Amount Of Horseradish Peroxidase Research Articles

A Conductive Microcavity Created by Assembly of Carbon Nanotube Buckypapers for Developing Electrochemically Wired Enzyme Cascades.

We describe the creation of a conductive microcavity based on the assembly of two pieces of carbon nanotube buckypaper for the entrapment of two enzymes, horseradish peroxidase (HRP) and glucose oxidase (GOx), as well as a redox mediator: 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid diammonium salt (ABTS). The hollow electrode, employing GOx, HRP, and the mediator, as an electrochemical enzyme cascade model, is utilized for glucose sensing at a potential of 50 mV vs. Ag/AgCl. This bienzyme electrode demonstrates the ability to oxidize glucose by GOx and subsequently convert H2O2 to water via the electrical wiring of HRP by ABTS. Different redox mediators (ABTS, potassium hexacyanoferrate (III), and hydroquinone) are tested for HRP wiring, with ABTS being the best candidate for the electroenzymatic reduction of H2O2. To demonstrate the possibility to optimize the enzyme cascade configuration, the enzyme ratio is studied with 1 mg HRP combined with variable amounts of GOx (1-4 mg) and 2 mg GOx combined with variable amounts of HRP (0.5-2 mg). The bienzyme electrode shows continuous operational stability for over a week and an excellent storage stability in phosphate buffer, with a decay of catalytic current by only 29% for 1 mM glucose after 100 days.

Immobilized horseradish peroxidase on boric acid modified polyoxometalate molecularly imprinted polymer for biocatalytic degradation of phenol in wastewater: Optimized immobilization, degradation and toxicity assessment

The degradation of phenol from wastewater is crucial for environmental protection. Biological enzymes, such as horseradish peroxidase (HRP), have shown great potential in the degradation of phenol. In this research, we prepared a hollow CuO/Cu2O octahedron adsorbent with a carambola matrix shape through the hydrothermal method. The surface of the adsorbent was modified by silane emulsion self-assembly, where 3-aminophenyl boric acid (APBA) and polyoxometalate (PW9) were combined with silanization reagents and grafted onto the surface. The adsorbent was then molecularly imprinted with dopamine to obtain boric acid modified polyoxometalate molecularly imprinted polymer (Cu@B@PW9@MIPs). This adsorbent was used to immobilize HRP, which served as a biological enzyme catalyst from horseradish. The adsorbent was characterized, and its synthetic conditions, experimental conditions, selectivity, reproducibility, and reusability were evaluated. The maximum adsorption amount of HRP under optimized conditions was 159.1 mg g−1, as determined using high-performance liquid chromatography (HPLC). At pH 7.0, the immobilized enzyme showed a high efficiency of up to 90.0% in removing phenol, after 20 min of reaction with 25 mmol L−1 H2O2 and 0.20 mg mL−1 Cu@B@PW9@HRP. Growth tests of aquatic plants confirmed that the adsorbent reduced harm. Gas chromatography-mass spectrometry (GC-MS) tests revealed that the degraded phenol solution contained about fifteen phenol derivatives intermediates. This adsorbent has the potential to become a promising biological enzyme catalyst for dephenolization.

Electrochemical H2O2 biosensor based on horseradish peroxidase encapsulated protein nanoparticles with reduced graphene oxide-modified gold electrode

In this study, an electrochemical biosensor composed of a horseradish peroxidase (HRP)-encapsulated protein nanoparticles (HEPNP) was fabricated for the sensitive and selective detection of H2O2. The HEPNP has a three-dimensional structure that can contain a large amount of HRP; therefore, HEPNP can amplify the electrochemical signals necessary for the detection of H2O2. Furthermore, reduced graphene oxide (rGO) was used to increase the efficiency of electron transfer from the HEPNP to an electrode, which could enhance the electrochemical signal. This biosensor showed a sensitive electrochemical performance for detection of H2O2 with signals in the range from 0.01–100 μM, and it could detect low concentrations up to 0.01 μM. Furthermore, this biosensor was operated against interferences from glucose, ascorbic acid, and uric acid. In addition, this fabricated H2O2 biosensor showed selective detection performance in human blood serum. Therefore, the proposed biosensor could promote the sensitive and selective detection of H2O2 in clinical applications.

