Polarized SERS Controlled by Anisotropic Growth on Ordered Curvature Substrate.

Colloidal lithography is an efficient and low-cost method to prepare an ordered nanostructure array with new shapes and properties. In this study, square-shaped and cone-shaped Au nanostructures were obtained by 70° angle deposition onto polystyrene bead array with the diameter of 500 nm when a space of 120 nm is created between the neighbor beads by plasma etching. The gaps between the units decrease when the Au deposition time increases, which leads to the polarized enhanced local field, in agreement with the surface-enhanced Raman scattering spectra (SERS) observations and finite-difference time-domain (FDTD) simulations. When the Au deposition time increased to 5 min, 5 nm gaps form between the neighbor units, which gave an enhancement factor of 5 × 109. The SERS chip was decorated for the detection of the liver cancer cell marker Alpha-fetoprotein (AFP) with the detection limit down to 5 pg/mL.

Laboratory screening and diagnosis of open neural tube defects, 2019 revision: a technical standard of the American College of Medical Genetics and Genomics (ACMG).

Open neural tube defects (ONTDs) include open spina bifida (OSB) and anencephaly. These defects are caused by incomplete closure of the neural tube at about 4 weeks of pregnancy. Levels of early second-trimester maternal serum (ms) alpha-fetoprotein (AFP) are sufficiently elevated in affected pregnancies to be used as a population-based screening test. The basic screening methodology was described in the late 1970s and screening programs were active a few years later. By identifying pregnancies with the highest msAFP levels, about 80% of OSB and 95% of anencephaly can be identified as early as 16 weeks gestation. The interpretation of msAFP levels is complicated by the need to consider multiple factors such as gestational age, maternal weight, maternal race, multiple gestations, and more. Testing for AFP and acetylcholinesterase in amniotic fluid and/or identification of the lesion by targeted ultrasound is considered diagnostic of ONTD. When a diagnosis is made, options include termination, surgery after delivery, or in utero surgery, depending on factors such as location and size of the defect, and the presence of any additional anomalies. Screening for ONTD should be performed as part of a comprehensive program linking primary obstetrical care providers, laboratorians, and high-risk clinicians.

Photoswitching enzymatic activity of horseradish peroxidase by graphene oxide for colorimetric immunoassay.

In contrast to the conventional means that the activity of horseradish peroxidase (HRP) is initiated and terminated by the additives of peroxides and strongly acidic stop solutions, this study demonstrates that the enzymatic activity of HRP is switched through the visible light irradiated graphene oxide (GO). And this visible light driven activity of HRP can realize time-precise control without the aids of peroxides (typically H2O2) and acidic stop solutions. The superoxide anions (O2•-) and photogenerated holes (h+) produced by the photo irradiated GO are responsible for activating HRP and the subsequent oxidation of the typical substrates, i.e., 3, 3', 5, 5'-tetramethylbenzidine (TMB) and 2, 2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). It is also validated that the photoswitchable HRP-GO mixture can act as an efficient signal reporter of bioassays by taking the sandwich immunoassay of alpha-fetoprotein (AFP) as an example. The AFP can be detected sensitively and selectively in the linear range from 0.2 fg/mL to 1.0 ng/mL, with a very low detection limit of 0.1 fg/mL. Advantages of the photoswitchable HRP-GO mixture include high catalytic ability, precise time control, and free of additionally harmful reagents.

In situ H2O2 generation with gold nanoflowers as the coreactant accelerator for enzyme-free electrochemiluminescent immunosensing.

