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Cobalt-modified graphene oxide 3D-nanoarchitecture is fabricated here for its effective use as an electrode material for the sensing of rutin flavonoid and for supercapacitor applications. The graphene oxide preparation was accomplished here comparatively in a shorter period avoiding the tedious and time-consuming preparative pathways in other graphene-oxide-based systems. A sol-gel method was employed for hybridizing graphene with cobalt oxide/hydroxide. Material characterization studies revealed the coexistence of β-Co(OH)2 and spinel Co3O4 in the nanocomposite, whereas FESEM images revealed the 3D nanostructured morphology. The strong interaction between the carbon atoms of graphene sheets with the cobalt species is revealed from the XPS analysis. The synergistic effect provided a good current sensitivity of 1.68 μA/μM towards rutin sensing within a linear detection range of 0.1 μM–20 μM over Co(OH)2–Co3O4/graphene oxide (CoG) modified electrode. High selectivity is offered by the nanocomposite towards rutin and additionally, the sensor succeeded in the detection of a real sample, the rutin tablet. Repeatability and reproducibility in measurements are the added features of the CoG-modified electrode. The diffusion-controlled electrochemical behaviour over CoG was investigated using a redox probe K4[Fe(CN)6]. As a supercapacitor electrode material, the nanocomposite exhibited a maximum specific capacitance of 559.2 F/g at a scan rate of 10 mV/s and 288.4 F/g at 4 A/g current density. Also, it exhibited a high cyclic stability of 109.78% after 1800 continuous charge-discharge cycles displaying its excellence as an energy storage device. The nanocomposite exhibited a dominant contribution from EDLC towards the total capacitance with a low charge transfer resistance.

Fabricating a pit array on the surface of indium phosphide wafer can change its photoelectric properties, improve its photoelectric conversion efficiency, and expand its application range. There are few reviews devoted to the fabrication of regular hole arrays on the surface of indium phosphide wafers by electrochemical methods. In this paper, twelve electrochemical approaches for assembling pit arrays on the surface of indium phosphide wafers were introduced, the structure and experimental process of the electrochemical device were highlighted, and the resulting top and section views were also shown by animation. It can provide a useful reference guide for the large-scale fabrication of regular hole arrays on the surface of indium phosphide wafers.

The differentiation of valence states plays a crucial role in determining the toxicity of chromium (Cr) in environmental samples. In this work, two modes of colorimetric and electrochemical analytical methods based on a fungus like porous CoS (FP CoS) nanosensor were developed for rapid, specific, and portable detection trace/ultra-trace chromium species (Cr(VI) and Cr(III)). The FP CoS exhibited peroxidase activity as a nanozyme for the colorimetric detection of Cr(VI), catalyzing the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to a blue oxidation product (oxTMB) in the presence of Cr(VI) instead of unstable H 2 O 2 as an oxidizer at room temperature over existing methods. Based on the promotion of colorimetric reaction by increasing in Cr(VI) concentration, an effective colorimetric detection of Cr(VI) method was established with a detection limit (LOD) low to 3.93 μg L -1 and unique selectivity for Cr(VI) over 21 interfering ions (containing 15 metal ions and 6 anions). Innovatively, Cr(VI) could be reduced to Cr(III) without TMB, then selectively enriched by redox reaction with FP CoS. Hence, Cr (III) can be selectively and effectively enriched by FP CoS applying voltage, and then detected using cyclic voltammetry, with a lower LOD of 0.116 μg L -1 and high sensitivity ignoring background interferences. By integrating the dual-mode detection channel, the FP CoS nanosensor offers a convenient and flexible method for simultaneously determining Cr(VI), Cr(III), and total chromium in diverse samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

