Electrochemical immunosensor based on hyperbranched structure for carcinoembryonic antigen detection

A hair-ball heterostructure of MnS-MnS2/CdS with compact linking interface for ultrasensitive photoelectrochemical bioanalysis of carcinoembryonic antigen

The heterostructured photoelectric material is supposed to markedly promote the photoelectrochemical (PEC) property. Herein, the species heterostructured MnS/CdS and MnS-MnS2/CdS(1∼2) composites derived from Mn-ZIF MOFs via a sulfofication reaction using Cd(NO3)2, CdC12 cadmium source, respectively. Under irradiation, the PEC tests showed that the photocurrent response of MnS-MnS2/CdS(1∼2) signally enhanced compared to globose MnS/CdS heterostructure and pure MnS or CdS. It was ascribed to the matching band-gap to form type II heterojunction in MnS-MnS2/CdS(1∼2) which dramatically facilitated photo-induced electron/hole (e-/h+) separation and transfer. The hair-ball morphologies structure of MnS-MnS2/CdS(1∼2) with large number of pores was beneficial to improve penetrating efficiency of the electrolyte liquid. Meanwhile, the well-synergistic effect on the MnS, MnS2, CdS components and with tight connecting heterojunction interface among MnS-MnS2/CdS(1∼2) which also led to violently photocurrent output. Besides, the chitosan (CS) was covalently coupled with glutaraldehyde (GLD) to obtain steady composite film, and the cross-linker of GLD can achieve the high efficiency to graft the Apt-CEA (aptamer) biomolecules, which resulting in the promotion of hybridization reaction efficiency of the CEA target. Hence, this created biosensor of Apt-CEA/GLD-CS/MnS-MnS2/CdS(1)/ITO for the CEA detection displayed a wide linear range from 0.001 to 18 ng mL-1 and with ultralow detection limit of 0.313 pg mL-1. This research innovatively prepared a contact heterojunction interface with special porosities structure, which had superior PEC nature for the fabrication of high-performance biosensor.

Achieving enhanced sensitivity and accuracy in carcinoembryonic antigen (CEA) detection as an indicator of cancer monitoring using thionine/chitosan/graphene oxide nanocomposite-modified electrochemical immunosensor

The current study has focused on electrochemical immunosensing of carcinoembryonic antigen (CEA) employing an immobilized antibody on a thionine, chitosan, or graphene oxide nanocomposite modified glassy carbon electrode (anti-CEA/THi-CS-GO/GCE) as an indicator of cancer monitoring. THi-CS-GO nanocomposites were made using ultrasonication, and analyses of their morphology and crystal structure using SEM, FTIR, and XRD showed that thionine and chitosan molecules were intercalated with stacking interactions with both the top and bottom of GO nanosheets. Electrochemical experiments revealed anti-CEA, THi-CS-GO/GCE to have exceptional sensitivity and selectivity towards CEA compounds. The detection limit value was established to be 0.8 pg/mL when it was discovered that variations in the decrease peak current were directly proportional to the logarithm concentration of CEA over a wide range from 10-3 to 104 ng/mL. Results of testing the immunosensor's application capability for detecting CEA in a sample of human serum show that ELISA and DPV results are very congruent. The produced immunosensor demonstrated adequate immunosensor precision in determining CEA in prepared genuine samples of human serum and clinical applications.

Electrochemical Immunosensor Using Electroactive Carbon Nanohorns for Signal Amplification for the Rapid Detection of Carcinoembryonic Antigen

In this work, a novel sandwich-type electrochemical immunosensor was developed for the quantitative detection of the carcinoembryonic antigen, an important tumor marker in clinical tests. The capture antibodies were immobilized on the surface of a gold disk electrode, while detection antibodies were attached to redox-tagged single-walled carbon nanohorns/thionine/AuNPs. Both types of antibody immobilization were carried out through Au-S bonds using the novel photochemical immobilization technique that ensures control over the orientation of the antibodies. The electroactive SWCNH/Thi/AuNPs nanocomposite worked as a signal tag to carry out both the detection of carcinoembryonic antigen and the amplification of the detection signal. The current response was monitored by differential pulse voltammetry. A clear dependence of the thionine redox peak was observed as a function of the carcinoembryonic antigen concentration. A linear detection range from 0.001-200 ng/mL and a low detection limit of 0.1385 pg/mL were obtained for this immunoassay. The results showed that carbon nanohorns represent a promising matrix for signal amplification in sandwich-type electrochemical immune assays working as a conductive and binding matrix with easy and versatile modification routes to antibody and redox tag immobilization, which possesses great potential for clinical diagnostics of CEA and other biomarkers.

