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Abstract: A carbon paper electrode was modified with the conducting copolymer of 3-methylthiopene and thiophene-3-acetic acid prepared electrochemically on the electrode, and an enzyme electrode was fabricated by covalent immobilization of glucose oxidase on the modified electrode. The modification with the conducting copolymer increased the surface area of the electrode and the amount of the immobilized enzyme. As a result, the enzyme electrode showed a high catalytic activity. Moreover, it was found that the increased surface area led to a high rate of electron transfer reaction between the electrode and p-benzoquinone employed as an electron mediator. The enzyme electrode fabricated with the modified carbon paper gave a larger glucose oxidation current than that fabricated with the bare one. In addition, the glucose oxidation current was found to increase with increasing content of the conducting copolymer in the modified carbon paper. Corresponding to the large glucose oxidation current, high performance was confirmed for the glucose fuel cell constructed with the enzyme electrode based on the modified carbon paper. [Copyright &y& Elsevier]

[Display omitted] • Microbial electrochemical snorkel is applicable for gold recovery. • More gold is gained on the cathode at short circuit than at MFC. • 95% gold removal and recovery are reached within a day. • Au0 is deposited with a cathodic efficiency of 100%. • MES is applicable for gold reduction from its complex solutions. The applicability of microbial electrochemical technologies for the recovery of gold was investigated. Two-chamber microbial fuel cells (MFC) with bioanodes buried in sediment were used in two operating modes. The cathodes (gold foil or graphitized paper), submerged in HAuCl 4 , solutions, were short-circuited with the bioanodes, and thus for the first time, the microbial electrochemical snorkel (MES) was applied for gold recovery. Operation in MFC mode, where the cathode and the anode were connected through an external resistor equal to the internal resistance of the system was also implemented. The electrochemical results along with the microscopic analyses, XPS data, and the estimated rate constants show the better performance of the MES over the MFC and predict the putative mechanism of the cathodic gold deposition. The gold removal and recovery reached ca. 95% within a day and the cathodic efficiency approached almost 100%. 7% higher gold recovery and 5% higher gold removal were achieved in the MES mode, which reveals the advantage of the operation under short-circuit conditions. The deposited on the cathode gold is in its elemental state. The similar results obtained with the two types of cathodes justify replacing the gold electrodes with much cheaper graphitized paper to reduce the cost. In addition, it has been demonstrated that gold can be also recovered by MES from the aqueous solutions of its complex Na 3 [Au(S 2 O 3) 2 ], simulating leachates from printed circuit board waste, which expands the limits of its practical application. [ABSTRACT FROM AUTHOR]

[Display omitted] • A sensing platform with In 2 S 3 /AgInS 2 in the form of a hollow hexagonal tube. • In situ Z-type heterojunctions are formed between In 2 S 3 and AgInS 2. • A strategy of "photo-modulated interface charge" is proposed. • The PEC sensor has excellent performance in detecting PD-L1. The construction of heterostructure photoelectrodes can enhance the performance of photoelectrochemical (PEC) sensors. However, it is still a critical challenge to achieve efficient transfer of interface carriers. In this paper, we propose a strategy of "photo-modulated interface charge" to design a PEC sensor based on a hollow hexagonal tubular In 2 S 3 /AgInS 2 in situ Z-type heterojunction for the susceptible detection of Programmed Death-ligand 1 (PD-L1). The hollow structured In 2 S 3 /AgInS 2 is ingeniously synthesized employing indium-sourced MIL-68 as a sacrificial template and in situ cation exchange technique. This composite material has close contact interfaces due to in situ growth, which facilitates the spontaneous establishment of a robust and stable built-in electric field between the interfaces. Moreover, the inner cavity structure promotes multiple light refractions and scatterings, significantly enhancing light trapping capability. Under the influence of both light irradiation and electric field force, the migration direction of the interfacial charge is reversed, forming a Z-transfer path, which effectively delays the compounding of the electron-hole pairs (e-/h+) and further improves the sensitivity of the sensor. The minimum detection threshold of the PEC sensor is 26.58 fg/mL, and the feasibility of real samples is investigated, providing new insights for early diagnosis and prognostic treatment of diseases. [ABSTRACT FROM AUTHOR]