In traditional electrochemiluminescence (ECL) analysis, gold nanomaterials are commonly used as a tool for signal amplification and linking antibodies due to their good electrical conductivity and biocompatibility. Here, we found that multitipped gold nanoparticles-gold nanoflowers (AuNFs) as coreactant accelerator have good catalytic activity for the reduction of dissolved oxygen (O2) to hydrogen peroxide (H2O2) using tris (hydroxymethyl) aminomethane (Tris) as electron donor. Based on this, a new enzyme-free and label-free ECL immunosensor have been constructed for the detection of α-fetoprotein (AFP). In this system, due to the unique geometric and spatial effects of AuNFs, the dissolved O2 as endogenous coreactant was catalyzed by AuNFs to produce H2O2 using Tris as an electron donor. The in situ generated H2O2 can more efficiently produce various electrogenerated reactive oxygen species (ROSs) as the important intermediates on the electrode surface. Then, oxidation of luminol reacts with ROSs significantly amplifies the luminol ECL signal. Under optimal experimental conditions, the proposed ECL immunosensor was able to detect the AFP concentration from 0.01 to 100 ng mL-1, with a low detection limit of 3.4 pg mL-1 (S/N = 3). In addition, the prepared ITO-based sensor is similar to a micro-test chip and convenient to use, thus making it suitable for clinical use as a disposable device in point-of-care tests (POCTs).

Engineering of CdTe/SiO2 nanocomposites: Enhanced signal amplification and biocompatibility for electrochemiluminescent immunoassay of alpha-fetoprotein.

Electrochemiluminescent (ECL) performance and cytotoxicity of CdTe quantum dots (QDs)-based nanocomposites and its possible application for ECL immunoassay were investigated. Two types of CdTe-based nanocomposites, i.e., SiO2-coated CdTe (CdTe@SiO2) and CdTe-functionalized SiO2 (SiO2@CdTe), were synthesized and comprehensively compared in regarding of the cytotoxicity and ECL performance. The in vitro cytotoxicity of SiO2@CdTe and CdTe@SiO2 nanoparticles was assessed in L02 cells using standard CCK-8 assay, and their ECL performance was investigated by constructing sandwiched immunosensor using SiO2@CdTe and CdTe@SiO2 as tags for the labelled antibody, respectively. The results showed that CdTe@SiO2 exhibited much lower cytotoxicity and a higher ECL intensity than SiO2@CdTe. Taking the analysis of alpha-fetoprotein (AFP) as an example, the ECL immunosensor using CdTe@SiO2 as an emitter was proved to have a wide linear dynamic range from 1.0 pg mL-1 to 100 ng mL-1 with a low detection limit of 0.22 pg mL-1 (S/N ratio of 3). The ECL immunosensor also demonstrated satisfactory recovery and excellent reproducibility and stability, indicating that this method has prospects in practical application in the clinical diagnosis of AFP.

Growth of Spherical Gold Satellites on the Surface of Au@Ag@SiO2 Core-Shell Nanostructures Used for an Ultrasensitive SERS Immunoassay of Alpha-Fetoprotein.

The identification and detection of cancer biomarkers in early stages is an important issue for the therapy of cancer. However, most methods are time-consuming and have limited sensing sensitivity and specificity. In this work, we prepared a novel plasmonic multilayered core-shell-satellite nanostructure (Au@Ag@SiO2-AuNP) consisting of a gold nanosphere with a silver coating core (Au@Ag), an ultrathin continuous silica (SiO2) shell, and a high coverage of gold nanosphere (AuNP) satellites. The Au@Ag core is a prominent surface enhanced Raman scattering (SERS) platform, and the thin SiO2 layer exhibits a long-range plasmon coupling between the Au@Ag core to the AuNP satellites, further leading to enhanced Raman scattering. Meanwhile, the outer AuNP satellites have a high biocompatibility and long-term stability. Combining the above advantages, the well-designed metallic nanoassemblies would be a promising candidate for SERS-based applications in biochemistry. For specific detection of alpha-fetoprotein (AFP), we utilized the SERS-active core-shell-satellite nanostructures modified with AFP antibody as immune probes and nitrocellulose membrane (NC) stabilized captured anti-AFP antibodies as solid substrate. To improve the detection performance, we further systematically optimized the parameters, including the silver coating thickness of the Au@Ag core and the density and size of the satellite AuNPs. Under the optimized conditions, AFP could be detected by the SERS-based sandwich immunoassay with an ultralow detection limit of 0.3 fg/mL, and the method exhibited a wide linear response from 1 fg/mL to 1 ng/mL. The limit of detection (LOD) was considerably lower than conventional methods in the literature. This work relies on the unique Au@Ag@SiO2-AuNP nanostructures as the immune probe develops a new outlook for the application of multilayered nanoassemblies and demonstrates the great potential in early tumor marker detection.