Branched, dendritic, and hyperbranched polymers in liquid biopsy device design

The development of minimally invasive tests for cancer diagnosis and prognosis will aid in the research of new treatments and improve survival rates. Liquid biopsies seek to derive actionable information from tumor material found in routine blood samples. The relative scarcity of tumor material in this complex mixture makes isolating and detecting cancerous material such as proteins, circulating tumor DNA, exosomes, and whole circulating tumor cells a challenge for device engineers. This review describes the chemistry and applications of branched and hyperbranched to improve the performance of liquid biopsy devices. These polymers can improve the performance of a liquid biopsy through several mechanisms. For example, polymers designed to increase the affinity of capture enhance device sensitivity. On the other hand, polymers designed to increase binding avidity or repel nonspecific adsorption enhance device specificity. Branched and hyperbranched polymers can also be used to amplify the signal from small amounts of detected material. The further development of hyperbranched polymers in liquid biopsy applications will enhance device capabilities and help these critical technologies reach the oncology clinic where they are sorely needed. This article is categorized under: Diagnostic Tools > Biosensing Diagnostic Tools > Diagnostic Nanodevices.

Research progress of using micro/nanomotors in the detection and therapy of diseases related to the blood environment

Micro/nanomotors bring new possibilities for the detection and therapy of diseases related to the blood environment with their unique motion effect. This work reviews the research progress of using micro/nanomotors in the detection and therapy of diseases related to the blood environment. First, we outline the advantages of using micro/nanomotors in blood-related disease detection. To be specific, the motion capability of micro/nanomotors can increase plasma or blood fluid convection and accelerate the interaction between the sample and the capture probe. This allows the effective reduction of the amount of reagents and treatment steps. Therefore, the application of micro/nanomotors significantly improves the analytical performance. Second, we discuss the key challenges and future prospects of micro/nanomotors in the treatment of blood-environment related diseases. It is very important to design a unique treatment plan according to the etiology and specific microenvironment of the disease. The next generation of micro/nanomotors is expected to bring exciting progress to the detection and therapy of blood-environment related diseases.

Flexible and wearable electrochemical biosensors based on two-dimensional materials: Recent developments

The research interest in wearable sensors has tremendously increased in recent years. Amid the different biosensors, electrochemical biosensors are unparalleled and ideal for the design and manufacture of such flexible and wearable sensors because of their various benefits, including convenient operation, quick response, portability, and inherent miniaturization. A number of studies on flexible and wearable electrochemical biosensors have been reported in recent years for invasive/non-invasive and real-time monitoring of biologically relevant molecules such as glucose, lactate, dopamine, cortisol, and antigens. To attain this, novel two-dimensional nanomaterials and their hybrids, various substrates, and detection methods have been explored to fabricate flexible conductive platforms that can be used to develop flexible electrochemical biosensors. In particular, there are many advantages associated with the advent of two-dimensional materials, such as light weight, high stretchability, high performance, and excellent biocompatibility, which offer new opportunities to improve the performance of wearable electrochemical sensors. Therefore, it is urgently required to study wearable/flexible electrochemical biosensors based on two-dimensional nanomaterials for health care monitoring and clinical analysis. In this review, we described recently reported flexible electrochemical biosensors based on two-dimensional nanomaterials. We classified them into specific groups, including enzymatic/non-enzymatic biosensors and affinity biosensors (immunosensors), recent developments in flexible electrochemical immunosensors based on polymer and plastic substrates to monitor biologically relevant molecules. This review will discuss perspectives on flexible electrochemical biosensors based on two-dimensional materials for the clinical analysis and wearable biosensing devices, as well as the limitations and prospects of the these electrochemical flexible/wearable biosensors.Graphical abstract.

An AIEgen-based 2D ultrathin metal-organic layer as an electrochemiluminescence platform for ultrasensitive biosensing of carcinoembryonic antigen

