Structural characteristics of alpha-fetoprotein, including N-glycosylation, metal ion and fatty acid binding sites.

Alpha-fetoprotein (AFP), a serum glycoprotein, is expressed during embryonic development and the pathogenesis of liver cancer. It serves as a clinical tumor marker, function as a carcinogen, immune suppressor, and transport vehicle; but the detailed AFP structural information has not yet been reported. In this study, we used single-particle cryo-electron microscopy(cryo-EM) to analyze the structure of the recombinant AFP obtained a 3.31 Å cryo-EM structure and built an atomic model of AFP. We observed and identified certain structural features of AFP, including N-glycosylation at Asn251, four natural fatty acids bound to distinct domains, and the coordination of metal ions by residues His22, His264, His268, and Asp280. Furthermore, we compared the structural similarities and differences between AFP and human serum albumin. The elucidation of AFP's structural characteristics not only contributes to a deeper understanding of its functional mechanisms, but also provides a structural basis for developing AFP-based drug vehicles.

Application of Machine Learning Techniques to Assess Alpha-Fetoprotein at Diagnosis of Hepatocellular Carcinoma.

Hepatocellular carcinoma (HCC) is the most common primary liver tumor and is associated with high mortality rates. Approximately 80% of cases occur in cirrhotic livers, posing a significant challenge for appropriate therapeutic management. Adequate screening programs in high-risk groups are essential for early-stage detection. The extent of extrahepatic tumor spread and hepatic functional reserve are recognized as two of the most influential prognostic factors. In this retrospective multicenter study, we utilized machine learning (ML) methods to analyze predictors of mortality at the time of diagnosis in a total of 208 patients. The eXtreme gradient boosting (XGB) method achieved the highest values in identifying key prognostic factors for HCC at diagnosis. The etiology of HCC was found to be the variable most strongly associated with a poorer prognosis. The widely used Barcelona Clinic Liver Cancer (BCLC) classification in our setting demonstrated superiority over the TNM classification. Although alpha-fetoprotein (AFP) remains the most commonly used biological marker, elevated levels did not correlate with reduced survival. Our findings suggest the need to explore new prognostic biomarkers for individualized management of these patients.

Electrochemical immunosensor based on Fe3O4/MWCNTs-COOH/AuNPs nanocomposites for trace liver cancer marker alpha-fetoprotein detection.

An electrochemical biosensor based on iron tetroxide (Fe3O4)/carboxylated carbon nanotubes (MWCNTs-COOH)/gold nanoparticles (AuNPs) was designed for the detection of alpha-fetoprotein (AFP), which is often used as an important indicator for the early clinical diagnosis of liver cancer markers. The Fe3O4/MWCNTs-COOH nanocomposite was synthesized by a solvothermal method and it combined with gold nanoparticles (AuNPs) deposited at the constant potential on a glassy carbon electrode to form Fe3O4/MWCNTs-COOH/AuNPs, which intensifies the electrical signal while the large active sites enable more stable immobilization of the AFP monoclonal antibodies on the electrode. The electrochemical performance of Fe3O4/MWCNTs-COOH/AuNPs was investigated in detail and the electrochemical response signal after the immune reaction with the AFP antigen-antibody was recorded. The peak current Ip of the response signal is linearly proportional to the lgcAFP in the range of 1 pg mL-1-10 µg mL-1, with a detection limit of 1.09034 pg mL-1 and good performance in clinical sample testing. The proposed sensor has shown great application and development potential in clinical medicine field.

Detection of Alpha Fetoprotein Based on AIEgen Nanosphere Labeled Aptamer Combined with Sandwich Structure of Magnetic Gold Nanocomposites.

As a biomarker, alpha-fetoprotein (AFP) is valuable for detecting some tumors in men, non-pregnant women, and children. However, the detection sensitivity in some methods needs to be improved. Therefore, developing a simple, reliable, and sensitive detection method for AFP is important for non-malignant diseases. An aptamer binding was developed based on aggregation-induced emission luminogen (AIEgen) nanosphere labeled with Fe3O4@MPTMS@AuNPs. AFP was detected with a sandwich structure of AuNPs magnetic composite particles. An aggregation-induced emission (AIE) molecule and polystyrene (PS) nanosphere complex were assembled, enhancing the fluorescence and improving the sensitivity of detection. The limit of detection (LOD) was at a given level of 1.429 pg/mL, which can best be achieved in serum samples. Finally, the results obtained showed the complex to be promising in practical applications.