• Combined study of electroporation of cells by MTNM and Gielis'superformula. • At the cell pole region, cancer cells were electroporated earlier than normal cells. • A unidirectional neighboring effect in the multicellular model inhibit electroporation evolution of cancer cells. Electroporation (EP) of the normal cell and cancer cell both in single-cell and multicellular models was investigated by the meshed transport network method (MTNM) in this paper. The simulation results suggest that the cancer cell undergoes faster and more significant local EP than that of the corresponding normal cell induced by nanosecond pulsed electric fields (nsPEFs) both in single-cell and multicellular models. Furthermore, the results of the multicellular model indicate that there is a unidirectional neighboring effect in the multicellular model, meaning that cells at the center are affected and their pore formation is significantly reduced, but this effect is very weak for cells at the edges of the system. This means that the electric field selectively kills cells in different distribution locations. This work can provide guidance for the selection of parameters for the cancer cell EP process. [ABSTRACT FROM AUTHOR]

Electric field-induced membrane changes are an important approach in the life sciences. However, the developments in knowledge and translational applications face problems of reproducibility. Indeed, a quick survey of the literature reveals a lack of transparent and comprehensive reporting of essential technical information in many papers. Too many of the published scientific papers do not contain sufficient information for proper assessment of the presented results. The general rule/guidance in reporting experimental data should require details on exposure conditions such that other researchers are able to evaluate, judge and reproduce the experiments and data obtained. To enhance dissemination of information and reproducibility of protocols, it is important to agree upon nomenclature and reach a consensus on documentation of experimental methods and procedures. This paper offers recommendations and requirements for reporting on applications of electric pulse delivery for electroporation of biological samples in life science. [ABSTRACT FROM AUTHOR]

[Display omitted] • GO/PANI nanocomplex electrode with high biocompatibility was fabricated. • GO/PANI@CP electrode showed 54 times of power density compared to blank CP. • Bacteria on electrode surface showed fast electron release and uptake. • Efficient bio-denitrification in cathode was developed via GO/PANI@CP electrode. Bidirectional electron transfer is about that exoelectrogens produce bioelectricity via extracellular electron transfer at anode and drive cytoplasmic biochemical reactions via extracellular electron uptake at cathode. The key factor to determine above bioelectrochemical performances is the electron transfer efficiency under biocompatible abiotic/biotic interface. Here, a graphene/polyaniline (GO/PANI) nanocomposite electrode specially interfacing exoelectrogens (Shewanella loihica) and augmenting bidirectional electron transfer was conducted by in-situ electrochemical modification on carbon paper (CP). Impressively, the GO/PANI@CP electrode tremendously improved the performance of exoelectrogens at anode for wastewater treatment and bioelectricity generation (about 54 folds increase of power density compared to blank CP electrode). The bacteria on electrode surface not only showed fast electron release but also exhibited high electricity density of extracellular electron uptake through the proposed direct electron transfer pathway. Thus, the cathode applications of microbial electrosynthesis and bio-denitrification were developed via GO/PANI@CP electrode, which assisted the close contact between microbial outer-membrane cytochromes and nanocomposite electrode for efficient nitrate removal (0.333 mM/h). Overall, nanocomposite modified electrode with biocompatible interfaces has great potential to enhance bioelectrochemical reactions with exoelectrogens. [ABSTRACT FROM AUTHOR]

