1-naphthyl Phosphate Research Articles

Ratiometric electrochemical detection of alkaline phosphatase based on SWCNTs/Cu-MOF modified graphite paper electrodes

Alkaline phosphatase (ALP) is integral to a diverse array of biological processes, consequently, its presence is frequently linked to the onset of various pathologies. In the current investigation, 1-naphthyl phosphate (1-Npp) served as a substrate, with the catalytic hydrolysis of phosphate groups by ALP being leveraged to engender a detectable current at an applied potential of 0.277 V. Initially, carbon nanotubes (SWCNTs) were deposited via drop-coating onto graphite paper (Gp), a material characterized by exceptional electrical conductivity. Subsequently, Cu-MOF was uniformly deposited on Gp/SWCNTs composites by rapid electrodeposition technique, that is, chronocurrent method (i–t), at a potential of −1.1 V for 240 s, thereby fabricating an electrochemical sensor platform denominated Gp/SWCNTs/Cu-MOF. This platform enabled the ratiometric electrochemical quantification of ALP, utilizing the signal from Cu-MOF as an internal standard. This platform’s integrated design facilitates signal amplification and provides an inbuilt reference, which was instrumental in mitigating the impact of environmental fluctuations and enhancing the precision of the obtained data. The ratiometric signals exhibited strong linear correlations within the 0.014–14.29 U mL−1 concentration, with a detection limit of 0.005 U mL−1. Moreover, the sensor exhibited robust selectivity, repeatability, and excellent detection performance in real-world samples, with recovery rates spanning 99.3 %–103.5 %, making it a suitable candidate for the expedient and precise quantification of ALP in serum.

Purification and characterization of acid phosphatase from larvae of the camel tick Hyalomma dromedarii: inhibition kinetics by sodium fluoride

ABSTRACTAcid phosphatases (ACPs) perform a fundamental role in the digestion of egg proteins (vitellins), ensuring the survival of ticks by providing nutrients necessary for their oogenesis. Here, acid phosphatase activity is detected during embryogenesis of the camel tick Hyalomma dromedarii and reached its highest activity level in the larval stage. The tick larvae acid phosphatase which was named TLACP is homogeneously purified using CM cellulose cation exchange chromatography followed by gel filtration on Sephacryl S-300 column. TLACP is purified to 11 times purification folds and 51.3% yield with a specific activity of 12.9 U mg−1 protein. The molecular weight of TLACP was derived from both the gel filtration column and SDS-PAGE as monomer protein of 40 kDa. The Km of TLACP for p-nitrophenyl phosphate (p-NPP) was 1.25 mM and Vmax was 6.4 Umg−1. TLACP exhibited its optimum enzymatic activity at pH 4.8. TLACP was found highly specific to p-NPP followed by ATP, ADP, glucose-6-phosphate, naphthyl phosphate, phospho-enol-pyruvate, creatine phosphate, AMP, and GMP. The ions of Ca2+, Co2+, Mg2+, Ni2+, and Zn2+ motivated TLACP activity while Mn2+, Cu2+, and Fe2+ suppressed it. TLACP is noncompetitively inhibited with sodium fluoride with Ki value 0.15 mM. Thus, the presence of TLACP in tick embryonic and larval cells classifies this enzyme as an important molecular target for evolving potential vaccines in further studies aiming to find new strategies to control ticks.

Genosensing on a 3D-printed nanocarbon electrode

In this paper we present the characterization of 3D-printed nanocarbon electrodes (3DnCes) and their application in electrochemical enzyme-linked detection of DNA hybridization. The approach takes advantage of a facile procedure based on adsorption of target DNA on the electrode surface followed by hybridization with a biotinylated probe and binding of streptavidin–alkaline phosphatase conjugate. The alkaline phosphatase converts 1-naphthyl phosphate in the background electrolyte into electrochemically oxidizable 1-naphthol, which is subsequently detected using linear sweep voltammetry. The preparation, characterization, and analytical performance of the 3DnCes are reported. The results show the applicability of such 3DnCes in detection of target DNA hybridization specifically with the complementary biotinylated probe, and indicate the potential of 3D printed electrodes for use in various bioanalytical approaches.

