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A simple electrochemical deposition method for the immobilization of protein-conjugated graphene onto an electrode has been developed. A unique one-step electrochemical deposition of cytochrome c (Cyt c) conjugated with electrochemically reduced graphene oxide ( ErGO) onto the surface of glassy carbon electrode ( GCE) without any cross-linkers and the direct electron transfer between Cyt c and the electrode was obtained by the Cyt c- ErGO-modified GCE. The characteristics of the ErGO-Cyt c-modified GCE were compared with those of an ErGO-modified GCE without Cyt c. The direct electron transfer rate constant ( ket) was found to be 6.2/s. This approach provides an avenue for the immobilization of various proteins and enzymes with ErGO and could be expanded for diverse biosensor applications. [ABSTRACT FROM AUTHOR]

Abstract: A new approach for an amperometric array sensor platform employing arrays of sensors in a 24-well cell culture plate format has been developed for simultaneous in vitro determination of nitric oxide (NO) and superoxide free radicals (O2 −) produced by stimulated cells. The work reported focuses on the direct, real-time monitoring of extracellular production of these two analytes, as well as the effects of their interaction. The sensor platform was manufactured by a combination of sputtering gold electrodes and screen-printing carbon electrodes. The O2 − sensor uses covalent immobilization of cytochrome c via a binder, DTSSP (3,3′-dithio-bis(sulphosuccinimidylpropionate) onto the surface of the Au electrodes, whereas the NO sensor system involves an NiTSPc (nickel tetrasulfonated phthalocyanine) film electrodeposited onto the surface of the carbon electrodes and subsequently covered with an external layer of Nafion®. For in vitro demonstration of the platforms as a potential drug-screening system, A172 glioblastoma cells were cultured and transferred into the 24-well arrays. Simultaneous and direct monitoring of NO and O2 − production as a response to chemicals of biomedical relevance was carried out. The results obtained demonstrated that it would be possible to envisage a drug screening platform for compounds designed to be inhibitors of nitric oxide synthase or to have an inhibitory effect on superoxide free radical production. By suitable modification of the electrodes employed it would also be possible to extend the platform to measure alternative species. [Copyright &y& Elsevier]

Four electrode materials: Pt, Au, Pd and glassy carbon (GC), were studied to investigate their suitability as substrates in the development of two different classes of glutamate biosensor. Glutamate oxidase cross-linked onto poly(o-phenylenediamine) was chosen as the type 1 biosensor (PPD/GluOx), incorporating PPD as the permselective element to detect H2O2 directly on the electrode surface at relatively high applied potentials. GluOx and horseradish peroxidase/redox polymer modified electrodes (Os2+PVP/HRP/GluOx) that relied on enzyme-catalysed H2O2 detection at lower applied potentials were used as type 2 biosensors.The voltammetric and amperometric responses to the enzyme signal transduction molecule, H2O2, and the archetypal interference species in biological applications, ascorbic acid, were determined on the bare and PPD/GluOx-modified surfaces. The amperometric responses of these electrodes were stable over several days of continuous recording in phosphate buffered saline (pH 7.4). The sensitivity of the type 1 biosensors to H2O2 and glutamate showed parallel trends with low limits of detection and good linearity at low concentrations: Pt>Au∼Pd≫GC. Type 2 biosensors out-performed the type 1 design for all electrode substrates, except Pt. However, the presence of the permselective PPD membrane in the type 1 biosensors, not feasible in the type 2 design, suggests that Pt/PPD/GluOx might have the best all-round characteristics for glutamate detection in biological media containing interference species such as ascorbic acid. Other points affecting a final choice of substrate should include factors such as mass production issues. [Copyright &y& Elsevier]

A new disposable amperometric bi-enzyme sensor system for detecting phenols has been developed. The phenol sensor developed uses horseradish peroxidase modified screen-printed carbon electrodes (HRP-SPCEs) coupled with immobilized tyrosinase prepared using poly(carbamoylsulfonate) (PCS) hydrogels or a poly(vinyl alcohol) bearing styrylpyridinium groups (PVA-SbQ) matrix. Optimization of the experimental parameters has been performed with regard to buffer composition, pH, operating potential and storage stability. A co-operative reaction involving tyrosinase and HRP occurs at a potential of −50 mV versus Ag/AgCl without the requirement for addition of extraneous H2O2, thus, resulting in a very simple and efficient system. Comparison of the electrode responses with the 4-aminoantipyrine standard method for phenol sample analysis indicated the feasibility of the disposable sensor system for sensitive ‘in-field’ determination of phenols. The most sensitive system was the tyrosinase immobilized HRP-SPCE using PCS, which displayed detection limits for phenolic compounds in the lower nanomolar range e.g. 2.5 nM phenol, 10 nM catechol and 5 nM p-cresol. [Copyright &y& Elsevier]

Heavy metal ions (HMIs) have become a significant contaminant in recent years. The increase in heavy metal pollution is a serious situation, requiring progressively robust, fast sensing, highly sensitive, and suitable techniques for heavy metal detection. Compared to other classical analytical methods, electroanalytical techniques, especially stripping voltammetric techniques with modified screen-printed electrodes (SPEs), have several advantages, such as fast sensing, great sensitivity, specificity, and long-time stability. Therefore, these techniques are more suitable for HMI detection. In this review, the nanostructured materials used to coat SPEs for the electrochemical determination of HMI are summarized. Additionally, the electrode fabrication method, modification steps, and electroanalytical study of these materials are systematically discussed. Hence, this review will support the researchers in precisely evaluating the electrochemical HMIs detection through highly sensitive stripping voltammetric techniques using SPE modified with nanostructured carbon and their allotropes, metal, metal oxides and their nanocomposites as sensor materials. Moreover, modified electrodes real time detection of HMIs in different food and environmental samples were briefly discussed. [Display omitted] • Emerging pollutant of HMIs detection through electrochemical methods based on multifunctional materials reviewed. • HMIs environmental and human impact related challenges are discussed. • Nanostructured carbon, metal, metal oxide and their composites for electrode fabrication, HMIs sensing mechanism are discussed. • HMIs detection long-term vision, challenges and feature scenarios was discussed. [ABSTRACT FROM AUTHOR]