A novel ECL sensor based on a boronate affinity molecular imprinting technique and functionalized SiO2@CQDs/AuNPs/MPBA nanocomposites for sensitive determination of alpha-fetoprotein.

In this work, a boronate-affinity sandwich electrochemiluminescence (ECL) sensor was constructed to detect alpha-fetoprotein (AFP) based on a multiple signal amplification strategy. Gold nanoparticles (AuNPs) were utilized and modified on the surface with chitosan in order to facilitate electron transfer. The composite of the molecularly imprinted polymer (MIP) enhanced the selectivity of alpha-fetoprotein detection. 4-mercaptophenylboronic acid (MPBA) was used as the tracing tag for capture of alpha-fetoprotein. SiO2 nanoparticles carried carbon quantum dots (CQDs) labeled with gold nanoparticles and produced an ECL signal. Under the optimum experimental conditions, the linear range for alpha-fetoprotein was between 0.001 and 1000 ng/mL with a correlation coefficient of 0.9952, and the detection limit was 0.0004 ng/mL (S/N = 3). This proposed ECL sensor displayed several advantages, including outstanding selectivity, fine reproducibility, high sensitivity, low detection limit and wide linear range. Furthermore, the newly constructed boronate-affinity sandwich ECL sensor was successfully applied to the determination of alpha-fetoprotein in serum samples, indicating great potential for application in clinical diagnostics.

Ultrasensitive label- and amplification-free photoelectric protocols based on sandwiched layer-by-layer plasmonic nanocomposite films for the detection of alpha-fetoprotein.

A label- and amplification-free photoelectric immunosensor based on well-defined layer-by-layer sandwich-structured AuNP/TNW/AuNP composite is proposed for direct and ultrasensitive detection of α-fetoprotein (AFP). The AuNP/TNW/AuNP composite is produced by assembling an Au nanoparticle underlayer and anatase TiO2 nanowires (TNW) onto the FTO substrate, followed by decorating Au nanoparticles onto the TNW surface, through a simple sputtering and hydrothermal process. The resulting AuNP/TNW/AuNP electrode exhibits a 14-fold and 2-fold enhancement in photocurrent density under simulated sunlight compared with that of bare TNW and AuNP/TNW, respectively, which benefits from the SPR-induced photoabsorption increment and charge separation improvement in Au nanoparticle and interfacial charge transfer promotion at the TiO2/substrate interface in the Au underlayer. As a proof of concept, the AFP antigen can be quantitatively detected by the proposed AuNP/TNW/AuNP coupled with anti-AFP through the analysis of the photocurrent change. This novel AFP photoelectric immunosensor exhibited sensitive detection of AFP with an ultrahigh sensitivity of 0.001 ng mL-1 and good specific selectivity. Moreover, the practical determination of AFP in human serum is also investigated, demonstrating its applicability and potential attraction for clinical tests and disease diagnosis.

Direct Monitoring of Fucosylated Glycopeptides of Alpha-Fetoprotein in Human Serum for Early Hepatocellular Carcinoma by Liquid Chromatography-Tandem Mass Spectrometry with Immunoprecipitation.