A novel chemiluminescence imaging immunosensor for prostate specific antigen detection based on a multiple signal amplification strategy

A novel chemiluminescence (CL) imaging platform was constructed for prostate specific antigen (PSA) detection in a multiple signal amplifying manner. To construct the platform, the primary antibody for PSA was firstly immobilized on a O-ring area of a glass slide for recognizing the PSA. The horseradish peroxidase (HRP) and the secondary antibody of PSA (Ab2) functionalized Au NPs (HRP-Au NPs-Ab2) were modified on the platform through immunoreaction between PSA and Ab2. The excellent catalytic effect of Au NPs and HRP on the HRP-Au NPs-Ab2 to the luminol-H2O2 CL system provided the dual-signal amplification for PSA detection. To further enhance the sensitivity, tyramine signal amplification (TSA) strategy was introduced: tyramine-HRP conjugates were added into the O-ring reservoir and thus tyramine-HRP repeats formed in the presence of H2O2, generating a multiple signal amplification because of the large amounts of HRP on the sensing interface. The excellent performance of HRP-Au NPs-Ab2 and TSA strategy endows the CL platform with high sensitivity. The PSA was detected with a photomultiplier tube (PMT) and visually analyzed by a charge coupled device (CCD), respectively. The linear ranges of PMT and CCD for PSA are 0.1–100.0 ng mL-1 with a detection limit of 0.05 pg mL-1 and 0.5 – 100.0 ng mL-1 with a detection limit of 0.1 pg mL-1, respectively. The levels of PSA in several human serum samples were determined and the recoveries are ranged from 82.5% – 117.0%. This CL immunosensing platform holds great potential for bioactive molecules detection visually and sensitively.

Detection of colorectal cancer-derived exosomes based on covalent organic frameworks

Covalent organic frameworks (COFs) have attracted more and more attention due to their diverse structures and multifunctionality. Their unique physicochemical properties make them exhibit great application potential in the field of biosensing. In this work, we have designed and fabricated a novel COFs-based nanoprobe named HRP-pSC4-AuNPs@COFs, where spherical COFs are functionalized with para-sulfocalix [4] arene hydrate (pSC4)-modified gold nanoparticles (AuNPs) and horseradish peroxidase (HRP). Then, we have applied it for the electrochemical detection of colorectal cancer (CRC)-derived exosomes. In this design, pSC4 as amicable linker can recognize and bind with various amino acid residues on the exosomes surface, while AuNPs with excellent conductivity can accelerate the migration of charge carriers and improve the response of biosensors. Noteworthy, the high porosity of COFs allows them to load a large amount of HRP, endowing COF with high catalytic activity. Meanwhile, the exoskeleton of COFs can maintain the functionality of HRP with significantly elevated stability. With such design, the proposed method shows excellent analytical performance for the detection of CRC-derived exosomes in the linear range from 5 × 102 to 107 particles/μL with a detection limit down to 160 particles/μL. Further, this method has also been used to analyze clinical serum sample, and can successfully distinguish CRC patients from healthy people, indicating the promising potential in clinical diagnosis.

