Label-free immunosensor based on hyperbranched polyester for specific detection of α-fetoprotein

Leveraging self-signal amplifying poly(acrylic acid)/polyaniline electrodes for label-free electrochemical immunoassays in protein biomarker detection

Accurate quantification of specific biomarkers is essential for clinical diagnosis and evaluating therapeutic efficacy. A self-signal-amplifying poly(acrylic acid) (PAA)/polyaniline (PANI) film-modified disposable and cost-effective screen-printed carbon electrode (SPCE) has been developed for constructing new label-free immunosensors targeting two model biomarkers: human immunoglobulin G (IgG) and alpha-fetoprotein (AFP). The electrochemically deposited PAA/PANI film on the SPCE serves a dual function: both a bio-immobilization support and a signal amplifier, enhancing biomarker detection sensitivity and efficiency. The self-signal amplification properties of PANI streamline the detection process. At the same time, the high-density surface carboxyl groups from embedded PAA enable covalent conjugation with capture antibodies (anti-IgG and anti-AFP). Subsequently, antibody-immobilized PAA/PANI film-modified SPCEs, as immunosensors, successfully detect IgG and AFP without the need for external redox probes. The reductions in the electrochemical PANI signals of the immunosensors are linearly proportional to the logarithm of IgG and AFP concentrations. The proposed immunosensors exhibit sufficiently wide ranges of calibration curves from 0.10 to 50 ng mL-1, with limits of detection of 0.080 ng mL-1 for IgG and 0.090 ng mL-1 for AFP. The sensors exhibit satisfactory sensitivity and selectivity, indicating their potential for accurate and reliable detection.

A Signal-On Microelectrode Electrochemical Aptamer Sensor Based on AuNPs-MXene for Alpha-Fetoprotein Determination

As a crucial biomarker for the early warning and prognosis of liver cancer diseases, elevated levels of alpha-fetoprotein (AFP) are associated with hepatocellular carcinoma and germ cell tumors. Herein, we present a novel signal-on electrochemical aptamer sensor, utilizing AuNPs-MXene composite materials, for sensitive AFP quantitation. The AuNPs-MXene composite was synthesized through a simple one-step method and modified on portable microelectrodes. As signal molecules, AFP aptamers were conjugated with methylene blue (MB) and immobilized on the electrode surface. When interacting with AFP, conformational changes in the aptamer-target complex caused MB to approach the electrode, and the electrochemical signal was enhanced through signal-on mechanisms. The developed sensor demonstrated high sensitivity and selectivity for AFP, with a log-linear relationship defined as 1-300 ng/mL, and the LOD was 0.05 ng/mL (S/N = 3). The method was applied to laboratorial and real clinical samples and presented satisfactory selectivity, reproducibility, and long-term stability. The proposed high-performance sensor highlights the potential of electrochemical aptamer sensors in improving the warning capabilities in disease management.

Preparation of COPs Mixed Matrix Membrane for Sensitive Determination of Six Sulfonamides in Human Urine

In this study, TpDMB-COPs, a specific class of covalent organic polymers (COPs), was synthesized using Schiff-base chemistry and incorporated into a polyvinylidene fluoride (PVDF) polymer for the first time to prepare COPs mixed matrix membranes (TpDMB-COPs-MMM). A membrane solid-phase extraction (ME) method based on the TpDMB-COPs-MMM was developed to extract trace levels of six sulfonamides from human urine identified by high-performance liquid chromatography (HPLC). The key factors affecting the extraction efficiency were investigated. Under the optimum conditions, the proposed method demonstrated an excellent linear relationship in the range of 3.5-25 ng/mL (r2 ≥ 0.9991), with the low limits of detection (LOD) between 1.25 ng/mL and 2.50 ng/mL and the limit of quantification (LOQ) between 3.50 ng/mL and 7.00 ng/mL. Intra-day and inter-day accuracies were below 5.0%. The method's accuracy was assessed by recovery experiments using human urine spiked at three levels (7-14 ng/mL, 10-15 ng/mL, and 16-20 ng/mL). The recoveries ranged from 87.4 to 112.2% with relative standard deviations (RSD) ≤ 8.7%, confirming the applicability of the proposed method. The developed ME method based on TpDMB-COPs-MMM offered advantages, including simple operation, superior extraction affinity, excellent recycling performance, and easy removal and separation from the solution. The prepared TpDMB-COPs-MMM was demonstrated to be a promising adsorbent for ME in the pre-concentration of trace organic compounds from complex matrices, expanding the application of COPs and providing references for other porous materials in sample pre-treatment.