A Novel Electrochemical Sensing Strategy Based on Poly (3, 4-ethylenedioxythiophene): Polystyrene Sulfonate, AuNPs, and Ag+ for Highly Sensitive Detection of Alkaline Phosphatase.

Alkaline phosphatase (ALP) is a crucial marker for the clinical analysis and detection of many diseases. In this study, an accurate signal amplification strategy was proposed for the sensing and quantification of alkaline phosphatase using poly (3, 4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), gold nanoparticles (AuNPs), and Ag+. Signal amplification was achieved by the modification of PEDOT:PSS and AuNPs on glassy carbon electrodes. Atomic force microscopy was performed to characterize the morphology of the modified nanomaterials. To detect ALP, 1-naphthyl phosphate (1-NP) was used as the substrate, and alkaline phosphatase catalyzed 1-NP into 1-naphthol (1-N), which resulted in the reduction of Ag+ to Ag0 on the surface of the modified electrode (AuNPs/PEDOT:PSS/GCE). The deposition of Ag drastically enhanced the detection signal. Differential pulse voltammograms of 1-N, which is the enzymatic product from the ALP reaction with 1-NP, were recorded. In the linear range of 0.1–120 U L−1, a quantitative analysis of alkaline phosphatase was achieved, with high sensitivity and a low detection limit of 0.03 U L−1. Stable, selective, and reproducible electrochemical sensors were designed. Moreover, the proposed electrochemical sensor exhibited a prominent sensing performance in the spiked diluted human serum. Thus, the sensor can be used in numerous applications in alkaline phosphatase or other analyte detection.

How the type of interface can alter the behavior of an aprotic ionic liquid-water mixture entrapped in different reverse micelles: An exploratory study using an enzymatic reaction as a sensor

In this work, we decipher how an aprotic Ionic Liquid (IL)-water mixture structure can be altered upon confinement in different reverse micelles (RMs) media. Thus, the effect of the polar pseudophase composition in RMs formulated by anionic or cationic surfactants was monitored using the well-known enzymatic hydrolysis reaction of 1-naphthyl phosphate (1-NP) with alkaline phosphatase (AP). Water and an aqueous mixture formed by the IL 1-butyl-3-methylimidazolium trifluoromethanesulfonate ([C4C1im, TfO]) as the polar pseudophase were used. As surfactants, the anionic sodium diethylhexyl sulfosuccinate (AOT) and the cationic benzyl-n-hexadecyldimethylammonium chloride (BHDC) were employed. The effect of the nanoconfinement, as well as the impact of the polar solvent content and the type of interface, were analyzed by determining the Michaelis-Menten parameters. In homogeneous media, the catalytic efficiency of the hydrolysis reaction is strongly dependent on the amount of water in the mixtures evaluated. In RMs the catalytic efficiency is dependent on both, the polar content and the type of surfactant used. Thus, by using a model reaction with an enzyme entrapped inside different RMs it was possible to learn that an aprotic IL:water mixture can be strongly disturbed when it is confined in a cationic or anionic RMs. This particular behavior can produce a deep impact on the technological applications of these organized systems.

Competitive measurement of β/α naphthyl phosphate catalytic efficiency by phosphatases utilizing quantitative NMR

The two constitutional isomers of naphthyl phosphate have different steric properties, analogous to those of phosphotyrosine versus phosphoserine/threonine within a peptide or protein. The ratios of their respective rates of hydrolysis, assayed by measuring rates of inorganic phosphate release, have been used to probe the steric requirements around the active sites of many phosphatases in the literature. We report an NMR-based competitive method that is simpler to execute and has other advantages. It directly yields the ratio of catalytic efficiencies (V/K) of the two substrates, a more biologically relevant comparison than the ratio of initial rates (vo) or maximal rates (Vmax). The competitive method ensures that temperature, pH, enzyme and substrate concentrations, and the presence of any potential inhibitors are identical and will not skew the results. The method can be easily applied at any chosen temperature or pH, and to mutants, or under any other condition that might influence protein conformation and, thus, substrate specificity. It provides a facile screening method to select conditions for a detailed phosphopeptide screen to provide deeper insight into substrate preference.