Nanoplastics (NPs) exposure to humans can occur through various routes, including the food chain, drinking water, skin contact, and respiration. NPs are plastics with a diameter of less than 100 nm and have the potential to accumulate in tissues, leading to toxic effects. This study aimed to investigate the neurotoxicity of polystyrene NPs on neural progenitor cells (NPCs) and hippocampal neurogenesis in a rodent model. Toxicity screening of polystyrene NPs based on their charge revealed that cationic amine-modified polystyrene (PS–NH 3 +) exhibited cytotoxicity, while anionic carboxylate-modified polystyrene (PS–COO-) and neutral NPs (PS) did not. NPCs treated with PS-NH 3 + showed a significant reduction in growth rate due to G1 cell cycle arrest. PS-NH 3 + increased the expression of cell cycle arrest markers p21 and p27, while decreasing cyclin D expression in NPCs. Interestingly, PS-NH 3 + accumulated in mitochondria, leading to mitochondrial dysfunction and energy depletion, which caused G1 cell cycle arrest. Prolonged exposure to PS-NH 3 + in C17.2 NPCs increased the expression of p16 and senescence-associated secretory phenotype factors, indicating cellular senescence. In vivo studies using C57BL/6 mice demonstrated impaired hippocampal neurogenesis and memory retention after 10 days of PS-NH 3 + administration. This study suggests that NPs could deplete neural stem cell pools in the brain by mitochondrial dysfunction, thereby adversely affecting hippocampal neurogenesis and neurocognitive functions. [Display omitted] • Positively charged polystyrene NP (PS–NH 3 +) is toxic to NPCs. • PS-NH 3 + induces p53-independent cell cycle arrest at the G1 phase in NPCs. • PS-NH 3 + accumulates in mitochondria, causing mitochondrial dysfunction in NPCs. • Long-term exposure to PS-NH 3 + induces senescence in NPCs. • The exposure to PS-NH 3 + impairs hippocampal neurogenesis and mememory retention in young mice. [ABSTRACT FROM AUTHOR]

Electroanalytical and optical techniques are widely used in the development of nanomaterials-based sensor platforms. These techniques have a quick response, high sensitivity, and selectivity. Electroanalytical and optical techniques are widely used in the development of nanomaterial-based sensor platforms. These sensors must be able to detect biomarkers, pathogens, toxins, and pharmaceuticals in biological matrices associated with cardiovascular disease, cancer, and neurodegenerative diseases. Considering these pathophysiologies, numerous investigations have been undertaken to develop sensors for early diagnosis and treatment, utilizing nanomaterials such as quantum dots. Graphene quantum dots (GQDs), which are ideally nanometer-sized graphene fragments, have recently received increased attention due to their excellent physicochemical properties such as fast electron mobility, photostability, water solubility, biocompatibility, high specific surface area, and nontoxicity. Apart from the properties mentioned above, GQDs provide π–π interactions, electrostatic, and covalent interactions with an analyte, and ease of synthesis as well as the ability to combine with other nanomaterials, which have enabled their use in various sensing platforms. This review summarizes recent advances in GQDs-based nanocomposites for sensor applications, with a focus on electroanalytical and optical techniques, as well as current challenges and future prospects. [ABSTRACT FROM AUTHOR]

[Display omitted] • The accurate measurement of creatinine (Ctn) in human biofluid samples is a challenge. • A stable carboxyl (C=O, COOH) groups were introduced on the electrode surface during electrochemical activation. • ePAD* was applied for the selective non-enzymatic detection of Ctn. • ePAD* detects Ctn in blood serum and urine samples with high reliability. • ePAD* is economic and accurate compared to existing methods for Ctn detection. Selective detection of creatinine (Ctn) is crucial for the clinical diagnosis of early-stage kidney dysfunction. A non-enzymatic electrochemical method for a highly selective and sensitive detection of Ctn in blood serum and urine samples was developed using an electrochemically activated carbon-coated paper-based analytical device (ePAD*). During activation, the growth of stable carboxyl (C = O, COOH) groups on the edge planes of the carbon surface was observed. The prepared ePAD* was characterized using various microscopic, spectroscopic, and electrochemical techniques. The ePAD* was utilized as a medium exchanger, and the voltammetric response of Ctn detection in the linear concentration from 0.03 to 45 mM with a detection limit of 5.41 µM was achieved. In addition, the selective detection of Ctn in the presence of potential interferences (i.e., uric acid, ascorbic acid, ammonia, and urea) was examined. The examination revealed a remarkable selectivity toward Ctn detection. Real-time detection of Ctn in blood serum and urine samples was performed. The results were correlated with the classical Jaffé colorimetric method. Our ePAD* exhibited a better electrochemical response. Thus, it is a highly potential diagnostic method for further development as a rapid and precise detection platform for point-of-care (POC) devices for examining patients with kidney disease. [ABSTRACT FROM AUTHOR]

Neurodegenerative diseases such as Parkinson's disease (PD) are known to be related to oxidative stress and neuroinflammation, and thus, modulating neuroinflammation offers a possible means of treating PD-associated pathologies. Morin (2′,3,4′,5,7-pentahydroxy flavone) is a flavonol with anti-oxidative and anti-inflammatory effects found in wines, herbs, and fruits. The present study was undertaken to determine whether a morin-containing diet has protective effects in an MPTP-induced mouse model of PD. Mice were fed a control or morin diet for 34 days, and then MPTP (30 mg/kg, i.p.) was administered daily for 5 days to induce a PD-like pathology. We found that dietary morin prevented MPTP-induced motor dysfunction and ameliorated dopaminergic neuronal damage in striatum (STR) and substantia nigra (SN) in our mouse model. Furthermore, MPTP-induced neuroinflammation was significantly reduced in mice fed morin. In vitro studies showed that morin effectively suppressed glial activations in primary microglia and astrocytes, and biochemical analysis and a docking simulation indicated that the anti-inflammatory effects of morin were mediated by blocking the extracellular signal-regulated kinase (ERK)-p65 pathway. These findings suggest that morin effectively inhibits glial activations and has potential use as a functional food ingredient with therapeutic potential for the treatment of PD and other neurodegenerative diseases associated with neuroinflammation. [ABSTRACT FROM AUTHOR]