An electrochemical immunosensor for an alpha-fetoprotein cancer biomarker on a carbon black/palladium hybrid nanoparticles platform

The early detection of cancer is a key step in cancer survival. Thus, there is a need to develop low-cost technologies, such as electrochemical immunosensor technologies, for timely screening and diagnostics. The discovery of alpha-feto protein (AFP) as a tumour-associated antigen lends AFP as a biomarker for cancer detection and monitoring. Thus, immunosensors can be developed to target AFP in cancer diagnostics. Hence, we report the application of a hybrid nanocomposite of carbon black nanoparticles (CBNPs) and palladium nanoparticles (PdNPs) as a platform for the electrochemical immunosensing of cancer biomarkers. The hybrid carbon-metal nanomaterials were immobilised by using the drop-drying and electrodeposition technique on a glassy carbon electrode, followed by the immobilisation of the anti-AFP to fabricate an immunosensor. The nanoparticles were characterised with electron microscopy, voltammetry, and electrochemical impedance spectroscopy (EIS). Square wave voltammetry (SWV) and EIS were used to study the immunosensor signal toward the bio-recognition of the AFP cancer biomarker. The hybrid nanoparticles enhanced the immunosensor performance. A linear detection range from 0.005 to 1000 ng mL^-1 with low detection limits of 0.0039 ng mL^-1 and 0.0131 ng mL^-1 were calculated for SWV and EIS, respectively. The immunosensor demonstrated good stability, reproducibility, and selectivity. Its real-life application potential was tested with detection in human serum matrix.

A functionalized magnetic nanoparticle regulated CRISPR-Cas12a sensor for the ultrasensitive detection of alpha-fetoprotein

Alpha-fetoprotein (AFP) is an important clinical tumor marker of hepatoblastoma, and the concentration of AFP in serum is closely related to the staging of hepatoblastoma. We report a magnetic bead separation platform based on a switching aptamer triggered hybridization chain reaction (SAT-HCR) and the CRISPR-Cas12a sensor for the in vitro detection of AFP. AFP aptamer, as an easily regulated nucleic acid strand, is responsible for binding to AFP into nucleic acid detection, while HCR-CRISPR-Cas12a, regulated by functionalized magnetic nanoparticles, is responsible for highly specific nucleic acid signal amplification. Under the optimal conditions, the fluorescence intensity was proportional to the concentration of AFP in the range of 0.5-10⁴ ng mL^-1 and the limit of detection was 0.170 ng mL^-1. In addition, we have successfully applied this biosensor to detect AFP in clinical samples from patients with hepatoblastoma, with greater sensitivity relative to ELISA. Our proposed method showed great potential application in clinical diagnosis and pharmaceutical-related fields with the properties of high sensitivity, low cost and high selectivity.

Electrochemical Immunosensor Modified with Nitrogen-Doped Reduced Graphene Oxide@Carboxylated Multi-Walled Carbon Nanotubes/Chitosan@Gold Nanoparticles for CA125 Detection

Lung cancer is one of the malignant tumors with the highest mortality rate, and the detection of its tumor marker carcinoma antigen 125 (CA125) is significant. Here, an electrochemical immunoassay for CA125 was described. Nitrogen-doped reduced graphene oxide (N-rGO), carboxylated multi-walled carbon nanotubes (CMWCNTs) and gold nanoparticles (AuNPs) were applied to co-modify glassy carbon electrode (GCE), after incubation with Anti-CA125, the modified electrode was employed for the specific detection of CA125. The N-rGO@CMWCNTs (Nitrogen-doped reduced graphene oxide@carboxylated multi-walled carbon nanotubes) were used as a matrix, while CS@AuNPs (Chitosan@gold nanoparticles) with high conductivity and biocompatibility was immobilized on it through the reaction between carboxyl groups from CMWCNTs and amino groups, hydroxyl groups from chitosan (CS), resulting in the effect of double signal amplification. The immunosensor demonstrated excellent electrochemical performance with a linear detection range of 0.1 pg mL−1–100 ng mL−1, and the detection limit was as low as 0.04 pg mL−1 (S/N = 3). It had been verified that this method had good precision and high accuracy, and the immunosensor could remain stable for 10 days. This research provided a new method for the detection of CA125 in serum.

