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In the present work, an innovative biocompatible heterogeneous organo‐nanocatalyst is prepared based on the grafting of arginine amino acid on the channels and pores of dendritic fibrous nano silica. The designed organo‐nanocatalyst (KCC‐1‐nPr‐NH‐Arg) was characterized by using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X‐ray spectroscopy, map analysis, and adsorption/desorption instruments. The results of analysis show that the engineered catalyst has uniform fibrous spheres and dendritic structure with high surface area (104.9 m2/g) and great pore volume (0.83 cm3 g−1). Because of exceptional dendritic structure of the prepared organo‐nanocatalyst, the active sites are available and the difusion and adsorption capacity of the reagents and products increase in the pores and channels of the catalyst. Hence, KCC‐1‐nPr‐NH‐Arg was used as an capable heterogeneous basic nanocatalyst in the synthesis of 1,8‐dioxo decahydroacridine derivatives from the one‐pot four component reactions of aromatic aldehydes, dimedone, and ammonium acetate in solvent free conditions with shorter reaction times (13‐35 minutes) and higher yields (94%‐98%) in evaluation with other reported works. It is expected that the green organo‐nanocatalyst can be used to synthesize other organic compounds. [ABSTRACT FROM AUTHOR]

An innovative nanocatalyst (KCC‐1‐nPr‐Met) has been prepared from the covalent attachment of metformin on the channels and the pores of n‐propyl amine functionalized dendritic fibrous nanosilica (DFNS) and used towards efficient, green, and high yield synthesis of tetrahydro‐4H‐chromenes derivatives by one‐pot three‐component reaction of aromatic aldehydes, malononitrile, and dimedone in H2O‐EtOH at room temperature. The designed nanocatalyst has been characterized by energy dispersive X‐ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT‐IR), and adsorption/desorption analysis (BET) techniques. Also, field emission scanning electron microscopy (FE‐SEM) was used to study the morphology of prepared nanocatalyst. The engineered nanocatalyst with uniform fibrous spheres has dendritic structure, high pore volume (0.35 cm3/g), and great surface area (178 m2/g). Hence, the specific dendritic structure of the prepared nanocatalyst not only improve the diffusion ability of the reactants and products, but also, increase the availability of dynamic sites in the pores and channels of the catalyst. According to the obtained results, a unique strategy was proposed towards the synthesis of important biologically active scaffolds in the presence of nontoxic and environmental friendly nanocatalyst and media. Milder reaction conditions (room temperature), shorter reaction times (5‐30 minutes), excellent yields (92%‐98%) of the products with higher purity, very simple workup procedure, and using of EtOH: H2O as a green solvent are the advantages of the presented work. [ABSTRACT FROM AUTHOR]

In the present work, an innovative leach proof nanocatalyst based on dendritic fibrous nanosilica (DFNS) modified with ionic liquid loaded Fe3O4 NPs and CuI salts was designed and applied for the rapid synthesis of imidazo[1,2‐a]pyridines from the reaction of phenyl acetylene, 2‐aminopyridine, and aldehydes in aqueous medium. The structure of the synthesized nanocatalyst was studied by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared (FT‐IR), flame atomic absorption spectroscopy (FAAS), energy‐dispersive X‐ray (EDX), and X‐ray diffraction (XRD), vapor–liquid–solid (VLS), and adsorption/desorption analysis (Brunauer–Emmett–Teller [BET] equation) instrumental techniques. CuI/Fe3O4NPs@IL‐KCC‐1 with high surface area (225 m2 g−1) and porous structure not only exhibited excellent catalytic activity in aqueous media but also, with its good stability, simply recovered by an external magnet and recycled for eight cycles without significant loss in its intrinsic activity. Higher catalytic activity of CuI/Fe3O4NPs@IL‐KCC‐1 is due to exceptional dendritic fibrous structure of KCC‐1 and the ionic liquid groups that perform as strong anchors to the loaded magnetic nanoparticles (MNPs) and avoid leaching them from the pore of the nanocatalyst. Green reaction media, shorter reaction times, higher yields (71–97%), easy workup, and no need to use the chromatographic column are the advantages of the reported synthetic method. [ABSTRACT FROM AUTHOR]

In the present work, Cu@KCC‐1‐NH‐CS2 as a green, efficient, and reusable nano‐reactor was designed and used for the one‐pot, three‐component synthesis of 2‐amino‐4H‐chromene derivatives using the reaction of cyclic 1,3‐diketones, arylglyoxals, and malononitrile, under reflux conditions in EtOH. Engineered nanocatalyst characterized using different methods including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT‐IR), adsorption/desorption analysis (BET), and energy dispersive X‐ray spectroscopy (EDS). According to the obtained results, presented protocol for the synthesis of 2‐amino‐4H‐chromenes using Cu@KCC‐1‐NH‐CS2 gave the desired products in higher yields (89–98%) with short reaction times. Also, under mild reaction conditions this green nanocatalyst indicated recyclable behavior five times with minor reduce in its catalytic activity. [ABSTRACT FROM AUTHOR]

Dye removal from industrial waste water has become an important issue. The highvisibility, undesirability and recalcitrance are the significant environmental problemfor the dyes. In the present work,β‐cyclodextrin functionalized KCC‐1 (KCC‐1‐NH‐β‐CD)was synthesized and utilized to the removal of hazardous malachite green. In order to study the morphology of the synthesized nano adsorbent, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) were obtained from the surface of the sample. Additionally, the functionalization of KCC‐1 with β‐cyclodextrin was confirmed with Furrier Transform Infrared spectroscopy (FTIR). The textural property of KCC‐1 was verified using nitrogen adsorption/ desorption analysis (BET equation). UV‐Vis spectroscopy utilized for the investigation of malachite green by KCC‐1‐NH‐β‐CD. Specific surface area of the adsorbent was calculated to be 140 m2/g and it can be stated that the synthesized nano adsorbent has high removal efficiency. It should be noted that the adsorption capacity of the employed nano adsorbent was more than 95%, which could be attributed to high porosity of β‐cyclodextrin functionalized KCC‐1. [ABSTRACT FROM AUTHOR]