We present a design method to characterize uniform flows in a microreactor for high performance surface plasmon resonance (SPR) a general-purpose biosensor chips. The shape of the microreactor is designed based on an approximate pressure drop model. The number of micro-pillars and the slopes of the inlet and outlet linear chambers are two dominant parameters used to minimize the velocity difference in the microreactor. The flow uniformity was examined quantitatively by numerical and experimental visualization methods. A computational fluid dynamics (CFD) analysis demonstrates that the designed microreactor has a fairly uniform velocity profile in the reaction zone for a wide range of flow rates. The velocity field in the fabricated microreactor was measured using the micro-particle image velocimetry (μ-PIV) method, and the flow uniformity was confirmed experimentally. The performance of the uniform flow microreactor was verified using the fluorescence antibody technique. [ABSTRACT FROM AUTHOR]

Di-n-butyl phthalate (DBP) is commonly used as a plasticizer and its usage continues to increase in conjunction with plastic consumption. DBP is readily released into air, drinking water, and soil, and unfortunately, is a potent endocrine disrupter that impairs central nervous system functions. Previously DBP was found to (1) arrest the cell cycle of C17.2 neural progenitor cells (NPCs) at the G1 phase, (2) reduce numbers of newly generated neural stem cells in the mouse hippocampus, and (3) adversely affect learning and memory. Other investigators also noted DBP-mediated neurotoxic effects, but as yet, no study has addressed the adverse effects of DBP on neuronal differentiation. Data demonstrated that at 200 μM DBP induced apoptosis in rat embryo primary neurons by increasing reactive oxygen species levels and inducing mitochondrial dysfunction. However, no significant effect was detected on neurons at concentrations of ≤100 μM. In contrast, doublecortin/microtubule associated protein-2 (DCX/MAP2) immunocytochemistry showed that DBP at 100 μM delayed neuronal maturation by increasing protein levels of DCX (an immature neuronal marker), without markedly affecting cell viability. Further in vivo studies confirmed that DCX+ cell numbers were significantly elevated in the hippocampus of DBP-treated mice, indicating that DBP delayed neuronal maturation, which is known to be associated with impaired memory retention. Data demonstrated that DBP might disrupt neuronal maturation, which is correlated with reduced neurocognitive functions. [ABSTRACT FROM AUTHOR]

Abstract: An enzymatic biosensor was fabricated by the covalent immobilization of pyruvate oxidase (PyO) onto the nano-particle comprised poly-5,2′:5′,2″-terthiophene-3′-carboxylic acid, poly-TTCA (nano-CP) layers on a glassy carbon electrode (GCE) for the amperometric detection of the phosphate ions. The direct electron transfer reaction of the immobilized PyO onto the nano-CP layers was investigated and the electron transfer rate constant was determined to be 0.65s−1. The electrochemically prepared nano-CP lowered the oxidation potential (+0.40V versus Ag/AgCl) of an enzymatically generated H2O2 by PyO in a phosphate solution. Experimental parameters affecting the sensitivity of the biosensors, such as amounts of the cofactors, the pH, the applied potential, and the temperature were optimized. A linear response for the detection of the phosphate ion was observed between 1.0μM and 100μM and the detection limit was determined to be about 0.3μM. The response time of the biosensors was about 6s. The biosensor showed good selectivity towards other interfering anions. The long-term storage stability of the phosphate biosensor was studied and the sensor was applied in a human serum sample for the phosphate ions detection. [Copyright &y& Elsevier]

Fish farms often suffer from viral infections that can lead to mass mortality. Early detection of these infections can help prevent the spread of the infection. microRNA (miRNA) is a new biomarker for detecting early infections in farmed olive flounder. We developed a disposable miRNA biosensor by utilizing screen-printed carbon electrodes with polymer-dispersed silver nanowires (P-AgNWs). The target miRNA here was miR-15b-5p, which is considered a specific candidate for detecting viral hemorrhagic septicemia virus (VHSV) infection in fish. A capture probe (CP), a thiol-modified DNA oligonucleotide chain complementary to the miR-15b-5p, was immobilized on the surface of P-AgNWs. While the hybridization of miR-15b-5p with the CP is monitored using square wave voltammetry techniques based on the specific binding of methylene blue (MB) to the DNA-RNA hybrid formed between CP and the miR-15b-5p. The miRNA biosensor demonstrated a wide linear response range of 1.0–100 fM under optimum conditions with a low detection limit of 0.70 fM. According to a series of voltammetric experiments, the approach demonstrated acceptable precision and sensitivity for determining the miR-15b-5p levels in olive flounder infected with VHSV. • Disposable miRNA (miR-15b-5p) biosensor by modified screen-printed carbon electrodes. • Detection of viral hemorrhagic septicemia virus (VHSV) infection in fish. • The miR-15b-5p biosensor showed a linear range: 1.0–100 fM & LOD: 0.70 fM. • The performance of the miR-15b-5p biosensor was validated using qPCR results. [ABSTRACT FROM AUTHOR]

A novel voltammetric sensor was developed to selectively determine dopamine (DA) concentration in the presence of ascorbic acid (AA) and 3,4-dihydroxyphenylacetic acid (DOPAC). This sensor utilizes a modified pencil graphite electrode (PGE) coated with a newly synthesized poly (3,4-ethylene dioxythiophene) (PEDOT):poly (styrene sulfonate- co -2-(3-(6-Methyl-4-oxo-1,4-dihydropyrimidin-2-yl) ureido) ethyl methacrylate) (P(SS- co -UPyMA)) composite. The PEDOT:P(SS-co-UPyMA) (PPU) composite was characterized using nuclear magnetic resonance, X-ray photoelectron, and Raman spectroscopies. The PPU-coated PGE was characterized using electrochemical techniques, including cyclic and differential pulse voltammetry. Compared to uncoated, PPU-coated PGE demonstrated improved sensitivity and selectivity for DA. The sensor exhibited a dynamic linear range of 0.1–300 μM for DA, with a detection limit of 44.4 nM (S/N = 3). Additionally, the PPU-coated PGE showed high reproducibility and storage stability for four weeks. To demonstrate its practical applicability, the PPU-coated PGE sensor was used for ex vivo brain slice samples from control and Parkinson's disease model mice. [Display omitted] • Disposable voltametric dopamine sensor based on modified pencil graphite electrode. • Newly synthesized PEDOT:PSS copolymer as electrode modifier. • The dopamine sensor showed a linear range: 0.1–300 μM & LOD: 44.4 nM. • The sensor was used on ex vivo brain samples from Parkinson's disease model mice. [ABSTRACT FROM AUTHOR]

