Development of a Time-Resolved Fluorescence Immunoassay for the Diagnosis of Hepatocellular Carcinoma Based on the Detection of Glypican-3

Sandwich-type supersensitive electrochemical aptasensor of glypican-3 based on PrGO-Hemin-PdNP and AuNP@PoPD

A new sandwich-type electrochemical biosensing platform was developed by gold @polyphthalenediamine nanohybrids (AuNP@PoPD) as the sensing platform and phosphorus doped reduced graphene oxide-hemin-palladium nanoparticles (PrGO-Hemin-PdNP) as the signal amplifier for phosphatidylinositol proteoglycan 3 (GPC3). AuNP@PoPD, co-electrodeposited into the screen printed electrode with high conductivity and stability, is dedicated to assembling the primary GPC3 aptamer (GPC3Apt). The second GPC3Apt immobilized on the high conductivity and large surface area of PrGO-Hemin-PdNP was utilized as an electrochemical signal reporter by hemin oxidation (PrGO-Hemin-PdNP-GPC3Apt). In the range 0.001-10.0 ng/mL, the hemin oxidation current signal of the electrochemical aptasensor increased log-linearly with the concentration of GPC3, the lowest detection limit was 0.13 pg/mL, and the sensitivity was 2.073 μA/μM/cm2. The aptasensor exhibited good sensing performance in a human serum sample with the relative error of 4.31-8.07%. The sandwich sensor showed good selectivity and stability for detection GPC3 in human serum samples, providing a new efficient and sensitive method for detecting HCC markers.

H-rGO-Pd NPs Nanozyme Enhanced Silver Deposition Strategy for Electrochemical Detection of Glypican-3

Glypican-3 (GPC3), as an emerging biomarker, has been shown to be beneficial for the early diagnosis and treatment of hepatocellular carcinoma (HCC). In this study, an ultrasensitive electrochemical biosensor for GPC3 detection has been constructed based on the hemin-reduced graphene oxide-palladium nanoparticles (H-rGO-Pd NPs) nanozyme-enhanced silver deposition signal amplification strategy. When GPC3 specifically interacted with GPC3 antibody (GPC3_Ab) and GPC3 aptamer (GPC3_Apt), an "H-rGO-Pd NPs-GPC3_Apt/GPC3/GPC3_Ab" sandwich complex was formed with peroxidase-like properties which enhanced H₂O₂ to reduce the silver (Ag) ions in solution to metallic Ag, resulting in the deposition of silver nanoparticles (Ag NPs) on the surface of the biosensor. The amount of deposited Ag, which was derived from the amount of GPC3, was quantified by the differential pulse voltammetry (DPV) method. Under ideal circumstances, the response value was linearly correlated with GPC3 concentration at 10.0-100.0 μg/mL with R² of 0.9715. When the GPC3 concentration was in the range from 0.01 to 10.0 μg/mL, the response value was logarithmically linear with the GPC3 concentration with R² of 0.9941. The limit of detection was 3.30 ng/mL at a signal-to-noise ratio of three and the sensitivity was 1.535 μAμM^-1cm^-2. Furthermore, the electrochemical biosensor detected the GPC3 level in actual serum samples with good recoveries (103.78-106.52%) and satisfactory relative standard deviations (RSDs) (1.89-8.81%), which confirmed the applicability of the sensor in practical applications. This study provides a new analytical method for measuring the level of GPC3 in the early diagnosis of HCC.

A highly sensitive strategy for glypican-3 detection based on aptamer/gold carbon dots/magnetic graphene oxide nanosheets as fluorescent biosensor

