Thionine Research Articles

Sensitive electrochemical immunosensor for cancer biomarker with signal enhancement based on nitrodopamine-functionalized iron oxide nanoparticles

A novel electrochemical immunosensor for sensitive detection of cancer biomarker prostate specific antigen (PSA) based on nitrodopamine (NDA) functionalized iron oxide nanoparticles (NDA–Fe3O4) is described. NDA–Fe3O4 was used both for the immobilization of primary anti-PSA antibody (Ab1) and as secondary anti-PSA antibody (Ab2) label. For the preparation of the label, mediator thionine (TH) was first conjugated onto NDA–Fe3O4 based on the amino groups of NDA, and then the amino group of TH was used to immobilize horseradish peroxidase (HRP) and Ab2. Due to the high amount of NDA anchored onto Fe3O4 surface, the loading of antibodies as well as mediator and enzyme onto NDA–Fe3O4 was substantially increased, which increased the sensitivity of the immunosensor. The resulting immunosensor displayed a wide range of linear response (0.005–50ng/mL), low detection limit (4pg/mL), good reproducibility and stability. The immunosensor was used to detect the PSA contents in serum samples with satisfactory results.

A selective novel non-enzyme glucose amperometric biosensor based on lectin–sugar binding on thionine modified electrode

A novel non-enzyme glucose amperometric biosensor was fabricated based on biospecific binding affinity of concanavalin A (Con A) for d-glucose on thionine (TH) modified electrode. TH can be covalently immobilized on potentiostatically activated glassy carbon electrode through Schiff-base reaction. Subsequently, the surface-adherent polydopamine film formed by self-polymerization of dopamine attached to TH and afforded binding sites for the subsequent immobilization of Con A molecules via Michael addition and/or Schiff-base reaction with high stability. Thus, a sensing platform for specific detection towards d-glucose was established. The binding of Con A towards d-glucose can be monitored through the decrease of the electrode response of the TH moiety. Due to the high affinity of Con A for d-glucose and high stability of the resulting sensing platform, the fabricated biosensor exhibited high selectivity, good sensitivity, and wide linear range from 1.0 × 10 −6 to 1.0 × 10 −4 M with a low detection limit of 7.5 × 10 −7 M towards d-glucose.

Understanding the Electrophoretic Separation of Single-Walled Carbon Nanotubes Assisted by Thionine as a Probe

Single-walled carbon nanotubes (SWNTs) dispersed by sodium dodecyl sulfate (SDS) can be simply and effectively separated into semiconducting (s) and metallic (m) fractions by the method of agarose gel electrophoresis, in which s-SWNTs cannot migrate like m-SWNTs and remain unmoved under electric field. The role of SDS is suggested to be crucial for such separation effect. Its mechanism, however, is still unclear and hard to probe. In the present study, by employing thionine (TN), a positively charged dye molecule which may show unique interaction with SDS molecules, we can roughly evaluate the changes of SDS aggregates during the agarose gel electrophoresis. On the basis of the results of the electrophoretic and spectroscopic characterizations, we propose that the unique interaction of s-SWNTs with agarose and the exfoliation of some SDS molecules from SDS-s-SWNT entities lead to the separation of s- and m-SWNTs.

High-Performance Amperometric Sensors Using Catalytic Platinum Nanoparticles-Thionine-Multiwalled Carbon Nanotubes Nanocomposite

Thionine (TH) adsorbed on multiwalled carbon nanotubes (MWCNTs) increases the load and dispersion of platinum nanoparticles (PtNPs) generated by chemical reduction of H2PtCl6 with NaBH4. Under the optimum conditions, the PtNPs-TH-MWCNTs/Au electrode electrocatalyzed the reduction and oxidation of H2O2 with high sensitivity, and after glucose oxidase (GOx) adsorption it responded to glucose concentration with a sensitivity of 0.14 A M−1 cm−2. The cyclic voltammetric cathodic peak current for NO2− reduction on PtNPs-TH-MWCNTs/Au responded linearly to NO2− concentration from 0.5 to 150 µM, with a sensitivity of 5.52 A M−1 cm−2 and a detection limit of 0.2 µM.

