A nanoscale electrochemical guanine DNA-biosensor based on a flower-like nanocomposite of Tb-doped ZnO for the sensitive determination of pemetrexed.

Pemetrexed is an antineoplastic drug used in chemotherapeutic treatments, especially in malignant mesothelioma and non-small cell lung carcinoma, but can also cause a variety of complications, like stomach pain, nausea, burning, vomiting, numbness, and tingling, emphasizing the need for an approach to quantify the drug in biological matrices. Herein, a DNA-based biosensor was introduced for pemetrexed determination. A hydrothermal approach was used for synthesizing flower-like nanoparticles (NPs) of zinc oxide (ZnO) doped with Tb (FL-NP Tb3+/ZnO). Moreover, energy dispersive X-ray (EDX), field-emission scanning electron microscopy (FESEM), zeta potential, Brunauer-Emmett-Teller (BET), and X-ray diffraction (XRD) analyses were used for characterizing the as-prepared nanocomposite. According to the impedance analysis, FL-NP Tb3+/ZnO was accompanied by very good electrochemical functions for a simple transfer of electrons. In the case of the immobilization of double-stranded deoxyribonucleic acid (ds-DNA) on the FL-NP Tb3+/ZnO and polypyrrole (PP)-modified pencil graphite electrode (ds-DNA/PP/FL-NP Tb3+/ZnO/PGE), a considerable enhancement was found in the electrochemical oxidation of guanine in ds-DNA residue bases. Since there was an interaction between ds-DNA and pemetrexed, the voltammetric current of guanine over the ds-DNA/PP/FL-NP Tb3+/ZnO/PGE declined in the presence of pemetrexed in the electrolytic solution. Moreover, under optimum conditions (25 mg L-1 of ds-DNA and 10 min incubation time, in acetate buffer at 25 °C), a linear decrease in the guanine signal was observed on the ds-DNA/PP/FL-NP Tb3+/ZnO/PGE as the pemetrexed concentration increased in the range from 0.001 µM to 175.0 µM with a limit of detection of 0.17 nM. Finally, the new DNA-based biosensor was successfully used for determining pemetrexed in real samples, indicating its application potential.

Electrochemical detection of kynurenic acid in the presence of tryptophan with the carbon paste electrode modified with the flower-like nanostructures of zinc oxide doped with terbium.

With the help of a hydrothermal approach in this study, we could provide flower-like nanostructures (NSs) of zinc oxide (ZnO) doped with Tb (FL-NS Tb3+/ZnO). Then, FL-NS Tb3+/ZnO morphology was investigated by energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and map analysis. The results revealed higher activity centers and porosity of this nanocomposite, which were followed by acceptable electrochemical function. Hence, it can be utilized for fabricating an electrochemical sensor with an appropriate response for the simultaneous determination of kynurenic acid (KYN) and tryptophan (TRP). However, as compared with the modified carbon paste electrode (FL-NS Tb3+/ZnO/CPE), the bare carbon paste electrode (BCPE) exhibited a weak response toward KYN and TRP but the modified electrode was followed by a high current response for KYN and TRP at a potential 0.35 and 0.809 V. Therefore, cyclic voltammetry (CV) was applied in optimal experimental conditions to study the electrochemical behaviors of KYN and TRP over the surface of the proposed modified electrode. Moreover, we used differential pulse voltammetry (DPV) for quantitative measurements. It was found that this new modified electrode linearly ranged from 0.001 to 700.0 µM, with detection limits of 0.34 nM and 0.22 nM for KYN and TRP, respectively. In addition, KYN and TRP in real samples can be analyzed by this sensor, with a recovery of 97.75%-103.6% for the spiked KYN and TRP in real samples.

A novel and ultrasensitive electrochemical DNA biosensor for pralatrexate detection.