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths in China. Glypican-3 (GPC3) is a specific antigen related to HCC, which is widely used in clinical detection as a reliable marker of HCC. In this paper, a highly sensitive homogeneous apatasensor was designed for GPC3 detection based on fluorescence resonance energy transfer (FRET) where the GPC3 aptamer labelled gold carbon dots (AuCDs-GPC3_Apt) are used as a donor and magnetic graphene oxide (Fe₃O₄/GO) nanosheets are used as an acceptor. A one-step hydrothermal method was used to synthesize AuCDs to provide sufficient fluorescence. The FRET phenomenon exists between AuCDs-GPC3_Apt and Fe₃O₄/GO, which weakens the fluorescence intensity of the whole system. When the target GPC3 is added to the FRET system, the fluorescent AuCDs-GPC3_Apt binds to the GPC3 and forms a folded structure, which leads to AuCDs-GPC3_Apt separation from Fe₃O₄/GO nanosheets. The Fe₃O₄/GO is then magnetically separated so that the fluorescence of free labelled AuCDs-GPC3_Apt is restored. Under the optimum conditions, the fluorescence recovery rate is linearly correlated with the concentration of GPC3 (5-100 ng·mL^-1) and the detection limit is 3.01 ng·mL^-1 (S/N = 3). This strategy shows recoveries from 98.76 to 101.29% in real human serum samples and provides an immediate and effective detection method for the quantification of GPC3 with great potential applications for early diagnosis of HCC. A sensitive homogeneous FRET-based apatasensor was designed for GPC3 detection where the AuCDs-GPC3_Apt is a donor and Fe₃O₄/GO nanosheets are an acceptor. The GPC3 fluorescent aptasensor combines wider output range with low cost, high specificity, and good anti-interference.

A fluorescence aptasensor based on GSH@GQDs and RGO for the detection of Glypican-3

Glypican-3 (GPC3), a heparin sulfate proteoglycan, is a potential diagnostic and therapeutic target for hepatocellular carcinoma. In this paper, a novel fluorescent aptasensor for GPC3 detection is constructed via glutathione@graphene quantum dots-labeled GPC3 aptamer (GSH@GQDs-GPC3_Apt) as a fluorescence probe. First, GSH@GQDs is screened out with higher fluorescence intensity, which emits bright blue fluorescence under ultraviolet light. Then, the fluorescence-labeled GSH@GQDs-GPC3_Apt probe is formed by the combination of amination GPC3_Apt and GSH@GQDs using EDC/NHS coupled reaction. Under hydrogen bond and π-π interaction/stacking, the fluorescence of GSH@GQDs-GPC3_Apt could be quenched by reductive graphene oxide (RGO) with the help of the photoinduced electron transfer and the fluorescence resonance energy transfer mechanism. In the presence of GPC3, the GSH@GQDs-GPC3_Apt specifically recognizes and binds to GPC3, giving rise to the change of secondary structure of GPC3_Apt to form the GPC3/GPC3_Apt-GSH@GQDs complex, which would lead to the disintegration of the GSH@GQDs-GPC3_Apt-RGO compound. Therefore, the energy transfer process is blocked and the fluorescence intensity is restored, enabling a highly sensitive response to GPC3. When the concentration of GPC3 is from 5.0 ng/mL to 150.0 ng/mL, the fluorescence recovery rate is well linearly related to GPC3 concentration with the limit of detection of 2.395 ng/mL (S/N = 3). This strategy shows recoveries from 98.31% to 101.89% in human serum samples and provides simple, fast and cheap analysis of GPC3, which suggests that it has great potential applications in clinical diagnosis for hepatocellular carcinoma.

A label-free electrochemical aptasensor based on platinum@palladium nanoparticles decorated with hemin-reduced graphene oxide as a signal amplifier for glypican-3 determination

An electrochemical aptasensor for highly sensitive detection of glypican-3 has been developed using the GPC3 aptamer as the biorecognition probe and H-rGO-Pt@Pd NPs as an electroactive reagent.

Proteoglycans and their functions in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a highly malignant disease that has a poor prognosis. Its high lethality is mainly due to the lack of symptoms at early stages, which culminates in diagnosis at a late stage when the tumor has already metastasized. Unfortunately, the common cancer biomarkers have low sensitivity and specificity in esophageal cancer. Therefore, a better understanding of the molecular mechanisms underlying ESCC progression is needed to identify novel diagnostic markers and therapeutic targets for intervention. The invasion of cancer cells into the surrounding tissue is a crucial step for metastasis. During metastasis, tumor cells can interact with extracellular components and secrete proteolytic enzymes to remodel the surrounding tumor microenvironment. Proteoglycans are one of the major components of extracellular matrix. They are involved in multiple processes of cancer cell invasion and metastasis by interacting with soluble bioactive molecules, surrounding matrix, cell surface receptors, and enzymes. Apart from having diverse functions in tumor cells and their surrounding microenvironment, proteoglycans also have diagnostic and prognostic significance in cancer patients. However, the functional significance and underlying mechanisms of proteoglycans in ESCC are not well understood. This review summarizes the proteoglycans that have been studied in ESCC in order to provide a comprehensive view of the role of proteoglycans in the progression of this cancer type. A long term goal would be to exploit these molecules to provide new strategies for therapeutic intervention.