Hemoglobin-modified nanoparticles for electrochemical determination of haptoglobin: Application in bovine mastitis diagnosis

Mastitis is the most common inflammatory disease in cattle, with an important economic impact on dairy farms and on the animals’ health. Haptoglobin (Hp) has been proposed as a novel and effective biomarker for this disease. This work reports on the fabrication and characterization of novel hemoglobin (Hb)-modified magnetic nanoparticles (MNPs) and their application in bovine Hp detection. Firstly, chitosan-modified MNPs (MNPs-Chi) were synthesized and coated with polydopamine (pDA). MNPs-Chi@pDA were then modified with Hb because of its high affinity to Hp. The different stages during the MNPs synthesis and their modifications were evaluated with UV–Vis spectroscopy, XRD, FT-IR, thermogravimetric, electrical impedance and BET analysis. Finally, the MNPs were incorporated as solid support for Hp immobilization, and its further quantification was performed by means of an alkaline phosphatase-based assay with electrochemical detection. To do this, an electroactive substrate (1-naphthyl phosphate) and differential pulse voltammetry (DPV) were used for the indirect Hp determination. After the optimization of the main assay parameters such as incubation steps, antibody concentrations, enzymatic reaction time, among others; the Hp biosensing capacity was demonstrated in milk. The strategy presented in this work shows a wide range of detection (25–800 μg mL−1), achieving a limit of detection of 43 ng mL−1. The accuracy of the strategy was determined by recovery assays at four Hp concentrations in spiked milk samples, showing excellent results. The performance of the electrochemical sensing strategy offers an excellent and real alternative as on farm screening method for sub-clinical bovine mastitis detection.

Novel Ti3C2Tx MXene nanozyme with manageable catalytic activity and application to electrochemical biosensor

In this work, Ti3C2Tx MXene was identified as efficient nanozyme with area-dependent electrocatalytic activity in oxidation of phenolic compounds, which originated from the strong adsorption effect between the phenolic hydroxyl group and the oxygen atom on the surface of Ti3C2Tx MXene flake. On the basis of the novel electrocatalytic activity, Ti3C2Tx MXene was combined with alkaline phosphatase to construct a novel cascading catalytic amplification strategy using 1-naphthyl phosphate (1-NPP) as substrate, thereby realizing efficient electrochemical signal amplification. Taking advantage of the novel cascading catalytic amplification strategy, an electrochemical biosensor was fabricated for BCR/ABL fusion gene detection, which achieved excellent sensitivity with linear range from 0.2 fM to 20 nM and limit of detection down to 0.05 fM. This biosensor provided a promising tool for ultrasensitive fusion gene detection in early diagnosis of chronic myelogenous leukemia and acute lymphocytic leukemia. Moreover, the manageable catalytic activity of MXene broke a path for developing nanozymes, which possessed enormous application potential in not only electrochemical analysis but also the extensive fields including organic synthesis, pollutant disposal and so on.Graphical

Copper(I) Alkynyl Clusters with Crystallization-Induced Emission Enhancement.

Four copper(I) alkynyl complexes incorporating phosphate ligands, namely, [Cu16(tBuC≡C)12(PhOPO3)2]n (1; PhOPO3 = phenyl phosphate), [Cu16(tBuC≡C)12(1-NaphOPO3)2]n (2; 1-NaphOPO3 = 1-naphthyl phosphate), [VO4@Cu25(tBuC≡C)19(1-NaphOPO3)](PF6)0.5(F)0.5 (3), and [PO4@Cu25(tBuC≡C)19(1-NaphOPO3)](PF6)0.5(F)0.5 (4), were solvothermally synthesized and well-characterized by IR spectroscopy, powder X-ray diffraction, and single-crystal X-ray diffraction. Single-crystal X-ray analysis revealed that the Cu16 cluster-based coordination chain polymers 1 and 2 are formed by assembly during crystallization, while 3 and 4 contain high-nuclearity copper(I) composite clusters enclosing orthovanadate and phosphate template ions, respectively, that are supported by ROPO32- ligands. Complexes 1-4 exhibit crystallization-induced emission enhancement. Their crystalline state shows strong luminescence, in striking contrast to the weak emission of the amorphous state and solution phase. A detailed investigation of the crystal structure suggests that well-arranged C-H···π and π···π interactions between the ligands are the major factors for this enhanced emission. Clusters 3 and 4 also exhibit photocurrent responses upon visible-light illumination.