An attempt was made to develop a new sensitive biosensor for pralatrexate, as an anticancer drug, based on its interaction with the guanine of fish sperm DNA anchored on a screen-printed electrode (SPE) modified with polypyrrole (PP)/octahedral Pd-doped Co3O4 composite (Oh-Pd-doped Co3O4 C). Electrochemical techniques like differential pulse voltammetry verified the mechanism of such an interaction on the dsDNA/PP/Oh-Pd-doped Co3O4 C/SPE surface. A reduction in the peak current of guanine oxidation elucidated the interaction in acetate buffer with pH = 4.8. The optimization of response was performed for the interaction method according to potential, accumulation time, reproducibility and drug content. The linear dynamic range was estimated at 1.0 nM to 150.0 µM as well as a limit of detection as low as 0.61 nM for the DNA and pralatrexate concentrations. The practical potential of the proposed sensor was verified by determining pralatrexate in its pharmaceutical matrices.

Synthesis of a dual-functional terbium doped copper oxide nanoflowers for high-efficiently electrochemical sensing of ofloxacin, pefloxacin and gatifloxacin.

The current effort introduces a facile construction of peony-like CuO:Tb3+ nanostructure (P-L CuO:Tb3+ NS), whose characterization was determined via techniques of X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. We investigated ofloxacin, pefloxacin and gatifloxacin oxidation electrochemically on P-L CuO:Tb3+ NS-modified glassy carbon electrode (P-L CuO:Tb3+ NS/GCE), the results of which revealed the irreversible oxidation of drugs through a two-electron oxidation process. An admirable resolution was found for this modified electrode between voltammetric peaks of ofloxacin, pefloxacin and gatifloxacin, suggesting its appropriateness for simultaneous detection of these drugs in pharmaceutical media. In addition, our nanostructure synergistically influenced the electro-catalytic oxidations of these three compounds. Differential pulse voltammetric measurements of ofloxacin, pefloxacin and gatifloxacin through our sensor showed a limit of detection of 1.9, 2.3 and 1.2 nM a as well as a linear dynamic range between 0.01 and 800.0 µM in phosphate buffered solution (0.1 M, pH = 6.0), respectively. Moreover, as-fabricated sensor could successfully co-detect these drugs in real serum and tablets specimens. In addition, since we use animal foods such as milk it is very important to detect their fluoroquinolone residues. For this purpose, the proposed sensor was tested to determine the residues of ofloxacin, pefloxacin and gatifloxacin in milk.

Lanthanum-based metal organic framework (La-MOF) use of 3,4-dihydroxycinnamic acid as drug delivery system linkers in human breast cancer therapy.

Metal organic frameworks (MOFs) have received a lot of attention in the research community due to their unique physical properties, which make them ideal materials for targeted drug delivery systems. In this paper, we describe the synthesis of a non-toxic La-based MOF with 3,4-dihydroxycinnamic acid (3,4-DHCA) as a linker. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), nitrogen adsorption-desorption measurements, and X-ray powder diffraction (XRD) have all been used to characterize it thoroughly. The La-based MOF showed good biocompatibility with the human breast cancer cell line MDA-MB-468. The ability of 3,4-DHCA to treat MDA-MB-468 cells was confirmed by 40.35% cell viability with La-based MOF. Based on the findings, La-based MOF can be recommended as a promising candidate for anticancer delivery.

Simultaneous Electrochemical Determination of Chlorzoxazone and Diclofenac on an Efficient Modified Glassy Carbon Electrode by Lanthanum Oxide@ Copper(I) Sulfide Composite.

This study synthesized a La2O3@snowflake-like Cu2S composite to fabricate an electrochemical sensor for sensitively simultaneous detection of diclofenac and chlorzoxazone exploiting an easy hydrothermal approach, followed by analysis with XRD, FE-SEM, and EDX methods. According to voltammetric studies, the electrocatalytic diclofenac and chlorzoxazone oxidations on the electrode modified with La2O3@SF-L Cu2S composites were increased, with greater oxidation currents, as well as the oxidation potential was significantly decreased due to synergetic impact of La2O3@SF-L Cu2S composites when compared with the pure SF-L Cu2S NS-modified electrode. The differential pulse voltammetry findings showed wide straight lines (0.01-900.0 µM) for La2O3 NP@SF-L Cu2S NS-modified electrode with a limit of detection (LOD) of 1.7 and 2.3 nM for the detection of diclofenac and chlorzoxazone, respectively. In addition, the limit of quantification was calculated to be 5.7 and 7.6 nM for diclofenac and chlorzoxazone, respectively. The diffusion coefficient was calculated to be 1.16 × 10-5and 8.4 × 10-6 cm2/s for diclofenac and chlorzoxazone oxidation on the modified electrode, respectively. Our proposed electrode was examined for applicability by detecting diclofenac and chlorzoxazone in real specimens.