This review (with 118 refs.) discusses the progress made in electroanalytical methods based on the use of organic and inorganic nanomaterials for the determination of bacteria, specifically of E. coli, Salmonella, Staphylococcus, Mycobacterium, Listeria and Klebsiella species. We also discuss advantages and limitations of electrochemical methods. Strategies based on the use of aptamers, DNA and antibodies are covered. Following an introduction into electrochemical biosensing, a first large section covers methods for pathogen detection using metal nanoparticles, with subsections on silver nanoparticles, gold nanoparticles, magnetic nanoparticles and carbon-based nanomaterials. A second large section covers methods based on the use of organic nanocomposites, graphene and its derivatives. Other nanoparticles are treated in a final section. Several tables are presented that give an overview on the wealth of methods and materials. A concluding section summarizes the current status, addresses challenges, and gives an outlook on potential future trends. [ABSTRACT FROM AUTHOR]

Abstract The good mechanical and biological performance of natural biopolymers is important factor in biomedical science. In metabolism, nicotinamide adenine dinucleotide (NAD) is involved in redox reactions, carrying electrons from one reaction to another. On such a basis, much attention has been devoted to developing procedures to monitoring the presence of NAD at very low concentrations in a physiological environment and biological fluids. The good mechanical and biological performance of natural biopolymers is important factor in bone tissue engineering. Herein, a new platform based on silver nanoparticles (Ag NPs) and nitrogen doped graphene quantum dots (N-GQD S) is developed for sensitive voltammetric detection of NAD in human plasma samples. N-GQD S -Ag NPs film were prepared by the full electrochemically method onto the surface of GCE. Ag NPs were covalently bonded to N-GQD S films and used to bind of NAD biomarker. The novel detection scheme is a suitable electrochemical assay, which makes the NAD detection simple and rapid. The engineered electrochemical sensor showed a linear dynamic range and low limit of quantification limit of 1.45–7.9 μM and 1.45 μM, respectively. The proposed sensor showed excellent analytical performance for the detection of NAD with high sensitivity and reproducibility. The prepared sensor detected NAD ion human plasma samples with high recovery values. We hope that this platform has the potential to be used in clinical applications and point-of-care diagnosis of disease. Graphical abstract Unlabelled Image Highlights • A novel electrochemical sensor for sensing hydrogen-transmitting coenzyme is proposed. • SWVs were applied in analysis for NAD in human plasma samples. • The newly developed sensor is rapid, economical, convenient and sensitive. • The N-GQDS-Ag NPs-GCE is superior to electrochemical analysis. [ABSTRACT FROM AUTHOR]

Graphene quantum dot-β-cyclodextrin modified glassy carbon electrode was used as a new nanosensor for determination of L-tyrosine (L-Tyr). It was found that graphene quantum dot-β-cyclodextrin has been stably electrodeposited on glassy carbon electrode modified by simple technique. The cyclic voltammograms of the modified electrode in an aqueous solution displayed a pair of well-defined, stable and irreversible reductive/oxidation redox systems. The apparent electron transfer rate constant (ks) and transfer coefficient (α) determined by cyclic voltammetry were approximately equal to 8.0 s-1 and 0.7, respectively. The modified electrode showed excellent catalytic activity towards the oxidation of L-Tyr at positive potential in buffer solution. The nanosensor also displayed fast response time, high sensitivity, low detection limit and a remarkably positive potential oxidation of L-Tyr that decreased the effect of interferences in analysis. [ABSTRACT FROM AUTHOR]

Nanosized hydrogels have emerging as versatile supramolecules materials with application in various electrochemical biosensing devices. This review reports a systematic study of the usefulness of nano-sized hydrogels in the different steps of the process of development of electrochemical biosensing systems. The advantages offered by nano-sized hydrogels in detection of analytes are illustrated with representative recent examples that highlight the scientific interest in widening the use of hydrogel nanoparticles in electrochemical biosensing methods. In this review, different types of hydrogel nanoparticles-based electrochemical biosensors, such as enzyme, protein, and nucleic acids are reviewed in terms of their sensing performance and potential of future development. Various aspects of nano-sized hydrogels, from the point of view of electrochemical biosensor design, were considered hoping that this review will excite researchers into exploiting the exceptional properties of nano-sized hydrogels in electrochemical biosensor development. Finally, some future applications of electrochemical biosensors based on nano-sized hydrogels were discussed. [ABSTRACT FROM AUTHOR]

Rapid and effective differentiation between normal and cancer cells is an important objective for the diagnosis, prognosis and theranosis of tumors. This short review highlights some of the most recent developments on the application of molecular bioimprinting in detection of cancer cells using antibody-based cancer cell recognition method. The particular emphasis of this review is on sample-to-answer devices and approaches that enable down-stream investigation of the properties of the cells. Given the speed, portability, sensitivity and selectivity achieved using molecular bioimprinting technology on cancer cell monitoring, these methods hold the promise of transformative change in clinical practice. [ABSTRACT FROM AUTHOR]