Glutamate (GLU) is a primary excitatory neurotransmitter, and its dysregulation is associated with several neurodegenerative disorders. A major challenge in GLU estimation is the existence of other biomolecules in the brain that could directly get oxidized at the electrode. Hence, highly selective electroenzymatic biosensors that enable rapid estimation of GLU are needed. Initially, a copolymer, poly(2-dimethylaminoethyl methacrylate- styrene) was synthesized through reversible addition-fragmentation chain transfer polymerization to noncovalently functionalize reduced graphene oxide (rGO), named DS–rGO. Glutamate oxidase macromolecule immobilized DS–rGO formed enzyme nanosheets, which was drop-coated over Prussian blue electrodeposited disposable electrodes to fabricate the GLU biosensor. The interconnectivity between the enzyme nanosheets and the Prussian blue endows the biosensor with enhanced conductivity and electrochemical activity. The biosensor exhibited a linearity: 3.25–250 μM; sensitivity: 3.96 μA mM−1 cm−2, and a limit of detection: 0.96 μM for GLU in the Neurobasal Medium. The biosensor was applied to an in vitro primary rat cortical model to discriminate GLU levels in Neurobasal Medium, before and after KCl mediated depolarization, which provides new insights for elucidating neuronal functioning in the brain. Amperometric biosensor for detecting GLU in the in vitro model of primary rat cortical neurons before and after KCl mediated depolarization. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Miniaturized electrochemical sensors for HMIs detection has been discussed. • Different types of modified electrodes and their surface modifications with nanomaterials have briefly been discussed. • Electrochemical sensing mechanism of different nanomaterials for HMs detection has been discussed. • Exposing the feature challenges and perspectives of the miniaturized electrochemical sensors filed. Despite the significance of the environment for human subsistence, many daily activities and industrial processes introduce numerous pollutants, which may result in environmental damage and pose a substantial risk to human health. To address these issues, the rapid and efficient screening of pollutants such as heavy metals (HMs) in environmental matrices is highly desirable. Electrochemical techniques, particularly electrochemical sensors (screen printed, paper based, and laser induced graphene based electrodes) have considerable potential for the on-site screening of HM pollutants in complex sample matrices owing to their high sensitivity, long-term stability, low cost, compact instrumentation (onsite analysis), simple sample handling requirements, and high accuracy. Consequently, numerous miniaturized electrochemical devices modified with different nanomaterials (carbon nanocomposites, metal, and metal oxide nanocomposites) have been developed, and miniaturized electrochemical sensing techniques have been applied in a wide variety of areas. Herein, we review recent research on miniaturized electrochemical sensing techniques for the detection of environmental heavy metal pollutants with the aim of providing an overview of the latest progress and perspectives in this field. [ABSTRACT FROM AUTHOR]

A new type of disposable flexible sensor for hydrogen peroxide (H2O2) detection was developed by in situ synthesis of copper–ruthenium bimetallic nanoparticles on a laser-induced graphene surface (Cu–Ru/LIG). The approach produced Cu–Ru/LIG via a solid phase transfer mechanism which loaded the metal precursor onto LIG, followed by laser scribing without demanding chemical vapor deposition or solution-based reactions. Cu–Ru/LIG showed a high electrocatalytic response toward H2O2 reduction at −0.4 V vs. Ag/AgCl. The sensor also showed good selectivity and reproducibility. This method provides an alternative route to easily synthesize various catalysts on conductive substrates for sensor applications. [ABSTRACT FROM AUTHOR]

A simple and cost-effective electrochemical synthesis of carbon-based nanomaterials for electrochemical biosensor is of great challenge these days. Our study describes a single-step electrochemical deposition strategy to prepare a nanocomposite of electrochemically reduced graphene oxide (ErGO), multi-walled carbon nanotubes (MWCNTs), and polypyrrole (PPy) in an aqueous solution of pH 7.0 for dopamine (DA) detection. The ErGO/MWCNTs/PPy nanocomposites show enhanced electrochemical performance due to the strong π–π* stacking interactions among ErGO, MWCNTs, and PPy. The efficient interaction of the nanocomposites is confirmed by evaluating its physical and electrochemical characteristics using field-emission scanning electron microscopy, Raman spectroscopy, electrochemical impedance spectroscopy, cyclic voltammetry, and amperometry. The deposited nanocomposites are highly stable on the substrates and possess high surface areas, which is vital to improve the sensitivity and selectivity for DA detection. The controlled deposition of the ErGO/MWCNTs/PPy nanocomposites can provide enhanced electrochemical detection of DA. The sensor demonstrates a short time response within 2 s and is a highly sensitive approach for DA detection with a dynamic linear range of 25–1000 nM (R2 = 0.999). The detection limit is estimated to be 2.3 nM, and the sensor sensitivity is calculated to be 8.96 μA μM−1 cm−2, with no distinct responses observed for other biological molecules. [ABSTRACT FROM AUTHOR]

