Bacteria-templated ZIF-8 embedded in polyacrylonitrile nanofibers as a novel sorbent for thin film microextraction of benzoylurea insecticides.

In the present work, the rod-like ZIF-8 (ZIF8@E coli) was prepared by fast, easy and environmentally friendly method of biomimetic mineralization with Escherichia coli bacteria as a bio-template and was exploited for the first time in the microextraction. In this regard, electrospun nanofiber mats of polyacrylonitrile (PAN) and ZIF8@E coli were prepared by electrospinning method and used as a new sorbent for thin film microextraction (TFME) of benzoylurea insecticides such as Hexaflumuron and Teflubenzuron as model analytes. The PAN/ZIF8@E coli nanocomposite was characterized using electron scanning microscopy and various spectroscopy techniques.

Keggin-type polyoxometalate embedded polyvinylidene fluoride for thin film microextraction of organophosphorus pesticides.

The present research is the first report on the application of Keggin-type phosphotungstic acid/polyvinylidene fluoride membrane. This compound as a simple, cost-effective and novel sorbent was used for the extraction and pre-concentration of two organophosphorus pesticides in real samples in the thin film solid-phase microextraction (TFME) method. TFME as one of the sub-branches of solid phase microextraction resolves the problems of SPME methods, including their limited absorption capacity.

Nanoporous carbon fiber derived from Cu-BDC metal organic framework @pencil graphite as a sorbent for solid phase microextraction of acetamiprid and imidacloprid.

Solid-phase microextraction (SPME) is a sample pretreatment technique for enrichment of trace level of compounds from complex matrices. The fiber coating, as an extraction phase, is the significant part of SPME, which specifying the analytical performance of the developed SPME. In this study, a novel in situ fabricated Cu@porous carbon fiber that derived from copper benzene-1,4-dicarboxylate framework@pencil graphite (Cu-BDC MOF@PG) fiber was prepared as a SPME fiber.

Keggin type phosphotungstic acid intercalated copper-chromium-layered double hydroxide reinforced porous hollow fiber as a sorbent for hollow fiber solid phase microextraction of selected chlorophenols besides their quantification via high performance liquid chromatography.

Herein, a copper-chromium-layered double hydroxide (Cu/Cr-LDH) was synthesized by the co-precipitation method. The Cu/Cr-LDH was intercalated to the Keggin-type polyoxometalate (HPWO). The modified LDH accommodated in the pores of hollow fiber (HF), to prepare the extracting device for the HF-solid phase microextraction method (HF-SPME).

Electrochemical aptasensor based on carboxylated graphene oxide modified carbon paste electrode for strontium ultrasensitive detection.

Determination of strontium ions (Sr) is crucial with regard to human health and environmental protection. In this work, an electrochemical aptasensor was designed using carboxylated graphene oxide (CGO)-modified carbon paste electrode (CGO/CPE) for ultrasensitive determination of Sr ions. The electrochemical determination was accomplished with employing the constructed G-quadruplex (G4) aptamer at the surface of aptasensor in presence of carmoisine (CA) as an electrochemical label.

Combination of in-situ electro synthesized Zn-Al-LDH@ pencil graphite fiber and three phase hollow fiber LPME for microextraction of some antibiotics in urine samples and quantification via HPLC-UV.

In the present study, a combination of two useful extraction techniques including fiber solid phase microextraction based on the new synthesized sorbent and the porous hollow fiber liquid phase microextraction is reported. The selective anion-exchangeable Zn-Al-layered double hydroxide as a fiber was electrodeposited on the surface of pencil graphite substrate through simple and cost-effective method. The prepared fiber was characterized and put into the lumen of the porous hollow fiber, which was filled by alkaline solution.

In situ electrodeposition of Cu-BDC metal-organic framework on pencil graphite substrate for solid-phase microextraction of some pesticides.

The study focuses on the electrochemical deposition of copper benzene-1,4-dicarboxylate framework (Cu-BDC MOF) on the surface of a very cheap pencil graphite (PG) substrate for utilization as the sorbent in fiber solid-phase microextraction (SPME) of two chosen pesticides, including abamectin and amitraz for the first time. The extracted pesticides were quantified by high-performance liquid chromatography-ultraviolet detection (HPLC-UV). The UV detector was set at 236 nm wavelength.

Phytic acid determination in food products using the extract of rice sprout and SBA@DABCO nanoparticle-modified filter paper as a novel electrochemical biosensor.

We outline the fabrication of a highly sensitive biosensor for phytic acid (PA) determination using the extract of rice sprout and SBA@DABCO nanoparticles. The nanoparticles were first added to the surface of small paper disks. After drying, the extract of rice sprout in phosphate buffered saline was immobilized on the paper disks.