A DNA Biosensor Based on a Raspberry-like Hierarchical Nano-structure for the Determination of the Anticancer Drug Nilotinib.

It is crucial to design fast, sensitive and affordable deoxyribonucleic acid (DNA) recognition instruments, and elucidate changes in DNA structure, for studying the interaction between DNA and chemotherapy drugs. Therefore, a DNA biosensor, based on a carbon paste electrode (CPE), modified with raspberry-like indium(III)/nickel oxide hierarchical nano-structures (In3+ /NiO RLHNSs) was constructed. An electrochemical readout should then give information on the interactions between anticancer drugs and double-stranded (ds)-DNA. The morphology as well as the electrochemical description of this new biosensor is described. Based on experimentally determined optimal conditions, ds-DNA modified with In3+ /NiO RLHNSs/CPE was used to evaluate the binding interaction of nilotinib, as an anti-cancer drug, with DNA through differential pulse voltammetry (DPV), UV-Vis spectroscopy, viscosity measurements and a computational docking process. The analyses indicated the linearity of the guanine oxidation signal at nilotinib concentration is given between 0.01 and 50.0 µm, with the limit of detection (LOD) equal to 0.62 nm. Additionally, the equilibrium constant (K) for the binding was determined to 1.5×104  m-1 . Through the quantitative measurement of nilotinib in serum samples with a high recovery rate of 101.3-98.0 %, the applicability of this approach was demonstrated. As a whole, this DNA biosensor may be promising for various bio-interactions.

Development of the DNA-based voltammetric biosensor for detection of vincristine as anticancer drug.

In the article presented herein, a deoxyribonucleic acid (DNA) biosensor is introduced for Vincristine determination in pharmaceutical preparations based on the modification of screen printed electrode (SPE) with double-stranded DNA (ds-DNA), polypyrrole (PP), peony-like CuO:Tb3+ nanostructure (P-L CuO:Tb3+ NS). The developed sensor indicated a wide linear response to Vincristine concentration ranged from 1.0 nM to 400.0 µM with a limit of detection as low as .21 nM. The intercalation of Vincristine with DNA guanine led to the response. The optimized parameters for the biosensor performance were ds-DNA/Vincristine interaction time, DNA concentration and type of buffer solution. The docking investigation confirm the minor groove interaction between guanine base at surface of or ds-DNA/PP/P-L CuO:Tb3+ NS/SPE and Vincristine. The proposed sensor could successfully determine Vincristine in Vincristine injections and biological fluids, with acceptable obtains.

In vitro anticancer and antibacterial activates of the yttrium(III) complex and its nano-carriers toward DNA cleavage and biological interactions with DNA and BSA; An experimental and computational studie.