Early alpha-fetoprotein response predicts prognosis of immune checkpoint inhibitor and targeted therapy for hepatocellular carcinoma: a systematic review with meta-analysis.

BACKGROUND: The prognostic value of alpha-fetoprotein (AFP) response for efficacy of targeted therapy or immune checkpoint inhibitors (ICIs) has not been established. The purpose of this meta-analysis is to elucidate the relationship between AFP response and survival outcomes in hepatocellular carcinoma (HCC) patients who received targeted therapy or ICIs. METHODS: The hazard ratio (HR) with 95% confidence interval (CI) was used to evaluate the relationship between AFP response and overall survival (OS)/progression-free survival (PFS). RESULTS: Twenty-six articles containing 3056 HCC patients were finally included in the study. The pooled results showed that after targeted therapy or ICIs, patients with decrease in AFP had better prognosis (OS:HR = 0.48, 95%CI:0.40-0.56; PFS:HR = 0.39, 95%CI:0.33-0.46), while patients with increase in AFP had worse prognosis (OS:HR = 2.30, 95%CI:1.82-2.89; PFS:HR = 2.34, 95%CI = 1.69-3.24). Subgroup analysis revealed that compared to AFP decrease >50%, AFP decrease >20% can better predict the prognosis of patients who received targeted therapy (OS:HR = 0.51, 95%CI:0.41-0.62; PFS:HR = 0.39, 95%CI:0.30-0.51) or ICIs treatment (OS:HR = 0.34, 95%CI:0.16-0.71; PFS:HR = 0.22, 95%CI:0.10-0.47), and 8 weeks after targeted therapy may be the appropriate time point for AFP assessment. CONCLUSION: AFP decrease >20% within 8 weeks may be the appropriate definition for early AFP response which probably works best in predicting the efficacy of therapy. REGISTRATION: The review was not registered.

High-Risk Pregnancy Is Associated With Increased Alpha-Fetoprotein Concentrations in the Amniotic Fluid and Foal Plasma.

This study aimed to determine alpha-fetoprotein (AFP) concentrations in amniotic fluid, plasma of mares and respective foals: carrying normal pregnancies and delivering healthy foals (n = 20; Group 1); carrying apparently normal pregnancies and delivering sick foals (n = 15; Group 2); carrying high-risk pregnancies and delivering sick foals (n = 14; Group 3). High-risk pregnancy was defined by a history of premature udder development/lactation or increased of the combined thickness of the uterus and placenta, or vulvar discharge and/or mares' systemic illness. Sick foals were affected by neonatal encephalopathy, sepsis, prematurity/dysmaturity, or hypoxic-ischemic encephalopathy. Based on histological examination of the chorioallantois, AFP trend was analyzed in pregnancies with pathologic (PFM) and normal fetal membranes (NFM). Concentrations of AFP were measured using a commercially available immunoassay previously validated for horses. Mares' plasma AFP did not change during the last 15-20 days of pregnancy in the three groups, and there was no difference among them. Amniotic fluid AFP was higher in Group 3 (P = .014). Foals' plasma AFP concentration was higher from birth to 72hours in foals of Group 2 and 3 than in healthy ones, and foals of Group 3 had the highest value. The strong association (r = 0.84; P < .0001) between AFP in amniotic fluid and foals' plasma at birth is likely due to the presence of AFP in fetal urine. AFP was higher in pregnancy with PFM than with NFM in mare's plasma at admission (P = .031), amniotic fluid (P = .004), foal's plasma at birth (P = .002), at 24 (P = .005) and at 72 hours of life (P = .004). AFP is higher in pregnancy with histopathological lesions of the chorioallantois providing the evidence of the differences between pregnancy with a normal placental barrier and the more compromised ones. The increased AFP concentration in the amniotic fluid and plasma of high-risk foals suggests upregulation.

Quantitative Detection of Gastrointestinal Tumor Markers Using a Machine Learning Algorithm and Multicolor Quantum Dot Biosensor.