In this work, a novel two-dimensional (2D) ultrathin metal-organic layer (MOL) based on the aggregation-induced emission (AIE) ligand H4ETTC (H4ETTC = 4',4''',4''''',4'''''''-(ethene-1,1,2,2-tetrayl)tetrakis(([1,1'-biphenyl]-4-carboxylic acid))) was developed and used to construct a novel electrochemiluminescence (ECL) aptasensor for ultrasensitive detection of carcinoembryonic antigen (CEA). The newly synthesized AIE luminogen (AIEgen)-based MOL (Hf-ETTC-MOL) yielded a higher ECL intensity and efficiency than did H4ETTC monomers, H4ETTC aggregates and 3D bulk Hf-ETTC-MOF. This improvement occurred not only because the ETTC ligands were coordinatively immobilized in a rigid MOL matrix, which restricted the intramolecular free rotation and vibration of these ligands and then reduced the non-radiative transition, but also because the porous ultrathin 2D MOL greatly shortened the transport distances of ions, electrons, coreactant (triethylamine, TEA) and coreactant intermediates (TEA˙ and TEA˙+), which made more ETTC luminophores able to be excited and yielded a high ECL efficiency. On the basis of using the Hf-ETTC-MOL as a novel ECL emitter and rolling circle amplification (RCA) as a signal amplification strategy, the constructed ECL aptasensor exhibited a linear range from 1 fg mL-1 to 1 ng mL-1 with a detection limit of 0.63 fg mL-1. This work has opened up new prospects for developing novel ECL materials and is expected to lead to increased interest in using AIEgen-based MOLs for ECL sensing.

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

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

Design of organic/inorganic nanocomposites for ultrasensitive electrochemical detection of a cancer biomarker protein

A new type of nanocomposite composed of carboxylated single-walled carbon nanotubes (CNTs-COOH), reduced graphene oxide (rGO), bovine serum albumin-Ag hybride (Ag@BSA), and poly(3,4-ethylenedioxythiophene) (PEDOT) was fabricated to develop an ultrasensitive electrochemical platform for the detection of carcinoembryonic antigen (CEA) as a model of biomarkers. Two steps are involved for the fabrication of the organic/inorganic nanocomposites. The Ag@BSA nanoflowers were first synthesized to be doped with CNTs-COOH and rGO followed by the adsorption of PEDOT resulting in CNTs-COOH/rGO/Ag@BSA/PEDOT. The as-prepared nanocomposites were then deposited onto an Au electrode together with subsequent immobilization of CEA antibody (anti-CEA) to construct the electrochemical immunosensor. This unique structure and composition of the developed immunosensor can expect an excellent electrochemical response. The immunosensor offers a linear relationship between the electrochemical responses and the CEA concentrations from 0.002 to 50 ng∙mL^-1 with a detection limit of 1 × 10^-4 ng∙mL^-1. Moreover, the ultrasensitive immunoassay can detect CEA in real human serum samples, and the results are comparable to those obtained from the commercial ELISA. Therefore, this strategy can monitor diseases, offer clinical diagnosis, and may be valuable for the development of new biomedical devices.

Nanomaterials for Healthcare Biosensing Applications

In recent years, an increasing number of nanomaterials have been explored for their applications in biomedical diagnostics, making their applications in healthcare biosensing a rapidly evolving field. Nanomaterials introduce versatility to the sensing platforms and may even allow mobility between different detection mechanisms. The prospect of a combination of different nanomaterials allows an exploitation of their synergistic additive and novel properties for sensor development. This paper covers more than 290 research works since 2015, elaborating the diverse roles played by various nanomaterials in the biosensing field. Hence, we provide a comprehensive review of the healthcare sensing applications of nanomaterials, covering carbon allotrope-based, inorganic, and organic nanomaterials. These sensing systems are able to detect a wide variety of clinically relevant molecules, like nucleic acids, viruses, bacteria, cancer antigens, pharmaceuticals and narcotic drugs, toxins, contaminants, as well as entire cells in various sensing media, ranging from buffers to more complex environments such as urine, blood or sputum. Thus, the latest advancements reviewed in this paper hold tremendous potential for the application of nanomaterials in the early screening of diseases and point-of-care testing.

Single-step and ultrasensitive detection of carcinoembryonic antigen based on an aptamer transduction-mediated exonuclease III-assisted dual-amplification strategy

Herein, a single-step, rapid and homogenous fluorescence approach for highly sensitive and specific detection of CEA was successfully constructed for the first time using an aptamer binding-induced exonuclease III (Exo III)-mediated dual-amplification strategy. When present, CEA can specifically combine with the aptamer region in H1, resulting in a conformational change of H1 and the exposure of the occluded DNA fragment in the stem regions. Successively, the exposed DNA fragment partially hybridizes with H2 to initiate Exo III-assisted cycling cleavage to release another DNA fragment, which can in turn activate the cycling cleavage of the DNA fluorescence substrate (FS). Therefore, many fluorophore fragments are liberated to produce a significantly amplified fluorescence signal toward CEA detection. By virtue of the Exo III-assisted dual-amplification strategy, this method allows the detection of CEA at the fg mL-1 level with excellent selectivity. Compared with other reported strategies for CEA detection, the Exo III-assisted dual-amplification homogeneous platform only requires a one-step reaction, offering a very simple and low-cost detection. The practical ability of the developed strategy is demonstrated by the detection of CEA in human serum with satisfactory results. Thus, this method shows great potential in assays of many other biological analytes in clinical diagnosis.