Rapid analyses of some water soluble vitamins (Vitamin B2, B9, and C) in commercial multi vitamins could be routinely performed in analytical laboratories. This study reports on the electropolymerization of a low toxic and biocompatible polymer “poly aspartic acid-graphene quantum dots” as a novel strategy for surface modification of glassy carbon electrode and preparation a new interface for measurement of selected vitamins in commercial multi vitamins. Electrochemical deposition, as a well-controlled synthesis procedure, has been used for subsequently layer-by-layer preparation of graphene quantum dots nanostructures on a poly aspartic acid using cyclic voltammetry techniques in the regime of −1.5 to 2 V. The field emission scanning electron microscopy indicated immobilization of graphene quantum dots onto poly aspartic acid film. The modified electrode possessed as an effective electroactivity for detection of water soluble vitamins by using cyclic voltammetry, chronoamperometry and differential pulse voltammetry. Enhancement of peak currents is ascribed to the fast heterogeneous electron transfer kinetics that arise from the synergistic coupling between the excellent properties of poly aspartic acid as semiconducting polymer, graphene quantum dots as high density of edge plane sites and chemical modification. Under the optimized analysis conditions, the prepared sensor for detection of VB2, VB9, and VC showed a low limit of quantification 0.22, 0.1, 0.1 μM, respectively. [ABSTRACT FROM AUTHOR]

Caspases, especially caspase-3, play a critical role in the intrinsic and extrinsic pathways of apoptosis. In addition, caspase-3 is involved in mental disorders like Alzheimer disease. Any up and down regulation of caspase-3 activity may cause cancer. This review (with 58 references) summarizes recent advances in electrochemical and electrochemiluminescent quantitation of the activity of caspase-3 based on the use of nanomaterials. The nanomaterials and nanolabels are classified in three main subgroups, namely electrochemical signal amplification strategies, amplification based on modified electrodes, and the combination of both modes. The potential of various electrochemical and electrochemiluminescence bioassays is discussed, and methods to circumvent certain limitations are oresented. Finally, current trends in the detection of caspase-3 such as system integration and the application of advanced nanomaterials are discussed. [ABSTRACT FROM AUTHOR]

Timely monitoring of apoptosis can effectively assist early diagnosis of related diseases and continuous evaluation of the efficacy of drugs. Therefore, developing advanced methods for apoptosis evaluation has attracted more and more attention. In addition, the increased demand for understanding the early stages of apoptosis is pushing the envelope for solutions in early instance real-time monitoring of death kinetics. In this review, various types of electro-analytical methods for detection of apoptosis were discussed. The emphasis is placed in diagnosis of apoptosis based on cyto-, immune-, geno-, apta-, and peptide based biosensing strategies. In the first part of review, various electrochemical cytosensing methods for the detection of programmed cell death and their potential as a new method were discussed. In the second part of review, we discuss critical aspects of peptide based biosensors design with particular emphasis on analytical characteristics and bioanalytical aspects. Finally, most frequently applied principles in immunosensing and genosensing methods were described. More importantly, we discussed in detail different aspects such as type of materials, injection and detection techniques, labels, analytes, corresponding sample matrix, and sensitivity. Furthermore, we address the remaining challenges and opportunities to integrate electrochemical biosensing platforms into point-of-care solutions. [ABSTRACT FROM AUTHOR]

p53 is a gene that codes for a protein that regulates the cell cycle and hence functions as a tumor suppression. p53 plays an important role in cell cycle control and apoptosis. Defective p53 could allow abnormal cells to proliferate, resulting in cancer. Recently, much attention has been devoted to developing procedures to detect the presence of p53 protein at very low concentrations in a physiological environment. This article reviews DNA biosensors (genosensors) reported for the qualitative and quantitative determination of p53. We discuss critical aspects of genosensor design with particular emphasis on analytical characteristics and analysis of real samples. We assess the design and the construction of electrochemical, electrochemiluminescence, optical, and photoelectrochemical genosensors, describing the contributions so far in the p53 field and the analytical challenges involved in this research area. [ABSTRACT FROM AUTHOR]

Recently researchers have driven their attention in the development of biosensors for breast cancer detection using different biomarkers. This review reports a systematic study of the usefulness of marker-based electrochemical biosensors in breast cancer and its early diagnosis. Also, various types of electro-analytical methods for early stage screening of breast cancer were discussed. The emphasis is placed on immune-, geno- cyto- and enzyme-biosensing strategies. In addition, the advantages offered by some nano-materials in detection of breast cancer biomarkers are illustrated with representative recent examples that highlight the scientific interest in widening the use of new materials/methods in electrochemical biosensing methods. We also present a comprehensive overview of current developments and key issues in the determination of some breast cancer biomarkers, with an emphasis on evaluating the methods. [ABSTRACT FROM AUTHOR]

Oral cancer is a kind of head and neck cancer and is each cancerous tissue growth located in the oral cavity. Non-invasive early diagnosis of oral cancer is the most effective means to reduce death from this disease or increase the survival time. In this review, various types of electro-analytical methods for detection of oral cancer were discussed. The emphasis is placed on non-invasive detection of oral based on immune-, geno-, cyto-, apta-, and enzyme-biosensing strategies. In the first part of review, various electrochemical immunosensing methods for the detection of common biomarker in oral cancer and examines their potential as a new method were discussed. In the second part of review, we discuss critical aspects of genosensor design with particular emphasis on analytical characteristics and non-invasive analysis of oral cancer. Finally, most frequently applied principles in non-invasive enzyme and cytosensing of oral cancer were described. Furthermore, we address the remaining challenges and opportunities to integrate electrochemical biosensing platforms into non-invasive point-of-care solutions. [ABSTRACT FROM AUTHOR]

