Intercalation Of Methylene Blue Research Articles

Investigation of Adsorptive Removal of Methylene Blue from Synthetic Wastewater Using Polymeric Composite

Recycling polymeric waste into another useful material is considered to be the preferred way of taking care of the issues of slow degradable plastic waste, particularly in anticipation of natural contamination. In this study, the adsorptive treatment of Methylene Blue (MB) using adsorbents from chemically recycled polymeric waste was investigated. Three polymeric materials were employed in this study: styrofoam waste (EPS1), intruded extended polystyrene (EPS2), and sunflower xylem (Tithonia diversifolia xylem) (TDX). The alterations in microscopic surface morphology before and after the adsorption process were examined using scanning electron microscopy (SEM) system to resolve the intercalation of MB with the adsorbent. The experimental batch data was collected and the effects of concentration and contact time on the removal of MB from synthetic wastewater were studied. Adsorption kinetics, equilibrium, and thermodynamics were studied and fitted by various models. According to the result, the uptake of adsorbate increased as contact time and concentration rose, with the pseudo-second-order model best depicting the adsorption kinetics.

Methylene blue intercalated vanadium oxide with synergistic energy storage mechanism for highly efficient aqueous zinc ion batteries

With the rise of aqueous multivalent rechargeable batteries, inorganic-organic hybrid cathodes have attracted more and more attention due to the complement of each other's advantages. Herein, a strategy of designing hybrid cathode is adopted for high efficient aqueous zinc-ion batteries (AZIBs). Methylene blue (MB) intercalated vanadium oxide (HVO-MB) was synthesized through sol–gel and ion exchange method. Compared with other organic–inorganic intercalation cathode, not only can the MB intercalation enlarge the HVO interlayer spacing to improve ion mobility, but also provide coordination reactions with the Zn2+ to enhance the intrinsic electrochemical reaction kinetics of the hybrid electrode. As a key component for the cathode of AZIBs, HVO-MB contributes a specific capacity of 418 mA h g−1 at 0.1 A g−1, high rate capability (243 mA h g−1 at 5 A g−1) and extraordinary stability (88% of capacity retention after 2 000 cycles at a high current density of 5 A g−1) in 3 M Zn(CF3SO3)2 aqueous electrolyte. The electrochemical kinetics reveals HVO-MB characterized with large pseudocapacitance charge storage behavior due to the fast ion migration provided by the coordination reaction and expanded interlayer distance. Furthermore, a mixed energy storage mechanism involving Zn2+ insertion and coordination reaction is confirmed by various ex-situ characterization. Thus, this work opens up a new path for constructing the high performance cathode of AZIBs through organic-inorganic hybridization.

Methylene blue intercalated aptamer to amplify signals toward sensitively electrochemical detection of dopamine released from living Parkinson's disease model cells

Dopamine plays a critical role in some fatal diseases including Parkinson's disease, schizophrenia, Tourette syndrome and HIV infection studies but its detection sensitivity demands further improvement. Aptamer-based biosensor has good selectivity to detect biologically active substances; however, it is very challenging to achieve high sensitivities for practical applications. Here an electrochemical biosensor is constructed by hollow carbon spheres, aptamer and methylene blue (MB) to monitor dopamine released from Parkinson's disease model (SH-SY5Y) cells with a low detection limit, wide detection range, high sensitivity and good selectivity for much better performance than reported aptamer sensors. Investigation discovers that MB intercalation in aptamers can offer two sites to absorb two dopamine through π-π interaction instead of one DA absorption on an aptamer alone, thereby doubling the detection sensitivity. The sensor was further used to monitor dopamine released from SH-SY5Y cells, clearly confirming the effect of 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine on dopamine synthesis in SH-SY5Y cells and demonstrating the great potential of the sensor in real-time detect dopamine released from living cells. This work renders a new avenue to amplify the detection sensitivity by intercalating redox small molecule to increase the aptamer reaction sites while bridging the interfacial electron transfer.