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.

Antibody mounting capability of 1D/2D carbonaceous nanomaterials toward rapid-specific detection of SARS-CoV-2

Carbonaceous immunosensors are ideal nanoplatforms for developing rapid, precise, and ultra-specific diagnostic kits capable of early detection of viral infectious illnesses such as COVID-19. However, developing a proper carbonic immunosensor requires stepwise protocols to find optimum operating conditions to minimize drawbacks. Herein, for the first time and through a stepwise protocol, activation, and monoclonal IgG antibody mounting capability of multi-walled carbon nanotubes (MWCNTs) at two diverse outer diameters (ODs), viz., 20-30 nm and 50-80 nm, and graphene deriv atives (graphene oxide (GO) and reduced graphene oxide (rGO)) were examined and compared with each other toward finding the prime carbonaceous nanomaterial(s) for maximized antibody loading efficiency along with an ideal detection limit (DL) and sensitivity. Next, the effect of common amplifying agents, i.e., Au nanostars (Au NSs) and Ag nanowires (Ag NWs), on the total performance of the best carbonaceous structure was carefully assessed, and the responsible detection mechanism is investigated in detail. Next, the developed carbonaceous immunosensors were assessed via voltammetric and impedance assays, and their performances toward specific detection of SARS-CoV-2 antigen through immunoreaction were examined in detail. The study's outcome showed the superior performance of conjugated rGO-based immunosensor with Au NSs toward specific and quick (1 min) detection of SARS-CoV-2 antigen in biological fluids compared with other 1D/2D carbonaceous nanomaterials.

Dual-heteroatom-templated lanthanoid-inserted heteropolyoxotungstates simultaneously comprising Dawson and Keggin subunits and their composite film applied for electrochemical immunosensing of auximone

Two unprecedented PIII–SbIII-heteroatom templated lanthanide-inserted heteropolyoxotungstates were obtained and their composite film was applied for the electrochemical immunosensing of auximone.

A simple label-free electrochemical sensor for sensitive detection of alpha-fetoprotein based on specific aptamer immobilized platinum nanoparticles/carboxylated-graphene oxide

A label-free electrochemical aptamer-based sensor has been fabricated for alpha-fetoprotein (AFP) detection. Platinum nanoparticles on carboxylated-graphene oxide (PtNPs/GO-COOH) modified screen-printed graphene-carbon paste electrode (SPGE) was utilized as an immobilization platform, and the AFP aptamer was employed as a bio-recognition element. The synthesized GO-COOH helps to increase the surface area and amounts of the immobilized aptamer. Subsequently, PtNPs are decorated on GO-COOH to enhance electrical conductivity and an oxidation current of the hydroquinone electrochemical probe. The aptamer selectively interacts with AFP, causing a decrease in the peak current of the hydroquinone because the binding biomolecules on the electrode surface hinder the electron transfer of the redox probe. Effects of aptamer concentration and AFP incubation time were studied, and the current changes of the redox probe before and after AFP binding were investigated by square wave voltammetry. The developed aptasensor provides a linear range from 3.0–30 ng mL⁻¹ with a detection limit of 1.22 ng mL⁻¹. Moreover, the aptamer immobilized electrode offers high selectivity to AFP molecules, good stability, and sensitive determination of AFP in human serum samples with high recoveries.

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.

Metal Nanoparticles/MoS2 Surface-Enhanced Raman Scattering-Based Sandwich Immunoassay for α-Fetoprotein Detection