Electrochemical aptasensors, which are based on the specificity of aptamer-target recognition, with electrochemical transduction for analytical purposes have received particular attention due to their high sensitivity and selectivity, simple instrumentation, as well as low production cost. This review summarizes advances from 2009 to January 2017 in the development of electrochemical aptasensors for biological molecules, including small molecules, nucleic acids, and proteins. Various aptasensing strategies are assessed according to their potential for reaching relevant limits of sensitivity, specificity, and degrees of multiplexing. Furthermore, we address the remaining challenges and opportunities to integrate electrochemical aptasensing platforms into point-of-care solutions. [ABSTRACT FROM AUTHOR]

The utility of detection of p53 in tomorrow's personalized health care field will mean early and accurate diagnosis of many types of cancers. This review is meant to provide an overview of the various types of immunosensors and immunoassay have been developed for determination of p53, along with significant advances over the last several years in related technologies. In addition, this review described: • Most frequently applied principles in immunoassay/immunosensing of p53. • The aspects of fabrication in the perspective of immunoassay/immunosensing applications. • The potential of various electrochemical, electrochemiluminescence immunosensors for the determination of p53 within sub-nanomolar range and the circumvention of the most serious problem in immunosensing will be discussed. • Some of multiplex electrochemical immunosensors have been discussed with and without labels. • We also summarize the latest developments in the applications of immunoassay/immunosensing methods for detection of p53 in real samples. • The development trends of electrochemical and electrochemiluminescence based immunosensors are also introduced, including newly developed integrated immunosensors, and the application of nanotechnology and microfluidic technology. [ABSTRACT FROM AUTHOR]

This review (with 196 refs.) covers the state of the art in electrochemical and optical immunoassays for the carcinoembryonic antigen (CEA). In essence, it has sections on (a) frequently applied principles and types of CEA immunoassays; (b) aspects of sensor fabrication including immunological and immobilization procedures and the proper choice of nanomaterials; (c) electrochemical immunoassays, with subsections on assays based on the use of nanoparticles and other nanomaterials (such as conducting polymers and graphenes); (d) optical immunoassays based on the use of nanoparticles such as quantum dots, gold nanoparticles, upconversion nanoparticles, graphenes and their derivatives; (d) lateral flow and lab-on-a-chip (microfluidic) immunoassays; and (e) on multiplexed electrochemical and optical immunoassays with and without labels. Examples for applications to real samples are given. A final section discusses current limitations and trends in terms of sensing schemes and nanomaterials. [ABSTRACT FROM AUTHOR]

Graphene quantum dots-based immunosensors have recently gained importance for detecting antigens and biomarkers responsible for cancer diagnosis. This paper reports a literature survey of the applications of graphene quantum dots for sensing cancer biomarkers. The survey sought to explore three questions: (1) Do graphene quantum dots improve immunosensing technology? (2) If so, can graphene quantum dots have a critical, positive impact on construction of immuno-devices? And (3) What is the reason for some troubles in the application of this technology? The number of published papers in the field seems positively answer the first two questions. However additional efforts must be made to move from the bench to the real diagnosis. Some approaches to improve the analytical performance of graphene quantum dots-based immunosensors through their figures of merit have been also discussed. [ABSTRACT FROM AUTHOR]

Analysis of neurotransmitters is useful for the diagnosis of central nervous system diseases. This review gives a general view of recent advances in the development of electrochemical sensors for detection/determination of neurotransmitters. The purpose of the review is to provide useful insights in terms of ( a ) choice of materials, ( b ) methods/techniques preferably applied, ( c ) immobilization procedures, and ( d ) other practical aspects. Following an introduction into the field, we give a short account on the principle and general types of electrochemical sensors, and then treat sensing methods for neurotransmitters. It is subdivided into sections on ( i ) Dopamine ( ii ) Acetylcholine; ( iii ) Serotonin; ( iv ) Epinephrine; ( v ) Norepinephrine ( vi ) Nitric Oxide ( vii ) Glutamate and finally ( viii ) Tryptamine. The review also covers aspects of surface modifications, the effect of structure properties on sensing performance, and the applications of different materials in conjunction with different kind of signal transducers. More importantly, we discuss in detail different aspects of the electrochemical sensors ( e.g., detection techniques, analytes (type of neurotransmitters) and the corresponding sensitivity and sample matrix, and several prominent characteristics). Accordingly, we discuss research opportunities and future development trends in these areas. [ABSTRACT FROM AUTHOR]

This review (with 86 refs.) covers the state of the art in electrochemical and optical immunoassay of carcinoembryonic antigen (CEA). The purpose of the review is to provide useful insights in terms of (a) choice of materials, (b) methods/techniques preferably applied, (c) immunological procedures, (d) immobilization procedures, and (d) other practical aspects. Following an introduction into the field, we give a short account on the principle and general types of immunoassay, and then treat immunoassay for CEA. The first section covers nanomaterial based electrochemical immunoassay, with subsections on using of nanoparticles, hyperbranched polymers, graphene and their derivatives for detection of CEA. A further large section covers photoelectrochemical immunoassay, with assays based on the use of various kinds of nanoparticles, also in combination with carbonaceous nanomaterials, or using upconversion nanoparticles (UCNPs), graphene quantum dots, and other nanomaterials of interest. The next large section covers optical immunoassay, with examples on assays based on the use of various kinds of conventional nanoparticles (quantum dots), upconversion nanoparticles, graphenes and their derivatives. The review also covers aspects of surface modifications, the effect of nanostructure properties on sensing performance, and the applications of these nanomaterials in conjunction with different kind of signal transducers. [ABSTRACT FROM AUTHOR]