Designing a novel DNA-based electrochemical biosensor to determine of Ba ions both selectively and sensitively.

This work describes a novel electrochemical biosensor based on G-quadruplex (G4) DNA for the sensitive and selective detection of Ba ions using a Carbon Paste Electrode modified with Ag nanoparticles incorporated in reduced Graphene Oxide via a simple wet chemical method (Ag-rGO/CPE), in the presence of carmoisine (CA) as a new electrochemical indicator. The peak current of CA increased with increasing Ba ions concentration and the DNA-based sensor showed linear ranges of 0.06-0.

An impedimetric biosensor for DNA damage detection and study of the protective effect of deferoxamine against DNA damage.

The detection and inhibition of DNA damage are of great importance in the prevention and treatment of diseases. Developing a simple and sensitive tool for this purpose would be a chance to monitor the DNA damage and could be helpful in introducing some drugs which can prevent this phenomenon. Here, we report a novel and sensitive electrochemical biosensor based on DNA/Au nanoparticles (AuNPs) modified screen printed gold electrode (DNA/AuNPs/SPGE) to investigate the DNA damage process and also to study the protective behavior of deferoxamine (DFO).

Development of a new paper based nano-biosensor using the co-catalytic effect of tyrosinase from banana peel tissue (Musa Cavendish) and functionalized silica nanoparticles for voltammetric determination of l-tyrosine.

In this paper, a new and facile method for the electrochemical determination of l-tyrosine was designed. First, 3-mercaptopropyl trimethoxysilane-functionalized silica nanoparticles were added to a paper disc. Then, the banana peel tissue and the mediator potassium hexacyanoferrate were dropped onto the paper, respectively.

Design of an electrochemical DNA-based biosensor for selective determination of cadmium ions using a DNA hybridization indicator.

A simple electrochemical DNA- based biosensor was designed for determination of Cd using ethyl green (EG) as a DNA hybridization indicator on the surface of carbon paste electrode (CPE). The interaction of Cd with double strand DNA (dsDNA) led to the destabilizing of dsDNA and the increase in the reduction peak currents of EG. The difference in the values of electrochemical responses of EG before and after DNA helix destabilization in the presence of Cd (ΔI) was used for Cd determination and was linearly related to the concentration of Cd over the ranges of 1.

Construction of a highly sensitive signal-on aptasensor based on gold nanoparticles/functionalized silica nanoparticles for selective detection of tryptophan.

In this work, a highly sensitive, low-cost, and label-free aptasensor based on signal-on mechanisms of response was developed by immobilizing the aptamer on gold nanoparticles (AuNPs)/amine-functionalized silica nanoparticle (FSN)/screen-printed electrode (SPE) surface for highly selective electrochemical detection of tryptophan (Trp). The hemin (Hem), which interacted with the guanine bases of the aptamer, worked as a redox indicator to generate a readable electrochemical signal. The changes in the charge transfer resistance have been monitored using the voltammetry and electrochemical impedance spectroscopic (EIS) techniques.

Design of a novel electrochemical biosensor based on intramolecular G-quadruplex DNA for selective determination of lead(II) ions.

An electrochemical DNA biosensor based on a G-quadruplex (G4) for the sensitive determination of Pb was reported using a carbon paste electrode (CPE) or a multi-walled carbon nanotube paste electrode (MWCNTPE) as working electrodes, ethyl green (EG) as a new G4 intercalator, and a single-stranded nucleic acid sequence rich in guanine (G) as DNA probe. Electrochemical determination of Pb relied on probe structural changes from single - stranded to the stabilized intramolecular G4 in the presence of Pb, which caused a change in the current of the EG reduction peak due to the intercalation of EG into the G4 structure. The change in the reduction peak of EG before and after its intercalation into the stabilized G4 (∆I) had a linear correlation to the concentration of Pb ions.

A sensitive voltammetric detection of pramipexole based on 1,1,3,3-tetramethyldisilazanecarbon nanotube modified electrode.

A simple low-cost method is proposed to fabricate a functionalized multi-wall carbon nanotube (MWCNT) with 1,1,3,3-tetramethyldisilazane (TMDS) molecule. The techniques of scanning electron microscope (SEM) with electron diffraction and energy dispersive X-ray (EDAX) analysis were applied to characterize the functionalized TMDS-MWCNT. The results showed that a MWCNT with high functionalization of TMDS can be obtained using this simple method.

Ultrasensitive electrochemical aptasensor based on sandwich architecture for selective label-free detection of colorectal cancer (CT26) cells.

Colorectal cancer is one of the most common cancers in the world and has no effective treatment. Therefore, development of new methods for early diagnosis is instantly required. Biological recognition probes such as synthetic receptor and aptamer is one of the candidate recognition layers to detect important biomolecules.