OBJECTIVES: In this research, the biological properties of the yttrium (III) (Y) complex, with 2,9-dimethyl- 1,10-phenanthroline (Me2Phen) ligand, were examined for in vitro fish DNA (FS-DNA)/ bovine serum albumin (BSA) interactions, DNA-cleavage, anticancer and antibacterial activities. METHODS: Multi-spectrophotometric techniques and computational calculations were used for the interaction studies of the BSA and FS-DNA with the Y-complex. Absorption and fluorescence spectroscopy methods were used to define thermodynamic parameters, the binding constants (Kb), and the probable binding mechanism. Also, the DFT (density functional theory) study and molecular docking calculation of the Y-complex were done. Besides, the nanocarriers of Y-complex (lipid nanoencapsulation (LNEP) and the starch nanoencapsulation (SNEP)), as active anticancer candidates, were prepared. Finally, DNA-cleavage, anticancer, and antibacterial activities of this complex were investigated. RESULTS: The absorption and fluorescence measurements were exhibited that the Y-complex has a high binding affinity to FS-DNA and BSA through a static mechanism. The negative thermodynamic parameter values for both DNA/BSA binding were confirmed that the hydrogen bonds and van der Waals forces played an essential role in the spontaneous bonding procedure. The site marker competitive studies for BSA confirmed that the Y-complex bonds to the sub-domain IB of protein (site III) on BSA, which was entirely agreement by docking calculation. The complex has displayed efficient DNA cleavage, antifungal and antibacterial activities. The anticancer activity of the Y-complex and its starch/lipid nano-encapsulated was carried out in cancer cell lines, which exposed considerably high activity. CONCLUSIONS: Thus, Y-complex can be transported professionally through BSA in the blood and bonds in the groove of DNA. Base on biological applications of the Y-complex, it can be concluded that this complex and its nanocarriers can suggest as novel anticancer and antibacterial candidates.

An electrochemical sensor based on hierarchical nickel oxide nanostructures doped with indium ions for voltammetric simultaneous determination of sunset yellow and tartrazine colorants in soft drink powders.

The current study was designed to develop a single-step and simple approach to effectively fabricate three-dimensional raspberry-like In3+/NiO hierarchical nanostructures (In3+/NiO RLHNSs) as a modifier, which was subsequently characterized by the techniques of X-ray diffraction (XRD), energy dispersive spectrometry (EDS) and field emission scanning electron microscopy (FE-SEM). The new prepared nano-modifier was practically used to co-detect electrochemically sunset yellow and tartrazine dyes. Potent sensitivity and acceptable selectivity were obtained for the produced In3+/NiO RLHNSs to co-detect both the food colorants, thus providing oxidation peaks in differential pulse voltammetry (DPV) with a peak potential separation of ca. 190 mV. The results showed a 5.14-fold and 8.07-fold increase in the electrochemical response of our modified electrode to sunset yellow and tartrazine, respectively, compared to the control (the unmodified electrode). Limits of detection of 2.7 and 3.1 nM were calculated for sunset yellow and tartrazine, respectively. The results from the interaction of common food additives showed satisfactory outcomes for the application of this method in determining sunset yellow and tartrazine in several beverage specimens. Other useful documentation was obtained for the production of portable food additive sensors.

A label-free electrochemical biosensor based on 3D cubic Eu3+/Cu2O nanostructures with clover-like faces for the determination of anticancer drug cytarabine.

The present research utilized a simplified procedure for developing a novel electro-chemical DNA biosensor based on a carbon paste electrode (CPE) modified with three-dimensional (3D) cubic Eu3+/Cu2O nanostructures with clover-like faces (Eu3+/Cu2O CLFNs). The modified electrode was applied to monitor electro-chemical interactions between dsDNA and cytarabine for the first time. Then, the decreased oxidation signal of guanine following the interactions between cytarabine and dsDNA was utilized as an indicator for selectively determining cytarabine using differential pulse voltammetry (DPV). According to the findings, the oxidation peak current of guanine was linearly proportionate with the cytarabine concentration in the range between 0.01 and 90 µM. Additionally, the limit of quantification (LOQ) and the limit of detection (LOD) respectively equaled 9.4 nM and 2.8 nM. In addition, the repeatability, applicability and reproducibility of this analysis to drug dosage forms and human serum samples were investigated. Furthermore, UV-vis spectroscopy, DPV, docking and viscosity measurements were applied to elucidate the interaction mechanism of dsDNA with cytarabine. It was found that this DNA biosensor may be utilized to sensitively, accurately and rapidly determine cytarabine.

Experimental and computational interaction studies of terbium (III) and lanthanide (III) complexes containing 2,2'-bipyridine with bovine serum albumin and their in vitro anticancer and antimicrobial activities.