The detection of cancer biomarkers at an early stage of tumor development is vital for effective diagnosis and treatment of cancer. Current diagnostic tools can often detect cancer only when the biomarker levels are already too high, so that the tumors have spread and treatments are less effective. It is urgent therefore to develop highly sensitive assays for the detection of such biomarkers at the lowest possible concentration. In this context, we developed a sandwich immunoassay based on surface-enhanced Raman scattering (SERS) for the ultrasensitive detection of α-fetoprotein (AFP), which is typically present in human serum as a biomarker indicative of early stages of hepatocellular carcinoma. In the immunoassay design, molybdenum disulfide (MoS2) modified with a monoclonal antibody was used as a capture probe for AFP. A secondary antibody linked to an SERS-encoded nanoparticle was employed as the Raman signal reporter, that is, the transducer for AFP detection. The sandwich immunocomplex "capture probe/target/SERS tag" was deposited on a silicon wafer and decorated with silver-coated gold nanocubes to increase the density of "hot spots" on the surface of the immunosensor. The developed SERS immunosensor exhibits a wide linear detection range (1 pg mL-1 to 10 ng mL-1) with a limit of detection as low as 0.03 pg mL-1 toward AFP with good reproducibility (RSD < 6%) and stability. These parameters demonstrate that the proposed immunosensor has the potential to be used as an analytical platform for the detection of early-stage cancer biomarkers in clinical applications.

Label-free detection of biomarker alpha fetoprotein in serum by ssDNA aptamer functionalized magnetic nanoparticles

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in the clinic, with the characteristics of occult onset, rapid progression, and high degree of malignancy. Alpha fetoprotein (AFP) is the most important biomarker of HCC, which is widely used in early screening, diagnosis, and prognosis observation. A series of immunoassays have been developed and frequently used in the detection of AFP based on antibodies. Unfortunately, the shortcomings of antibodies, such as thermal unstable and fluctuant activity by batches, lead to the inaccuracy in the detection of AFP. In this study, aptamers instead of antibodies were adopted as the specific recognition element for AFP, aiming to seek an alternative strategy to immunoassays. An AFP-specific ssDNA aptamer was grafted to magnetic nanoparticles (Fe₃O₄@SiO₂) via avidin-biotin interaction, and the resultant aptamer functionalized magnetic nanoparticles (Ap-MNPs) were adequately characterized and tested. The Ap-MNPs in solution exhibited a fast response to the outer magnetic field, and can be completely separated in several minutes. It was found that Ap-MNPs have good specificity to the target AFP, as the recovery of AFP (87.0%) was much higher than the competitive proteins IgG (38.9%), HSA (18.5%), and FIB (11.4%). A convenient and efficient label-free detection method of AFP in serum was developed based on Ap-MNPs in combination with high-performance liquid chromatography. The linearity of this method was over a range of 1-50 μg ml^-1 with a correlation coefficient of 0.9999, and the limit of detection was 0.27 μg ml^-1. This study indicated that aptamers are an ideal tool for the recognition and detection of biomarkers, and thus will find wide applications in clinical practice.

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.

Nanofabricated versatile electrochemical sensor for Leptospira interrogans detection

In this report, a LipL32 gene based nanofabricated electrochemical sensor for the detection of Leptospira interrogans has been developed using carboxylated multiwalled carbon nanotubes with gold nanoparticles (c-MWCNTs/nanoAu) electrode and graphene quantum dots (GQDs). The c-MWCNTs/nanoAu electrode was linked to GQDs using 4-aminothiophenol (ATP). The surface modifications on the electrode surface were delineated using Raman spectroscopy and field emission scanning electron microscopy (FE-SEM). 5'-Amino (NH₂) labeled single stranded DNA (ssDNA) probe was immobilized on the surface of c-MWCNTs/nanoAu/ATP/GQD composite electrode. The electrochemical changes of the developed sensor after hybridization with single stranded complementary DNA of L. interrogans were analyzed by differential pulse voltammetry (DPV) using 1 mM methylene blue. The sensor showed good linearity with complementary ssDNA concentration ranging from 0.37 to 12 ng/μl. The sensor exhibited high specificity to L. interrogans and showed good reproducibility when stored at 4°C.

A dual-responsive biosensor for blood lead detection

Simple and accurate detection of trace heavy metals in blood is very important. A novel dual-responsive electrochemical/fluorescent biosensor based on magnetic hyperbranched polyamide with heparin modification (MHPAM-H) for blood lead detection has been successfully developed. Upon conjugated with blood lead ions, dual-biosensor could not only display electrochemical signal but also fluorescence signal owing to the enriched amino groups, cavity structure, and good fluorescence properties of HPAM. Blood biocompatibility, construction of the dual-responsive biosensor, electrochemical/fluorescent detection of lead ions in water phase and blood condition, selectivity and stability of the dual-responsive biosensor were investigated in detail. The proposed dual-responsive biosensor displays good linear relationship (1.5 pM- 4.8 × 10³ pM for electrochemical detection and 0.5 pM-4.8 × 10³ pM for fluorescent detection) with low detection limit (4.4 pM for electrochemical detection and 1.0 pM for fluorescent detection) for blood lead, providing potential application for blood lead detection in the future.