A bimetallic nanocomposite modified genosensor for recognition and determination of thalassemia gene.

The main roles of DNA in the cells are to maintain and properly express genetic information. It is important to have analytical methods capable of fast and sensitive detection of DNA damage. DNA hybridization sensors are well suited for diagnostics and other purposes, including determination of bacteria and viruses.

SiO2 nanoparticles modified CPE as a biosensor for determination of i-motif DNA/Tamoxifen interaction.

Cytosine-rich DNA sequences can form a highly ordered structure known as i-motif in slightly acidic solutions. The stability of the folded i-motif structure is a good strategy to inhibit the telomerase reaction in cancer cells. The electrochemical biosensor was prepared by modifying carbon paste electrode with SiO2 nanoparticles to investigate drugs which can stabilize this structure.

A novel self-powered and sensitive label-free DNA biosensor in microbial fuel cell.

In this work, a novel self-powered, sensitive, low-cost, and label-free DNA biosensor is reported by applying a two-chambered microbial fuel cell (MFC) as a power supply. A graphite electrode and an Au nanoparticles modified graphite electrode (AuNP/graphite electrode) were used as anode and cathode in the MFC system, respectively. The active biocatalyst in the anodic chamber was a mixed culture of microorganisms.

Label-free and sensitive aptasensor based on dendritic gold nanostructures on functionalized SBA-15 for determination of chloramphenicol.

A highly sensitive and low-cost electrochemical aptasensor was developed for the determination of chloramphenicol (CAP). The system was based on a CAP-binding aptamer, a molecular recognition element, and 1,4-diazabicyclo[2.2.

A switchable Gquadruplex device with the potential of a nanomachine for anticancer drug detection.

The unique ability of living systems to translate biochemical reactions into mechanical work has inspired the design of synthetic DNA motors which generate nanoscale motion via controllable conformational change. It is believable that G-quadruplex structures in certain regions of the genome may play a role in the poor maintenance of genomic stability, which is a characteristic of many types of cancers. In this regards, formation and stabilization of the quadruplex structures at the telomeric repeats is an effective way to hamper the telomere extension and blocking the elongation step.

A Voltammetric Sensor Based on Modified Multi-Walled Carbon Nanotubes for N-Acetyl-L-Cysteine Determination in the Presence of Tryptophan Using 4-Chlorocatechol as a Homogenous Electrochemical Catalyst.

Simultaneous determination of N-acetyl-L-cysteine (NAC) and Tryptophan (Trp) has been studied at the surface of glassy carbon electrode (GCE) modified with multi-walled carbon nanotubes (MWCNTs) in the presence of 4-chlorocatechol as homogenous electrochemical catalyst in aqueous media. The electrocatalytic properties of GCE modified with MWCNTs in the presence of 4-chlorocatechol toward the electrocatalytic oxidation of NAC and Trp was studied using cyclic voltammetry (CV), double-step potential chronoamperometry and differential pulse voltammetry (DPV). The results has shown that NAC participates in Michael type addition reaction with electrogenerated quinone from electrooxidation of 4-chlorocatechol at MWCNT/GCE to form the corresponding thioquinone derivative.

A Novel Electrochemical Genosensor Based on Banana and Nano-Gold Modified Electrode Using Tyrosinase Enzyme as Indicator.

The electrochemical behavior of the tyrosinase enzyme at the surface of two electrodes, carbon paste electrode (CPE) and nano-gold modified carbon paste electrode (NGCPE), has been studied by cyclic voltammetry. Tyrosinase showed one oxidation peak (around +0.85 V) and one reduction peak at + 0.

Voltammetric characterization of human telomeric G-quadruplex: A label free method for anticancer drug detection.

Human telomeric DNA typically consists of many tandem repeats of the guanine-rich sequences d (TTAGGG) termed an intermolecular Gquadruplex structure. This structure plays an important role in the protection, stabilization and replication of chromosome ends and so is an active target for therapeutic purposes. Recently ligands that are able to stabilize Gquadruplex structure, have received great attention because quadruplex-binding ligands have potential applications in cancer therapy.

Novel electrochemical DNA hybridization biosensors for selective determination of silver ions.

In this work, novel electrochemical biosensors for Ag(+) determination based on Ag(+)-induced DNA hybridization, using Ethyl green (EG) as an electroactive label on the surface of bare carbon paste electrode (CPE) and gold nanoparticles-modified carbon paste electrode (GN-CPE) are reported. Two single-strand poly-C (100% cytosine bases) DNAs are used as oligonucleotide probe and target. In the presence of Ag(+), the target DNA with full cytosine-cytosine (C-C) mismatches could hybridize with the probe DNA by forming C-Ag(+)-C complex.