How the external solvent in biocompatible reverse micelles can improve the alkaline phosphatase behavior.

In the last decade, the nature of the nonpolar solvents that can be part of reverse micelles (RMs) has been the topic of several investigations to improve their applications. In this sense, the hydrolysis of 1-naphthyl phosphate catalyzed by the enzyme alkaline phosphatase (AP) was used as a probe to investigate the effect of the change of the external solvent on RMs formulated with the anionic surfactant sodium diethylhexyl sulfosuccinate (AOT). As external nonpolar solvents, two biocompatible lipophilic esters, isopropyl myristate and methyl laurate, and the traditional nonpolar solvents, n-heptane and benzene, were used. The results were compared among the RMs investigated and with the reaction in homogeneous media. Thus, the effect of the nanoconfinement as well as the impact of the replacement of a conventional external nonpolar solvent by biocompatible solvents were analyzed. The results indicate that the catalytic efficiency in the AOT RMs is larger than that in homogeneous media, denoting a different hydration level over the AP enzyme, which is directly related to the different degrees of nonpolar solvent penetration to the RM interface. Our findings demonstrated that toxic solvents such as n-heptane and benzene can be replaced by nontoxic ones (isopropyl myristate or methyl laurate) in AOT RMs without affecting the performance of micellar systems as nanoreactors, making them a green and promising alternative toward efficient and sustainable chemistry.

Mycotoxins aptasensing: From molecular docking to electrochemical detection of deoxynivalenol

This work proposes a voltammetric aptasensor to detect deoxynivalenol (DON) mycotoxin. The development steps of the aptasensor were partnered for the first time to a computational study to gain insights onto the molecular mechanisms involved into the interaction between a thiol-tethered DNA aptamer (80mer-SH) and DON. The exploited docking study allowed to find the binding region of the oligonucleotide sequence and to determine DON preferred orientation. A biotinylated oligonucleotide sequence (20mer-BIO) complementary to the aptamer was chosen to carry out a competitive format. Graphite screen-printed electrodes (GSPEs) were electrochemically modified with polyaniline and gold nanoparticles (AuNPs@PANI) by means of cyclic voltammetry (CV) and worked as a scaffold for the immobilization of the DNA aptamer. Solutions containing increasing concentrations of DON and a fixed amount of 20mer-BIO were dropped onto the aptasensor surface: the resulting hybrids were labeled with an alkaline phosphatase (ALP) conjugate to hydrolyze 1-naphthyl phosphate (1-NPP) substrate into 1-naphthol product, detected by differential pulse voltammetry (DPV). According to its competitive format, the aptasensor response was signal-off in the range 5.0–30.0 ng·mL−1 DON. A detection limit of 3.2 ng·mL−1 was achieved within a 1-hour detection time. Preliminary experiments on maize flour samples spiked with DON yielded good recovery values.

Development of novel carbon black-based heterogeneous oligonucleotide-antibody assay for sulfur mustard detection

Herein, a novel configuration for the detection of a chemical warfare agent, namely sulfur mustard (bis(2-chloroethyl)sulphide) was designed to develop a biosensor that can play a relevant role in the monitoring of such a chemical threat in risk and war areas. In detail, a tailor-made heterogeneous oligonucleotide-antibody biosensor was realised, based on the formation of a sulfur mustard-oligonucleotide adduct on the surface of a screen-printed electrode. Thus, the immunoassay was carried out through a sequential immobilisation process, involving a primary antibody, ad hoc synthesised for the selective recognition of the sulfur mustard-oligonucleotide adduct, followed by an alkaline phosphatase-conjugated anti-mouse anti-IgG as secondary antibody. The detection was performed by adding the substrate 1-naphthyl phosphate and measuring the enzymatic product in differential pulse voltammetry. In order to improve the electroanalytical performances of the novel heterogeneous oligonucleotide-antibody sensor, we have explored the advantageous use of carbon black for the detection of alkaline phosphatase by-products. The electrochemical response of graphite-based screen-printed electrodes modified with three types of carbon black (i.e. N220, N115, and HP160) was thoroughly investigated by using cyclic voltammetry and amperometry for the detection of different enzymatic by-products namely 1-naphthol, hydroquinone, 4-nitrophenol, and ascorbic acid. This study allowed to shed light on the capacity of carbon black of remarkably enhancing the measurement of alkaline phosphatase’s products. Particularly, carbon black N220 and 1-naphthol were selected for developing a highly performant heterogeneous oligonucleotide-antibody assay for the detection of sulfur mustard. Under optimized conditions, the carbon black-based biosensor showed a linear range from 20 μM to 80 mM and a LOD of 12 μM in liquid samples, demonstrating high sensitivity as well as selectivity in presence of some possible interfering sources in the war field.