• Facile synthesis of S and O-doped graphitic carbon nitride (S, O-GCN). • S, O-GCN linked poly(1,3,4-thiadiazole-2,5-dithiol) film was prepared by electropolymerization. • S, O-GCN@PTD-SPCE has enhanced electrochemical properties. • S, O-GCN@PTD-SPCE was tested for sensing of Hg2+ ions in food and water samples. Screen-printed carbon electrodes (SPCE) were modified with sulfur and oxygen-incorporated graphitic carbon nitride (S, O-GCN) linked poly(1,3,4-thiadiazole-2,5-dithiol) film (PTD) through thioester linkage. The promising interaction between the Hg2+ and modified materials containing sulfur as well as oxygen through strong affinity was studied. This study was utilized for the electrochemical selective sensing of Hg2+ ions by differential pulse anodic stripping voltammetry (DPASV). After, optimizing the different experimental parameters, S, O-GCN@PTD-SPCE was used to improve the electrochemical signal of Hg2+ ions and achieved a concentration range of 0.05–390 nM with a detection limit of 13 pM. The real-world application of the electrode was studied in different water, fish, and crab samples and their obtained results were confirmed with Inductive Coupled Plasma - Optical Emission Spectroscopy (ICP-OES) studies. Additionally, this work established a facile and consistent technique for enhancing the electrochemical sensing of Hg2+ ions and discusses various promising applications in water and food quality analysis. [ABSTRACT FROM AUTHOR]

Highlight • MHY908 attenuated MPTP-induced motor deficits and dopaminergic neuronal death. • MHY908 also ameliorated MPTP-induced glial activation in the STR and SN. • MHY908 pretreatment protected SH-SY5Y neuroblastoma cells against MPP+ toxicity. • Pretreatment of MHY908 inhibited MPP+-induced ROS generation. • MHY908 treatment attenuated MPP+-induced primary astrocyte activation and nuclear translocation of NF-κB. Abstract Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors and are considered promising therapeutic targets in several neurodegenerative diseases. A number of PPAR agonists have been shown to have neuroprotective properties in the presence of oxidative stress, neuroinflammatory response, and apoptosis in various neurodegenerative disease. MHY908 is a novel PPAR α/γ dual agonist, which has been shown to suppress inflammatory response and attenuate insulin resistance in aged rats and db/db mice. Here, we evaluated the neuroprotective effects of MHY908 in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse model of PD. Pretreatment with MHY908 attenuated MPTP-induced dopaminergic neuronal loss and motor deficit. MPTP-induced glial activations were mitigated by MHY908 in the nigrostriatal pathway, and MHY908 effectively blocked 1-methyl-4-phenylpyridinium (MPP+)-induced cell death and ROS production in SH-SY5Y neuroblastoma cells. Further study revealed MHY908 inhibited MPP+-induced astroglial activation by suppressing NF-κB signaling in primary astrocytes. Taken together, the present study suggests that PPAR α/γ dual agonists be considered potentially useful preventions for PD and other neurodegenerative diseases associated with neuroinflammation. [ABSTRACT FROM AUTHOR]

A simple sensing methodology for rapid detection of multiple biomolecules in human health diagnostics remains a significant challenge. Herein, we developed a novel dispersant-free supra single-walled carbon nanotube (supra SWCNT)-coated glassy carbon electrode (GCE) for simultaneous sensing of biomolecules, such as ascorbic acid (AA), dopamine (DA), and uric acid (UA), in ex vivo mouse tissues. Supra SWCNTs with stable hydrogen bonds were synthesized via a simple chemical modification, after which they were characterized and confirmed using different physicochemical and electrochemical techniques. The supra SWCNT-coated GCE exhibited simultaneous sensing of AA, DA, and UA at linear dynamic ranges with lower detection limits of 12, 0.02, and 0.36 μM, respectively. Furthermore, they demonstrated high selectivity (with co-existing interference) and excellent reproducibility for effective sensing of the target biomolecules in different real samples. The rapid functioning, low cost, scalable preparation, and enhanced applicability for simultaneous sensing of target biomolecules in Parkinson's disease-induced mouse liver, kidney, and brain tissues suggest the suitability of the developed sensor for real-world applications. [Display omitted] • Dispersant-free supra SWCNT was prepared to facilitate step chemical modifications. • Supra SWCNTs freely dispersed in water without the addition of dispersing agents. • Supra SWCNTs/GCE were tested for highly sensitive simultaneous biomolecule sensing. • Real-time biomolecule sensing in PD mouse models achieved satisfying results. [ABSTRACT FROM AUTHOR]

Acrylamide (ACR) is a neurotoxin known to produce neurotoxicity characterized by ataxia, skeletal muscle weakness, cognitive impairment, and numbness of the extremities. Previously, investigators reported that high-dose (50 mg/kg) ACR impaired hippocampal neurogenesis and increased neural progenitor cell death; however, the influence of subchronic environmentally relevant low dose-(2, 20, or 200 μg/kg) ACRs have not been examined in adult neurogenesis or cognitive function in mice. Accordingly, the aim of the present study was to investigate whether low-dose ACR adversely affected mouse hippocampal neurogenesis and neurocognitive functions. Male C57BL/6 mice were orally administered vehicle or ACR at 2, 20, or 200 μg/kg/day for 4 weeks. ACR did not significantly alter the number of newly generated cells or produce neuroinflammation or neuronal loss in hippocampi. However, behavioral studies revealed that 200 μg/kg ACR produced learning and memory impairment. Furthermore, incubation of ACR with primary cultured neurons during the developmental stage was found to delay neuronal maturation without affecting cell viability indicating the presence of developmental neurotoxicity. These findings indicate that although exposure to in vivo low-dose ACR daily for 4 weeks exerted no apparent marked effect on hippocampal neurogenesis, in vitro observations in primary cultured neurons noted adverse effects on learning and memory impairment suggestive of neurotoxic actions. [ABSTRACT FROM AUTHOR]

Chronic exposure to cadmium (Cd) causes remarkable damage to the kidneys, a target organ of accumulated Cd after oral administration. The aim of the present study was to investigate the protective effect of curcumin against Cd-induced nephrotoxicity. Sprague–Dawley male rats were divided into the following four treatment groups: control, curcumin (50 mg/kg, oral), CdCl 2 , (25 mg/kg, oral), and pre-treatment with curcumin (50 mg/kg) 1 h prior to the administration of CdCl 2 (25 mg/kg, oral) for 7 days. At 24 h after the final treatment, the animals were killed, and the biomarkers associated with nephrotoxicity were measured. Our data indicated that blood urea nitrogen (BUN) and serum creatinine (sCr) levels were significantly reduced by curcumin pre-treatment in CdCl 2 -treated animals. Histopathological studies showed hydropic swelling and hypertrophy of the proximal tubular cells in the renal cortex after Cd treatment. Pretreatment with curcumin ameliorated the histological alterations induced by Cd. The urinary excretion of kidney injury molecule-1 (Kim-1), osteopontin (OPN), tissue inhibitor of metalloproteinases 1 (TIMP-1), neutrophil gelatinase-associated lipocalin (NGAL), and netrin-1 significantly reduced by curcumin treatment compared to that in the CdCl 2 -treated group. The administration of curcumin provided a significant protective effect against Cd-induced nephrotoxicity. [ABSTRACT FROM AUTHOR]