Estimation of immobilized horseradish peroxidase in a low salt concentration for an irreversible electrochemical system

We examined the direct electron transfer of horseradish peroxidase (HRP) at HRP/carbon paste (CP)-modified electrodes under irreversible electrochemical conditions. The amount of electroactive HRP (Γ) was estimated as 2.0 × 10−9 to 3.9 × 10−9 mol, indicating that the effectiveness factor, defined as the ratio of the amount of electroactive HRP to the amount of HRP incorporated into CP, was 0.14–0.24. In the presence of potassium ferricyanide(III) (K3Fe(CN)6) and potassium hexacyanoferrate(II) (K4Fe(CN)6) as mediators, the electroactive surface area of only HRP on the HRP/CP-modified electrode was 0.0164 cm2. The theoretically calculated coverage area of electroactive HRP on the HRP/CP-modified electrode was much greater than the electroactive surface area of the CP electrode. In addition, the rate constant (k°) of the electrochemical reaction of HRP at the HRP/CP-modified electrode was 0.006 s−1 for the oxidation process.

Two-step signal amplification for high-sensitivity detection of biomarkers using gold nanoparticle-based conjugates.

The measurement of biomarkers in bodily fluids is extremely important for diagnosing disease, monitoring disease progression, and evaluating treatment efficacy. In this paper, we present a highly sensitive and compatible gold nanoparticle (AuNP)-based, two-step signal amplification system for biomarker detection. First, AuNPs were coated onto the surfaces of 96-well plates to generate rough surfaces, which enable immobilization of many more capture antibodies than a smooth substrate. As a result, detection sensitivity was enhanced significantly. Second, the horseradish peroxidase (HRP)-conjugated detection antibodies were labeled on large-size AuNPs, which increase the localized amounts of HRP and thus further lower the detection limit. Based on the consecutive signal amplification system, a high-sensitivity assay was achieved, with a LOD of 0.07 ng/mL for prostate-specific antigen (PSA). This assay was allowed to detect the PSA levels in clinical samples without changing the current standard immunoassay setups, showing great potential in many settings where immunoassays are needed.

Immobilization of Horseradish Peroxidase on Multi-Armed Magnetic Graphene Oxide Composite: Improvement of Loading Amount and Catalytic Activity.

SUMMARYIn this study, a novel type of multi-armed polymer (poyltehylene glycol, PEG) magnetic graphene oxide (GO) composite (GO@Fe3O4@6arm-PEG-NH2) has been synthesized as a support for immobilization of horseradish peroxidase (HRP) for the first time. The loading amount of HRP was relatively high (186.34 mg/g) due to the surface of carrier material containing a large amount of amino groups from 6arm-PEG-NH2, but degradation rate of phenols was also much higher (95.4%), which is attributed to the synergistic effect between the free HRP (45.4%) and the support material of GO@Fe3O4@6arm-PEG-NH2 (13.6%). Compared with the free enzyme, thermal, storage and operational stability of the immobilized HRP improved. The immobilized HRP still retained over 68.1% activity after being reused 8 times. These results suggest that the multi-armed magnetic composite has good application prospect for enzyme immobilization.

NAD+ Cofactor Regeneration by TMB‐Mediated Horseradish‐Peroxidase‐Catalyzed Reactions

AbstractThe regeneration of nicotinamide adenine dinucleotide (NAD+) has attracted substantial interest in the enzymatic chemical transformations. In this work, we report the use of a traditional horseradish peroxidase (HRP)/H2O2 system for the catalytic transformation of reduced nicotinamide adenine dinucleotide (NADH) into NAD+, in the presence of a common HRP substrate, 3,3′,5,5′‐tetramethylbenzidine (TMB), as an electron mediator. The effect of H2O2, HRP or TMB concentration on the oxidization rate of NADH was systematically investigated. The results show that a small amount of HRP and TMB resulted in high efficient oxidization of NADH into NAD+, through the switching between the oxidized and reduced states of TMB. The enzymatic system also exhibited pH‐dependent catalytic properties, so that a XOR logic gate was constructed with H2O2 and H+ as the gate inputs, and the generated TMB charge transfer complex as the output signals. The addition of glucose dehydrogenase (GDH)/glucose allows the cycling between the NADH and NAD+ and the coupled activation of HRP and GDH. This work provides a strategy for efficient regeneration of the NAD+ cofactor and enzyme‐driven transformations.