Ultrasensitive electrochemical aptasensing of kanamycin antibiotic by enzymatic signal amplification with a horseradish peroxidase-functionalized gold nanoprobe

Based on the signal transduction with a horseradish peroxidase (HRP)-functionalized gold nanoprobe, this work develops a new electrochemical aptasensing method for kanamycin (Kana) detection. The aptasensor was constructed through the hybridization of biotinylated Kana-aptamer at its complementary oligonucleotide strand-modified electrode, followed by intercalating methylene blue (MB) into the formed double-stranded DNA (dsDNA). Then, the streptavidin and high-content HRP functionalized gold nanoparticle probes were bound onto the aptasensor. As the MB-mediated HRP-catalytic reaction could produce sensitive electrochemical signal and the aptamer-biorecognition toward Kana could cause quantitative decrease of MB intercalation and nanoprobe capture, convenient electrochemical signal transduction was achieved. Both the enzymatic reaction and nanoprobe signal amplification greatly enhance the electrochemical signal, offering ultrahigh sensitivity of the method. The MB intercalation into dsDNA not only provides necessary electron mediator for the enzymatic reaction but also simplifies the electrochemical measurement. Under optimal conditions, this method showed a wide linear range over four-order of magnitude with a low detection limit of 0.88 pg/mL. In addition, the aptasensor features high specificity, excellent repeatability and stability as well as satisfactory reliability. Thus it possesses valuable application potentials.

The determination of Ochratoxin A based on the electrochemical aptasensor by carbon aerogels and methylene blue assisted signal amplification

In this work, a novel aptamer-based electrochemical biosensor was developed for the determination of Ochratoxin A (OTA) by using carbon aerogels (CAs) and methylene blue (MB) as signal amplification strategy. CAs was used as carrier to load the abundant of complementary DNA (cDNA), which could enhance the hybridization between CAs-cDNA and aptamer immobilized on the electrode surface, thus provide more double-stranded DNA for MB intercalation. The current of MB on the CAs-cDNA/apt/AuE sensor was twice that on the cDNA/apt/AuE sensor, which indicated that the CAs with high surface area enabled a higher loading of the cDNA and absorbed more MB, thus realized the signal amplification strategy. The optimum experimental conditions including MB incubation time of 15 min, aptamer concentration of 4.0 μmol/L, hybridization time of 2.0 h, and OTA incubation time of 18 min were obtained. The change of peak current was linearly proportional to the OTA concentration in the range of 0.10–10 ng/mL with the actual detection limit of 1.0 × 10−4 ng/mL. The experimental results showed that the prepared CAs-cDNA/apt/AuE exhibited good specificity, acceptable reproducibility and repeatability. This sensor was applied to detect OTA in the spiked corn samples, and obtained an acceptable average recovery of 89%.

Nanogap‐Rich Au Nanowire SERS Sensor for Ultrasensitive Telomerase Activity Detection: Application to Gastric and Breast Cancer Tissues Diagnosis

Telomerase has attracted much attention as a universal cancer biomarker because telomerase is overexpressed in more than 85% of human cancer cells while suppressed in normal somatic cells. Since a strong association exists between telomerase activity and human cancers, the development of effective telomerase activity assay is critically important. Here, a nanogap‐rich Au nanowire (NW) surface‐enhanced Raman scattering (SERS) sensor is reported for detection of telomerase activity in various cancer cells and tissues. The nanogap‐rich Au NWs are constructed by deposition of nanoparticles on single‐crystalline Au NWs and provided highly reproducible SERS spectra. The telomeric substrate (TS) primer‐attached nanogap‐rich Au NWs can detect telomerase activity through SERS measurement after the elongation of TS primers, folding into G‐quadruplex structures, and intercalation of methylene blue. This sensor enables us to detect telomerase activity from various cancer cell lines with a detection limit of 0.2 cancer cells mL−1. Importantly, the nanogap‐rich Au NW sensor can diagnose gastric and breast cancer tissues accurately. The nanogap‐rich Au NW sensors show strong SERS signals only in the presence of tumor tissues excised from 16 tumor‐bearing mice, while negligible signals in the presence of heated tumor tissues or normal tissues. It is anticipated that nanogap‐rich Au NW SERS sensors can be used for a universal cancer diagnosis and further biomedical applications including a diverse biomarker sensing.