Electrochemical Sensing of α-Fetoprotein Based on Molecularly Imprinted Polymerized Ionic Liquid Film on a Gold Nanoparticle Modified Electrode Surface

A molecularly imprinted sensor was fabricated for alpha-fetoprotein (AFP) using an ionic liquid as a functional monomer. Ionic liquid possesses many excellent characteristics which can improve the sensing performances of the imprinted electrochemical sensor. To demonstrate this purpose, 1-[3-(N-cystamine)propyl]-3-vinylimidazolium tetrafluoroborate ionic liquid [(Cys)VIMBF₄] was synthesized and used as a functional monomer to fabricate an AFP imprinted polymerized ionic liquid film on a gold nanoparticle modified glassy carbon electrode (GCE) surface at room temperature. After removing the AFP template, a molecularly imprinted electrochemical sensor was successfully prepared. The molecularly imprinted sensor exhibits excellent selectivity towards AFP, and can be used for sensitive determination of AFP. Under the optimized conditions, the imprinted sensor shows a good linear response to AFP in the concentration range of 0.03 ng mL⁻¹~5 ng mL⁻¹. The detection limit is estimated to be 2 pg mL⁻¹.

Multiple Drug Delivery from Mesoporous Coating Realizing Combination Therapy for Bare Metal Stents

The simultaneous loading of multifunctional drugs has been regarded as one of the major challenges in the drug delivery system. Herein, a mesoporous silica coating was constructed on a bare metal stent surface by an evaporation-induced self-assembly method, in which both hydrophilic and hydrophobic drugs (heparin and rapamycin) were encapsulated by a one-pot method for the first time, and the release behaviors of these drugs were studied. The releasing mechanisms of these drugs were investigated in detail. Rapid release of heparin can achieve anticoagulation and endothelialization, whereas slow release of rapamycin can realize antiproliferative therapy for long term. In vitro hemocompatibility and promotion for proliferation of vein endothelial cells and the inhibition of smooth muscle cells were conducted. In vivo stent implantation results verify that the mesoporous silica coating with both heparin and rapamycin can successfully accelerate the endothelialization process and realize the antiproliferative therapy for as long as 3 months. These results indicate that this multifunctional mesoporous coating containing both hydrophilic and hydrophobic drugs might be a promising stent coating in the future.

Detection of Alpha-Fetoprotein in Hepatocellular Carcinoma Patient Plasma with Graphene Field-Effect Transistor

The detection of alpha-fetoprotein (AFP) in plasma is important in the diagnosis of hepatocellular carcinoma (HCC) in humans. We developed a biosensor to detect AFP in HCC patient plasma and in a phosphate buffer saline (PBS) solution using a graphene field-effect transistor (G-FET). The G-FET was functionalized with 1-pyrenebutyric acid N-hydroxysuccinimide ester (PBASE) for immobilization of an anti-AFP antibody. AFP was detected by assessing the shift in the voltage of the Dirac point (ΔV_Dirac) after binding of AFP to the anti-AFP-immobilized G-FET channel surface. This anti-AFP-immobilized G-FET biosensor was able to detect AFP at a concentration of 0.1 ng mL⁻¹ in PBS, and the detection sensitivity was 16.91 mV. In HCC patient plasma, the biosensor was able to detect AFP at a concentration of 12.9 ng mL⁻¹, with a detection sensitivity of 5.68 mV. The sensitivity (ΔV_Dirac) depended on the concentration of AFP in either PBS or HCC patient plasma. These data suggest that G-FET biosensors could have practical applications in diagnostics.