The Effects of Lipopolysaccharide on the Disrupted Blood-Brain Barrier in a Rat Model of Preeclampsia

BackgroundPreeclampsia is a disorder characterized by high blood pressure and often proteinuria during pregnancy. It is known that a subseptic dose of bacterial lipopolysaccharide (LPS) induces production of proinflammatory cytokines, and possibly increasing the risk for developing preeclampsia. We investigated the effects of LPS on the blood-brain barrier (BBB) integrity in pregnant rats with N(omega)-nitro-l-arginine methyl ester (L-NAME) induced preeclampsia. MethodsStarting from the 10th day of gestation, pregnant rats were given L-NAME for 10 days to produce hypertension and proteinuria. Animals were then treated with a single injection of LPS on the 19th day of pregnancy. Arterial blood pressure and proteinuria were measured on the day of the experiment, which was 24 hours after the LPS injection. The BBB integrity was assessed by using Evans blue (EB) and horseradish peroxidase (HRP) tracers. ResultsProteinuria was observed in varying degrees, and the arterial blood pressure increased in L-NAME-treated pregnant rats (P < .01). The overall brain EB content did not increase in these preeclamptic rats when compared to pregnant animals, and LPS treatment also did not change EB content. Ultrastructurally, frequent vesicles containing HRP reaction products were observed in the capillary endothelial cells in the cerebral cortex and hippocampus of pregnant rats treated with L-NAME (P < .01). However, LPS did not change the amounts of HRP that mainly accumulated in brain capillary endothelial cells of these animals. ConclusionOur results suggest that, in this experimental setting, LPS does not change the severity of BBB disruption observed in preeclamptic animals.

A molecularly imprinted sensor with enzymatic enhancement of electrochemiluminescence of quantum dots for ultratrace clopyralid determination.

A new molecularly imprinted polymer electrochemiluminescence (ECL) sensor was developed for the detection of clopyralid (CPD) based on enzyme-biocatalyzed amplification. CdTe quantum dots were immobilized on the surface of an electrode by reaction with p-aminothiophenol preadsorbed on the electrode. Then a molecularly imprinted film was formed by electrochemical polymerization of o-phenylenediamine in the presence of CPD on the CdTe-modified gold electrode. During the analytical cycle, horseradish peroxidase (HRP)-labeled CPD was replaced by CPD in the sample. The amount of HRP on the molecularly imprinted polymer electrode decreased, and then less H2O2 was catalytically decomposed. Subsequently, the ECL intensity of the CdTe-H2O2 system was enhanced. There was a good linear relationship between ECL intensity and the concentration of CPD in the range from 2.0 × 10-11 to 2.5 × 10-10 mol/L and in the range from 2.5 × 10-10 to 3.5 × 10-8 mol/L. The detection limit was 4.1 × 10-12 mol/L. The sensor was applied to determine CPD in vegetable samples. Graphical abstract A molecularly imprinted electrochemiluminescence sensor was fabricated for ultratrace clopyralid determination. The sensitivity was significantly improved with the enhancement of the ECL intensity of quantum dot via the enzymatic reaction of HRP.

Electrochemical immunoassay of E. coli in urban sludge using electron mediator-mediated enzymatic catalysis and gold nanoparticles for signal amplification

An electrochemical immunosensor was developed for sensitive assay of E. coli in urban sludge, in which electron mediator-mediated enzymatic catalysis and gold nanoparticles(AuNPs) were utilized for signal amplification. The immnuosensing platform chitosan-thionine(chit-thio)/poly(amidoamine) dendrimer-encapsulated AuNPs [PAMAM(Au)] composites were first prepared from chit-thio and PAMAM(Au) using the layer-by-layer method to provide a matrix for high-stability and high-bioactivity bindings of the capture antibody(cAb). Moreover, the {dAb-AuNPs-HRP} nanoprobes were designed to exploit the amplification effect of the carrier AuNPs due to the loading amounts of horseradish peroxidase(HRP) and the detection antibody(dAb). The sandwich-type immunoassay was then successfully used to assay E. coli based on the oxidation of thionine as a result of H2O2-induced enzymatic catalytic reaction by HRP. This study presents a powerful tool in electrochemical immunoassay for E. coli detection with rapid response, high-sensitivity and high-specificity, providing a potential new tool for feasibility assessment of sludge recycle.