In this approach, folic acid (FA) sensor was fabricated with wet-chemically prepared Fe2O3/NiO/Mn2O3 nanoparticles (NPs), which was coated on a glassy carbon electrode (GCE) in the form of thin layers to create the desired sensor. The synthesized NPs were characterized by X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD), Tunneling Electron Microscopy (TEM), surface area (BET), and Field Emission Scanning Electron Microscopy (FESEM) equipped with Energy-dispersive X-ray spectroscopy (EDS). The fabricated sensor, Fe2O3/NiO/Mn2O3 NPs/Nafion/GCE is responded linearly in electrochemical method over 0.1 nM to 0.01 mM of folic acid (FA) and denoted as a dynamic range of detection (LDR). The slope of LDR is designated as the sensor sensitivity, which is appreciable (48.588 µA µM-1 cm−2). The lower limit of FA detection is evaluated at a signal-to-noise ratio of 3, and it is equal to 96.89 ± 4.85 pM. The sensor analytical parameters such as stability, reproducibility, sensitivity, response time and long-time stability in buffer phase are found as outstanding. The FA sensor was valued to analyze the biological samples and found acceptable and satisfactory results. This prospective sensor might be an efficient probe for diagnosis of bio-samples in field of health career sector.

This study reports the development of a fast and facile route for the synthesis of novel TiO2-CeO2 nanocomposite film using sol-gel spin coating method with the mixture of commercial CeO2, titanium-iso-propoxide (TTIP) and aqueous ammonia. Solutions of TTIP in ethanol were mixed with CeO2 nanoparticles to form a mixed sol-gel. The sol containing TiO2-CeO2 was coated over the glass substrate and the resulting nanocomposite thin film were characterized in terms of phase and surface morphology by XRD, TEM, SEM and FT-IR. Conventional methods of the synthesis of CeO2–TiO2 nanocomposite require a long time, and TiO2 is rarely found as a coated material. In contrast, the sol-gel spin coating method was able to synthesize CeO2–TiO2 sol within a very short time. The particle size of the TiO2–CeO2 nano-composite film was found to be 23 nm. The Uric acid biosensor was fabricated by immobilizing mixed enzyme [urease (Urs) and glutamate dehydrogenase (GLDH)] on this nano-composite film showed a response time of 10 s, sensitivity as 0.9016 µAcm−2 mM−1 and detection limit of 0.165 mM. The value of Michaelis–Menten constant (Km) estimated using Line weaver–Burke plot as 4.8 mM which indicates the high affinity of uricase towards its analyte (uric acid). The enhanced sensitivity and linear range of the nanobiocomposite film obtained by cyclic voltammetry measurements suggested that the mixed enzyme and TiO2-CeO2 composite material has novel characteristics for uric acid determination in the human blood for the application of arthritis diseases.

Conjugated polyelectrolyte/MWCNT/poly(pyrrole) (CPE-K/MWCNT/PPY) composites have been prepared by a simple solution mixing technique. Synthesis of PPY/CPE/MWCNT composites was characterized by scanning electron microscopy and thermogravimetric analysis. These nanocomposites of CPE-K/MWCNT/PPY were deposited onto a glassy carbon electrode (GCE) in order to fabricate a reliable Mg2+ cationic sensor. A plot called the calibration curve is produced from the current as a function of concentration of Mg2+ ion. This plot was found to be linear in the range 0.1 nM to 0.01 mM, which is defined as the linear dynamic range. According to the surface area of the GCE (0.0316 cm2) and the slope of the calibration curve, a high sensitivity (19.4968 µA µM–1 cm–2) of the Mg2+ ion sensor was calculated. A significant lower limit of detection (97.71 ± 4.89 pM) was obtained in association with a signal to noise ratio of 3. Sensor parameters such as reproducibility, long-time stability, and short response time were measured and found to be quite satisfactory. This new approach to Mg2+ detection with high sensitivity is suggested for application as a novel multifunctional sensing system. Besides, it was found to be very effective to analyze real environmental samples.