Single-step cycle pulse operation of the label-free electrochemiluminescence immunosensor based on branched polypyrrole for carcinoembryonic antigen detection

A novel label-free electrochemiluminescence (ECL) immunosensor based on luminol functional-Au NPs@polypyrrole has been developed for the detection of carcinoembryonic antigen (CEA). In this work, polypyrrole prepared by chemical polymerization provided a large surface area to load amounts of gold nanoparticles (Au NPs). Au NPs could not only attach abundant luminol for the enhancement of ECL signal, but also provide a friendly microenvironment for the immobilization of antibodies. Moreover, 1-butylpyridinium tetrafluroborate ([BPy]BF₄) were used to disperse luminol functional-Au NPs@polypyrrole nanocomposites, resulting in the film-formation of composites on the electrode, which could improve the stability of immunosensor. In particular, employment of single-step cycle pulse could limit the consecutive reaction between luminol and H₂O₂ efficiently, thus leading to stable and strong signals. The proposed method presents good ECL response for the detection of CEA allowing a wide linear range from 0.01 pg/mL to 10 ng/mL and a limit of detection as low as 3 fg/mL. The immunosensor would be a promising tool in the early diagnosis of CEA due to its high sensitivity, simplicity and cost-effective.

Screen-printed electrode produced by printed-circuit board technology. Application to Cancer Biomarker Detection by means of plastic antibody as sensing material

This research work presents, for the first time, a screen-printed electrode (SPE) made on a PCB board with silver tracks (Ag) and a three electrode configuration (AgxO-working, AgxO-counter and Ag/AgxO-reference electrodes), following the same approach as printed-circuit boards (PCBs). This low cost and disposable device was tested for screening a cancer biomarker in point-of-care. The selected biomarker was carcinogenic embryonic antigen (CEA) protein, routinely used to follow-up the progression of specific cancer diseases. The biosensor was constructed by assembling a plastic antibody on the Ag-working electrode area, acting as the biorecognition element of the device. The protein molecules that were entrapped on the polymer and positioned at the outer surface of the polypyrrole (PPy) film were removed by protease action. The imprinting effect was tested by preparing non-imprinted (NPPy) material, including only PPy as biorecognition element. Infrared and Raman studies confirmed the surface modification of these electrodes. The ability of the sensing material to rebind CEA was measured by several electrochemical techniques: cyclic voltammetry (CV), impedance spectroscopy (EIS) and square wave voltammetry (SWV). The linear response ranged from 0.05 to 1.25 pg/mL against logarithm concentration. Overall, producing screen-printed electrodes by means of conventional PCB technology showed promising features, mostly regarding cost and prompt availability. The plastic antibody-based biosensor also seems to be a promising tool for screening CEA in point-of-care, with low response time, low cost, good sensitivity and high stability.

Ternary Pt@Pd@Ru nanodendrite-decorated graphene oxide for sensitive electrochemical immunoassy of CEA

Nobel metal nanoparticles have attracted intense attentions in biological immunoassay due to the inhereted good catalytic activity.

Simple and signal-off electrochemiluminescence immunosensor for alpha fetoprotein based on gold nanoparticle-modified graphite-like carbon nitride nanosheet nanohybrids

A simple, signal-off electrochemiluminescence immunosensor for sensitive and selective detection of alpha fetoprotein was developed based on gold nanoparticle modified graphite-like carbon nitride nanosheet nanohybrids.

A porous CuO nanowire-based signal amplification immunosensor for the detection of carcinoembryonic antigens

A novel electrochemical immunosensor was developed for the detection of CEA based on CNTs–AuNPs as a platform and pCuOw@Fc as labels. The immunosensor showed enhanced electrochemical performance toward the detection of CEA.