Fluorescent silicon nanoparticles-based ratiometric fluorescence immunoassay for sensitive detection of ethyl carbamate in red wine

Abstract Herein, a ratiometric fluorescence (RF) enzyme-linked immunosorbent assay (RF-ELISA) for sensitive detection of ethyl carbamate (EC) was developed by introducing fluorescent silicon nanoparticles (Si NPs) into the chromogenic substrate system (o-phenylenediamine (OPD)/H 2 O 2 ) of a conventional horseradish peroxidase (HRP)-based ELISA platform to assemble a RF-based signal output system. For this system, the fluorescence of Si NPs at 440 nm (I 440 ) was acted as the reference signal which could be efficiently quenched by 2,3-diaminophenazine (DAP), the HRP-catalyzed oxidation product of OPD; Meanwhile, the fluorescence of DAP at 570 nm (I 570 ) was served as response signal. Therefore, variation in the amount of HRP labeled secondary antibody bound on the microplate which is associated with antibody-antigen recognition events in conventional HRP-based ELISA could be transferred into a more sensitive RF signal (I 570 /I 440 ). On the basis of monoclonal antibody (mAb) which could specifically recognize EC derivative, xanthyl ethyl carbamate (XEC), a Si NPs-based RF-ELISA for EC via a simple pre-analysis derivatization was developed. When detecting the EC content in red wine, this method exhibits a working range from 3.9 to 105.0 μg/L and a limit of detection (LOD) of 2.6 μg/L with excellent specificity, accuracy and reproducibility. The sensitivity is approximately 33-fold higher than that of traditional colorimetric ELISA. The proposed Si NPs-based RF-ELISA is not only highly suitable for screening EC in a large number of samples, but also provides a potential platform for high-throughput and sensitive determination of other analytes for food safety monitoring.

Immobilization of horseradish peroxidase on ZnO nanowires/macroporous SiO2 composites for the complete decolorization of anthraquinone dyes.

A zinc oxide (ZnO) nanowires/macroporous silicon dioxide composite was used as support to immobilize horseradish peroxidase (HRP) simply by in situ cross-linking method. As cross-linker was adsorbed on the surface of ZnO nanowires, the cross-linked HRP was quite different from the traditional cross-linking enzyme aggregates on both structure and catalytic performance. Among three epoxy compounds, diethylene glycol diglycidyl ether (DDE) was the best cross-linker, with which the loading amount of HRP with pI of 5.3 reached as high as 118.1 mg/g and specific activity was up to 14.9 U/mg-support. The mass loss of HRP cross-linked with DDE was negligible during 50-H leaching at 4 °C, and the thermal stability of the immobilized HRP was also quite good. The catalytic performance of immobilized HRP to decolorize anthraquinone dye was explored by using Reactive Blue 19 (RB 19) and Acid Violet 109 (AV 109) as model substrates. The results indicated that the immobilized HRP exhibited high decolorization efficiency and good reusability. The decolorization efficiency reached 94.3% and 95.9% for AV 109 and RB 19 within the first 30 Min, respectively. A complete decolorization of these two dyes has been realized within 2-3 H by using this new biocatalysis system.