Generation of Dual functional Nanobody-Nanoluciferase Fusion and its potential in Bioluminescence Enzyme Immunoassay for trace Glypican-3 in Serum

Glypican-3 (GPC3) is a serological biomarker for the diagnosis of Hepatocellular carcinoma (HCC), but it is a challenging task to develop a bioassay for determination of the trace GPC3 in serum. In this study, Bioluminescense immunoassay based on bifunctional nanobody-nanoluciferase fusion was developed with the ultra-sensitive feature to achieve this goal. First, nanobodies special against GPC-3 binder as biological recognition element were generated by immunization and phage display technology. Second, The best clone GPN2 was fused with nanoluciferase as a dual-functional immunoreagent to establish an ultra-sensitive bioluminescence enzyme immunoassay (BLEIA), which is 30 and 5 times more sensitive than the traditional colorimetric assay and fluorescent assay, respectively. The cross-reactivity analysis of BLEIA showed that there was no cross-reactivity with HCC related tumor markers AFP, CEA, CA19-9 and GPC1/GPC2. The limit of detection (LOD) of developed BLEIA was 1.5 ng/mL, which assured its application in the diagnosis of GPC3 in 94 serum samples. This study indicates that BLEIA based on nanobody-nanoluciferase fusion could be used as a useful tool for the diagnosis of HCC patients.

Label-free electrochemical aptasensor based on reduced graphene oxide–hemin–chitosan nanocomposite for the determination of glypican-3

A GPC3 electrochemical aptasensor was constructed using an RGO–H–CS-modified SPE as a biosensing platform and GPC3 aptamer as the recognition element.

Highly sensitive electrochemical aptasensor for Glypican-3 based on reduced graphene oxide-hemin nanocomposites modified on screen-printed electrode surface

Glypican-3 (GPC3) is a highly specific tumor marker for hepatocellular carcinoma (HCC), and plays an important role in reflecting the existence, therapeutic evaluation, monitoring and prognosis of HCC. Herein, an electrochemical aptasensor was designed for GPC3 detection with the reduced graphene oxide-hemin nanocomposites (RGO-Hemin) modified on the screen-printed electrode surface as the sensing platform and GPC3 aptamer as recognize molecule. In the existence of GPC3, the aptamer can specifically bind with the target GPC3 and form GPC3-aptamer conjugations on the sensing surface, which would increase the resistance of the electron transfer on the electrode and make the decrease of electrochemical signals of Hemin in RGO-Hemin nanocomposites. The electrochemical current change was recorded by differential pulse voltammetry (DPV). Scanning electron microscopy (SEM), Raman microscope (RM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to characterize the GPC3 electrochemical aptasensor. Under the optimum conditions, the current response of the electrochemical aptasensor is linearly correlated with the concentration of GPC3 (0.001-10.0 μg/mL) with the detection limit of 2.86 ng/mL (S/N = 3) and the sensitivity of 0.134 μA/μM/cm². In addition, the aptasensor was applied to the determination of GPC3 in spiked human plasma and the recoveries fluctuated from 102.68% to 117.29%. All these results show that the aptasensor has good specificity, sensitivity, stability and reproducibility for GPC3 detection.

Glypican-3 electrochemical aptamer nanobiosensor based on hemin/graphene nanohybrids peroxidase-like catalytic silver deposition

