50ng/mL with a detection limit of 3.2pg/mL. The proposed PEC immunosensor exhibited good stability, high sensitivity as well as reproducibility and storage stability. Moreover, the obtained PEC immunosensor also showed a satisfied result in human serum sample analysis.

Enhanced fluorescence detection of proteins using ZnO nanowires integrated inside microfluidic chips.

Nanostructure-enhanced detection is promising for a number of applications such as early cancer diagnosis, environmental monitoring and mine safety, among which nanostructures integrated microfluidic chips offers unique advantage of ultra-low quantitative analyses. Here, dense ZnO nanowires of varied diameter and length were obtained by changing the content of polyethyleneimine (PEI) and growth time via simple hydrothermal growth in microfluidic channels for protein detection. We showed that this approach was superiorly efficient compared to the conventional hydrothermal method due to the flow-induced replenishment of nutrient and the effect of shear stress. When immobilizing FITC conjugated anti-bovine immunoglobulin G (IgG) on ZnO nanowires, the fluorescence emission was significantly amplified compared to glass substrate and ZnO seed layer. Under the different growth conditions, the most remarkable fluorescence enhancement was observed on the ZnO nanowire substrate grown for 3h with 5mM PEI in solution. It is ascribed not only to the increase of the binding surface area of proteins but also the intrinsic fluorescence enhancement of ZnO nanowires as waveguides. We further used the optimized ZnO nanowires to demonstrate multiple detection of cancer biomarkers, achieving a superior limit of detection (LOD) as low as 1pg/mL in human α-fetoprotein (AFP) assay and 100 fg/mL in carcinoembryonic antigen (CEA) assay with large dynamic range of 6-7 orders, which suggests that ZnO nanowire integrated microfluidic chips are promising for high-throughput fluorescence-based diagnostic assays.

Perylenetetracarboxylic acid and carbon quantum dots assembled synergistic electrochemiluminescence nanomaterial for ultra-sensitive carcinoembryonic antigen detection.

It is important to design a nice electrochemiluminescence (ECL) biological nanomaterial for fabricating sensitive ECL immunosensor to detect tumor markers. Most reported ECL nanomaterial was decorated by a number of mono-luminophore. Here, we report a novel ECL nanomaterial assembled by dual luminophores perylenetetracarboxylic acid (PTCA) and carbon quantum dots (CQDs). In the ECL nanomaterial, graphene was chosen as nanocarrier. Significant ECL intensity increases are seen in the ECL nanomaterial, which was interpreted with the proposed synergistic promotion ECL meachanism of PTCA and CQDs. Furthermore, this ECL nanomaterial was used to label secondary antibody and fabricate a sandwiched carcinoembryonic antigen (CEA) immunosensor. The CEA immunosensor exhibits high sensitivity and the linear semilogarithmical range was from 0.001fgmL-1 to 1ngmL-1 with low detection limit 0.00026fgmL-1. And the CEA immunosensor is also suitable for various cancers' sample detection providing potential specific applications in diagnostics.

Effective immobilization of Au nanoparticles on TiO2 loaded graphene for a novel sandwich-type immunosensor.

A novel and sensitive sandwich immunosensor for amperometric determination of carcinoembryonic antigen (CEA) was designed using Au nanoparticles-titanium dioxide-graphene (AuNPs-TiO2-graphene) nanocomposites. Dopamine-functionalized graphene was firstly prepared by π-stacking interaction, and TiO2 was then attached to the surface of dopamine-graphene by the specificity and high affinity of enediol ligands to Ti (IV). Afterwards, AuNPs-TiO2-graphene nanocomposites were synthesized with photo-reduction approach under ultraviolet irradiation. The morphology and conductivity of the as-prepared nanocomposites were characterized by transmission electron microscopy, Fourier transform infrared spectra, X-ray powder diffraction, cyclic voltammetry and electrochemical impedance spectroscopy. Taking the advantage of large specific surface area and excellent biocompatibility, AuNPs could covalently link horseradish peroxidase labeled secondary antibody (HRP-Ab2) through the interaction between AuNPs and mercapto or primary amine groups of HRP-Ab2 for sandwich-type immunosensor construction. Under optimum conditions, the modified electrode exhibited a linear current response to CEA concentration in a wide range of 0.005-200ngmL-1 (R2 = 0.994) with low detection limit of 3.33pgmL-1 (S/N = 3).

Electrochemical detection of carcinoembryonic antigen.

In this work, a sandwich-type electrochemical immunosensor for carcinoembryonic antigen (CEA) detection has been constructed and tested. Unlike many other sensors using external electrochemical species in the electrolyte to generate an electrochemical signal, a ferrocene derivative has been integrated into the design of the sensor to provide an internal reporting system, allowing detection of CEA in buffers and biological samples. Gold nanoparticles, which have been used to increase the conductivity of sensing surfaces, also carry immobilized secondary anti-CEA and a ferrocene derivative. The shelf life testing of the sensor shows good performance after storage for 4 weeks. The sensor has been calibrated against different concentration of the target protein using square wave voltammetry. The calibration curve has been obtained in the range of 0.05-20ngmL-1, and the detection limit for CEA is ~ 0.01ngmL-1. The capability of the immunosensor has been verified by performing detection of CEA in human serum samples.

Multiplexed aptasensor for simultaneous detection of carcinoembryonic antigen and mucin-1 based on metal ion electrochemical labels and Ru(NH3)63+ electronic wires.

In this paper, a dual-target electrochemical aptasensor has been developed for simultaneous detection of carcinoembryonic antigen and mucin-1 based on metal ion electrochemical labels and Ru(NH3)63+ electronic wires. When targets are present, the interaction between targets and their respective aptamers leads to the dissociation of double-strand DNA because the targets have higher affinity to its aptamer than the complementary strand. And the qualitative and quantitative analyses of the two targets are realized by the differential pulse voltammetry (DPV) peaks generated by metal ion electrochemical labels. For the effective loading of a large number of metal ions, Au/bovine serum albumin (Au/BSA) nanospheres are employed as carriers to develop Au/BSA-metal ions. After Ru(NH3)63+ complexes are embedded into double-strand DNA to form the electronic wires, the electrical conductivity and the electron transfer of the detection system are greatly improved. The detection limit of the proposed assay was calculated as 3.33fM ranging from 0.01pM to 100nM. Therefore, this novel sensing assay provides a new and sensitive platform for detecting several targets simultaneously in biochemical research and clinical diagnosis.