A new approach based on differential pulse voltammetry (DPV) was developed for the simultaneous determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA) using a modified glassy carbon electrode (GCE). The sensor was constructed by a simple “one-step” technique, wherein de-bundled single-walled carbon nanotubes (SWCNTs) were drop-cast onto the GCE. Without de-bundling, the SWCNTs were poorly dispersed in aqueous solution and were ineffective for the one-step procedure. De-bundling of the SWCNTs was achieved using a small amount (0.1 wt%) of the synthesized polymer dispersant, sulfonated poly(ether sulfone) (SPES); the de-bundled SWCNTs had a high aspect ratio (length = 2.5 ± 1.0 μm; height = 2 ± 1 nm, as determined using transmission electron microscopy and atomic force microscopy). The de-bundled SWCNTs also led to enhanced electrocatalytic activity and selectivity of the modified sensor for the simultaneous determination of AA, DA, and UA in DPV measurements: the peak-to-peak separation values were 221, 119, and 340 mV (vs. Ag/AgCl) for DA–AA, UA–DA, and AA–UA, respectively. The dynamic linear ranges for AA, DA, and UA were 0.2–1.6 mM, 5.0–50 μM, and 5.0–60 μM, and the detection limits were 10.6 μM, 15 nM, and 113 nM (S/N = 3), respectively. The analytical performance of the developed sensor was demonstrated in the determination of AA and DA in commercial pharmaceutical samples (vitamin C tablets and DA injection). The characteristics of the modified sensor make it promising for the individual or simultaneous determination of AA, DA, and UA. [ABSTRACT FROM AUTHOR]

A new metal‐free, non‐enzymatic electrochemical sensor system for the detection of glucose was developed in this study. The developed sensor uses a de‐bundled single‐walled carbon nanotube (SWCNT)‐modified glassy carbon electrode (GCE). SWCNTs were de‐bundled in aqueous solution by adding a synthesized polymer dispersant, sulfonated poly(ether sulfone). The de‐bundled SWCNTs showed two significant characteristics: (1) improvement of the aspect ratio and dispersibility in aqueous solution and (2) suitability for use as a selective and sensitive sensing element in non‐enzymatic glucose sensors. The experimental results clearly demonstrated that the SWCNTs/GCE possesses high electro‐catalytic activity and efficient sensitivity with a stable and faster amperometric response production. Furthermore, interference by ascorbic acid, acetaminophen, uric acid, and dopamine is effectively avoided. Therefore, the proposed approach is favorable for the design and development of non‐enzymatic glucose sensors. [ABSTRACT FROM AUTHOR]

A new amperometric biosensor for hydrogen peroxide (H2O2) and superoxide anion (SO) has been developed. The biosensor developed uses cytochrome c (Cyt c) modified glassy carbon electrodes coupled with electrochemically reduced graphene oxide (ErGO). To immobilize Cyt c, the “one step” electrochemical deposition of vertically aligned and ErGO (VAErGO) has been performed by using a pulse reverse technique, thus resulting in a very simple and efficient system. The well-established vertical alignment of ErGO was confirmed by atomic force microscopy and the electrochemical characteristics of the biosensor were investigated by cyclic voltammetric, electrochemical impedance spectroscopy and amperometric techniques. The surface coverage (Γ) of immobilized Cyt c was effectively increased by the vertical alignment of ErGO and found to be 1.03 × 10−10 mol cm−2. The direct electron transfer property of Cyt c was also improved by VAErGO and the heterogeneous electron transfer rate constant (ket) was estimated to be 6.40 s−1. To detect H2O2 and SO, amperometric measurements were carried out at different operating potentials (0.0 V vs. Ag/AgCl for H2O2 and +0.2 V for SO). The sensitivity and detection limit for H2O2 were found to be 46.3 μA mM−1 cm−2 and 2.3 μM, and for SO were found to be 32.1 μM nA−1 cm−2 and 6.84 nM s−1, respectively. Additionally, the designed biosensor exhibited strong anti-interference ability and satisfactory reproducibility. [ABSTRACT FROM AUTHOR]

We developed a new strategy for construction of a biosensor for the neurotransmitter dopamine. The biosensor was constructed by one-step electrochemical deposition of a nanocomposite in aqueous solution at pH 7.0, consisting of molybdenum disulfide, multi-walled carbon nanotubes, and polypyrrole. A series of analytical methods was performed to investigate the surface characteristics and the improved electrocatalytic effect of the nanocomposite, including cyclic voltammetry, electrochemical impedance spectroscopy, field-emission scanning electron microscopy, atomic force microscopy, and Raman spectroscopy. The constructed biosensor showed high sensitivity (1.130 μAμM −1 cm −2 ) with a dynamic linearity range of 25–1000 nM and a detection limit of 10 nM. Additionally, the designed sensor exhibited strong anti-interference ability and satisfactory reproducibility. The practical application of the sensor was manifested for the ex vivo determination of dopamine neurotransmitters using brain tissue samples of a mouse Parkinson's disease model. [ABSTRACT FROM AUTHOR]