This work was to explore the application value of gastrointestinal tumor markers based on gene feature selection model of principal component analysis (PCA) algorithm and multicolor quantum dots (QDs) immunobiosensor in the detection of gastrointestinal tumors. Based on the PCA method, the neighborhood rough set algorithm was introduced to improve it, and the tumor gene feature selection model (OPCA) was established to analyze its classification accuracy and accuracy. Four kinds of coupled biosensors were fabricated based on QDs, namely, 525 nm Cd Se/Zn S QDs-carbohydrate antigen 125 (QDs525-CA125 McAb), 605 nm Cd Se/Zn S QDs-cancer antigen 19-9 (QDs605-CA19-9 McAb), 645 nm Cd Se/Zn S QDs-anticancer embryonic antigen (QDs 645-CEA McAb), and 565 nm Cd Se/Zn S QDs-anti-alpha-fetoprotein (QDs565-AFP McAb). The quantum dot-antibody conjugates were identified and quantified by fluorescence spectroscopy and ultraviolet absorption spectroscopy. The results showed that the classification precision of OPCA model in colon tumor and gastric cancer datasets was 99.52% and 99.03%, respectively, and the classification accuracy was 94.86% and 94.2%, respectively, which were significantly higher than those of other algorithms. The fluorescence values of AFP McAb, CEA McAb, CA19-9 McAb, and CA125 McAb reached the maximum when the conjugation concentrations were 25 µg/mL, 20 µg/mL, 30 µg/mL, and 30 µg/m, respectively. The highest recovery rate of AFP was 98.51%, and its fluorescence intensity was 35.78 ± 2.99, which was significantly higher than that of other antigens (P < 0.001). In summary, the OPCA model based on PCA algorithm can obtain fewer feature gene sets and improve the accuracy of sample classification. Intelligent immunobiosensors based on machine learning algorithms and QDs have potential application value in gastrointestinal gene feature selection and tumor marker detection, which provides a new idea for clinical diagnosis of gastrointestinal tumors.

Alpha-Fetoprotein (AFP) and AFP-L3 Is Most Useful in Detection of Recurrence of Hepatocellular Carcinoma in Patients after Tumor Ablation and with Low AFP Level.

Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver and is a leading cause of mortality worldwide. While there are many risk factors for HCC including alcohol, obesity, and diabetes, hepatitis B virus (HBV) and hepatitis C virus (HCV) infection still account for the majority of HCC worldwide. Globally, HBV is the leading risk factor for HCC. Patients with chronic hepatitis B (CHB) and advanced liver disease are at high risk for HCC. Screening for HCC is done routinely with ultrasound with or without alpha-fetoprotein (AFP) at six-month intervals. The combination of ultrasound and AFP has been shown to provide some additional detection of 6-8% of cases compared to ultrasound alone; however, this also increases false-positive results. This is because AFP can be elevated not only in the setting of HCC, but also in chronic hepatitis, liver cirrhosis, or ALT flare in CHB, which limits the specificity of AFP. AFP-L3 is a subfraction of AFP that is produced by malignant hepatocytes. The ratio of AFP-L3 to total AFP is reported as a percentage, and over 10% AFP-L3 is consistent with a diagnosis of HCC. Here, we review five cases of patients with CHB, cirrhosis, and HCC, and their levels of AFP and the AFP-L3% at various stages of disease including ALT flare, cirrhosis, initial diagnosis of HCC, and recurrence of HCC. These cases emphasize the utility of AFP-L3% in identifying early, new or recurrent HCC prior to the presence of imaging findings.

AFP-L3 for the diagnosis of early hepatocellular carcinoma: A meta-analysis.

BACKGROUND: The present study aimed to systematically evaluate the diagnostic value of an isoform of alpha-fetoprotein (AFP), AFP-L3, for early hepatocellular carcinoma (HCC) by a meta-analysis. METHODS: Diagnostic reports of AFP-L3% in early HCC were searched in the PubMed, Web of Science, Cochrane Library, and Embase databases up to December 2019. The retrieved literature was reviewed, and eligible articles were selected. Data were extracted from the eligible articles, and the risk of bias was evaluated according to the Quality Assessment of Diagnostic Accuracy Studies scale. Statistical analyses were conducted by MetaDiSc1.4 and RevMan5.3 software. The sensitivities, specificities, and diagnostic odds ratios were pooled. The summary receiver operating characteristic curve was drawn, and the area under the curve was calculated. RESULTS: Six studies with acceptable quality were included in the meta-analysis involving 2447 patients. No threshold effect was observed among the 6 studies, but there was obvious heterogeneity. The pooled sensitivity, specificity, and positive and negative likelihood ratios of AFP-L3% for the diagnosis of early HCC were 0.34 (95% CI 0.30-0.39, P < .0001), 0.92 (95% CI 0.91-0.93, P < .0001), 4.46 (95% CI 2.94-6.77, P = .0033), and 0.71 (95% CI 0.61-0.82, P = .0004), respectively. The diagnostic odds ratio was 6.78 (95% CI 4.02-11.44, P = .0074). The the area under the curve of the summary receiver operating characteristic was 0.755 (95% CI 0.57-0.94). CONCLUSION: AFP-L3% has high specificity but low sensitivity for diagnose early HCC, suggesting that AFP-L3% is more valuable for excluding HCC in conditions with elevated AFP than for diagnosing early HCC. In addition, a hypersensitive detection method can improve the diagnostic accuracy of AFP-L3% for early HCC.