Current needs for sustainable energy have popularized the development and use of fuel cell technology. Catalysts are vital fuel cell components, and in recent years research efforts have focused on the development new types of catalysts. This work describes application of a novel nanocatalyst based on graphene quantum dot functionalized by chitosan (GQD-CS) and β-cyclodextrin (GQD- β -CD) towards electrooxidation of methanol in alkaline solution. The catalysts were prepared by cycling the glassy carbon electrode in solutions containing graphene quantum dot and chitosan. The synergistic effects and catalytic activity of the modified electrodes were investigated by cyclic voltammetry (CV), chronoamperometry (CA) and electrochemical impedance spectroscopy (EIS). It was found that, in the presence of methanol, the modified electrodes [(GQD-CS-GCE) and (GQD- β -CD-GCE)] exhibited a significantly higher catalytical response for methanol oxidation compared to the other samples. The anodic peak currents showed a linear dependency on the square root of the scan rate, which is a characteristic of a diffusion controlled process. The graphene quantum dots functionalized with chitosan and β-CD electrodes is further extended to the demonstration of novel electrocatalyst through the transfer of the electrode fabricated by bare GQDs. For comparison of the recognition efficiency, other electrodes including bare GCE, and GQDs-GCE were used for the control experiments. Comparison of recorded CVs and CHs in the presence of methanol using GQD-CS-GCE, β-CD-GQDs-GCE shows ΔE p was decreased as GQD-CS-GCE > GQDs-β-CD-GCE > GQDs-GCE. The higher peak current observed in the presence of GQD-CS-GCE, GQDs-β-CD-GCE clearly indicates β-CD and CS essential roles in the observed electrocatalytical behavior. In general, the attachment of chitosan and β-cyclodextrin to structure of GQDs provides new opportunities towards the direct methanol fuel cell application. [ABSTRACT FROM AUTHOR]

Graphene and mesoporous silica nanomaterials have attracted much interest for applications in orthopaedic implants. This review focuses on more recent advances in orthopaedic implants based on Graphene and mesoporous silica nanomaterials during 2013 to May 2016. The purpose of this article was to give a general description of studies of nanostructured graphene/mesoporous silica for orthopaedic implants. In this review, we highlight how graphene/mesoporous silica family nanomaterials are being exploited for orthopaedic implants. Firstly, the main requirements for orthopaedic implants were discussed. Also, the effects of structural properties of graphene/mesoporous silica-based nanomaterials on the development of new orthopaedic implants were discussed. Finally, the present review intends to provide the reader an overview of the current state of the graphene/mesoporous silica-based biomaterials in orthopaedic implants, its limitations and hopes as well as the future research trends for this exciting field of science. [ABSTRACT FROM AUTHOR]

Graphene is a 2-D carbon nanomaterial with many distinctive properties that are electrochemically beneficial, such as large surface-to-volume ratio, lowered power usage, high conductivity and electron mobility. Graphene-based electrochemical immune-devices have recently gained much importance for detecting antigens and biomarkers responsible for cancer diagnosis. This review describes fabrication and chemical modification of the surfaces of graphene for immunesensing applications. We also present a comprehensive overview of current developments and key issues in the determination of some biological molecules with particular emphasis on evaluating the models. This review focuses mostly on new developments in the last 5 years in development of chip architecture and integration, different sensing modes that can be used in conjunction with microfluidics, and new applications that have emerged or have been demonstrated; it also aims to point out where future research can be directed to in these areas. [ABSTRACT FROM AUTHOR]

For the first time, β-Cyclodextrin (β-CD) attachment to graphene quantum dot (GQD) structure was performed using simultaneous electrodeposition of GQD and β-CD on the surface of glassy carbon electrode (GCE). Cyclic voltammetry at potential range − 1.0 to 1.0 V from mixture of GQD and β-CD produced a well-defined β-CD-GQD deposited on the surface of glassy carbon electrode. β-CD-GQD modified GCE was used as a new electrocatalytical nanocomposite towards electrooxidation of Vitamin C (as sample analyte). The synergistic effects and the catalytic activity of the β-CD-GQD modified GCE were investigated by cyclic voltammetry (CV), differential pulse voltammetry (DPV) chronoamperometry (CA) and square wave voltammetry (SWV). The process of oxidation involved and its kinetics were established by using cyclic voltammetry, chronoamperometry techniques. It has been found that in the course of an anodic potential sweep the electro-oxidation of Vitamin C is catalyzed by synergetic effect of β-CD and GQD through a mediated electron transfer mechanism. Therefore, β-CD-GQDs promote the rate of oxidation by increasing the peak current. The cyclic voltammetric results indicate that β-CD-GQDs-GCE can remarkably enhance electroactivity towards the oxidation of Vitamin C in buffer solution. We have illustrated that the as-obtained β-CD-GQDs-GCE exhibited a much higher electrocatalytical behavior than GQDs for the electrooxidation and detection of Vitamin C which was about two fold higher than for GQDs. The electrochemical behavior was further exploited as detection scheme for the Vitamin C electrooxidation by square wave voltammetry. [ABSTRACT FROM AUTHOR]