Inkjet-printed electrochemically reduced graphene oxide microelectrode as a platform for HT-2 mycotoxin immunoenzymatic biosensing

The design and application of an inkjet-printed electrochemically reduced graphene oxide microelectrode for HT-2 mycotoxin immunoenzymatic biosensing is reported. A water-based graphene oxide ink was first formulated and single-drop line working microelectrodes were inkjet-printed onto poly(ethylene 2,6-naphthalate) substrates, with dimensions of 78 μm in width and 30 nm in height after solvent evaporation. The printed graphene oxide microelectrodes were electrochemically reduced and characterized by Raman and X-ray photoelectron spectroscopies in addition to microscopies. Through optimization of the electrochemical reduction parameters, differential pulse voltammetry were performed to examine the sensing of 1-naphthol (1-N), where it was revealed that reduction times had significant effects on electrode performance. The developed microelectrodes were then used as an immunoenzymatic biosensor for the detection of HT-2 mycotoxin based on carbodiimide linking of the microelectrode surface and HT-2 toxin antigen binding fragment of antibody (anti-HT2 (10) Fab). The HT-2 toxin and anti-HT2 (10) Fab reaction was reported by anti-HT2 immune complex single-chain variable fragment of antibody fused with alkaline phosphatase (anti-IC-HT2 scFv-ALP) which is able to produce an electroactive reporter – 1-N. The biosensor showed detection limit of 1.6 ng ∙ mL−1 and a linear dynamic range of 6.3 – 100.0 ng ∙ mL−1 within a 5 min incubation with 1-naphthyl phosphate (1-NP) substrate.

Fast enzyme-linked electrochemical sensing of DNA hybridization at pencil graphite electrodes. Application to detect gene deletion in a human cell culture

In this paper we present a rapid electrochemical enzyme-linked DNA hybridization assay using disposable pencil graphite electrodes (PeGE) to detect target DNA (tDNA) sequences in DNA fragments amplified by polymerase chain reaction. The procedure consists of several short (1–2 min) incubation steps, including adsorption of the tDNA at unpretreated PeGE from denaturing medium, surface blocking with milk proteins, hybridization with a biotinylated oligonucleotide probe and binding of streptavidin-alkaline phosphatase conjugate to the biotin tags. Then the PeGE is transferred into background electrolyte solution containing 1-naphthyl phosphate, which is enzymatically dephosphorylated to give electrochemically oxidizable indicator 1-naphthol. The assay, which can be performed within 7–8 min, offers a perfect discrimination between specific and nonspecific DNA amplicons and easy detection of about ~40 femtomoles of tDNA in large excesses of non-complementary DNA. An application on the detection of p53 gene deletion in a human cell culture, featuring a real biological model, is presented. The designed setup has a potential to be applied as one of simple, fast, robust ultralow cost “do-it-yourself “instruments recently introduced as diagnostic tools for third world countries.