Poly(L-lysine) (PLL)-3-hydroxyphenylboronic acid (3-PBA) composite was prepared onto an Au electrode via cyclic voltammetry (CV), which was characterized by electrochemical and quartz crystal microbalance (QCM) techniques, and used to promote adhesion of plant cells. 3-PBA can interact with glycosyl compounds on the cell wall to form negatively charged covalent compounds while PLL increases the number of positively charged sites, which enhances the electrostatic interactions with the negatively charged cell wall, both promoting cell adhesion. The PLL-poly(3-PBA) composite was successfully modified on the Au electrode surface, as demonstrated by QCM and Fourier transform infrared spectrophotometry (FTIR). Moreover, we confirmed the synergistic effect of PLL and 3-PBA to adhere rice suspension cells using CV, electrochemical impedance spectroscopy (EIS), QCM and optical microscope observations. Finally, the dynamic process of rice cells’ adhesion to PLL-poly(3-PBA)/Au followed by salt stress treatment of NaCl was monitored in real-time by QCM. The cells softened at first then hardened under the action of 40 mM NaCl. This work presents a novel and conventional way to immobilize plant cells onto sensors, and has importance in the study of the structure, function and behavior of plants under various stresses at the cellular level.

Monitoring hypochlorite levels in water is of great importance because of its high toxicity and wide applications as water disinfectants. In this manuscript, carbon dot (CD) was electrochemically prepared by using dopamine and epigallocatechin gallate (molar ratio 1:1) as the carbon source for efficient hypochlorite determination. By electrolyzing the solution at 10 V for 12 min with PBS as an electrolyte, dopamine would react with epigallocatechin at the anode, and through polymerization, dehydration, and carbonization, strong blue-fluorescent CDs were obtained. CDs were characterized by UV-Vis spectroscopy, fluorescence spectroscopy, high-resolution transmission electron microscopy, FT-IR, etc. These CDs have an excitation wavelength at 372 nm and an emission wavelength at 462 nm, owing an average particle size of 5.5 nm. The presence of hypochlorites can quench the fluorescence of CDs, and its reduction in intensity is linear with hypochlorite concentration over the range of 0.5-50 μM, ΔF/F 0  = 0.0056 + 0.0194C ClO - , R 2 =0.997. The detection limit achieved 0.23 μM (S/N = 3). The mechanism for fluorescence quenching is via a dynamic process. Different from many other fluorescence methods based on the strong oxidizing ability of hypochlorites, our method shows strong selectivity toward hypochlorites over other oxidizing agents such as H 2 O 2 . The assay was validated by the detection of hypochlorites in water samples, with recoveries between 98.2% and 104.3%., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Chloramphenicol (CAP) is a harmful antibiotic that inevitably enters our food chain through natural or manmade means. Its ineradicable residue pollutes soils and water, accumulates in plants and animal products, and eventually affects human health. An ultrasensitive method for detecting and monitoring CAP is therefore urgently required. Herein, we report an ultrafast extraction and amperometry detection method based on a graphite-sulfate-modified electrode for detecting CAP in soil, water, and food samples. The graphite sulfate is prepared by the oxidation method and its structural properties are comprehensively investigated. The developed sensor electrode showed a wider linear range of 0.3-32.0 μg kg -1 and an ultralow detection limit of 0.1 μg kg -1 , both of which meet the European Commission Reg 1871/2019 reference points for action. The method works well with both meat and plant samples, achieving CAP recoveries ranging from 90.8 to 99.1% even at low concentrations. Moreover, the sensor electrode shows more than 95% selectivity toward CAP detection in the soil, water, and food matrices. The developed method exhibits good repeatability and reproducibility in the analysis of real samples., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Exosome is an emerging tumor marker, whose concentration level can reflect the occurrence and development of tumors. The development of rapid and sensitive exosome detection platform is of great significance for early warning of cancer occurrence. Here, a strategy for electrochemical detection of A549-cell-derived exosomes was established based on DNA/ferrocene-modified single-walled carbon nanotube complex (DNA/SWCNT-Fc). DNA/SWCNT-Fc complexes function as a signal amplification platform to promote electron transfer between electrochemical signal molecules and electrodes, thereby improving sensitivity. At the same time, the exosomes can be attached to DNA/SWCNT-Fc nanocomposites via the established PO 4 3- -Ti 4+ -PO 4 3- method. Moreover, the application of EGFR antibody, which can specifically capture A549 exosomes, could improve the accuracy of this sensing system. Under optimal experimental conditions, the biosensor showed good linear relationship between the peak current and the logarithm of exosomes concentration from 4.66 × 10 6 to 9.32 × 10 9 exosomes/mL with a detection limit of 9.38 × 10 4 exosomes/mL. Furthermore, this strategy provides high selectivity for exosomes of different cancer cells, which can be applied to the detection of exosomes in serum samples. Thus, owing to its advantages of high sensitivity and good selectivity, this method provides a diversified platform for exosomes identification and has great potential in early diagnosis and biomedical applications., (Copyright © 2022. Published by Elsevier Inc.)

