Immunosensor For Detection Of Alpha-fetoprotein Research Articles

Photoelectrochemical immunosensor for sensitive detection of alpha-fetoprotein based on a graphene honeycomb film

Alpha-fetoprotein (AFP) in adult serum often appears in early liver cancer. Therefore, early detection of an abnormal elevation of AFP concentration is important for the early diagnosis and treatment of primary liver cancer. In this work, a photoelectrochemical (PEC) electrode was fabricated for AFP-sensitive detection based on a reduced graphene oxide (rGO) honeycomb structure. After layer-by-layer bioconjugation, the immunoassay graphene electrode was modified with anti-AFP antibodies (Ab). Meanwhile, polymer nanoparticles (PFBT dots) were prepared via a nanoprecipitation method. In addition, the AFP was modified by using the PFBT dots and glucose oxidase (GOD), which formed a fluorescent probe (AFP-PFBT-GOD). By the competitive linkage of AFP and AFP-PFBT-GOD onto the anti-AFP modified honeycomb structure electrode, an immunosensor for AFP detection was obtained. During the PEC test, the electrons produced by the catalytic reaction of glucose and GOD can scavenge the photogenerated holes on the PFBT dots, which can reduce the recombination of photogenerated holes and electrons on the PFBT dots. The PEC immunosensor based on a rGO honeycomb structure exhibited a linear detection range of 0.05–100 ng/mL with a detection limit of 0.05 ng/mL. The excellent detection performance of the graphene PEC biosensor provides an opportunity for the early diagnosis of primary liver cancer.

Triple amplified ultrasensitive electrochemical immunosensor for alpha fetoprotein detection based on MoS2@Cu2O-Au nanoparticles

Recently, alpha fetoprotein (AFP), a tumour marker to identify adult primary liver cancer, has attracted increasingly widespread attention. In this work, an ultrasensitive sandwich-type electrochemical biosensor was fabricated for AFP detection. Electrodeposited gold nanoparticles (D-Au NPs) modified on glassy carbon electrodes (GCE) were used as antibody carriers and sensing platforms. Furthermore, a molybdenum disulfide @ cuprous oxide hybrid (MoS2@Cu2O) was prepared to combine gold nanoparticles (Au NPs) as a strategy for achieving signal amplification. The experimental results revealed that molybdenum disulfide @ cuprous oxide-gold nanoparticles (MoS2@Cu2O-Au) showed superb tri-amplification electrochemical signals when catalyzing hydrogen peroxide (H2O2) reduction. This method was demonstrated as a novel tool for the highly reliable separation and quantification of AFP. Under the most suitable experimental conditions, the proposed method exhibits a linear range from 0.1 pg/mL to 50 ng/mL and a low detection limit of 0.037 pg/mL (S/N = 3). The ultrasensitive electrochemical immunosensor has been tested for human serum, and satisfactory recoveries were obtained, indicating that the proposed method is promising for practical applications in the clinical diagnosis of AFP detection.

A sensitive label-free immunosensor for alpha fetoprotein detection using platinum nanodendrites loaded on functional MoS2 hybridized polypyrrole nanotubes as signal amplifier

Sensitive detection of alpha fetoprotein (AFP) in serum is an important prerequisite to prompt definitive treatment decisions for reducing mortality rate of hepatocellular carcinoma. In this study, a label-free amperometric immunosensor was developed to detect AFP sensitively. It was based on platinum nanodendrites loaded on poly(diallyldimethylammonium chloride) functionalized molybdenum disulfide nanosheet hybridized polypyrrole nanotubes (Pt NDs/PDDA/MoS2@PPy NTs). The Pt NDs and MoS2 nanosheet improved the catalytic activity, PPy NTs and PDDA increased electron transfer and enhanced the stability. The Pt NDs/PDDA/MoS2@PPy NTs nanocomposite also had large active surface area and immobilized antibodies effectively. Therefore, the nanocomposite showed high catalytic activity, enhancing the electron transfer and immobilizing antibodies effectively, which amplified the current signal. Based on above advantages, the immunosensor had low detection limit of 17fgmL−1, wide linear concentration range from 50fgmL−1 to 50ngmL−1 for AFP (signal-to-noise ratio of 3), good reproducibility, selectivity and stability. The good analysis results of human serum samples implied that the immunosensor had bright potential application in clinical monitoring biomarkers.