Introduction: Growing demands for ultrasensitive biosensing have led to the development of numerous signal amplification strategies. In this report, a novel electrochemiluminescence (ECL) method was developed for the detection and determination of caspase-3 activity based on reduced graphene oxide sheets decorated by gold nanoparticles as signal amplification element and horseradish peroxidase enzyme (HRP) as ECL intensity enhancing agent. Methods: The ECL intensity of the luminol was improved by using the streptavidin coated magnetic beads and HRP in the presence of hydrogen peroxide. The cleavage behavior of caspase-3 was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques using biotinylated peptide (DEVD containing peptide) which was coated on reduced graphene oxide decorated with gold nanoparticle. The surface modification of graphene oxide was successfully confirmed by FTIR, UV-vis and x-ray spectroscopy. Results: ECL based biosensor showed that the linear dynamic range (LDR) and the lower limit of quantification (LLOQ) were 0.5-100 and 0.5 femtomolar (fM), respectively. Finally, the performance of the engineered peptide based biosensor was validated in the A549 cell line as real samples. Conclusion: The prepared peptide based biosensor could be considered as an excellent candidate for early detection of apoptosis, cell turnover, and cancer related diseases. [ABSTRACT FROM AUTHOR]

Currently, the assay of whole blood has emerged as an important tool in modern biomedical research such as clinical diagnostics, drug discovery, and biodefense. Whole blood is a particularly complex mixture composed of various substances such as protein, glucose, inorganic salt, hormone, and biomarkers. Hence, considerable information can be obtained by investigating whole blood, for assessing the health status of the patient. Recently, significant advances have been made in electrochemical bio/immunosensing from whole blood using nanomaterials. This review describes the fabrication and chemical modification of surfaces of nanomaterials for bio/immunosensing applications in whole blood. We also present a comprehensive overview of current developments and key issues in the determination of some biological molecules, with an emphasis on evaluating the methods. We also discuss the incorporation of biorecognition elements into nanomaterial-based electrodes for immunosensing in unprocessed whole blood. [ABSTRACT FROM AUTHOR]

Small molecules that bind genomic DNA have proven that they can be effective anticancer, antibiotic and antiviral therapeutic agents that affect the well-being of millions of people worldwide. Drug–DNA interaction affects DNA replication and division; causes strand breaks, and mutations. Therefore, the investigation of drug–DNA interaction is needed to understand the mechanism of drug action as well as in designing DNA-targeted drugs. On the other hand, the interaction between DNA and drugs can cause chemical and conformational modifications and, thus, variation of the electrochemical properties of nucleobases. For this purpose, electrochemical methods/biosensors can be used toward detection of drug–DNA interactions. The present paper reviews the drug–DNA interactions, their types and applications of electrochemical techniques used to study interactions between DNA and drugs or small ligand molecules that are potentially of pharmaceutical interest. The results are used to determine drug binding sites and sequence preference, as well as conformational changes due to drug–DNA interactions. Also, the intention of this review is to give an overview of the present state of the drug–DNA interaction cognition. The applications of electrochemical techniques for investigation of drug–DNA interaction were reviewed and we have discussed the type of qualitative or quantitative information that can be obtained from the use of each technique. [ABSTRACT FROM AUTHOR]

Patterned paper has characteristics that lead to miniaturized assays that run by capillary action with small volumes of fluids. These methods suggest a path for the development of simple, inexpensive, and portable diagnostic assays that can be useful in remote settings, where simple immunoassays are becoming increasingly important for detecting disease and monitoring health. Incorporation of nanomaterials plays a major role in sensing probe immobilization and detection sensitivity of paper-based devices. Nanomaterial properties, such as increased surface area, have aided with signal amplification and lower detection limits. This review focuses on application of nanomaterials as signal amplification elements on origami paper-based electro-analytical devices for immune biomarkers detection with a brief introduction about various fabrication techniques and designs, biological and detection methods. In this review, we comprehensively summarize the selected latest research articles from 2013 to May 2015 on application of nanomaterials in various types of origami paper based electrochemical and photoelectrochemical immunosensors. The review breaks into two parts. The first part devotes to the development and applications of nanomaterials in electrochemical immunesensing. The second part provides an overview of recent origami paper based photoelectrochemical immunosensors. [ABSTRACT FROM AUTHOR]

Bone disorders are of significant concern due to increase in the median age of our population. It is in this context that tissue engineering has been emerging as a valid approach to the current therapies for bone regeneration/substitution. Tissue-engineered bone constructs have the potential to alleviate the demand arising from the shortage of suitable autograft and allograft materials for augmenting bone healing. Silica based mesostructured nanomaterials possessing pore sizes in the range 2–50 nm and surface reactive functionalities have elicited immense interest due to their exciting prospects in bone tissue engineering. In this review we describe application of silica-based mesoporous nanomaterials for bone tissue engineering. We summarize the preparation methods, the effect of mesopore templates and composition on the mesopore-structure characteristics, and different forms of these materials, including particles, fibers, spheres, scaffolds and composites. Also, the effect of structural and textural properties of mesoporous materials on development of new biomaterials for production of bone implants and bone cements was discussed. Also, application of different mesoporous materials on construction of manufacture 3-dimensional scaffolds for bone tissue engineering was discussed. It begins by giving the reader a brief background on tissue engineering, followed by a comprehensive description of all the relevant components of silica-based mesoporous biomaterials on bone tissue engineering, going from materials to scaffolds and from cells to tissue engineering strategies that will lead to “engineered” bone. [ABSTRACT FROM AUTHOR]

Considering the vital role of cells in life science and human health, cytosensors have become a hot research topic. Electrochemical cytosensors attract much attention. In this review, we discuss some recent efforts to construct novel and improved electrochemical cytosensors based on graphene, carbon nanotubes, some metal-nanoparticle composites, quantum dots, nanofibers and nanowires. In addition, we summarize examples of nanostructure applications in electrochemical cytosensing reported in the literature from 2009 to date, with their advantages and limitations, and stress their potential for future development. Also, we focus on the current surface-modification strategies with some nanostructures, the influence of nanostructure properties on cytosensor performance and the applications of these materials in conjunction with different transducers to the detection of cells. [ABSTRACT FROM AUTHOR]