A novel electrochemical immunosensor based on Au nanoparticles and horseradish peroxidase signal amplification for ultrasensitive detection of α-fetoprotein

An electrochemical double-layer Au nanoparticle membrane immunosensor was developed using an electrochemical biosensing signal amplification system with Au nanoparticles, thionine, chitosan, and horseradish peroxidase, which was fabricated using double self-adsorption of Au nanoparticle sol followed by anti-α-fetoprotein Balb/c mouse monoclonal antibody adsorption. The AuNPs sol was characterized by spectrum scanning and transmission electron microscopy. The immunosensor was characterized by atomic force microscopy, cyclic voltammetry, and alternating-current impedance during each stage of adsorption and assembly. The amperometric I-t curve method was used to measure α-fetoprotein (AFP) diluted in phosphate buffered saline. The result indicated a wide linear range, and the change rate of steady-current before and after immune response had linear correlation within the range 0.1-10⁴ pg/mL AFP. The current change rate equation was △I = 5.82334 lgC + 37.01195 (R² = 0.9922). The lowest limit of detection was 0.03 pg/mL (S/N = 3), and the reproducibility of the sensor was good. Additionally, the sensor could be stably stored above phosphate buffered saline at 4 °C for more than 24 days. More importantly, the sensor is label-free, reagentless and low fouling, making it capable of assaying AFP in real serum samples without suffering from significant interference or biofouling.

Label-free electrochemical aptasensor for detection of alpha-fetoprotein based on AFP-aptamer and thionin/reduced graphene oxide/gold nanoparticles

Sensitive and accurate detection of tumor markers is critical to early diagnosis, point-of-care and portable medical supervision. Alpha fetoprotein (AFP) is an important clinical tumor marker for hepatocellular carcinoma (HCC), and the concentration of AFP in human serum is related to the stage of HCC. In this paper, a label-free electrochemical aptasensor for AFP detection was fabricated using AFP-aptamer as the recognition molecule and thionin/reduced graphene oxide/gold nanoparticles (TH/RGO/Au NPs) as the sensor platform. With high electrocatalytic property and large specific surface area, RGO and Au NPs were employed on the screen-printed carbon electrode to load TH molecules. The TH not only acted as a bridging molecule to effectively capture and immobilize AFP-aptamer, but as the electron transfer mediator to provide the electrochemical signal. The AFP detection was based on the monitoring of the electrochemical current response change of TH by the differential pulse voltammetry. Under optimal conditions, the electrochemical responses were proportional to the AFP concentration in the range of 0.1-100.0 μg/mL. The limit of detection was 0.050 μg/mL at a signal-to-noise ratio of 3. The proposed method may provide a promising application of aptamer with the properties of facile procedure, low cost, high selectivity in clinic.

Dispersive micro-solid-phase extraction of benzoylurea insecticides in water samples with hyperbranched polyester composite as sorbent

Hyperbranched polyester was used as efficient and accessible sorbent in the dispersive micro-solid-phase extraction method.

A Fe3O4@Au-basedpseudo-homogeneous electrochemical immunosensor for AFP measurement using AFP antibody-GNPs-HRP as detection probe

In this study, a Fe₃O₄@Au-based pseudo-homogeneous electrochemical immunosensor was prepared for detection of alpha fetoprotein (AFP), a well-known hepatocellular carcinoma biomarker. The primary antibody (Ab1) was immobilized on Fe₃O₄@Au NPs as the capture probe. Horseradish peroxidase (HRP) and secondary antibody (Ab2) were conjugated on gold nanoparticles (GNPs) through electrostatic adsorption to form signal-amplifying labels. In the presence of AFP, a sandwich immunocomplex was formed via specific recognition of antigen-antibody in a Fe₃O₄@Au-basedpseudo-homogeneousreaction system. After the immunocomplex was captured to the surface of magnetic glassy carbon electrode (MGCE), the labeling HRP catalyzed the decomposition of H₂O₂, resulting in a substantial current for the quantitative detection of AFP. The amperometric (i-t) method was employed to record the response signal of the immunosensor based on the catalysis of the immobilized HRP toward the reduction of H₂O₂ with hydroquinone (HQ) as the redox mediator. Under the optimal conditions, the amperometric current response presented a linear relationship with AFP concentration over the range of 20 ng/mL-100 ng/mLwith a correlation coefficient of 0.9940, and the detection limit was 0.64 ng/mL at signal/noise [S/N] = 3. Moreover, the electrochemical immunosensor exhibited higher anti-interference ability, acceptable reproducibility and long-term stability for AFP detection.