A Glypican-3 (GPC3) electrochemical aptamer nanobiosensor based on hemin/graphene nanohybrids (HGNs) peroxidase-like catalytic silver deposition and GPC3 aptamer has been constructed for the determination of GPC3. The HGNs were prepared by an one-step reduction method. Fourier transform infrared spectroscopy (FT-IR), ultraviolet spectroscopy (UV-vis), and transmission electron microscopy (TEM) were used to study the structure and morphological characteristics of the HGNs. The GPC3 electrochemical aptamer nanobiosensor was constructed using HGNs-aptamer (HGNs-Apt) as the signal probe and GPC3 aptamer as the capture probe. With the help of the catalytic action of peroxidase-like properties of HGNs, H₂O₂ reduces the silver (Ag) ions in solution to metallic Ag, which deposit on the surface of the electrode. The amount of deposited Ag, which was derived from the amount of GPC3, was quantified by differential pulse voltammetry (DPV). Under optimal conditions, the current response of Ag had a good positive correlation with the GPC3 concentration in the range 10.0-100.0 μg mL^-1 with a correlation coefficient of 0.9958. The detection limit was 3.16 μg mL^-1 at a signal-to-noise ratio of 3, and the sensitivity was calculated to be 0.807 μA μM^-1 cm^-2. The method is validated by analyzing spiked human serum samples with good recovery ranging from 101 to 122%. In addition, the GPC3 electrochemical aptamer nanobiosensor has acceptable selectivity, stability, and reproducibility. Graphical abstract A Glypican-3 electrochemical aptamer nanobiosensor based on hemin/graphene nanohybrids (HGNs) peroxidase-like catalytic silver deposition and GPC3 aptamer has been constructed for the determination of GPC3. The electrochemical aptamer nanobiosensor exhibits high selectivity, acceptance reproducibility, and good recovery performances.

Amplified fluorescence by carbon nanotube (CNT)-assisted surface plasmon coupled emission (SPCE) and its biosensing application

The enhancement of SPCE by CNT assistance was investigated, and this strategy used an immunosensor to detect IgG.

VTIQ evaluates antitumor effects of NET-1 siRNA by UTMD in HCC xenograft models

The present study used a virtual touch tissue imaging and quantification (VTIQ) method to investigate the change in elasticity in xenograft tumor tissue models following silencing of the neuroepithelial-transforming protein 1 (NET-1) gene by ultrasound-targeted microbubble destruction (UTMD). A total of 24 xenograft models were established by subcutaneous injection of human hepatocellular carcinoma SMMC-7721 cells in BALB/c female nude mice. Then, NET-1 small interfering RNA (siRNA)-conjugated nanobubbles and a glypican-3 antibody were synthesized. The mean and maximum shear wave speed (SWS_mean and SWS_max) in the tumor tissue were measured prior to, during, and following therapy using VTIQ. The growth of the tumor size and survival time were recorded. The levels of NET-1 protein were evaluated by immunohistochemical staining. In addition, tumor, liver and kidney tissues of the nude mice were collected to confirm whether gene transfection treatment was toxic in vivo. In the UTMD delivery gene group, SWS_mean was correlated with the maximum diameter of the tumor (r=0.9806, P=0.0194). The immunohistochemical staining data indicated that the level of NET-1 protein in the treated groups was significantly decreased compared with those in the control groups. Additionally, no structural damage was observed in the nude mice liver and kidney tissues following treatment. Therefore, VTIQ measurement identified potential changes in the elastic properties of the tumors, which in turn may be associated with the stages of tumor development. The delivery method, UTMD, improves the antitumor effects of NET-1 siRNA and supports gene transfection as a promising therapeutic strategy.

Simultaneous detection of Mycoplasma pneumoniae IgG and IgM using dual-label time resolved fluoroimmunoassay

Anti-Mycoplasma pneumoniae (MP) IgM and IgG are useful serological markers for detection of MP infection. In this study, a simultaneous quantification of MP IgM and IgG was performed by time-resolved fluoroimmunoassay (TRFIA). The europium-labeled anti-human IgM and samarium-labeled anti-human IgG were used as tracers, and MP IgM and IgG were recognized in serum samples. After dissociating europium and samarium ions from the immune complex, their fluorescence intensity was recorded and used to calculate the concentrations. The linear range and sensitivity of detection were 2-5500 BU/mL and 0.5 BU/mL for IgM, and 1.5-1500 BU/mL and 0.2 BU/mL for IgG, respectively. The intra- and inter-assay coefficients of variation were 5.14% and 8.41% for IgM, and 5.44% and 8.76% for IgG, respectively. The recovery rate was 94.9-106.8% for IgM and 96.1-109.4% for IgG. The correlation rates of serum detection for 38 respiratory infected patients between dual-label TRFIA and ELISA were 0.9294 and 0.9366 for IgM and IgG, respectively. The coincidence rate between passive particle agglutination and TRFIA is 93.3%. Dual-label TRFIA is a sensitive and reliable technique for measuring MP IgM and IgG levels and could be useful for the early diagnosis of MP infection.