PURPOSE: Alpha-fetoprotein (AFP) is a widely used serological marker that is associated with hepatocellular carcinoma (HCC). Although the level of AFP is increased in HCC, its sensitivity for diagnosis is poor because AFP levels are also increased in liver diseases. Changes in glycoform, especially fucosylation, have been reported to be associated with the development of HCC. EXPERIMENTAL DESIGN: The authors introduce the monitoring of fucosylated glycopeptides by liquid chromatography (LC)-mass spectrometry (MS) combined with immunoprecipitation, where glycan-cleaved fragments with an amino acid sequence are used as transitions. Furthermore, neuraminidase for desialylation is useful to improve the MS detection limit (limit of detection [LOD] <2 ng mL-1 ) in 0.1 µL of serum. RESULTS: The performance of the relative percentage of fucosylated AFP (AFP-fuc%) for differentiating between early HCC and cirrhosis is better than that of serum AFP levels as indicated by a greater area under the receiver operator characteristic curve (area under the curve = 0.962 vs. 0.628) and sensitivity (92.3% vs. 53.9%), respectively. Furthermore, the inter- and intraday repeatability of AFP-fuc% in serum is less than 2.1%. CONCLUSIONS AND CLINICAL RELEVANCE: These findings suggest that glycopeptide-based LC-MS/MS is a promising method and that AFP-fuc% is a clinically useful parameter for differentiating between early HCC and liver cirrhosis.

Clinical characteristics and treatments of patients with alpha-fetoprotein producing gastric carcinoma.

Alpha-fetoprotein (AFP) is a well-known tumor marker of hepatic carcinoma and yolk sac tumor. Alpha-fetoprotein producing gastric carcinoma (AFPGC) is a rare type of gastric cancer with high malignancy and poor prognosis, which make it different from other types of gastric cancer. This rare gastric cancer patient subgroup is likely frequently misdiagnosed which may be related to lack of knowledge of the disease. The purpose of this article is to summarize the mechanism of AFP positive gastric cancer, classification, biological behavior and treatment, in order to assist clinical practitioners to detect AFPGC earlier and treat it better. Previous studies have showed that AFPGC has a complex pathophysiology mechanism. AFPGC is more aggressive and characterized by stronger proliferation, neovascularization, lymphatic invasion and distant metastasis. Furthermore, so far there has been no standard treatment for patients with AFPGC. Nevertheless, our present study summarizes some effective treatments based on previous research outcome. In conclusion, the present study demonstrates that the importance of detecting AFP routinely in serum and tissues in gastric cancer cases, which will greatly improve the diagnosis rate of AFPGC, and in regards to treatment, surgery, chemotherapy, targeted therapy and interventional treatment may have positive impacts on AFPGC treatment outcome. However, further study with a larger sample is required to confirm the reliability and validity of these methods.

Dual-wavebands-resolved electrochemiluminescence multiplexing immunoassay with dichroic mirror assistant photomultiplier-tubes as detectors.

A dual-wavebands-resolved electrochemiluminescence (ECL) multiplexing immunoassay (MIA) was developed for simultaneously detecting alpha fetoprotein antigen (AFP) in greenish waveband with CdSe550 (λmax = 550 nm) nanocrystals (NCs) and carbohydrate antigen 125 (CA125) in near-infrared waveband with CdTe790 (λmax = 790 nm) NCs via one-pot ECL reaction, in which dichroic mirror works as a key part to reflect ECL from CdSe550 to one photomultiplier-tube (PMT) and transmit ECL from CdTe790 to the other PMT for dual-wavebands-resolved assay. The proposed ECL-MIA strategy was capable of simultaneously determining AFP with linearly response from 5 pg/mL to 5 ng/mL and limit of detection at 1 pg/mL, and CA125 with linearly response from 5 mU/mL to 1 U/mL and limit of detection at 1 mU/mL, with desired specificity and without obvious energy-transfer between ECL tags. The dichroic mirror assistant ECL setup is easy-to-assemble and convenient for the popularization of color-resolved multiplexing ECL assay.

A graphene oxide-based label-free electrochemical aptasensor for the detection of alpha-fetoprotein.