To investigate the chemotherapeutic and pharmacokinetic aspects of two lanthanide complexes (Tb(III) and La(III) containing 2,2'-bipyridine ligand), in vitro binding studies were carried out with BSA by employing multiple biophysical methods and molecular modeling study. There are different techniques containing fluorescence, absorption spectroscopy and competitive experiments to determine the interaction mode between BSA and these complexes. These complexes efficiently quenched the BSA emission through a static procedure. The results showed that the terbium and lanthanum complexes exhibited a high propensity for BSA interaction via van der Waals force. Further, competitive examination and docking study showed that the interaction site of these complexes on BSA is site III. The results of docking calculations were in good agreement with experimental examinations. Also, the energy transfer from BSA to these complexes has happened with high possibility. Moreover, antimicrobial studies of different bacterial and fungi indicated its promising antibacterial activity. In vitro cytotoxicity of the Tb complex and La complex was carried out in MCF-7 and A-549 cell lines, which revealed significantly good activity.Communicated by Ramaswamy H. Sarma.

Simultaneous determination of theobromine, theophylline, and caffeine using a modified electrode with petal-like MnO2 nanostructure.

This study substantially synthesized the ß-type MnO2 nano-flowers assembled by the hierarchical nano-sheets using a simplified hydro-thermal procedure. According to the FESEM images, MnO2 nano-flower exhibited diameter of ∼800 nm and fabricated with a lot of irregular sheets as a petal-like structure with thickness of several nano-meters. Therefore, the study focused on the construction of an electro-chemical sensor to simultaneously determine theobromine (ThB), theophylline (ThP), as well as caffeine (CaF) on the basis of the ß-type hierarchical structure of the MnO2 nano-flowers (ßH-MnO2-NF) modified electrode (ßH-MnO2-NF/GCE). Analysis showed an acceptable linear association between the oxidation peak current and ThB, ThP and CaF concentration within the ranges between 0.01 and 320.0 µM with a limit of detection (LOD) equal to 8.7, 5.9, and 10.1 nM (S/N = 3), respectively. Additionally, this study intended to investigate ThB, Thp and CaF bio-availability in the five commercially available brands of the chocolate products and drug.

Synthesis of La2O3/MWCNT nanocomposite as the sensing element for electrochemical determination of theophylline.

In this study, an electrochemical sensor was applied for the determination of theophylline, a bronchodilator drug, using differential pulse voltammetry (DPV). A glassy carbon electrode (GCE) surface was modified with the La2O3/MWCNT nanocomposite. The design is simplistic, efficient, greener and solvent-free microwave procedure for synthesizing La2O3/MWCNT nanocomposites. Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) techniques are used to characterize the features of the La2O3/MWCNT nanocomposite morphology and structure. The use of the modified sensor remarkably enhanced the current density and displayed a linear response ranging between 0.1 and 400.0 µM, with a limit of detection of 0.01 µM (S/N = 3). Using optimized conditions, the modified sensor demonstrated very good stability, selectivity and improved accuracy. Acceptable outputs were achieved in the analysis of real specimens, indicating that it is possible to use the modified sensor for practical analyses.

Evaluation of parent and nano-encapsulated terbium(III) complex toward its photoluminescence properties, FS-DNA, BSA binding affinity, and biological applications.