Relationship between mycotoxin-induced hormesis and reactive oxygen species (ROS) has not been systematically investigated due to the lack of an effective analysis method. To monitor cellular release and intracellular level of O 2 ·- , carboxymethyl cellulose-Mn 3 (PO 4 ) 2 nanocomposite was synthesized to fabricate an electrochemical biosensor, which selectively detects O 2 ·- over the range of 57.50 nM ∼ 2.95 μM (R 2  = 0.99) with the sensitivity of 78.67 μA μM -1 cm -2 and the detection limit of 8.47 nM. Transient exposure to zearalenone (ZEA) induces the enhancement on cell viability, immediate O 2 ·- release from cells, and reduction of intracellular O 2 ·- level. After post-treatment culture, intracellular O 2 ·- initially increases to a high level and then decreases to the normal level. Concurrently, the ZEA-induced hormesis disappears. Based on the findings, we propose a mechanism, involving the ROS release, increase of succinate dehydrogenase activity and recovery of intracellular ROS, to explain the occurrence and disappearance of hormesis in intestinal porcine enterocytes., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier B.V. All rights reserved.)

Infectious diseases are a potential risk for public health and the global economy. Fast and accurate detection of the pathogens that cause these infections is important to avoid the transmission of the diseases. Conventional methods for the detection of these microorganisms are time-consuming, costly, and not applicable for on-site monitoring. Biosensors can provide a fast, reliable, and point of care diagnostic. Nanomaterials, due to their outstanding electrical, chemical, and optical features, have become key players in the area of biosensors. This review will cover different nanomaterials that employed in electrochemical, optical, and instrumental biosensors for infectious disease diagnosis and how these contributed to enhancing the sensitivity and rapidity of the various sensing platforms. Examples of nanomaterial synthesis methods as well as a comprehensive description of their properties are explained. Moreover, when available, comparative data, in the presence and absence of the nanomaterials, have been reported to further highlight how the usage of nanomaterials enhances the performances of the sensor., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Herein, a simple and selective electrochemical method was developed for sulfadimethoxine detection based on the triggered cleavage activity of nuclease P1 by the formation of aptamer and sulfadimethoxine conjugate. After probe DNA was immobilized on gold electrode surface, aptamer DNA labeled with biotin at its 5'-terminal was then captured on electrode surface through the hybridization reaction between probe DNA and aptamer DNA. The formed double-stranded DNA (dsDNA) can block the digestion activity of Nuclease P1 towards the single-stranded probe DNA. Then, the anti-dsDNA antibody was further modified on electrode surface based on the specific interaction between dsDNA and antibody. Due to the electrostatic repulsion effect and steric-hindrance effect, a weak electrochemical signal was obtained at this electrode. However, in the presence of sulfadimethoxine, it can interact with aptamer DNA, and then the formation of dsDNA can be blocked. As a result, the probe DNA at its single-strand state can be digested by Nuclease P1, which leads to the failure of the immobilization of anti-dsDNA antibody. At this state, a strong electrochemical signal was obtained. Based on the change of the electrochemical signal, sulfadimethoxine can be detected with linear range of 0.1-500 nmol/L. The detection limit was 0.038 nmol/L. The developed method possesses high detection selectivity and sensitivity. The applicability of this method was also proved by detecting sulfadimethoxine in veterinary drug and milk with satisfactory results., (Copyright © 2019 Elsevier B.V. All rights reserved.)