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.

Caracterización clínica epidemiológica de los defectos congénitos del tracto genitourinario / Clinical-epidemiological Characterization of Congenital Defects of the Urinary Tract

Introducción: La malformación congénita es una alteración estructural de un órgano o parte de este, que sucede como consecuencia de una alteración durante la morfogénesis y que puede corresponder a defectos menores o mayores, únicos, múltiples o asilados. Objetivo: Caracterizar clínica y epidemiológicamente los defectos congénitos del tracto genitourinario. Métodos: Se realizó un estudio observacional retrospectivo en 453 fetos con diagnóstico por ecografía bidimensional de defecto congénito del tracto genitourinario. Para ello se tomó en cuenta la edad materna y gestacional al diagnóstico, antecedentes personales y familiares de interés clínico genético y la conducta terapéutica según criterio médico. Los datos fueron procesados mediante el Programa Microsoft Excel 2010, aplicándoles el método porcentual y los resultados expuestos en forma de tablas. Resultados: El 75,27 por ciento de las anomalías se presentaron en gestantes con edad materna entre 20 y 34 años. El 62,6 por ciento de los defectos fueron diagnosticados en el segundo trimestre del embarazo, con predominio del sexo masculino en los fetos estudiados. La pielocaliectacia (27,3 por ciento) resultó la principal causa de evaluación inicial seguida de la hidronefrosis (26,2 por ciento). Hubo correlación entre el diagnóstico definitivo por ultrasonido y el resultado de la necropsia. Los casos en seguimiento no presentaron ninguna complicación y solo en nueve gestantes se registró interrupción anterior por defectos genitourinarios. Conclusiones: Se constató aumento progresivo del diagnóstico de anomalías congénitas del tracto genitourinario por años de estudio, las pielocaliectacias bilaterales resultaron la principal causa de evaluación inicial(AU)

Introduction: A congenital malformation is a structural alteration of an organ or part of it, which happens as a consequence of an alteration during morphogenesis and may correspond to minor or major, unique, multiple or isolated defects. Objective: To characterize, clinically and epidemiologically, the congenital defects of the genitourinary tract. Methods: A retrospective observational study was carried out in 453 fetuses diagnosed with a congenital defect of the genitourinary tract by using two-dimensional ultrasound. For this, we considered the maternal and gestational ages at diagnosis, personal and family history of clinical genetic interest, and therapeutic behavior according to medical criteria. The data was processed using the program Microsoft Excel 2010, applying the percentage method and the results presented in tables. Results: 75.27 percent of the anomalies occurred in pregnant women with maternal ages between 20 and 34 years. 62.6 percent of the defects were diagnosed at second trimester of pregnancy, with a predominance of the male sex in the studied fetuses. Pyelocaliectasis (27.3 percent) was the main cause of initial evaluation, followed by hydronephrosis (26.2 percent). There was a correlation between the definitive ultrasound diagnosis and the outcome of the autopsy. The follow-up cases did not present any complications and only nine pregnant women presented a previous interruption due to genitourinary defects. Conclusions: A progressive increase in the diagnosis of congenital anomalies of the genitourinary tract was verified for years of study. Bilateral pyelocaliectasis was the main cause of initial evaluation(AU)

Intensive and Persistent Chemiluminescence System Based on Nano-/Bioenzymes with Local Tandem Catalysis and Surface Diffusion.