Co-polymers of oligolactic acid and tetrasubstituted thiacalix[4]arenes as a new material for electrochemical sensor development

New derivatives of oligolactic acid (OLA) have been obtained by cross-esterification with carboxylated thiacalix[4]arene derivatives in cone, paco and 1,3-alternate configurations. The products of the reaction characterized by NMR 1H, FTIR-ATR spectroscopy, MALDI-TOF mass spectroscopy and elemental analysis have been applied for surface modification of glassy carbon electrode (GCE). Electrochemical characterization with redox probes (ferricyanide ion and Methylene blue (MB)) showed predominant influence of electrostatic interactions influencing the flux of the charge carriers over the diffusion control. The role of a macrocycle moiety on the surface morphology and sensitivity toward measurement conditions has been established. The electrodes covered with new materials were applied as transducers in sensing specific DNA interactions and acetylcholinesterase (AChE) based hydrolysis of acetylthiocholine. This made it possible to distinguish factors affecting the DNA structure (MB intercalation, oxidative DNA damage, thermal denaturing) whereas immobilization of the AChE on the silver dendrites deposited in the inner volume of the polymers allowed recording the signal of thiocholine oxidation at extremely low working potential (0mV vs. Ag/AgCl).

Multilayer film of thiourea and gold nanoparticles as an effective platform for immobilization of activated non-labeled-DNA and construction of an ultrasensitive electrochemical DNA biosensor

In this work, self assembly of thiourea and gold nano-particle multilayer built up on a thiourea modified gold nanoparticles Au electrode, has been used as a platform for immobilization of activated ss-DNA. Two NH2 group of thiourea on a multilayer surface can interact with an activated phosphate group of non-labeled ss-DNA. Activated non-labeled ss-DNA was prepared using N-(3 dimethylaminopropyl)-N-ethyl-carbodiimide hydrochloride (EDC) and N-hydroxy-succinimide (NHS). The whole DNA biosensor fabrication process was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods with the use of ferricyanide as an electrochemical redox indicator. Methylene Blue (MB) was used as the electrochemical indicator for monitoring the hybridization reaction after hybridized with the target ssDNA and the reduction current of MB intercalation decreased with increasing the concentration of target DNA, ranging from 7.9 × 10–13 to 1.2 × 10–8 M with a very low detection limit of 3.8 × 10–13 M (S/N = 3).

ELCR: electrochemical detection of single DNA base changes via Ligase Chain Reaction

Simple, inexpensive and wide-scaled analysis of single DNA base changes ('point mutations' which include SNP's, somatic mutations and epigenetic changes) is one of the holy grail's of point-of-care diagnostics. Herein, we present eLCR: a simple methodology that fuses Ligase Chain Reaction (LCR) with electrochemical detection based on DNA-mediated charge transport. LCR generates long and short "knife" motifs representing the presence or absence of single DNA base changes, which are then detected electrochemically by either methylene blue intercalation or horseradish peroxidase labelling.

4‐Aminothiophenol Self‐Assembled Monolayer for the Development of a DNA Biosensor Aiming the Detection of Cylindrospermopsin Producing Cyanobacteria

AbstractThe development of a DNA biosensor for the detection of cylindrospermopsin, based on self‐assembled monolayers (SAMs) of 4‐aminothiophenol, is investigated. SAMs were characterized by electrochemical reductive desorption. Detection of probe immobilization and hybridization has been achieved by cyclic and square‐wave voltammetry (SWV), using methylene blue (MB) as electroactive indicator. The SWV data obtained in phosphate buffer, with and without NaCl, after MB accumulation, revealed an increase of the redox indicator current peaks after the hybridization step. This behavior is consistent with MB intercalation into DNA, for high ionic strength media and attributed to electrostatic interactions in the absence of salt. Evidence for surface modification is also provided by atomic force microscopy and ellipsometry.

Electrochemical scanning of DNA point mutations via MutS protein-mediated mismatch recognition

MutS protein is an important part of the DNA repair system which can specifically recognize and bind all possible single-base mismatches as well as 1–4 base insertion or deletion loops with varying affinities independent of other proteins or cofactors. In this paper, a new approach for electrochemical gene mutation detection based on the utilization of MutS protein for the mutation recognition and spontaneously intercalated methylene blue (MB) markers for electrochemical signal generation is described. This method involves the immobilization of MutS protein onto the gold electrode, the hybridization of target DNA to form homoduplex or heteroduplex DNA, the application of MutS protein for the mutation recognition, and finally the intercalation of MB. The background is very low because MutS protein binds DNA containing mispaired and unpaired bases but does not bind equally well to DNA without mismatches or single-stranded DNA. The proposed approach has been successfully implemented for the identification of single-base mutation in −28 site of the β-thalassemia gene with a detection limit of 5.6×10−13M, demonstrating that this method provides a highly specific and cost-efficient approach for point mutation detection.