Ultrasensitive electrochemical immunosensor for alpha fetoprotein detection based on platinum nanoparticles anchored on cobalt oxide/graphene nanosheets for signal amplification

An ultrasensitive sandwich-type electrochemical immunosensor was developed for quantitative monitoring of Alpha fetoprotein (AFP). To achieve this objective, an incorporated signal amplification strategy of platinum nanoparticles anchored on cobalt oxide/graphene nanosheets (Pt NPs/Co3O4/graphene) was proposed by acting as the label of secondary antibodies. The prepared label not only empowered by advantages of each component but exhibited better electrochemical performance than single Pt NPs, Co3O4 and graphene, which has shown large specific surface area and good catalytic activity towards the reduction of H2O2. Meanwhile, the nanocomposite of gold nanoparticles adhered on 3-mercaptopropyltriethoxysilane functionalized graphene sheets (Au@MPTES-GS) was used as matrix to accelerate electron transfer and immobilize primary antibodies in this system. The signal amplification mechanism of the matrix and the label were explored successfully. Under optimal conditions, the electrochemical immunosensor exhibited a wide linear range from 0.1 pg mL−1 to 60 ng mL−1 with a low detection limit of 0.029 pg mL−1for AFP. The proposed immunosensor may have promising application in the clinical diagnosis of AFP and other tumor markers.

A novel signal-on photoelectrochemical immunosensor for detection of alpha-fetoprotein by in situ releasing electron donor

A signal-on photoelectrochemical (PEC) immunosensor was constructed for detecting tumor marker in this work. α-fetoprotein (AFP) was chosen as a model analyte to investigate the prepared procedure and the analytical performance of the exploited sensor. In order to construct the sensor, CdSe QDs were used as photoactive material, biotin conjugated AFP antibody (Bio-anti-AFP) as detecting probe, streptavidin (SA) as signal capturing unit, biotin functionalized apoferritin encapsulated ascorbic acid (Bio-APOAA) as amplification unit, which were assembled onto the electrodes. The sensing strategy was based on in situ enzymatic hydrolysis of Bio-APOAA to release ascorbic acid (AA) as sacrificial electron donor to produce photocurrent. The photocurrent from the immunosensor was monitored as a result of AFP concentrations. The constructed sensing platform displayed high selectivity and good sensitivity for detecting AFP. Under optimal conditions, a wide linear range from 0.001 to 1000ng/mL and a low detection limit of 0.31pg/mL were obtained. The developed immunosensor is expected to be used to determine AFP and other tumor markers in human plasma in clinical laboratories either for pre-cancer screening or cancer monitoring. Moreover, this sensing platform further has the potential to use for the detection of trypsin activity and the corresponding inhibitor-screening.

Electrochemical Immunosensor for Detection of Alphafetoprotein Based on Polypyrrole Modified Expanded Graphite Electrode

An electrochemical immunosensor for rapid detection of alphafetoprotein(AFP) was proposed.Polypyrrole(PPy) was firstly synthesized on the surface of expanded graphite(EG) electrode by potentiostatic method,and then horseradish peroxidase(HRP) labeled AFP-antibody(HRP-anti-AFP) was fixed on the immunosensor interface by using glutaraldehyde(GA) as coupling reagent.After incubation of the immunosensor in the solution containing AFP sample at 35 ℃ for 50 min,Prussian blue(PB) was immobilized onto the immunosensor interface as electron mediator.The immune complexes produced by the combination of antibody and antigen reduced the oxidation peak current of PB.Under optimized experimental conditions,AFP was detected in a concentration range from 0.01 to 300 μg/L and a detection limit of 6.25 ng/L(S/N=3) was obtained.Considering its simplicity,high sensitivity and low cost,the immunosensor based on PPy modified EG electrode is feasible to be developed as a disposable electrochemical sensor for clinical purposes.