Preventing postoperative tissue adhesion using injectable carboxymethyl cellulose-pullulan hydrogels

An injectable adhesive hydrogel composed of carboxymethyl cellulose (CMC) and pullulan is developed and evaluated as a postoperative anti-adhesion barrier. CMC was modified with tyramine to introduce crosslinking site via an EDC-NHS reaction. The in situ hydrogel was prepared by an enzyme-mediated reaction of tyramine-immobilized CMC with horseradish peroxidase (HRP) and hydrogen peroxide (H2O2). Pullulan was added to the hydrogel solution to improve adhesiveness to the wound area and accelerate biodegradation. The modified CMC was confirmed by ATR-FTIR spectroscopy. The gelation time, storage modulus (G′), and weight loss of the hydrogels were measured as functions of the amounts of HRP and H2O2. The hydrogel group showed negligible cell proliferation and cytotoxicity, compared to that shown by the control group. The in vivo animal test demonstrated that significant decrease of postoperative tissue adhesion by applying the hydrogels. The CMC-pullulan hydrogel could be a useful treatment as an injectable in situ anti-adhesive agent.

Highly sensitive colorimetric immunosensor for influenza virus H5N1 based on enzyme-encapsulated liposome

Development of simple but sensitive biosensor for influenza detection is highly important in immediate and effective clinical treatment. In this study, a sensitive colorimetric immunosensor which combines the advantages of high selectivity of immunoassay and simplicity of colorimetric detection has been developed to detect influenza virus H5N1 based on enzyme-encapsulated liposome. Biotin-tagged liposome encapsulated with large amount of horseradish peroxidase (HRP) was firstly synthesized. In the presence of H5N1, H5N1 co-bound with the capture antibody and the biotinylated detection antibody to form sandwich immunocomplex. Subsequently, the HRP-encapsulated liposome was introduced to conjugate with the detection antibody through biotin-avidin-biotin linkage. Upon the addition of substrate (mixture of 3,3′,5,5′-tetramethylbenzidine (TMB) and H2O2), the liposome was directly lysed to release large amount of HRP by TMB. The released HRP catalyzed the H2O2-mediated oxidation of TMB, resulting in color change of the system, which was observed by naked eyes or UV–vis spectra. The result showed that the absorption intensity enhanced with the increase of H5N1 concentration ranging from 0.1 to 4.0 ng/mL, and the detection limit was calculated to be 0.04 ng/mL. The sensitivity of the proposed biosensor is much higher than that of conventional enzyme-linked immunosorbent assay method. The proposed immunosensor is relatively simple, low-cost, sensitive, and selective without using any sophisticated instruments, therefore it may have a promising prospect for detecting targets in clinical medicine, food safety analysis, and environmental monitoring.

Dual-Signal Amplified Electrochemiluminescent Immunosensor for Detecting Ractopamine Using Quantum Dots and Gold Nanoparticles-Labeled Horseradish Peroxidase

A dual-signal amplification strategy for electrochemiluminescence (ECL) immunosensor was designed based on L-cysteine capped CdSe quantum dots (QDs) and gold nanoparticles (AuNPs) conjugated horseradish peroxidase (HRP) for highly sensitive detection of ractopamine (RAC). The electrochemical detection was based on the HRP catalyzed o-phenylenediamine (OPD) to consume the self-produced H2O2, which has been extensively used as a co-reactant of QDs. The enzymatic reaction rate was proportional to the amount of HRP bound to the electrode. In the presence of RAC standard solution, the immobilized RAC coating antigen competed with RAC solution for the Ab-AuNPs-HRP complexes. With the increase of the RAC concentration, the amount of immobilized HRP decreased, which led to the increase of ECL intensity. Under optimized conditions, ECL intensity changed linearly with the logarithm of RAC concentration in the range of 0.005–500 ng mL−1 with the detection limit of 0.0017 ng mL−1 (S/N = 3). The ECL immunosensor possesses high sensitivity, satisfied reproducibility and selectivity, and may provide a feasible route for practical application of RAC detection.