Abstract: This work was conducted to examine the composition and electrochemical activity of the bacterial community inhabiting lake Furnas sediments (Azores). Fingerprinting analysis of the bacterial 16S rRNA gene fragment was done by denaturing gradient gel electrophoresis. The sequences retrieved from lake Furnas sediments were affiliated to Bacteroidetes/Chlorobi group, Chloroflexi, Alfa-, Delta-, and Gamma-subclasses of Proteobacteria, Cyanobacteria, and Gemmatimonadetes. A cyclic voltammetric study was carried out with an enriched sediment bacterial suspension in a standard two chamber electrochemical cell using a carbon paper anode. Cyclic voltammograms (scan rate of 50mV/s) showed the occurrence of oxidation–reduction reactions at the carbon anode surface. The benthic microbial fuel cell operated with lake Furnas sediments presented a low power density (1mW/m2) indicating that further work is required to optimise its power generation. These results suggested that sediment bacteria, probably from the Delta- and Gamma-subclasses of Proteobacteria, were electroactive under tested conditions. [Copyright &y& Elsevier]

Anolyte acidification is a drawback restricting the electricity generation performance of the buffer-free microbial fuel cells (MFC). In this paper, a small amount of alkali-treated anion exchange resin (AER) was placed in front of the anode in the KCl mediated single-chamber MFC to slowly release hydroxyl ions (OH − ) and neutralize the H + ions that are generated by the anodic reaction in two running cycles. This short-term alkaline intervention to the KCl anolyte has promoted the proliferation of electroactive Geobacter sp. and enhanced the self-buffering capacity of the KCl-AER-MFC. The pH of the KCl anolyte in the KCl-AER-MFC increased and became more stable in each running cycle compared with that of the KCl-MFC after the short-term alkaline intervention. The maximum power density ( P max ) of the KCl-AER-MFC increased from 307.5 mW·m − 2 to 542.8 mW·m − 2 , slightly lower than that of the PBS-MFC (640.7 mW·m − 2 ). The coulombic efficiency ( CE ) of the KCl-AER-MFC increased from 54.1% to 61.2% which is already very close to that of the PBS-MFC (61.9%). The results in this paper indicate that short-term alkaline intervention to the anolyte is an effective strategy to further promote the performance of buffer-free MFCs. [ABSTRACT FROM AUTHOR]

• B. velezensis demonstrated effective inhibition of X65 steel corrosion. • Biomineralized film prepared by B. velezensis exhibited corrosion resistance. • This paper offered a more environmental solution to corrosion inhibition. The issue of material failure attributed to microbiologically influenced corrosion (MIC) is escalating in seriousness. Microorganisms not only facilitate corrosion but certain beneficial microorganisms also impede its occurrence. This study explored the impact of marine B. velezensis on the corrosion behavior of X65 steel in simulated offshore oilfield produced water. B. velezensis exhibited rapid growth in the initial stages, and the organic acid metabolites were found to promote corrosion. Subsequently, there was an increase in cross-linked "networked" biofilms products, a significant rise in the prismatic shape of corrosion products, and a tendency for continuous development in the middle and late stages. The organic/inorganic mineralized film layer formed on the surface remained consistently complete. Metabolic products of amino acid corrosion inhibitors were also observed to be adsorbed into the film. B. velezensis altered the kinetics of the X65 steel cathodic reaction, resulting in a deceleration of the electrochemical reaction rate. The mineralization induced by B. velezensis effectively slowed down the corrosion rate of X65 steel. [ABSTRACT FROM AUTHOR]

[Display omitted] The accurate determination of organophosphorus pesticide residues is of great importance for human disease monitoring and environmental safety. Numerous detection methods exist, among which sensitive monitoring of organophosphorus compounds using electrochemical sensors has gradually become a research hotspot. This paper used acetylcholinesterase (AChE) as an indicator anchored on a zinc oxide-reduced graphene oxide (ZnO-rGO) composite rich in active sites, in which green non-toxic zinc oxide (ZnO) nanomaterials were uniformly distributed on the reduced graphene for rapid detection of organophosphorus. The effects of different ratios of ZnO to reduced graphene on the performance of ZnO-rGO nanocomposites were investigated. The AChE/ZnO-rGO biosensor detects organophosphorus by electrochemical inhibition of acetylcholinesterase in the presence of organophosphorus. The developed electrochemical biosensor has high selectivity and good linearity, and the ZnO-rGO nanocomposite as a matrix for immobilization of acetylcholinesterase and detection of organophosphorus has the potential for highly sensitive pesticide detection. [ABSTRACT FROM AUTHOR]