BACKGROUND: There is a crucial need for finding and developing new compounds as the anticancer and antimicrobial agents with better activity, specific target, and less toxic side effects. OBJECTIVES: Base on the potential anticancer properties of lanthanide complexes, in the paper, the biological applications of terbium (Tb) complex, containing 2,9-dimethyl- 1,10-phenanthroline (Me2Phen) such as anticancer, antimicrobial, DNA cleavage ability, the interaction with FS-DNA (Fish-Salmon DNA) and BSA (Bovine Serum Albumin) was examined. METHODS: The interaction of Tb-complex with BSA and DNA was studied by emission spectroscopy, absorption titration, viscosity measurement, CD spectroscopy, competitive experiments, and docking calculation. Also, the ability of this complex to cleave DNA was reported by gel electrophoresis. Tb-complex was concurrently screened for its antibacterial activities by different methods. Besides, the nanocarriers of Tb-complex (lipid nanoencapsulation (LNEP) and the starch nanoencapsulation (SNEP)), as active anticancer candidates, were prepared. MTT technique was applied to measure the antitumor properties of these compounds on human cancer cell lines. RESULTS: The experimental and docking results suggest significant binding between DNA as well as BSA with terbium-complex. Besides, groove binding plays the main role in the binding of this compound with DNA and BSA. The competitive experiment with hemin demonstrated that the terbium complex was bound at site III of BSA, which was confirmed by the docking study. Also, Tb-complex was concurrently screened for its DNA cleavage, antimicrobial, and anticancer activities. The anticancer properties of LNEP and SNEP are more than the terbium compound. CONCLUSIONS: Tb-complex can bond to DNA/BSA with high binding affinity. Base on biological applications of Tb-complex, it can be concluded that this complex and its nanocarriers can suggest as novel anticancer, antimicrobial candidates.

A review: Recent advances in ultrasensitive and highly specific recognition aptasensors with various detection strategies.

One of the most studied topics in analytical chemistry and physics is to develop bio-sensors. Aptamers are small single-stranded RNA or DNA oligonucleotides (5-25 kDa), which have advantages in comparison to their antibodies such as physicochemical stability and high binding specificity. They are able to integrate with proteins or small molecules, including intact viral particles, plant lectins, gene-regulation factor, growth factors, antibodies and enzymes. The aptamers have reportedly shown some unique characteristics, including long shelf-life, simple modification to provide covalent bonds to material surfaces, minor batch variation, cost-effectiveness and slight denaturation susceptibility. These features led important efforts toward the development of aptamer-based sensors, known as apta-sensors classified into optical, electrical and mass-sensitive based on the signal transduction mode. This review provided a number of current advancements in selecting, development criteria, and aptamers application with the focus on the effect of apta-sensors, specifically for disease-associated analyses. The review concentrated on the current reports of apta-sensors that are used for evaluating different food and environmental pollutants.

Synthesis of bifunctional cabbage flower-like Ho3+/NiO nanostructures as a modifier for simultaneous determination of methotrexate and carbamazepine.

Cabbage flower-like Ho3+/NiO nanostructure (CFL-Ho3+/NiO NSs) with significant electrocatalytic oxidation has been published for the first time. First, structure and morphology of CFL-Ho3+/NiO-NSs have been described by XRD, SEM, and EDX methods. Then, CFL-Ho3+/NiO-NSs have been applied as a modifier for simultaneous electrochemical detection of methotrexate (MTX) and carbamazepine (CBZ). Functions of the modified electrode have been dealt with through electrochemical impedance spectroscopy (EIS). It has been demonstrated that the electrode response has been linear from 0.001-310.0 µM with a limit of detection of 5.2 nM and 4.5 nM (3 s/m) through DPV for MTX and CBZ. Diffusion coefficient (D) and heterogeneous rate constant (kh) have been detected for MTX and CBZ oxidation at the surface of the modified electrode. Moreover, CFL-Ho3+/NiO-NS/GCE has been employed for determining MTX and CBZ in urine and drug specimens. Outputs showed the analyte acceptable recovery. Therefore, the electrode could be applied to analyze both analytes in drug prescription and clinical laboratories. Graphical abstract Electrochemical sensor based on bifunctional cabbage flower-like Ho3+/NiO nanostructures modified glassy carbon electrode for simultaneous detecting methotrexate and carbamazepine was fabricated.

Evaluation of DNA, BSA binding, DNA cleavage and antimicrobial activity of ytterbium(III) complex containing 2,2'-bipyridine ligand.