Improved biodegradation of synthetic azo dye by horseradish peroxidase cross-linked on nano-composite support

A ZnO nanowires/macroporous SiO2 composite was used as support to immobilize horseradish peroxidase (HRP) by in-situ cross-linking method. Using diethylene glycol diglycidyl ether (DDE) as a long-chained cross-linker, it was adsorbed on the surface of ZnO nanowires before reaction with HRPs, the resulted composite was quite different from the traditional cross-linking enzyme aggregates (CLEAs) on both structure and catalytic performance. The immobilized HRP showed high activity in the decolorization of azo dyes. The effect of various conditions such as the loading amount of HRP, solution pH, temperature, contact time and concentration of dye were optimized on the decolorization. The decolorization percentage of Acid Blue 113 and Acid black 10 BX reached as high as 95.4% and 90.3%, respectively. The immobilized HRP gave the highest decolorization rate under dye concentration as 50mg/L and reaction time of 35min. The immobilized HRP exhibited much better resistance to temperature and pH inactivation than free HRP. The storage stability and reusability were greatly improved through the immobilization, from the decolorization of Acid blue 113 it was found that 80.4% of initial efficiency retained after incubation at 4°C for 60 days, and that 79.4% of decolorization efficiency retained after 12 cycles reuse.

An electrochemical biosensor for DNA detection based on tungsten disulfide/multi-walled carbon nanotube composites and hybridization chain reaction amplification

We report the preparation and characterization of tungsten disulfide-multi-walled carbon nanotubes (WS2-MWCNTs) composite via a simple hydrothermal process and demonstrate its application as a biosensing platform for ultrasensitive determination of hepatitis B virus genomic DNA coupled with hybridization chain reaction (HCR) signal amplification. The sensing platform includes capture DNA probe (cDNA), auxiliary DNA, two DNA hairpins, and detection signal is amplified by horse radish peroxidase (HRP) on the DNA duplex. The biosensor is fabricated with the cDNA labeled at 3′ end using thiol immobilized on the WS2-MWCNTs/Au nanoparticels modified electrode. cDNA fixed onto electrode surface then reacts with target DNA through the 3′ end of auxiliary DNA. The remaining segment on 5′ end of auxiliary DNA then takes turns to open two alternating DNA hairpins. This leads to a HCR events to produce a nicked double-helix. A large amount of HRP is then combined on DNA helix by affinity interaction of biotin-avidin, each of which amplifies the final electrochemical signal through the catalytic reaction of H2O2 and hydroquinol. Under optimal conditions, a dynamic range of 10fM–0.1nM is obtained with a detection limit of 2.5fM. Synergistic effect of WS2-MWCNTs composite and HCR have proven to greatly improve sensitivity for DNA detection.

Electrochemical immunosensor for interferon-γ based on disposable ITO detector and HRP-antibody-conjugated nano gold as signal tag

Tuberculosis is the most frequent cause of infection-related death worldwide. A new disposable electrochemical immunosensor with low cost and simple fabrication was proposed to detect interferon-γ (IFN-γ). Diallyldimethylammonium chloride (PDDA) and Au nanoparticle (AuNP) composite were used to provide an efficient biointerface, horseradish peroxidase (HRP)-labeled antibody-conjugated AuNP (HRP-Ab2-AuNP) bioconjugates were used as a novel signal tag. The large amounts of HRP on the signal tag can catalyze the oxidation of Hydroquinone (HQ) by H2O2, which can induce an amplified reductive current. The catalytic reduction current was related to the amount of HRP immobilized on the surface, which itself was related to the concentration of IFN-γ. Under optimized conditions, the proposed immunosensor showed a high sensitivity and a linear range of 0.1–10,000pg/mL with a detection limit of 0.048pg/mL. The assay results of clinical serum samples obtained by the immunosensor were in acceptable agreement with the reference values. Therefore, the immunosensor possessed excellent clinical value in early diagnosis and control of tuberculosis.