A microbial fuel cell (MFC) is a potential bio-electrochemical technology that utilizes microorganisms to convert chemical energy into electrical energy. The low power output of MFCs remain the bottleneck for their practical applications. In this paper, a novel, biocompatible and bioelectrocatalytic composite chitosan-nitrogen doped carbon nanotubes-polyaniline (CS-NCNT-PANI) was prepared in situ on the 3D porous NCNT/sponge and applied to an MFC anode. The PANI was grafted on the CS-NCNT backbone to synthesize the ternary composite. This bioanode not only increased the active surface area and capacity but also facilitated bacterial adhesion and enrichment of microbes. Compared with the NCNT/sponge electrode, the charge transfer impedance of the ternary composite bioanode decreased from 14.07 Ω to 2.25 Ω, and the maximum power density increased from 1.4 W·m−3 to 4.2 W·m−3; meanwhile, during the chronoamperometric experiment with a charge-discharge time of 60–60 min, the cumulative charge of the composite bioanode was 18,865.8 C·m−2, which is much higher than that of the NCNT/S anode (3625.3 C·m−2). High-throughput sequencing technology revealed that the ternary composite bioanode had good biocompatibility and high diversity. Therefore, this synthesized ternary composite is a promising candidate as a capacitive and biocompatible anode material in MFC. • A biocompatible and capacitive composite anode (CS-NCNT-PANI/NCNT/S) was prepared by grafting and crosslinking reaction. • The MFC with the composite anode reached a high-power density of 4.2 W·m−3. • The bioanode exhibited a high biomass. • Various bacteria play an efficient synergistic role on electricity generation. [ABSTRACT FROM AUTHOR]

In this paper, we constructed MIL-53 (AlOHbdc, bdc = benzene-1,4-dicarboxylate) /CNTs and Prussian blue (PB) as the double sensitization material of the sensing platform, in which the MIL-53/CNTs hybrid can not only increase the specific surface area but also increase the conductivity of the sensor and PB can play a role in amplifying electrical signals and accelerating electron transmission. Pyrrole was used as monomer and E2 was used as template for electropolymerization to form conductive film. Moreover, the overoxidation/dedoping elution method were used to simplify the experimental process. Under optimal conditions, the MIECS exhibited an excellent sensitivity and high selectivity with a wide linear response range between 10−14 to 10−9 mol L−1 and an estimated detection limit of 6.19 × 10−15 mol L−1. • Double sensitization of MIL-CNTs and PB improved the performance of MIECS. • A simple overoxidation/dedoping process was used to elute template molecules. • PB was used to achieve better imprinted effect and waste less time. [ABSTRACT FROM AUTHOR]

There is still a growing interest in developing glucose sensors using glucose oxidase. Since 2012, over 1000 papers are published every year, while efficient commercial sensors exist on the market. Among those glucose sensors, few have been thought and well-engineered and do not solve the problems associated with glucose oxidase; among which the O 2 sensitivity of the enzyme or the competition between O 2 and redox mediators for GOx's electrons. Enzyme engineering has been employed to solve those issues but screening GOx in homogeneous solution with O 2 as an electron acceptor is not suitable. Very few reports describe the specific reengineering of GOx for electrochemical applications and are the subject of this review. It starts with a brief presentation of glucose oxidase and presents the recent progress in glucose oxidase reengineering by highlighting the kind of engineering/mutations performed to increase its electron transfer rate to electrode surfaces and, to decrease its O 2 sensitivity. In addition, the review highlights the need to develop new screening methods involving electrochemical probing, essential to develop the next generation of glucose sensors; specific to glucose, O 2 independent, biocompatible and stable over 2 weeks. • Redesigning glucose oxidase for improved electrochemical applications is needed. • Engineering strategies from the literature are presented. • Further challenges are discussed to develop the next generation of glucose sensors. [ABSTRACT FROM AUTHOR]