Cyclic voltammetric detection of chemical DNA damage induced by styrene oxide in natural dsDNA layer-by-layer films using methylene blue as electroactive probe

In this work, an electrochemical sensor for detecting damage of natural double-stranded DNA (dsDNA) was constructed based on PSS/{PDDA/dsDNA} 3 layer-by-layer films, where PSS was poly(styrene sulfonate) and PDDA was poly(diallyldimethyl ammonium). When the PSS/{PDDA/dsDNA} 3 films assembled on pyrolytic graphite (PG) electrodes were immersed into methylene blue (MB) solution and loaded MB into the films, the formed PSS/{PDDA/dsDNA} 3-MB films in blank buffers at pH 7.0 showed a reversible cyclic voltammetric (CV) peak pair at −0.23 V vs. SCE for MB redox couple. In blank solutions, the MB loaded into the films was released gradually from the films, but the complete reloading of MB into the films could be realized by immersing the films into MB solution again, indicating the good reversibility of MB incorporation. However, after incubation in the solution of known genotoxic agent styrene oxide (SO), the damaged PSS/{PDDA/dsDNA} 3-MB films could not return to their original and fully-loaded state with reloading of MB, and showed smaller CV peak currents than those of intact PSS/{PDDA/dsDNA} 3-MB films. The relative peak current ratio, I p,I/ I p,III, where I p,I was the anodic peak current of intact DNA films in blank buffers after fully loading with MB and I p,III was that of SO-damaged DNA films after reloading with MB, increased linearly with the incubation time with SO in the range of 5–40 min with a damage rate of 0.0099 min −1. While the formation of SO adducts with dsDNA had no substantial effect on the dsDNA conformation, the steric hindrance of SO adducts with guanine or adenine blocked the intercalation of MB into the base pairs of dsDNA, resulting in the decrease of CV peak currents of loaded MB. The specific intercalation of MB into dsDNA base pairs and the sensitive electrochemical response of MB, combined with the unique feature of loading reversibility of MB in the DNA layer-by-layer films, make the difference in CV response between the intact and damaged dsDNA films become pronounced in the “loading/release/reloading” procedure. This may provide a new and general approach for constructing a biosensor for screening genetoxic chemicals in vitro.

Hairpin DNA probe based electrochemical biosensor using methylene blue as hybridization indicator

In this paper, a label-free, rapid and simple method was proposed to study the hybridization specificity of hairpin DNA probe using methylene blue (MB) as a hybridization indicator. Thiolated hairpin DNA probe was immobilized on the gold electrode by self-assembly. The voltammetric signals of MB were investigated at these modified electrodes by means of cyclic voltammetry (CV) detection. Single-base mutation oligonucleotide and random oligonucleotide can be easily discriminated from complementary target DNA. The effect of mismatch position in target DNA was investigated. Experimental results showed that mutation in the center of target DNA had greatest effect on the hybridization with hairpin DNA probe. The relationship between electrochemical responses and DNA target concentration was also studied. The reduction current of MB intercalation decreased with increasing the concentration of target DNA. Taken together, these experiments demonstrate that the hybridization indicator MB provides great promise for rapid and specific measurement of target DNA.

Superconducting Transition Temperature of 2H−TaS2 Intercalation Compounds Determined by the Phonon Spectrum

The specific heat in the normal and superconducting states of single-crystal intercalation compounds of the host material 2H−TaS2 was measured from 1.7 to 9 K by use of a thermal relaxation method. By studying two extreme cases of charge transfer n, namely the 9 A methylene blue intercalation compound (9 A MB+−TaS2) (n = 0.06) and K0.33TaS2 (n = 0.33), and comparing the results with literature data, it is seen that charge transfer has only minor influence on the electronic specific heat in the normal state. This is in drastic contradiction to the expectation from a rigid band model. The contribution of the phonon-parameter β, however, varies with intercalation. No direct correspondence between Tc and the Debye temperature θD can be seen, but if θD is multiplied by a factor, characterizing the intercalation compound, scaling between Tc and the corrected Debye temperature is found. Furthermore, it is observed that the superconducting transition temperature of the methylene blue intercalation compound is sen...