Growing demands for ultrasensitive biosensing have led to the development of numerous signal-amplification strategies. Based on their unique properties (i.e., electro-conductivity, bio-compatibility and ease of synthesis), various iron magnetic nanoparticles (MNPs) have proved to be an excellent nanomaterial for applications in electrochemical biosensing. This review shows how iron MNPs have made significant contributions in the development of electrochemical nanobiosensors, including immuno-, enzyme, DNA and aptamer types. More importantly, we discuss in detail different aspects of the electrochemical biosensors (e.g., modes of magnetic particles, detection techniques, analytes and the corresponding sensitivity and sample matrix, and several prominent characteristics). Accordingly, we discuss research opportunities and future development trends in these areas. [ABSTRACT FROM AUTHOR]

Biology and medicine have seen great advancements in the development of nanobiosensors capable of characterizing and quantifying biomolecules. This review reports a systematic study of the usefulness of hydrogel nanoparticles (HNPs) in the different steps of the electroanalytical process developed in electrochemical biosensing systems. We illustrate the advantages offered by HNPs in detection of analytes with representative recent examples that highlight the scientific interest in widening the use of HNPs in electrochemical biosensing methods. We review different types of HNP-based electrochemical biosensors, such as enzyme, protein, and nucleic acids, in terms of their sensing performance and their potential for future development. [ABSTRACT FROM AUTHOR]

A strategy of phenylalanine-dehydrogenase (PheDH) entrapment within the polytaurine matrix is demonstrated to probe the direct electrochemistry of phenylalanine (Pha). It was found that PheDH has been stably immobilized on glassy carbon electrode modified by polytaurine based on simple technique. Cyclic voltammetric study indicated that the oxidation process is irreversible and diffusion controlled. The number of exchanged electrons in the electro-oxidation process was obtained, and the data indicated that Pha is oxidized via one-electron steps. The results revealed that Pha promotes the rate of oxidation by increasing the peak current. The diffusion coefficient and electron-transfer coefficient of Pha were found to be 0.2 x 10-6 cm² s-1 and 0.467, respectively. A sensitive, simple and time-saving differential-pulse voltammetric procedure was developed for the analysis of Pha. The results show that by using the proposed method, Pha can be determined with a detection limit of 9 nM. [ABSTRACT FROM AUTHOR]

Highlights: [•] Applying dendrimer-encapsulated metal nanoparticles to electrochemical biosensing. [•] Recent advances in electrochemical biosensors are based on nanosized dendrimers. [•] Dendrimer-core metal nanoparticles provide platform for electrochemical biosensors. [ABSTRACT FROM AUTHOR]

Abstract: Fe3O4-graphene oxide (GO) modified glassy carbon (GC) electrode was used as a new magnetic nanosensor for determination of phenylalanine (Phe). It was found that Fe3O4-GO has been stably absorbed on GC electrode modified by simple technique. The cyclic voltammograms of the modified electrode in an aqueous solution displayed a pair of well-defined, stable and irreversible reductive/oxidation redox systems. The apparent electron transfer rate constant (ks ) and transfer coefficient (α) were determined by cyclic voltammetry and were approximately 9.3s−1 and 0.67, respectively. The modified electrode showed excellent catalytic activity towards the oxidation of Phe at an unusually positive potential in buffer solution. This nanosensor also displayed fast response time, high sensitivity, low detection limit and had a remarkably positive potential oxidation of Phe that decreased the effect of interferences in analysis. [Copyright &y& Elsevier]

Highlights: [•] We introduce novel optical immunosensors for cardiac biomarkers. [•] We discuss recent advances in optical immunosensing of cardiac biomarkers. [•] We discuss multiplex optical immunosensors for detection of cardiac biomarkers. [•] We discuss the most serious problems in optical immunosensing of cardiac biomarkers. [ABSTRACT FROM AUTHOR]

Highlights: [•] An effective electroanalytical method was developed for the simultaneous determination of DA and 5-HT. [•] The utilization of the proposed method in real sample analysis was investigated. [•] The prepared electrochemical nanosensor shows excellent electrocatalytic activity for DA and 5-HT oxidation. [•] The prepared electrochemical sensor can be used as an amperometric detector for routine analysis of DA and 5-HT. [ABSTRACT FROM AUTHOR]

Highlights: [•] Novel electrochemical immunosensors for cardiac biomarkers are introduced. [•] Recent advances in electrochemical immunosensing of cardiac biomarkers are discussed. [•] Multiplex electrochemical immunosensors are discussed for detection of cardiac biomarkers. [•] Serious problems in electrochemical immunosensing of cardiac biomarkers are discussed. [ABSTRACT FROM AUTHOR]

Abstract: Magnetic (Fe2O3) mobile crystalline material-41 (MCM-41) was prepared and characterized using transmission electron microscopy (TEM) and nitrogen adsorption–desorption techniques. Due to the large surface area (1213 m2 g−1) and remarkable electrocatalytic properties of MCM-41-Fe2O3, the MCM-41-Fe2O3 modified glassy carbon electrode (MCM-41-Fe2O3/GCE) exhibits potent electrocatalytic activity toward the electro-oxidation of amino acids. MCM-41-Fe2O3/GCE brings new capabilities for electrochemical sensing by combining the advantages of Fe2O3 magnetic nanoparticles and MCM-41 with very large surface area. Cyclic voltammetry, hydrodynamic amperometry and flow injection analysis used to determination of amino acids at higher concentration range. Fast response time, excellent catalytic activity, and ease of preparation are the advantages of the proposed amino acid sensor. [Copyright &y& Elsevier]