A chemiluminescence (CL) system with long persistent and intensive emission is essential for accurate CL quantitative analysis and imaging assay. However, with most known CL systems being flash-type, it is still a great challenge to develop long-lasting CL systems. Here, by combining an iron porphyrin metal-organic frameworks (FePorMOFs) based peroxidase mimic with natural glucose oxidase (GOx), an intensive and persistent CL system is presented on the basis of local tandem catalysis and surface diffusion of the nano-/bioenzymes (FePorMOF/GOx). FePorMOF synthesized by iron porphyrin linker and zirconium ion node possesses high peroxidase catalytic activity and stability. Using luminol and glucose as substrate, the FePorMOF/GOx CL system can produce intensive CL emission containing a plateau period of 7.5 h. The strong CL signal is due to the local tandem generation and reaction of H2O2 by GOx and FePorMOF, which avoids the diffusion-limited kinetics and leads to a high catalytic efficiency of the nano-/bioenzymes. On the other hand, the long persistent CL emission is attributed mainly to the enzymatic reaction-controlled H2O2 supply and surface diffusion-controlled CL reaction. The proposed CL system is explored for CL imaging sensing of glucose and homogeneous immunoassay of α-fetoprotein. The nano-/bioenzymes CL system exhibits intensive and long constant CL emission in physiological condition, showing promising applications in real-time bioassay and bioimaging.

Dual-Aptamer Modified Graphene Field-Effect Transistor Nanosensor for Label-Free and Specific Detection of Hepatocellular Carcinoma-Derived Microvesicles.

Cancerous microvesicles (MVs), which are heterogeneous membrane-bound nanovesicles shed from the surfaces of cancer cells into the extracellular environment, have been widely recognized as promising "biofingerprints" for various cancers. High-performance identification of cancerous MVs plays a vital role in the early diagnosis of cancer, yet it is still technically challenging. Herein, we report a gold nanoparticle (AuNP)-decorated, dual-aptamer modified reduced graphene oxide (RGO) field-effect transistor (AAP-GFET) nanosensor for the label-free, specific, and sensitive quantification of HepG2 cell-derived MVs (HepG2-MVs). After GFET chips were fabricated, AuNPs were then decorated on the RGO surface. For specific capture and detection of HepG2-MVs, both sulfhydrylated HepG2 cell specific TLS11a aptamer (AptTLS11a) and epithelial cell adhesion molecule aptamer (AptEpCAM) were immobilized on the AuNP surface through an Au-S bond. This developed nanosensor delivered a broad linear dynamic range from 6 × 105 to 6 × 109 particles/mL and achieved a high sensitivity of 84 particles/µL for HepG2-MVs detection. Moreover, this AAP-GFET platform was able to distinguish HepG2-MVs from other liver cancer-related serum proteins (such as AFP and CEA) and MVs derived from human normal cells and other cancer cells of lung, pancreas, and prostate, suggesting its excellent method specificity. Compared with those modified with a single type of aptamer alone (AptTLS11a or AptEpCAM), such an AAP-GFET nanosensor showed greatly enhanced signals, suggesting that the dual-aptamer-based bio-nano interface was uniquely designed and could realize more sensitive quantification of HepG2-MVs. Using this platform to detect HepG2-MVs in clinical blood samples, we found that there were significant differences between healthy controls and hepatocellular carcinoma (HCC) patients, indicating its great potential in early HCC diagnosis.

Simultaneous Detection of Multiple Tumor Markers in Blood by Functional Liquid Crystal Sensors Assisted with Target-Induced Dissociation of Aptamer.

Multiplex detection of tumor markers in blood with high specificity and high sensitivity is critical to cancer diagnosis, treatment, and prognosis. Herein, we demonstrate a strategy for simultaneous detection of multiple tumor markers in blood by functional liquid crystal (LC) sensors assisted with target-induced dissociation (TID) of an aptamer for the first time. Magnetic beads (MBs) coated with an aptamer (apt1) are employed to specifically capture target proteins in blood. After incubation of the obtained protein-coated MBs with duplexes of another aptamer (apt2) and signal DNA, sandwich complexes of apt1/protein/apt2 are formed on the MBs due to specific recognition of target proteins by apt2, which induces release of signal DNA into the aqueous solution. Subsequently, signal DNA is specifically recognized by highly sensitive DNA-laden LC sensors. Using this strategy, a 3D printed optical cell was employed to enable simultaneous detection of multiple tumor markers such as carcinoembryonic antigen (CEA), alpha-fetoprotein (AFP), and prostate specific antigen (PSA) with high specificity and high sensitivity. Overall, this effective and low-cost multiplex approach takes advantage of the easy separation of MBs, high specificity of aptamer-based recognition, and high sensitivity of functional LC sensors. Plus, it offers a performance that is competitive to that of commercial ELISA kits without potential interference from hemolysis, which makes it very promising in multiplex detection of tumor markers in clinical applications.

Identification of an HLA-A*24:02-restricted α-fetoprotein signal peptide-derived antigen and its specific T-cell receptor for T-cell immunotherapy.