Nitinols (Nickel–titanium alloys) have a good electrical conductivity and biocompatibility with human tissue and bacteria and, therefore, can be effectively used as an anode material in bioelectrochemical systems. This paper aimed to use nitinols (at different Ni/Ti ratios) as an anode material for microbial fuel cells (MFCs) in order to achieve higher power density. The maximum power densities of the MFCs using NiTi-1, NiTi-2, and NiTi-3 electrodes were 555 mW/m2, 811 mW/m2, and 652 mW/m2, respectively. More bacterial adhesion was observed on the NiTi-2 electrode. Electrochemical impedance spectroscopy (EIS) results showed low charge transfer resistance at MFCs fabricated with NiTi. The biofilm observations indicate that bacterial attachment is better with NiTi-2 as compared with that on NiTi-1 and NiTi-3. The resulting mesopore and macropore rich structure significantly promote microbial colonization, enabling formation of compact electroactive biofilms with additional benefit from the excellent biocompatibility and chemical stability of NiTi-2. Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) results indicated that five groups of bacteria were the dominant phyla in the MFCs: environmental samples , b-proteobacteria , g-proteobacteria , d-proteobacteria , and CFB group bacteria. The high biocompatibility, electrical conductivity and stability of nitinols make them a more attractive anode material for MFCs. • Three different nitinol materials were produced and examined. • A macro-porous nitinol surface structure was obtained. • Exoelectrogenic biofilms were grown on new electrode materials • More electrogenic bacteria were detected at the anode biofilm. • A high-power density (811 mW/m2) was achieved. [ABSTRACT FROM AUTHOR]

Abstract Electroporation is a widely-used methodology for permeabilization of cells using pulsed electric field (PEF). In this paper, we compare the electroporation efficiency in terms of molecular transport and the generated reactive oxygen species (ROS) between low (1 Hz) and high (1 MHz) frequency nanosecond range PEF bursts. We used aluminum, copper and stainless-steel electrodes and evaluated the influence of electrode material on ROS generation and electroporation. Bursts of 25 or 50 pulses of 7–14 kV/cm amplitude and 200 ns duration were applied, and the results were compared to those obtained using electroporation with pulses of equivalent energy in conventional microsecond range. It was determined that electroporation efficiency scales with ROS generation and is highly affected by the material of electrodes and by the applied pulsing protocols. We present experimental evidence that metal ions, and not the pH fronts near the electrodes, play a major role in generation of ROS during electroporation. Highlights • ROS generation during electroporation depends on the frequency of the ns pulses. • Metal ions play the major role in generation of ROS during electroporation. • Electroporation efficiency scales with ROS generation. • Oxidative stress with aluminum electrodes is lower compared to copper and steel. [ABSTRACT FROM AUTHOR]

Abstract This paper reports the fabrication of an electrochemical DNA biosensor for the electrochemical determination of prednisone (PRD), which is a synthetic corticosteroid. For this purpose, silver nanoparticles (AgNPs) and a new polymer film poly(glyoxal-bis(2-hydroxyanil)) (P(GBHA)) were electrochemically deposited on a glassy carbon electrode (GCE), respectively. Then, an electrochemical DNA biosensor was prepared onto this electrode surface (GCE/AgNPs/P(GBHA)) by the immobilization of dsDNA using a chronoamperometry method. The proposed electrode was characterized by FESEM, XPS, and cyclic voltammetry (CV). The interaction between the PRD and dsDNA immobilized on the GCE/AgNPs/P(GBHA) electrode was investigated via a differential pulse voltammetry (DPV) method and UV–Vis spectrophotometry. The experimental factors affecting the interaction between the PRD concentration and dsDNA were optimized. The fabricated biosensor showed a wide linear response in a PRD concentration range of 1.0–50.0 μg mL−1 depending on both the adenine and guanine base signals. The detection limit based on the guanine and adenine signals was 0.3 μg mL−1 and 0.25 μg mL−1, respectively. The sensor exhibited excellent anti-interferential ability, good stability and reproducibility and was satisfactorily employed for the electrochemical assay of PRD in serum samples. The new DNA biosensor can be utilized for the sensitive, accurate and rapid analysis of PRD. Graphical abstract Unlabelled Image Highlights • Ag nanoparticles and poly(glyoxal-bis(2-hydroxyanil)) film were deposited on a GCE • DNA biosensor was prepared by immobilization of dsDNA onto the modified GCE • Interaction between prednisone (PRD) and dsDNA was examined by using DPV and UV-VIS • The fabricated biosensor has a wide linear response range of 1.0–50 μg mL−1 for PRD [ABSTRACT FROM AUTHOR]