Abstract: Silica-based electrochemical immunosensors recently gained much importance for detecting antigens and biomarkers responsible for cancer diagnosis. This review describes fabrication and chemical modification of the surfaces of mesoporous silica materials for biomedical and immunosensing applications. We also present a comprehensive overview of current developments and key issues in the determination of some biological molecules with particular emphasis on evaluating the models. [Copyright &y& Elsevier]

Electro-catalytic oxidation of formaldehyde on copper electrode in 100 mM NaOH solution at different concentrations of formaldehyde was studied in the steady state polarization technique. The CV curve shows evidence for two processes occurring at the interface: one is associated with the formaldehyde electro-oxidation leading to formic acid formation on the surface and the other is assigned to the oxidation of formic acid that leads to CO2 evolutions with low yield. Reaction orders for the faradic current on copper electrode have been determined as 0.21 for the higher and 0.76 for the lower concentration of formaldehyde. Reaction orders for CO2 evolution during formaldehyde oxidation are 1.4 times higher in each case. Tafel slopes in the range of 140-160 mV are found. This signifies that the first reaction step involving the formation of adsorbed CO2 is largely determining the overall reaction rate. [ABSTRACT FROM AUTHOR]

Abstract: Room-temperature ionic liquids (RTILs) have proved to be excellent materials for applications in electrochemistry. We review progress in constructing high-performance electrochemical biosensors. We also discuss: [•] different modified electrodes based on RTILs for biosensing applications; [•] different routes for enzyme biosensing based on RTIL-modified electrodes; [•] incorporation of biorecognition elements into RTIL-based electrodes; [•] electroanalytical applications of RTIL-based modified electrodes; and, [•] recent developments in which the advantages of ILs as a medium for biosensing were realized. We also summarize the latest developments in the applications of RTIL-based electrochemical biosensors in ultrasensitive detection of biological entities, especially nucleic acids and proteins. We review different types of RTIL-based electrochemical biosensors (e.g., based on enzymes, proteins and nucleic acids) in terms of their sensing performance and potential for future development. [Copyright &y& Elsevier]

Abstract: Biology and medicine have seen great advancements in the development of enzyme nanobiosensors capable of characterizing and quantifying biomolecules. We provide an overview of mesoporous silica (MPS)-based enzyme nanobiosensors developed for biological and medical applications, and we describe significant advances in these technologies. We review progress in constructing high-performance electrochemical enzyme biosensors. We also discuss: [•] MCM-41 and SBA-15-modified and MPS composite electrodes for enzyme biosensing; [•] incorporation of biorecognition elements into MPS material electrodes for enzyme biosensing; and, [•] MCM-41 and SBA-15-supported electrocatalytic MPS-based electrochemical enzyme biosensors. [Copyright &y& Elsevier]

MCM-41-SO3H, an ordered mesoporous silica material in which MCM-41 with covalently anchored sulfonic acid groups was used as an acidic catalyst for the rapid and 'green' synthesis of pyrano[3,2-c]pyridine derivatives under solvent-free conditions. Reusability of the catalyst, high yields, short reaction times, simplicity and easy workup are advantages of this novel synthetic procedure compared to the conventional methods reported in the literature. [ABSTRACT FROM AUTHOR]

Abstract: A new chemically modified carbon paste electrodes based on Fe (III) schiff base (Fe (III)-SBMCP)-containing graphite pastes were prepared and evaluated as electrochemical sensor for the voltammetric determination of mefenamic acid and indomethacin in aqueous solutions. The measurements were carried out by application of the differential pulse voltammetry (DPV) method in phosphate buffer solution with pH 3.5. Fe (III) loaded in schiff base can increase anodic peak currents by adsorption of mefenamic acid and indomethacin on electrode surface. The prepared electrode shows voltammetric responses with high sensitivity for mefenamic acid and indomethacin in optimal conditions, which makes it very suitable for simultaneous determination of these compounds. The proposed method was successfully applied for determination mefenamic acid and indomethacin in commercial tablet samples. [Copyright &y& Elsevier]

Abstract: For the first time MCM-41 functionalized by 3-aminopropyl (MCM-41-NH2) was used for electrode modification and electrocatalytic oxidation of amino acids. The modified electrode was applied for amino acids detection using cyclic voltammetry, differential pulse voltammetry (DPV) and flow injection analysis (FIA). The modified electrode shows many advantages as an amino acids sensor such as simple preparation method without using any specific electron transfer mediator or specific reagent, high sensitivity, excellent catalytic activity, short response time, long term stability and remarkable antifouling property toward for amino acids and its oxidation product. [Copyright &y& Elsevier]

Abstract: Zinc hydroxide nanoparticles have been used for electrocatalytic oxidation and determination of 21 parabens in aqueous solution. Zinc hydroxide nanostructures were characterized by X-ray, SEM and AFM. The kinetic parameters of 21 parabens and their chlorinated derivatives were investigated by means of cyclic voltammetry and differential pulse voltammetry as well as steady state polarization. In addition, the results of the present study indicated that the differential pulse voltammetry test was more sensitive than the cyclic voltammetry test for the determination of the kinetic data of parabens. [Copyright &y& Elsevier]

Abstract: There have been great advancements in the development of biosensors capable of characterizing and quantifying biomolecules. This article gives an overview of the formation, the properties and the electrochemical applications of ordered mesoporous silica-based materials in electrocatalysis, electrosorption, matrix immobilization, construction of systems for controlled release of active compounds, sensors, biosensors and immunosensors. We also present a comprehensive overview of current developments and key issues in the determination of some biological molecules with particular emphasis on the evaluation of models. [Copyright &y& Elsevier]