[Display omitted] • A facile single-step method was used to prepare PATT film on ASPE surface. • PATT film was coated on the surface via stable amide linkage. • The prepared PATT@ASPE has a large surface area with excellent electrochemical properties. • PATT@ASPE was used for detecting Hg2+ in different fish muscle samples. Anodized screen-printed electrode (ASPE) was modified by electrochemical polymerization of 5-amino-4H-1,2,4-triazole-3-thiol (ATT) to form a poly-ATT (PATT) film for the selective and sensitive detection of Hg2+ ions by Anodic Stripping Voltammetry (ASV). The porous PATT film was uniformly coated on the surface through disulfide (S S) linkage, free N H, and amide bonds for binding preconcentrated Hg2+ ions. The prepared PATT@ASPE was characterized by cyclic voltammetry, Field-Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM) with Energy Dispersive X-ray spectroscopy (EDS) and Attenuated Total Reflection Infrared Spectroscopy (ATR-IR). Under optimized experimental conditions (0.1 M KCl as supporting electrolyte and preconcentration at –0.1 V for 120 s), PATT@ASPE was successfully used for detecting Hg2+. A linear relationship between the anodic peak current and [Hg2+] was achieved in the concentration range of 0.03 to 245 nM, with a limit of detection (S/N = 3) of 0.005 nM and a calculated sensitivity of 15.0085 µA nM−1 L-1 cm−2. Further, selective detection of Hg2+ was demonstrated in the presence of interfering species such as other heavy metal ions (Pb2+, Cd2+, Cu2+, etc.), organic molecules, other cations, and various anions. The electroanalytical performance of PATT@ASPE exhibited outstanding long-term stability and reproducibility. Finally, PATT@ASPE was successfully applied to measure Hg2+ in fish muscle samples, and the results were validated using inductively coupled plasma-mass spectrometry. [ABSTRACT FROM AUTHOR]

[Display omitted] • Voltammetric norepinephrine sensor using de-bundled single-walled carbon nanotubes. • De-bundling was achieved with a newly synthesized co-polymer. • The sensor was tested by measuring norepinephrine levels in rat tissue samples. A voltammetric sensor for norepinephrine (NE) detection was developed by modifying a disposable screen-printed carbon electrode (SPCE) with de-bundled single-walled carbon nanotubes (D-SWCNTs). The de-bundling was carried out using a newly synthesized polymeric dispersant, a co-polymer of polystyrene sulfonate and methacrylate of lipoic acid. The D-SWCNTs/SPCE showed better sensitivity towards NE compared to the bare SPCE and that modified with bundled SWCNTs. The sensor was optimized for detecting NE by differential pulse voltammetry (DPV) in terms of the D-SWCNTs concentration, DPV parameters, and solution pH. Under the optimum conditions, the sensor exhibited a dynamic linear range of 100 nM–2.0 µM NE, and the detection limit was 62.0 nM (S/N = 3). Additionally, the effects of possible interferents were investigated. The relative standard deviation for five successive measurements of 2.0 µM NE was 7.6%, and approximately 75.8% of the sensor activity was retained after four weeks of storage. The practical potential of this sensor was demonstrated by quantifying NE in ex vivo rat tissue samples. [ABSTRACT FROM AUTHOR]

Pt nanoparticles are prepared by electrochemical reduction of solid K2PtCl6-supported polyethyleneimine coatings on a glassy carbon electrode in a phosphate buffer (pH 7.4). [ABSTRACT FROM AUTHOR]

Parkinson's disease (PD) is a progressive movement disorder caused by nigrostriatal neurodegeneration. Since chronically activated neuroinflammation accelerates neurodegeneration in PD, we considered that modulating chronic neuroinflammatory response might provide a novel therapeutic approach. Glycogen synthase kinase 3 (GSK-3) is a multifunctional serine/threonine protein kinase with two isoforms, GSK-3α and GSK-3β, and GSK-3β plays crucial roles in inflammatory response, which include microglial migration and peripheral immune cell activation. GSK-3β inhibitory peptide (IAGIP) is specifically activated by activated inhibitory kappa B kinase (IKK), and its therapeutic effects have been demonstrated in a mouse model of colitis. Here, we investigated whether the anti-inflammatory effects of IAGIP prevent neurodegeneration in the rodent model of PD. IAGIP significantly reduced MPP+-induced astrocyte activation and inflammatory response in primary astrocytes without affecting the phosphorylations of ERK or JNK. In addition, IAGIP inhibited LPS-induced cell migration and p65 activation in BV-2 microglial cells. In vivo study using an MPTP-induced mouse model of PD revealed that intravenous IAGIP effectively prevented motor dysfunction and nigrostriatal neurodegeneration. Our findings suggest that IAGIP has a curative potential in PD models and could offer new therapeutic possibilities for targeting PD. [ABSTRACT FROM AUTHOR]

Mitochondrial adenine nucleotide translocator (ANT) plays important roles in the regulation of mitochondrial permeability transition and cell bioenergetics. The mouse has three ANT isoforms (1, 2 and 4) showing tissue-specific expression patterns. Although ANT1 is known to have a pro-apoptotic property, the specific functions of ANT2 have not been well determined. In the present study, ANT2 expression was significantly lower in the aged rat liver and in a liver fibrosis model. To explore the protective role of ANT2 in the liver, we established a hepa1c1c7 cell line overexpressing ANT2. Overexpression of ANT2 caused hepa1c1c7 cells to be more resistant to oxidative stress, and mitochondrial membrane potential (MMP, ∆Ψm) was relatively intact in ANT2-overexpressing cells under oxidative stress. In addition, ANT2 was found to increase ATP production by influencing mitochondrial bioenergetics. These results imply that the hepatoprotective effect of ANT2 is due to the stabilization of MMP and enhanced ATP production, and thus, maintaining ANT2 levels in the liver might be important to enhance resistance to aging and oxidative stress. [ABSTRACT FROM AUTHOR]

Abstract: An all solid state potentiometric immunosensor (ASPI) has been developed to study the activation process of neuronal nitric oxide synthase (nNOS), the enzyme involved in the synthesis of nitric oxide generated under physiological conditions. At first, an all solid state H+-selective ISE was fabricated with the carboxylated poly(vinyl chloride) (PVC-COOH) film containing H+ ionophore, antibody was then immobilized on the polymer layer. The immunocomplex formation was detected by monitoring pH change due to interaction between urease labeled secondary antibody and antigen. Experimental parameters such as the amount of phosphorylated nNOS immobilized on the electrode surface and pH responses due to the antibody–antigen reaction were studied in detail. The calibration plot of the potentiometric potential vs. phosphorylated nNOS concentration exhibited a linear relationship in the range of 3.4–340.0μg/ml. The calibration sensitivity of the phosphorylated nNOS immunosensor was −0.073±0.002mV/μgml−1. The detection limit of nNOS was determined to be 0.2μg/ml based on five-time measurements (95% confidence level, k =3, n =5). The reliability of the immunosensor was examined with rat brain tissues as well as neuronal cells, and the results shown were good, implying a promising approach for a novel electrochemical immunosensor platform with potential applications to clinical diagnosis. [Copyright &y& Elsevier]