In order to estimate the biological potential of a synthesized complex [Yb(bpy)2Cl3.OH2] where bpy is 2,2'-bipyridine, its binding behavior with fish salmon-DNA (FS-DNA) and bovine serum albumin (BSA) were studied by different kinds of spectroscopy and molecular modeling methods. This complex was selected for its antibacterial and antifungal activities as well as the DNA cleavage activities were examined by agarose gel electrophoresis. The analyses of fluorescence data at four temperatures were done in order to evaluate the binding and thermodynamic parameters of the interaction of Yb(III) complex with DNA and BSA. The experimental results indicated that the major binding modes were based on groove binding with DNA and BSA. In addition, iodide quenching studies, ethidium bromide (EtBr) exclusion assay, ionic strength effect, circular dichroism, and viscosity studies reflected the binding of Yb(III) complex explicitly with the FS-DNA mainly in a groove binding mode. Moreover, molecular docking studies indicated that this complex was bound to the minor groove of DNA and to polar and apolar residues located in the subdomain IB of BSA (site 3). Also, the results of competitive experiments assessed site 3 of BSA as the most probable binding site for this complex. The molecular docking results were in good agreement with our experimental results. From both experimental and docking results, the binding constant values displayed the remarkably high affinity of Yb(III) complex to DNA as well as BSA.Communicated by Ramaswamy H. Sarma.

Green and facile microwave solvent-free synthesis of CeO2 nanoparticle-decorated CNTs as a quadruplet electrochemical platform for ultrasensitive and simultaneous detection of ascorbic acid, dopamine, uric acid and acetaminophen.

This study designed a simplistic, efficient, and greener procedure to synthesize CeO2-CNTs. The analysis of structural and morphological characteristics of nano-composites has been done with regard to different procedures (e.g., EDX, XRD, & FESEM). In addition, simultaneous detection of ascorbic acid (AA), dopamine (DA), uric acid (UA) and acetaminophen (AC) has been examined at the modified glassy carbon electrode with CeO2-CNTs nano-composites. The surface area and electron transfer speed of the interplay between neuro-transmitters and electrode may be efficiently enhanced due to the existence of CeO2 nano-particles on CNTs surfaces. Moreover, electro-chemical behavior of electrodes has been dealt with by differential pulse voltammetry (DPV), impedance analysis (EIS), and cyclic voltammetry (CV). Acceptable linear response of AA, DA, UA and AC respectively have been ranged 0.01-900.0 µM, 0.01-700.0 µM, 0.01-900.0 µM, and 0.01-900.0 µM with determination limits (S/N = 3) of 3.1 nM, 2.6 nM, 2.4 nM and 4.4 nM. Ultimately, this procedure was used with successful results for determining AA, DA, UA and AC in real specimens, which suggested probable uses in other sensing studies.

Experimental and theoretical investigations of Dy(III) complex with 2,2'-bipyridine ligand: DNA and BSA interactions and antimicrobial activity study.

In this study, the interactions of a novel metal complex [Dy(bpy)2Cl3.OH2] (bpy is 2,2'-bipyridine) with fish salmon DNA (FS-DNA) and bovine serum albumin (BSA) were investigated by experimental and theoretical methods. All results suggested significant binding between the Dy(III) complex with FS-DNA and BSA. The binding constants (Kb), Stern-Volmer quenching constants (KSV) of Dy(III)-complex with FS-DNA and BSA at various temperatures as well as thermodynamic parameters using Van't Hoff equation were obtained. The experimental results from absorption, ionic strength, iodide ion quenching, ethidium bromide (EtBr) quenching studies and positive ΔH˚ and ΔS˚ suggested that hydrophobic groove-binding mode played a predominant role in the binding of Dy(III)-complex with FS-DNA. Indeed, the molecular docking results for DNA-binding were in agreement with experimental data. Besides, the results found from experimental and molecular modeling indicated that the Dy(III)-complex bound to BSA via Van der Waals interactions. Moreover, the results of competitive tests by phenylbutazone, ibuprofen, and hemin (as a site-I, site-II and site-III markers, respectively) considered that the site-III of BSA is the most possible binding site for Dy(III)-complex. In addition, Dy(III) complex was concurrently screened for its antimicrobial activities. The presented data provide a promising platform for the development of novel metal complexes that target nucleic acids and proteins with antimicrobial activity.Communicated by Ramaswamy H. Sarma.