A Novel Amperometric Immunosensor for Detection of Alpha-Fetoprotein Based on Magnetic and Electroactive Nanoprobes

A novel three-dimensional, magnetic and electroactive nanoprobes were constructed for the first time. Using hemin (TPP) as electron mediator, mutli-walled carbon nanotubes with carboxyl groups (MCNTs) as supporter, a novel (MCNTs-TPP-Fe3O4)magnetic nanocomposites were first prepared. Then using alpha-fetoprotein (AFP) as model system, gold nanoparticles (Au NPs) as immobilizing matrix, the AFP/anti-AFP/Au NPs/ MCNTs-TPP-Fe3O4nanoprobes were prepared and then dropped on the surface of screen-printed working electrode (SPCE) to construct a new amperometric immunosensors for detecting biomakers. The microstructure of different nanoparticles were observed by transmission electron microscopy (TEM) andX-ray fluorescence spectrometery (XRFS). Under optimal experimental conditions, the logarithm of response signal was proportional to the logarithm of AFP concentration from 0.1 to 200 ng/mL, with a correlation coefficient of 0.998. The detection limit was 0.04 ng/mL at a signal-to-noise ratio of 3. The proposed method offered a platform for fast, sensitive and simultaneous determination for serum samples.

Nanosilver-penetrated polyion graphene complex membrane for mediator-free amperometric immunoassay of alpha-fetoprotein using nanosilver-coated silica nanoparticles

A facile and sensitive mediator-free electrochemical immunosensor for detection of alpha-fetoprotein (AFP) was designed by using nanosilver-coated silica nanoparticles (Ag-SiO 2) as bionanolabels. To construct such an electrochemical immunosensor, silver ions/single-stranded DNA/graphene nanosheets were initially immobilized on a gold electrode in turn, then silver ions were in situ reduced to silver nanoparticles with the aid of NaBH 4, and anti-AFP antibodies conjugated to silver nanoparticles were used. In the presence of AFP analyte, the sandwiched immunocomplex was formed on the electrode surface by using horseradish peroxidase-anti-AFP conjugate-labeled Ag-SiO 2 (HRP-anti-AFP-Ag-SiO 2) as secondary antibodies. Compared with pure silver nanoparticles, Ag-SiO 2 nanocomposites could provide a large room for the immobilization of HRP-anti-AFP, and improve the electrochemical responses of the immunosensor. Meanwhile, the presence of highly conductive graphene nanosheets and silver nanoparticles provided a good pathway for electron transfer. Under optimal conditions, the immunosensor exhibited good electrochemical responses toward AFP ranging from 0.3 to 200 ng/mL with a detection limit (LOD) of 0.05 ng/mL (at 3 σ) in pH 6.0 PBS-H 2O 2 system. Intra- and inter-assay displayed good precisions with coefficient of variation below 9.5%. In addition, the method was evaluated with 23 clinical serum samples, receiving good correlation with results from commercially available electrochemiluminescent analyzer.

Sandwich-type conductometric immunoassay of alpha-fetoprotein in human serum using carbon nanoparticles as labels

A simple and sensitive conductometric immunosensor for detection of alpha-fetoprotein (AFP) was designed using carbon nanoparticles as labels. The immunosensing probe was fabricated by means of the immobilization of monoclonal anti-AFP primary antibodies on an interdigitated conductometric transducer, while the detection antibodies were prepared using nanocarbon-conjugated horseradish peroxidase-labeled anti-AFP (CNP-HRP-anti-AFP). With a sandwich-type immunoassay format, the conjugated CNP-HRP-anti-AFP on the transducer was increased with the increase of AFP in the sample, and the conductivity of the immunosensor was decreased in the H2O2–KI system. Under optimal conditions, the immunosensor exhibited a wide dynamic range of 0.1–500ng/mL with a detection limit of 50pg/mL AFP at 3σ. The reproducibility and recovery were <10% and 83.9–112.3%, respectively. Interestingly, 45 clinical serum specimens were assayed using the conductometric immunosensor, and the results were in accordance with those obtained from our Clinical Laboratory using Roche 2010 Electrochemiluminescent Automatic Analyzer.