A triple-amplification differential pulse voltammetry for sensitive detection of DNA based on exonuclease III, strand displacement reaction and terminal deoxynucleotidyl transferase

In this research, a sensitive and specific electrochemical biosensor for DNA detection was constructed. The highly sensitivity of this biosensor is due to the exploitation of exonuclease III-assisted double recycling and toehold-mediated strand displacement recycling to achieve the target triple recycling amplification, thus generating a large amount of Y-shaped DNA structures. Combination with a terminal deoxynucleotidyl transferase (TDT)-mediated cascaded signal amplification strategy can catalyze the repetitive incorporation of biotin-dUTP to the 3'-OH of the Y-shaped DNA. Via biotin-streptavidin interaction, multiple streptavidin-alkaline phosphatases were conjugated to the surface of an Au electrode and generated a sharply increasing electrochemical signal in a 1-naphthyl phosphate (1-NP) solution. In this method, an impressive detection limit of 0.05 fM was obtained, presenting outstanding selectivity with a dynamic response scope between 0.1 fM and 1 nΜ. Thus, the designed biosensor opens an avenue for DNA detection in clinical molecular diagnostics, pathogen detection, gene therapy, food safety and environmental monitoring.

Electrochemical enzyme-linked oligonucleotide array for aflatoxin B1 detection

In this work, an electrochemical enzyme-linked oligonucleotide array to achieve simple and rapid multidetection of aflatoxin B1 (AFB1) is presented. The assay is based on a competitive format and disposable screen-printed cells (SPCs). Firstly, the electrodeposition of poly(aniline-anthranilic acid) copolymer (PANI-PAA) on graphite screen-printed working electrodes was performed by means of cyclic voltammetry (CV). Aflatoxin B1 conjugated with bovine serum albumin (AFB1-BSA) was then immobilized by covalent binding on PANI-PAA copolymer. After performing the affinity reaction between AFB1 and the biotinylated DNA-aptamer (apt-BIO), the solution was dropped on the modified SPCs and the competition was carried out. The biotinylated complexes formed onto the sensor surface were coupled with a streptavidin-alkaline phosphatase conjugate. 1-naphthyl phosphate was used as enzymatic substrate; the electroactive product was detected by differential pulse voltammetry (DPV). The response of the enzyme-linked oligonucleotide assay was signal-off, according to the competitive format. A dose-response curve was obtained between 0.1 ng mL−1 and 10 ng mL−1 and a limit of detection of 0.086 ng mL−1 was achieved. Finally, preliminary experiments in maize flour samples spiked with AFB1 were also performed.

Characteristics of the First Protein Tyrosine Phosphatase with Phytase Activity from a Soil Metagenome.

Protein tyrosine phosphatases (PTPs) fulfil multiple key regulatory functions. Within the group of PTPs, the atypical lipid phosphatases (ALPs) are known for their role as virulence factors associated with human pathogens. Another group of PTPs, which is capable of using inositol-hexakisphosphate (InsP6) as substrate, are known as phytases. Phytases play major roles in the environmental phosphorus cycle, biotechnology, and pathogenesis. So far, all functionally characterized PTPs, including ALPs and PTP-phytases, have been derived exclusively from isolated microorganisms. In this study, screening of a soil-derived metagenomic library resulted in identification of a gene (pho16B), encoding a PTP, which shares structural characteristics with the ALPs. In addition, the characterization of the gene product (Pho16B) revealed the capability of the protein to use InsP6 as substrate, and the potential of soil as a source of phytases with so far unknown characteristics. Thus, Pho16B represents the first functional environmentally derived PTP-phytase. The enzyme has a molecular mass of 38 kDa. The enzyme is promiscuous, showing highest activity and affinity toward naphthyl phosphate (Km 0.966 mM). Pho16B contains the HCXXGKDR[TA]G submotif of PTP-ALPs, and it is structurally related to PtpB of Mycobacterium tuberculosis. This study demonstrates the presence and functionality of an environmental gene codifying a PTP-phytase homologous to enzymes closely associated to bacterial pathogenicity.

Combined electrochemiluminescent and electrochemical immunoassay for interleukin 6 based on the use of TiO2 mesocrystal nanoarchitectures.