Abstract: A disposable amperometric immunosensor was studied for the rapid detection of carp (Carassius auratus) Vitellogenin (Vtg). The sensor was fabricated based on screen-printed carbon arrays (SPCAs) containing eight carbon working and an integrated carbon counter electrodes. To construct the sensor, a conducting polymer (poly-terthiophene carboxylic acid) was electropolymerized on the surface of working electrodes and the polymer-coated SPCAs was characterized by SEM. Horseradish peroxidase (HRP) and a monoclonal antibody (anti-Vtg) specific to carp Vtg were covalently attached onto the polymer modified SPCAs. The immobilization of HRP and anti-Vtg onto the polymer-coated SPCAs was examined using cyclic voltammetry and quartz crystal microbalance studies. In order to detect the amount of Vtg, glucose oxidase (GOx)-labelled Vtg bound to the sensor surface under competition with the Vtg analyte was quantified amperometrically using glucose as a substrate. The performance of the eight sensors in arrays was evaluated by obtaining the calibration plots for Vtg. The sensor arrays exhibit a linear range of the Vtg concentration from 0.25 to 7.8ng/ml and the detection limit was determined to be 0.09ng/ml. Furthermore, the performance of the immunosensor for the determination of Vtg was evaluated by a standard addition method performed in fish serum samples. [Copyright &y& Elsevier]

A new disposable amperometric biosensor for sarcosine (Sar, a biomarker for prostate cancer) was designed based on screen-printed carbon electrodes, Prussian blue, polymer dispersed reduced graphene oxide (P-rGO) nanosheets, and sarcosine oxidase (SOx). Poly(sodium 4-styrenesulfonate- r -LAHEMA) denoted as PSSL was newly synthesized as dispersant for rGO. The P-rGO was utilized for SOx immobilization, the sulfonate and disulfide functionalities in PSSL enable physical adsorption of SOx and its bioactivity and stability properties were improved. The biosensor was optimized by various enzyme concentration, applied potential, and operating pH. Under the optimized conditions, the biosensor exhibited maximum current responses within 5 s at an applied potential of −0.1 V vs. integrated Ag/AgCl reference electrode. The biosensor had a dynamic linear range of 10–400 μM, with a sensitivity of 9.04 μA mM−1 cm−2 and a low detection limit of 0.66 μM (S/N = 3). Additionally, the biosensor possesses strong anti-interference capability, high reproducibility, and storage stability over 3 weeks. Furthermore, its clinical applicability was tested in urine samples from both prostate cancer patients and healthy control, and the analytical recoveries were satisfactory. Therefore, this biosensor has significant potential in the rapid and non-invasive point-of-care testing for prostate cancer diagnosis. [Display omitted] • A new polymer dispersant synthesized to disperse reduced graphene oxide (P-rGO). • P-rGO and Prussian blue utilized for amperometric sarcosine biosensor. • SOxENs prepared using P-rGO and sarcosine oxidase (SOx). • High selectivity against major interferents in human urine. • The designed biosensor is more suitable for non-invasive prostate cancer diagnosis. [ABSTRACT FROM AUTHOR]

Oxidative stress, mitochondrial dysfunction, and neuroinflammation are strongly associated with the pathogenesis of Parkinson's disease (PD), which suggests that anti-oxidative and anti-inflammatory compounds might provide an alternative treatment for PD. Here, we evaluated the neuroprotective effects of evernic aid (EA), which was screened from a lichen library provided by the Korean Lichen Research Institute at Sunchon National University. EA is a secondary metabolite generated by lichens, including Ramalina, Evernia, and Hypogymnia, and several studies have described its anticancer, antifungal, and antimicrobial effects. However, the neuroprotective effects of EA have not been studied. We found that EA protected primary cultured neurons against 1-methyl-4-phenylpyridium (MPP+)-induced cell death, mitochondrial dysfunction, and oxidative stress, and effectively reduced MPP+-induced astroglial activation by inhibiting the NF-κB pathway. In vivo, EA ameliorated MPTP-induced motor dysfunction, dopaminergic neuronal loss, and neuroinflammation in the nigrostriatal pathway in C57BL/6 mice. Taken together, our findings demonstrate that EA has neuroprotective and anti-inflammatory effects in PD models and suggest that EA is a potential therapeutic candidate for PD. [ABSTRACT FROM AUTHOR]

A simple one-step electrochemical deposition/activation of graphitic carbon nitride (g-C3N4) is highly desired for sensor configurations and remains a great challenge. Herein, we attempt an electrochemical route to exfoliate the g-C3N4 nanosheets in an aqueous solution of pH 7.0 for constructing a sensor, which is highly sensitive for the detection of serotonin (5-HT). The significance of our design is to exfoliate the g-C3N4 nanosheets, a strong electrocatalyst for 5-HT detection. Investigations regarding the effect of neutral pH (pH 7.0) on the bulk g-C3N4 and g-C3N4 nanosheets, physical characterization, and electrochemical studies were extensively carried out. We demonstrate that the g-C3N4 nanosheets have a significant electrocatalytic effect for the 5-HT detection in a dynamic linear range from 500 pM to 1000 nM (R2 = 0.999). The limit of detection and sensitivity of the designed 5-HT sensor was calculated to be 150 pM and 1.03 µA µM−1 cm−2, respectively. The proposed sensor has great advantages such as high sensitivity, good selectivity, reproducibility, and stability. The constructed g-C3N4 nanosheets-based sensor platform opens new feasibilities for the determination of 5-HT even at the picomolar/nanomolar concentration range. [ABSTRACT FROM AUTHOR]