Abstract: This research details the isolation and purification of a new type of lactate dehydrogenase that is dependent upon the coenzyme pyrroloquinoline quinone (PQQ). PQQ-dependent enzymes have been of interest in the literature over the last decade due to the fact that many of them can undergo direct electron transfer (DET) at electrode surfaces which is of interest for biosensor and biofuel cell applications. In the paper, we detail the isolation of PQQ-dependent lactate dehydrogenase (PQQ-LDH) from two sources of Gluconobacter (Gluconobacter sp. 33 and Gluconobacter suboxydans). This paper also shows the first evidence that PQQ-LDH can undergo direct electron transfer at gold and carbon electrode surfaces for future use in biosensors and biofuel cells. [Copyright &y& Elsevier]

Abstract: In this paper we present a simple method allowing for stable laccase immobilization on various conducting surfaces that retains the activity of the enzyme. The strategy for laccase immobilization presented in this paper relies on Zr4+ ion coordination chemistry that involves –COO− terminal groups present on the protein. Using a host of techniques, including surface plasmon resonance (SPR), quartz crystal microbalance (QCM) gravimetry, atomic force microscopy (AFM), surface enhanced Raman scattering (SERS), resonance Raman scattering (RR) and electrochemical techniques, we show that laccase bound to a surface coordinatively through zirconium phosphonate/carboxylate (ZPC) functionalities forms a stable enzymatic layer with the enzyme retaining its activity to a significant extent. [Copyright &y& Elsevier]

Abstract: A convenient method for the measurement of the catalytic activity of laccase is proposed based on the voltammetric determination of catalytic reaction substrates: 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonate) diammonium salt (ABTS) and 1,4-benzenediol (hydroquinone). The measurement performed using microelectrodes working under spherical diffusion conditions is both accurate and simple, and allows to monitor parallely the consumption of substrate and formation of product of the catalytic reaction. The method proposed in this paper was compared with the two generally employed procedures based on oxygen measurement by Clark electrode and on spectrophotometry. The procedure described in the present paper was found to be simpler and more reproducible results were obtained than using Clark electrode. Compared to spectrophotometry a larger range of catalytic reaction substrates can be studied including colorless compounds. [Copyright &y& Elsevier]

• PEDOT:PSS ink allows electrodes modification for electroanalysis. • PEDOT:PSS confers to the electrode amplification of the electroanalytical signals. • Pyocyanin and PQS from Pseudomonas aeruginosa quorum sensing are detected at modified electrodes. • PEDOT:PSS modified electrode allows at recorded PA complex electrochemical fingerprint. Fast bacterial detection and identification is a crucial challenge in order to improve our antibiotics use and reduce the antimicrobial resistance. Electroanalysis of biological fluids is cheap and can be done in situ but the electrode material needs to be perfectly chosen. We previously studied electrochemical signature of Pseudomonas aeruginosa 's secretome, thanks to glassy carbon electrode. Some conductive polymers are particularly efficient for biological use because of their antifouling properties, biocompatibility and way of processing. In this paper, we described the fabrication, characterization and utilisation of PEDOT:PSS film to detect and identify Pseudomonas aeruginosa through three of its secreted molecules: pyocyanin, Pseudomonas quinolone PQS and 2′–aminoacetophenone. The electrochemical responses, clearly amplified by PEDOT:PSS, can be used to identify these bacteria quickly and efficiently. [ABSTRACT FROM AUTHOR]