Hepatocellular carcinoma (HCC) is the most common type of liver cancer with limited treatments. Asia has the highest HCC incidence rates; China accounts for over 50% of all HCC cases worldwide. T-cell receptor (TCR) -engineered T-cell immunotherapies specific for human leukocyte antigen (HLA) -A*02:01-restricted α-fetoprotein (AFP) peptide have shown encouraging results in clinics. HLA-A*24:02 is more common than HLA-A*02:01 in Asian countries, including China. Here we identified a novel HLA-A*24:02-restricted peptide KWVESIFLIF (AFP2-11 ) located in AFP signal peptide domain by mass spectrometric analysis of HLA-bound peptides from HepG2 cells. A TCR (KWV3.1) specific for AFP2-11 -HLA-A*24:02 was isolated from peripheral blood mononuclear cells of a healthy donor. The binding affinity of soluble KWV3.1 to its antigen was determined to be ~55 µm, within the affinity range of native TCRs for self-antigens. KWV3.1-transfected T cells could specifically activate and kill AFP2-11 pulsed T2-A24 cells and AFP+  HLA-A*24:02+ tumor cell lines, demonstrating that AFP2-11 can be naturally presented on the surface of AFP+ tumor cell lines. The newly identified antigenic peptide can provide a novel target for immunotherapeutic strategies for patients with AFP+  HLA-A*24:02+ HCC.

Calorimetric lateral flow immunoassay detection platform based on the photothermal effect of gold nanocages with high sensitivity, specificity, and accuracy.

BACKGROUND: Lateral flow assays (LFA) play an increasingly important role in the rapid detection of various pathogens, pollutants, and toxins. PURPOSE: To overcome the drawbacks of low sensitivity and poor quantification in LFA, we developed a new calorimetric LFA (CLFA) using gold nanocages (GNCs) due to their high photothermal conversion efficiency, good stability of photophysical properties, and stronger penetrating ability of NIR light. METHODS: Thiol-polyethylene glycol-succinyl imide ester (HS-PEG-NHS) was modified onto GNCs, and the complex was conjugated with an antibody. Subsequently, the antibody-conjugated GNCs were analyzed by UV/Vis spectrophotometer, transmission electron microscope, high-resolution transmission electron microscope with energy dispersive spectrometer, dynamic light scattering instrument, and Atom force microscope. The GNC-based CLFA of alpha-fetoprotein (AFP) and zearalenone (ZEN), a food toxin, required nitrocellulose strips, a NIR laser source, and an infrared camera. RESULTS: The GNC-labeled CLFA platform technique exhibited detection sensitivity, qualitative specificity, and quantitative accuracy. The superior performance of the technique was evident both in sandwich format detection of biomacromolecules (eg, AFP protein) or competitive format detection of small molecules (eg, ZEN). After optimizing various test parameters, GNC-labeled CLFA provided ca. 5-6-fold enhanced sensitivity, higher correlativity (R 2>0.99), and more favorable recovery (82-115%) when compared with visual LFA. CONCLUSION: GNC-labeled CLFA may be a promising detection platform with high sensitivity, specificity, and precision.

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).

Establishment and characterization of a fucosylated α-fetoprotein-specific monoclonal antibody: a potential application for clinical research.

The Lens culinaris agglutinin (LCA)-reactive fraction of α-fetoprotein (AFP-L3) is a well-known cancer biomarker for hepatocellular carcinoma (HCC) with very high specificity. Because LCA recognizes only bi-antennary N-glycans with a core fucose, some of fucosylated AFP in HCC patients may not be detected. Then glycan antibodies, which recognize both specific glycan and protein, are desired for glycobiology. Here, we successfully established a novel glycan antibody for fucosylated AFP and demonstrated its potential clinical application. After immunization with a fucosylated AFP peptide, positive screening was performed for fucosylated AFP peptides using solid-phase enzyme-linked immunosorbent assay (ELISA). The newly developed antibody was designated: fucosylated AFP-specific mAb (FasMab). Western blot analysis showed that FasMab reacted with AFP produced by HepG2 cells, but not with AFP produced by α-1,6-fucosyltransferase deficient HepG2 cells. The specific binding of FasMab to fucosylated AFP was confirmed with ELISA as well as western blot analysis. A preliminary high sensitivity chemiluminescence enzyme immunoassay kit showed increased levels of fucosylated AFP in the sera of patients with HCC, but not in the sera of normal patients, or patients with chronic liver diseases. Thus, the novel glycan antibody, FasMab, is a promising tool to study fucosylated AFP with clinical and basic research applications.