In this study, an electrochemical system was established for simultaneous harmless removal of nitrate and ammonia multiple contamination in an undivided single cell. Cyclic voltammetry was used to investigate the electrochemical cathode and anode coupling redox mechanism and concurring evolution of nitrate and ammonia. The cyclic voltammograms showed the cathodic reduction of nitrate to ammonia and nitrite, the chloride ion conversion to hypochlorite and hypochlorous acid, and the oxidation of ammonia to nitrogen gas and nitrate. A circular transformation process was formed in the electrochemical system and the final product was harmless nitrogen gas. The multiple nitrogen pollutants in the original contaminated system were gradually removed with the reaction predominantly produced harmless nitrogen gas. Response surface methodology was used to build mathematical models for optimizing the operating conditions. The optimum time, NaCl concentration, and current density were 85.38 min, 0.24 g/L, and 45.13 mA/cm 2 , respectively. Under the optimum conditions, the nitrate and ammonia concentrations in the treated solution were 9.17 and 0.00 mg/L, respectively., (Copyright © 2018 Elsevier B.V. All rights reserved.)

In this study, conducting polyaniline (PAni) and silicon dioxide (SiO 2 ) nanocomposites (NCs) were synthesized for chemical sensing applications by microwave assisted reaction technique. Facile synthesis and characterization of the PAni-SiO 2 nanocomposites were investigated in details and discussed in this report. For the potential application, 1,4-dioxane chemical sensor was fabricated with the PAni-SiO 2 nanocomposites deposited onto glassy carbon electrode (GCE). A very thin uniform film was deposited onto GCE with nanocomposite by using conducting 5% nafion binder at room conditions. To evaluate the sensor analytical performances, a calibration plot such as current versus concentration of 1,4-dioxane was drawn and calculated the analytical parameters from the slope of calibration curve. Results are found as sensitivity (0.5934 µAµmol - 1 L -2 cm -2 ), detection limit (16.0 ± 0.8 pmol L -1 ), and quantification limit (LOQ; 53.3 ± 1.5 pmol L -1 ) in this observation. Considering the linear region in calibration plot, the linear dynamic range of 1,4-dioxane chemical sensor was found (0.12 nmol L -1 ∼ 1.2 mmol L -1 ). Besides this, the proposed 1,4-dioxane chemical sensor was exhibited good reproducibility, long-term stability, high accuracy in detecting of 1,4-dioxane in real environmental samples. This research is to develop of a selective and an efficient electrochemical sensor. It might be a simple and easy way by applying electrochemical method to ensure the safe and sustainable green environment., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Galena weathering often occurs in nature and releases metal ions during the process. Humic acid (HA), a critical particle of natural organic matter, binds metal ions, thus affecting metal transfer and transformation. In this work, an electrochemical method combined with spectroscopic techniques was adopted to investigate the interfacial processes involved in galena weathering under acidic and alkaline conditions, as well as in the presence of HA. The results show that the initial step of galena weathering involved the transformation Pb 2+ and S°, regardless of whether the solution was acidic or alkaline. Under acidic conditions, S° and Pb 2+ further transform into anglesite, and HA adsorbs on the galena surface, inhibiting the transformation of sulfur. HA and Pb (II) ions form bridging complexes. Under alkaline conditions without HA, the sulfur produced undergoes no transformation, whereas Pb 2+ will transform into PbO. The presence of HA changes the galena weathering mechanism via ionization effect, and Pb 2+ is ultimately converted into anglesite. Higher acidity in acidic conditions or higher alkalinity in alkaline conditions causes galena corrosion when the electrolyte does not contain HA. Conversely, higher pH always accelerates galena corrosion when the electrolyte contains HA, whether the electrolyte is acidic or alkaline. At the same acidity/alkalinity, increasing the concentration of HA inhibits galena weathering. Galena will release 134.7 g m -2 ·y -1 Pb 2+ to solution at pH 2.5, and the amount decreases to 28.09 g m -2 ·y -1 in the presence of 1000 mg/L HA. This study provides an in situ electrochemical method for the assessment of galena weathering., (Copyright © 2018 Elsevier Inc. All rights reserved.)