A label-free method for the determination of alpha-fetoprotein (AFP) was successfully developed by graphene oxide (GO)-based electrochemical aptasensor. This aptasensor was constructed by covalently immobilizing NH2-functionalized AFP-specific aptamer on GO with plenty of carboxylic groups. Cyclic voltammetry (CV) and electrochemical impedance spectra (EIS) analysis were carried out to investigate the practicability of the fabrication procedures. Fourier transform infrared spectra (FTIR), Raman, atomic force microscopy (AFM) and scanning electron microscope (SEM) were performed to indicate the changes of the sensing interface. CV was used to detect the signal change of the aptasensor. Peak current of CVs changed before and after incubating the aptasensor with different concentration of AFP solution. The changes of peak current were proportional to the AFP concentration, with a wide linear range of 0.01-100 ng mL-1, a low detection limit of 3 pg mL-1 and good specificity. The proposed simple and cost-effective label-free strategy is promising for the determination of clinical biomarkers such as AFP.

Sandwich-type electrochemical immunoassay based on Co3O4@MnO2-thionine and pseudo-ELISA method toward sensitive detection of alpha fetoprotein.

In this study, a sensitive sandwich-type electrochemical immunosensor was fabricated for the detection of alpha fetoprotein (AFP) based on Co3O4@MnO2-thionine (Co3O4@MnO2-Th) and the screen printing technique. Meanwhile, the pseudo enzyme-linked immunosorbent assay (pseudo-ELISA) method was applied in fabricating the immunosensor. Screen-printed carbon electrode (SPCE) was applied for achieving the detection of AFP. Simultaneously, the amino functionalized Co3O4@MnO2-Th was employed as secondary label and could greatly improve the electrochemical response signal, which was beneficial for detecting AFP. Differential pulse voltammetry (DPV) was applied for the detection of AFP and electrochemical impedance spectroscopy (EIS) confirmed the successful fabrication of the immunosensor. Under optimal conditions, the immunosensor exhibited a linear response toward AFP in the range of 0.001-100 ng/mL, with a low detection limit of 0.33 pg/mL. Simultaneously, the proposed immunosensor displayed acceptable selectivity, excellent stability and well reproducibility. Furthermore, this proposed strategy may open up new ideas and find many potential applications in the detection of other tumor markers.

Sandwich-type electrochemical immunosensor based on Au@Ag supported on functionalized phenolic resin microporous carbon spheres for ultrasensitive analysis of α-fetoprotein.

Signal amplification is crucial for obtaining low detection limits in electrochemical immunosensor. In this work, we developed a novel signal amplification strategy using Au@Ag nanoparticles loaded by polydopamine functionalized phenolic resin microporous carbon spheres (Au@Ag/PDA-PR-MCS). Phenolic resin microporous carbon spheres (PR-MCS) possesses uniform size and a large surface area (1656.8 m2 g-1). Polydopamine (PDA) functionalized phenolic resin microporous carbon spheres (PDA-PR-MCS) retains the advantages of PR-MCS and possesses strong adsorption ability. With the unique structure of PDA-PR-MCS, it not only improves the loading capacity and dispersity of Au@Ag nanoparticles (Au@Ag NPs), but also enhances the stability for the combination of the Au@Ag NPs by chemical absorption between Au@Ag NPs and -NH2 of PDA. The Au@Ag/PDA-PR-MCS exhibits extraordinary electrocatalytic activity towards reduction of hydrogen peroxide (H2O2) to make the electrochemical response more sensitive. Furthermore, Au NPs with good biocompatibility and excellent conductivity were electrodeposited on the surface of electrode, which was used as a sensing platform to immobilize primary antibody (Ab1) and accelerate the electron transfer on the electrode interface. Herein, the designed immunosensor provided a broad linear range from 20 fg/mL to 100 ng/mL for alpha fetoprotein (AFP) detection and a low detection limit of 6.7 fg/mL (signal-to-noise ratio of 3) under optimal experimental conditions. Moreover, the excellent performance in detection of human serum samples indicated that the proposed immunosensor will provide promising applications in clinical monitoring of AFP.

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.

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.

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.