Characterization of the Binding of Methylene Blue to DNA by Spectroscopic Methods

ABSTRACT Methylene blue (MB) binds to the double helical DNA with a high affinity, as deduced from the absorption and fluorescence spectral data. Extensive hypochromism and red shifts in the absorption spectra were observed when MB binds to calf thymus DNA(CT DNA), which suggested the intercalation mechanism of MB into DNA bases. Upon binding to DNA, the fluorescence from MB was efficiently quenched by the DNA bases, with no shifts in the emission maximum. The large increases in the polarization upon binding to CT DNA supported the intercalation of MB into the helix. Ferrocyanide quenching studies showed that the magnitude of Ksv of the bound MB was lower than that of the free MB. The results of competitive binding studies showed that ethidium bromide could be displaced by MB from ethidium-DNA complex. The results of all above further studies also proved the intercalation of MB into DNA base stack.

Torque measurements on methylene blue intercalation compounds of 2H-TaS 2

The superconducting properties in high magnetic fields of three different methylene blue intercalation compounds of 2H-TaS 2 (compounds with 9å, 12å and 17å layer separation) are measured with a torquemeter. The superconducting magnetisation curves can be separated in two parts, a reversible part at high fields and an irreversible part at low fields, defining an irreversibility line as in the organic or high-T c superconductors. The angular dependence of H c2 of the 9å compound can be fitted by the anisotropic Ginzburg-Landau theory giving an anisotropy factor of about 60. The T c values of these compounds are 3.8 K for the 17å, 5. l K for the 12å and 5. l K or 4.6K (depending on the cooling rate) for the 9å compound, tested by ac-susceptibility. The estimated critical field of dimensional crossover is out of the measured temperature range and cannot be seen in this work.

Intercalation of Methylene Blue into Layered Phosphates in the Presence of Butylamine and Function of Alkylamine in the Intercalation Reaction

Abstract The intercalation of methylene blue (MB) into layered phosphates was examined in the presence of butylamine (BA) in order to clarify the mechanism of this reaction and the function of alkylamine, such as BA in the intercalation reaction. MB was not directly intercalated into layered phosphates, but could be intercalated in the presence of BA. The intercalation of MB was strongly influenced by the amount of BA used; that is, it was accelerated by the presence of BA, but inhibited by the presence of too much BA. Moreover, in the procedure which BA was previously intercalated into layered phosphates, it was found that the intercalation of MB can be achieved by removing BA from the interlayer region when BA is formed a monolayer in the phase, and depends on the orientation of BA in the interlayer region when BA forms a bilayer.

PHOTOPHYSICS OF METHYLENE BLUE‐POLYNUCLEOTIDE COMPLEXES IN THE PICOSECOND TIME RANGE: INFLUENCE OF THE LOCAL STRUCTURE OF THE POLYNUCLEOTIDE

Abstract—The photophysics of methylene blue (MB) complexed with 2'‐deoxycytidylyl‐2'‐deoxygua‐nosine, polydeoxyguanylic‐deoxycytidylic acid, polydeoxyguanylic‐polydeoxycytidylic acid and poly‐guanylic acid, respectively, was investigated by transient absorption spectroscopy with a time resolution of ˜1 ps. The decays of the transient difference spectra indicate that the radiationless process responsible for the strong shortening of the S, state lifetime of MB associated with a guanine in the polynucleotide chain is similar to that already observed in the case of the MB—guanosine‐5'‐monophosphate complex, that is, the excited state decays by return of molecules to the ground state without formation of a detectable intermediate state. The local structure of the polynucleotide apparently does not change the nature of the deactivation process but influences significantly the deactivation rate. Thus, the intercalation of MB between guanosine and cytosine increases this rate constant (as compared to that of the MB—guanosine‐5'‐monophosphate complex) while the interaction of MB intercalated with a supplementary guanine has an opposite effect. The results are discussed in connection with the photosensitizing effect of MB in nucleic acid damage.

Preparation of an intercalation compound of layered titanic acid H2Ti4O9 with methylene blue

Intercalation of methylene blue into layered titanic acid H2Ti4O9 was examined by a guest exchange method using a propylammonium-H x Ti4O9 intercalation compound as the intermediate. Methylene blue cations were arranged in the interlayer space obliquely to the layer surface. The visible spectrum of the intercalation compound suggested that the methylene blue cations were in an associated state in the interlayer space of H2Ti409. The intercalated methylene blue cations underwent a reversible electrochemical redox reaction in the dark, indicating that intercalation compounds of H2Ti4O9 can be applied to a modified electrode.