In this work, we have developed for the first time a carboxylic group riched graphene oxide based disposable electrochemical immunosensor for cancer biomarker detection using methylene blue (MB). The developed immunosensor is highly sensitive for detection of biomarker Mucin1 (MUC1) in human serum samples. Development of this disposable electrochemical immunosensor was premeditated by applying specific monoclonal antibodies against MUC1. In this method, we explored highly conductive surface of carboxylic group (-COOH-) rich graphene oxide (GO) on screen-printed carbon electrodes (SPCE). This modified GO-COOH-SPCE was employed for the detection of MUC1 protein based on the reaction with methylene blue (MB) redox probe using differential pulse voltammetry (DPV) technique. Developed immunosensor exhibited good detection range for MUC1 with excellent linearity (0.1 U/mL- 2 U/mL), with a limit of detection of 0.04 U/mL. Upon potential application of developed biosensor, good recoveries were recorded in the range of 96-96.67% with % R.S.D 4.2. Analytical performance of the developed immunosensor assures the applicability in clinical diagnostic applications., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Small molecules that may facilitate and stabilize the formation of G-quadruplexes can be used for cancer treatments, because the G-quadruplex structure can inhibit the activity of telomerase, an enzyme over-expressed in many cancer cells. Therefore, there is considerable interest in developing a simple and high-performance method for screening small molecules binding to G-quadruplex. Here, we have designed a simple electrochemical approach to screen such ligands based on the fact that the formation and stabilization of G-quadruplex by ligand may inhibit electron transfer of redox species to electrode surface. As a proof-of-concept study, two types of classical G-quadruplex ligands, TMPyP4 and BRACO-19, are studied in this work, which demonstrates that this method is fast and robust and it may be applied to screen G-quadruplex ligands for anticancer drugs testing and design in the future., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The common drawback of optical methods for rapid detection of nucleic acid by exploiting the differential affinity of single-/double-stranded nucleic acids for unmodified gold nanoparticles (AuNPs) is its relatively low sensitivity. In this article, on the basis of selective preconcentration of AuNPs unprotected by single-stranded DNA (ssDNA) binding, a novel electrochemical strategy for nucleic acid sequence identification assay has been developed. Through detecting the redox signal mediated by AuNPs on 1, 6-hexanedithiol blocked gold electrode, the proposed method is able to ensure substantial signal amplification and a low background current. This strategy is demonstrated for quantitative analysis of the target microRNA (let-7a) in human breast adenocarcinoma cells, and a detection limit of 16 fM is readily achieved with desirable specificity and sensitivity. These results indicate that the selective preconcentration of AuNPs for electrochemical signal readout can offer a promising platform for the detection of specific nucleic acid sequence., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A sensitive electrochemical DNA biosensor was developed for Helicobacter pylori (H. pylori) detection using differential pulse voltammetry. Single-stranded DNA probe was immobilized on a graphene oxide/gold nanoparticles modified glassy carbon electrode (GO/AuNPs/GCE). A hybridization reaction was conducted with the target DNA and the immobilized DNA on the electrode surface. Oracet blue (OB) was selected for the first time as a redox indicator for amplifying the electrochemical signal of DNA. Enhanced sensitivity was achieved through combining the excellent electric conductivity of GO/AuNPs and the electroactivity of the OB. The DNA biosensor displayed excellent performance to demonstrate the differences between the voltammetric signals of the OB obtained from different hybridization samples (non-complementary, mismatch and complementary DNAs). The proposed biosensor has a linear range of 60.0-600.0 pM and a detection limit of 27.0 pM for detection of H. pylori. In addition, the biosensor have responded very well in the simulated real sample evaluations, signifying its potential to be used in future clinical detection of the H. pylori bacteria., (Copyright © 2015 Elsevier B.V. All rights reserved.)