A dual-responsive sandwich-type immunosensor is described for the detection of interleukin 6 (IL-6) by combining electrochemiluminescent (ECL) and electrochemical (EC) detection based on the use of two kinds of TiO2 mesocrystal nanoarchitectures. A composite was prepared from TiO2 (anatase) mesocages (AMCs) and a carboxy-terminated ionic liquid (CTIL) and then placed on a glassy carbon electrode (GCE). In the next step, the ECL probe Ru(bpy)3(II) and antibody against IL-6 (Ab1) were immobilized on the GCE. Octahedral anatase TiO2 mesocrystals (OAMs) served as the matrix for immobilizing acid phosphatase (ACP) and secondary antibody (Ab2) labeled with horseradish peroxidase (HRP) to form a bioconjugate of type Ab2-HRP/ACP/OAMs. It was self-assembled on the GCE by immunobinding. 1-Naphthol, which is produced in-situ on the surface of the GCE due to the hydrolysis of added 1-naphthyl phosphate by ACP, is oxidized by HRP in the presence of added H2O2. This results in an electrochemical signal (typically measured at 0.4V vs. Ag/AgCl) that increases linearly in the 10fg·mL-1 to 90ng·mL-1 IL-6 concentration range with a detection limit of 0.32fg·mL-1. Secondly, the oxidation product of 1-naphthol quenches the ECL emission of Ru(bpy)32+. This leads to a decrease in ECL intensity which is linear in the 10 ag·mL-1 to 90ng·mL-1 concentration range, with a detection limit of 3.5 ag·mL-1. The method exhibits satisfying selectivity and good reproducibility which demonstrates its potential in clinical testing and diagnosis. Graphical abstract A dual-responsive sandwich-type immunosensor was fabricated for the detection of interleukin 6 by combining electrochemiluminescence and electrochemical detection based on the use of two kinds of TiO2 mesocrystal nanoarchitectures.

Enhanced dielectric properties and energy storage density of surface engineered BCZT/PVDF-HFP nanodielectrics

Polymer nanocomposites have proved to be promising energy storage devices for modern power electronic systems. In this work we have studied the dielectric properties and dielectric energy storage densities of 0–3 type BCZT/PVDF-HFP polymer nanocomposites with different filler volume concentrations. BCZT nanopowder was synthesized by solgel method through citrate precursor method. The structural and morphological features of the BCZT nanopowder were examined by X-ray diffraction and transmission electron microscopy. For better polymer ceramic interface coupling, BCZT was surface functionalized with extended aromatic ligand, naphthyl phosphate (NPh). The surface functionalization was validated and quantified by thermogravimetric analysis and X-ray photoelectron spectroscopy. The dielectric constant of surface passivated BCZT nanoparticles was estimated to be ~ 155 using slurry technique, while the dielectric permittivity of pristine BCZT nanopowder could not be assessed due to high innate surface conductivity. BCZT/PVDF-HFP polymer nanocomposite thin films were fabricated using solution casting technique. The dispersion quality of the ceramic fillers in the polymer matrix was examined by scanning electron microscopy. Due to better polymer ceramic interface, At 5 vol% filler concentration, NPh modified nanoBCZT/PVDF-HFP films showed enhanced dielectric breakdown strength and energy storage density than untreated nanoBCZT/PVDF-HFP and even pure polymer films. Maximum energy storage density of 8.5 J cm−3 was obtained at an optimum filler concentration of 10 vol% for surface functionalized BCZT/PVDF-HFP composite films of 10 μm thickness.

An Electrochemical Biosensor for Detection of DNA Species Related to Oral Cancer Based on a Particular Host-Guest Recognition-Assisted Strategy for Signal Tag In Situ

Herein, a novel host-guest recognition among tryptophan (Trp)-linked DNA, methyl viologen (MV2+) and cucurbit[8]uril (CB[8]) was introduced to construct a biosensor for the sensitive assay of oral cancer gene based on nicking enzyme signaling amplification (NESA) and Pt & Pd-MoS2 nanomaterial for the first time. A bioconjugates containing alkaline phosphatase (ALP) and complementary strand (S1) was designed as signal probe to catalyze the 1-naphthyl phosphate monosodium salt monohydrate (NPP) to in situ generate massive electroactive substance 1-naphthol, resulting in the generation of significant peak current with use of Pt & Pd-MoS2 nanomaterial as a catalyst. With target recycling amplification and highly efficient catalysis of ALP, the proposed biosensor for target DNA exhibited a satisfactory linear range from 10 fM to 10 nM. Importantly, the admirable performance of the proposed method shows a potential in biomedical research and clinical diagnosis.