Graphene oxide supported rhombic dodecahedral Cu2O nanocrystals for the detection of carcinoembryonic antigen

In this work, a simple electrochemical immunosensor was developed for the detection of carcinoembryonic antigen (CEA) based on rhombic dodecahedral Cu2O nanocrystals-graphene oxide-gold nanoparticles (rCu2O-GO-AuNPs). GO as the template and surfactant resulting in rCu2O exhibit improved rhombic dodecahedral structure uniformity and excellent electrochemical performance. Moreover, GO was found to be able to effectively improve the long stability of rCu2O on the electrode response. Under optimal conditions, the immunosensor showed a low limit of detection (0.004 ng ml(-1)) and a large linear range (0.01-120 ng ml(-1)). This work presents a potential alternative for the diagnostic applications of GO-supported special morphology materials in biomedicine and biosensors.

Electrochemical immunosensor for interferon-γ based on disposable ITO detector and HRP-antibody-conjugated nano gold as signal tag

Tuberculosis is the most frequent cause of infection-related death worldwide. A new disposable electrochemical immunosensor with low cost and simple fabrication was proposed to detect interferon-γ (IFN-γ). Diallyldimethylammonium chloride (PDDA) and Au nanoparticle (AuNP) composite were used to provide an efficient biointerface, horseradish peroxidase (HRP)-labeled antibody-conjugated AuNP (HRP-Ab2-AuNP) bioconjugates were used as a novel signal tag. The large amounts of HRP on the signal tag can catalyze the oxidation of Hydroquinone (HQ) by H2O2, which can induce an amplified reductive current. The catalytic reduction current was related to the amount of HRP immobilized on the surface, which itself was related to the concentration of IFN-γ. Under optimized conditions, the proposed immunosensor showed a high sensitivity and a linear range of 0.1-10,000pg/mL with a detection limit of 0.048pg/mL. The assay results of clinical serum samples obtained by the immunosensor were in acceptable agreement with the reference values. Therefore, the immunosensor possessed excellent clinical value in early diagnosis and control of tuberculosis.

Corallite-like Magnetic Fe3O4@MnO2@Pt Nanocomposites as Multiple Signal Amplifiers for the Detection of Carcinoembryonic Antigen

A nonenzymatic sandwich-type electrochemical immunosensor using corallite-like magnetic Fe3O4@MnO2@Pt nanocomposites was developed for the sensitive detection of carcinoembryonic antigen (CEA). First, aminated graphene (GS-NH2) sheets were synthesized from graphite oxide using the Hummers' method, which was used to immobilize the primary antibody via the active amino groups on the GS-NH2. Second, corallite-like Fe3O4@MnO2@Pt nanoparticles (NPs) were synthesized and characterized by transmission electron microscope (TEM), scanning electron microscope (SEM), and energy dispersive spectroscopy (EDS). They were used as labels to conjugate with a secondary antibody. The multiple amplification of Fe3O4@MnO2@Pt NPs and the promoted electron transfer of GS-NH2 lead to a broad linear range from 0.5 pg/mL to 20 ng/mL and a low detection limit with 0.16 pg/mL. In addition, the immunosensor performed with good selectivity and acceptable stability and reproducibility as well. The results are satisfactory when the proposed method has been applied to analyze human serum samples. Thus, there would be a promising future in the early diagnosis of cancer to detect CEA and other tumor markers.

Sensitive electrochemical detection of Salmonella with chitosan-gold nanoparticles composite film

An ultrasensitive electrochemical immunosensor for detection of Salmonella has been developed based on using high density gold nanoparticles (GNPs) well dispersed in chitosan hydrogel and modified glassy carbon electrode. The composite film has been oxidized in NaCl solution and used as a platform for the immobilization of capture antibody (Ab1) for biorecognition. After incubation in Salmonella suspension and horseradish peroxidase (HRP) conjugated secondary antibody (Ab2) solution, a sandwich electrochemical immunosensor has been constructed. The electrochemical signal was obtained and improved by comparing the composite film with chitosan film. The result has shown that the constructed sensor provides a wide linear range from 10 to 10(5) CFU/mL with a low detection limit of 5 CFU/mL (at the ratio of signal to noise, S/N=3:1). Furthermore, the proposed immunosensor has demonstrated good selectivity and reproducibility, which indicates its potential in the clinical diagnosis of Salmonella contaminations.

Dendritic Pt@Au nanowires as nanocarriers and signal enhancers for sensitive electrochemical detection of carcinoembryonic antigen

An electrochemical aptasensor for the sensitive and selective determination of carcinoembryonic antigen was constructed based on dendritic Pt@AuNWs as nanocarriers and signal enhancers.

A label-free hemin/G-quadruplex DNAzyme biosensor developed on electrochemically modified electrodes for detection of a HBV DNA segment

A label-free biosensor based on Au/G–CMWCNTs-GCE was proposed for the detection of a HBV DNA segment with a low LOD.