TiO2 nanotube arrays were synthesized on Ti surface by anodic oxidation. The elements of Ca and P were simultaneously incorporated during nanotubes growth in SBF electrolyte, and then Ag was introduced to nanotube arrays by cathodic deposition, which endowed the good osseointegration and antibacterial property of Ti. The bioactivity of the Ti surface was evaluated by simulated body fluid soaking test. The biocompatibility was investigated by in vitro cell culture test. And the antibacterial effect against Staphylococcus aureus was examined by the bacterial counting method. The results showed that the incorporation of Ca, P and Ag elements had no significant influence on the formation of nanotube arrays on Ti surface during electrochemical treatment. Compared to the polished or nanotubular Ti surface, TiO2 nanotube arrays incorporated with Ca, P and Ag increased the formation of bone-like apatite in simulated body fluid, enhanced cell adhesion and proliferation, and inhibited the bacterial growth. Based on these results, it can be concluded that the nanostructured Ti incorporated with Ca, P and Ag by electrochemical method has promising applications as implant material., (Copyright © 2015 Elsevier B.V. All rights reserved.)

A key issue associated with electrochemical DNA-based biosensors is how to enhance DNA immobilization on the substrates. In order to improve the immobilization of DNA and to optimize DNA interaction efficiency, different kinds of strategies have been developed. In this regard, nanomaterials have attracted a great deal of attention in electrode surface modification for DNA biosensor fabrication. In this study, nanostructured films were deposited at the surface of a pencil graphite electrode (PGE) as a working electrode. For the present purpose, common polyelectrolytes are used for surface modification with double-stranded DNA. Two positively charged polyelectrolyte, namely poly dialyldimethylammonium chloride (PDDA) and chitosan, are initially compared for DNA immobilization at the surface of MWCNTs and TiO2 nanoparticles (TiO2NPs). In a second step, the basic electrochemical properties of the sensors are investigated using voltammetric methods. The modified electrodes are also characterized by scanning electron microscopy and electrochemical impedance measurements. It will be shown that electrode modification with DNA and the nanostructure that disperses in PDDA leads to an enhanced sensitivity of the DNA voltammetric detection mechanism. In a previous study, a comparison was done between MWCNTs and TiO2NPs for determining the effect of nanoparticle effect on DNA immobilization on the electrode surface. In order to compare the efficiency of the prepared DNA-based biosensors, methylene blue is chosen as an electroactive probe. It will be shown that the stability of the immobilized DNA within several days will be much higher when MWCNTs rather than TiO2NPs are used., (Copyright © 2014 Elsevier B.V. All rights reserved.)

There is an ongoing search to develop techniques for detection of heavy metals which are highly toxic and can cause damaging effects even at very low concentrations. In this present study, we report a label-free electrochemical method based on the direct voltammetric response of human cervical carcinoma (HeLa) cells on a highly sensitive graphene modified electrode. Five heavy metals were tested with the method and the results were validated by the traditional methyl tetrazolium (MTT) assay. The results revealed that the most toxic metal was Cr, followed by Cd, Cu, Pb and Zn. A good correlation between the two methods was observed. This work will be beneficial in providing a novel monitoring method to detect hazardous pollutants in the field of environmental toxicology., (Copyright © 2014 Elsevier B.V. All rights reserved.)