Proximity hybridization-regulated electrogenerated chemiluminescence bioassay of α-fetoprotein via target-induced quenching mechanism.

A proximity hybridization-regulated electrogenerated chemiluminescence (PLA-ECL) bioassay was developed for the detection of α-fetoprotein (AFP) on basis of the sensitization of gold nanoparticles (AuNPs) and target-induced quenching mechanism. Ru(bpy)32+ was used as ECL signal while ferrocene (Fc) was used as ECL quencher. Ru(bpy)32+ was electrostatically adsorbed into the AuNPs/Nafion film prepared by casting the mixture of Nafion and AuNPs onto the surface of glassy carbon electrode (GCE) to form an ECL platform (Ru(bpy)32+/AuNPs/Nafion/GCE), which displayed strong ECL emissions. A recognition platform was fabricated by self-assembling a capture DNA via thiol-gold bond on the surface of Ru(bpy)32+/AuNPs/Nafion/GCE. After sandwich immunoassay and proximity hybridization assay among capture DNA, AFP, a pair of antibody-oligonucleotide conjugates and a signal probe (DNA-Fc), Fc in DNA-Fc was brought close to the surface of electrode in conjunction with target induced ECL quenching. The ECL intensity decreased with the increasing concentration of the AFP and AFP was monitored with a linear range of 0.05-50ng/mL along with a detection limit of 0.04ng/mL. The ECL bioassay is successfully applied to the detection of AFP in serum samples with one-step recognition, short operating time and good accuracy. This method displays great potential for point-of-care testing and commercial application.

Purification and characterization of a bioactive alpha-fetoprotein produced by HEK-293 cells.

Alpha-fetoprotein (AFP) is a biomarker that is used to diagnose hepatocellular carcinoma (HCC) and can promote malignancy in HCC. AFP is an important target in the treatment of liver cancer. To obtain enough AFP to screen for AFP inhibitors, we expressed and purified AFP in HEK-293 cells. In the present study, we produced AFP in the cells and harvested highly pure rAFP (or recombinant expression AFP in HEK-293 cells). We also analysed the bioactivity of rAFP and found that rAFP promoted growth of the human HCC cells, antagonize paclitaxel inhibition of HCC cell proliferation, suppress expression of active caspase-3, and promote expression of Ras and survivin. This study provides a method to produce significant amounts of AFP for use in biochemical assays and functional studies and to screen AFP inhibitors for use in HCC therapy.

A sensitive label-free immunosensor for detection α-Fetoprotein in whole blood based on anticoagulating magnetic nanoparticles.

Accurate values of tumor markers in blood play an especially important role in the diagnosis of illness. Here, based on the combination of three techniques include anticoagulant technology, nanotechnology and biosensing technology, a sensitive label-free immunosensor with anti-biofouling electrode for detection α-Fetoprotein (AFP) in whole blood was developed by anticoagulating magnetic nanoparticles. The obtained products of Fe3O4-ɛ-PL-Hep nanoparticles were characterized by fourier transform infrared (FT-IR) spectra, transmission electron microscopy (TEM), ζ-potential and vibrating sample magnetometry (VSM). Moreover, the blood compatibility of anticoagulating magnetic nanoparticles was characterized by in vitro coagulation tests, hemolysis assay and whole blood adhesion tests. Combining the anticoagulant property of heparin (Hep) and the good magnetism of Fe3O4, the Fe3O4-ɛ-PL-Hep nanoparticles could improve not only the anti-biofouling property of the electrode surface when they contact with whole blood, but also the stability and reproducibility of the proposed immunosensor. Thus, the prepared anticoagulating magnetic nanoparticles modified immunosensor for the detection of AFP showed excellent electrochemical properties with a wide concentration range from 0.1 to 100ng/mL and a low detection limit of 0.072ng/mL. Furthermore, five blood samples were assayed using the developed immunosensor. The results showed satisfactory accuracy with low relative errors. It indicated that our developed immunoassay was competitive and could be potentially used for the detection of whole blood samples directly.