Abstract Mt LPMO9 and Fo LPMO9 are two lytic polysaccharide monooxygenases (LPMOs), from the filamentous fungi Thermothelomyces thermophila and Fusarium oxysporum , respectively. In the present study an attempt has been made to achieve direct electron transfer between these enzymes and a glassy carbon electrode by immobilization in Nafion polyelectrolyte. The method used to ascertain the feasibility of direct electron transfer was large amplitude Fourier transform alternating current voltammetry (FTacV) and the formal potentials of these enzymes were determined at different temperatures. The findings of this paper indicate that LPMOs can be studied by direct electron transfer, which could be exploited in the near future for their biochemical characterization. Highlights • Direct electron transfer is detected for Mt LPMO9 and Fo LPMO9 by FTacV. • The formal potentials are estimated by FTacV. • The temperature dependence of formal potentials is determined. [ABSTRACT FROM AUTHOR]

The understanding of DNA-drug interaction mechanism is among the important aspects of biological studies for drug design, discovery and pharmaceutical development processes. Published rather detailed FTIR and UV–visible spectroscopic studies on the interactions of theophylline, theobromine and caffeine with calf thymus DNA have shown effective binding of these methylxanthine derivatives to DNA and RNA involving H-bonds. However, to our knowledge, there is no such investigation using electrochemical approach. As a novelty of the study, in this paper the bioelectrochemical approach has been chosen for the investigation of an interaction of low molecular salmon sperm dsDNA, ssDNA and mononucleotides with theophylline (TP) in aqueous phosphate buffered medium using DNA-based electrochemical biosensors and biosensing in solution phase. Exploitation of the electrochemical approach via changes in square wave voltammetric responses of deoxyguanosine (dGuo) and deoxyadenosine (dAdo) provided a new indication on preferential association of TP with dGuo in the case of double helical dsDNA structure which was not reported previously. Moreover, an attachment of TP molecules outside DNA was found in the presence of high concentration of 3.3 × 10 −4  M TP in solution which diminishes the electron transfer and leads to the difficulties in quantitative evaluation of the TP and dGuo voltammetric responses. The changes in UV–vis and FTIR spectra obtained in the same medium confirmed the association interaction of TP with both nucleobases. Utilizing the model and the published energies of hydrogen bonding stabilization, the formation of a DNA-TP complex was predicted through the intermolecular H-bonds between TP and the NH-CO moiety of guanine and the N-NH 2 moiety of adenine. [ABSTRACT FROM AUTHOR]

The C-peptide is a co-product of pancreatic β-cells during insulin secretion; its content in body fluid is closely related to diabetes. This paper reports an immune-sensing strategy for a simple and effective assay of C-peptide based on label-free electrochemiluminescent (ECL) signaling, with high sensitivity and specificity. The basal electrode was constructed of an indium tin oxide (ITO) glass as a conductive substrate, which was decorated by Au nanoparticles (AuNPs) with hydrolysed (3-aminopropyl)trimethoxysilane as the linker. The characteristics of the fabricated electrode were investigated by electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. After immobilizing the C-peptide antibody, which takes great advantage of AuNPs' binding capacity, this immunosensor can quantify C-peptide using luminol as the ECL probe. By measuring ECL inhibition, calibration can be established to report the C-peptide concentration between 0.05 ng mL −1 and 100 ng mL −1 with a detection limit of 0.0142 ng mL −1 . As a proof of concept, the proposed strategy is a promising and versatile platform for the clinical diagnosis, classification, and research of diabetes. [ABSTRACT FROM AUTHOR]