Role of monoamine oxidase, nitric oxide synthase and regional brain monoamines in the antidepressant-like effects of methylene blue and selected structural analogues

Dual action antidepressants have important therapeutic implications. Methylene blue (MB), a charged compound structurally related to tricyclic antidepressants, acts on both monoamine oxidase (MAO) and the nitric oxide (NO)-cGMP pathway, and has demonstrated antidepressant activity in rodents. We investigated the antidepressant properties of MB and selected structural analogues and whether their actions involve MAO, NO synthase (NOS) and regional brain monoamines.Acute imipramine (IMI, 15mg/kg), saline, MB, acriflavine (ACR), methylene green (MG), methylene violet (MV), thionine (THI) and tacrine (TAC) (1-60mg/kg i.p.) were tested for antidepressant activity in the forced swim test (FST), as well as MAO-A/B inhibitory activity. Active antidepressant compounds were subsequently studied at their most effective dose during sub-chronic treatment, followed by behavioural sampling in the FST and assay of cortico-limbic monoamines and hippocampal nitrate (for NOS activity).Only IMI, MB (15, 30, 60mg/kg) and MG (7.5, 25, 40mg/kg) reduced immobility in the acute FST. MB, MG and ACR were potent inhibitors of especially MAO-A. Following sub-chronic treatment, IMI (15mg/kg) increased noradrenergic behaviour in the FST, while MB (15mg/kg) and MG (15mg/kg) enhanced serotonergic behaviour. MB and MG bolstered cortico-limbic serotonin (5HT) levels and to a lesser extent l-norepinephrine (l-NE), but did not significantly alter regional dopamine (DA) levels. MB, and to lesser degree MG, reduced hippocampal nitrate levels.MB and MG present with structure-specific antidepressant-like effects following acute and sub-chronic treatment, possibly involving NOS and MAO-A inhibition and cortico-limbic 5HT and l-NE release. A role for MAO-B and DA appears minimal.

Ultrasensitive immunosensor for the detection of cancer biomarker based on graphene sheet

An ultrasensitive electrochemical immunosensor based on graphene sheet (GS) has been developed. GS was used to immobilize mediator thionine (TH), horseradish peroxidase (HRP) and secondary anti-prostate-specific antigen (PSA) antibody (Ab 2) and the resulting nanostructure (GS-TH-HRP-Ab 2) was used as the label for the immunosensor. With primary anti-PSA antibody (Ab 1) also immobilized onto the GS, the immunosensor displayed a wide range of linear response (0.002–10 ng/mL), low detection limit (1 pg/mL), good reproducibility, selectivity and stability. The good performance of the immunosensor is attributed to the graphene sheet's high surface-to-volume ratio which allows the immobilization of a high-level of Ab 1, Ab 2, TH and HRP and its good electrical conductivity which can improve the electron transfer among TH, HRP, H 2O 2 and electrode. The immunosensor was used to detect the PSA contents in serum samples from patients and satisfactory test results were obtained in comparison with the ELISA test results. Thus, graphene-based labels may provide many potential applications for the detection of different cancer biomarkers.

Electrochemical immunosensor for norethisterone based on signal amplification strategy of graphene sheets and multienzyme functionalized mesoporous silica nanoparticles

Norethisterone is one kind of widely used anabolic steroid hormones which can help to promote livestock growth and sometime has been illegally used for livestock breeding. The residues of norethisterone in animal food will harm people's health, therefore, it has been banned to use for the growth promotion purposes in livestock. In this study, amino-group functionalized mesoporous silica nanoparticles (MSN) were prepared and used to immobilize Au nanoparticles, which was further utilized for the adsorption of horseradish peroxidase (HRP) and the secondary antibody (Ab 2). The resulting nanoparticles, Au-MSN-HRP-Ab 2 were used as labels for immunosensors to detect norethisterone antigen. A sandwich-type protocol was used to prepare the immunosensor with the primary antibody (Ab 1) immobilized onto thionine (TH) and graphene sheet (GS) modified glassy carbon electrode surface. The sensitivity of the sandwich-type immunosensor using Au-MSN-HRP-Ab 2 as labels for norethisterone antigen detection was much higher than that using either Au-MSN-Ab 2 or MSN-HRP-Ab 2 as labels. Within norethisterone concentration range (0.01–10 ng/mL), a linear calibration plot ( Y = 0.55671 + 8.27101 X, r = 0.9993) was obtained with a detection limit of 3.58 pg/mL under optimal conditions. The proposed immunosensor shows good reproducibility, selectivity, and acceptable stability. This new type of labels for immunosensors may provide many potential applications for the detection of growth hormone in animal derived food.

A novel label-free electrochemical immunosensor based on graphene and thionine nanocomposite

A novel label-free electrochemical immunosensor for the detection of alpha fetoprotein (AFP) has been developed by immobilizing anti-AFP on graphene sheet (GS) and thionine (TH) modified glassy carbon electrode. The modification procedure was characterized by cyclic voltammetry (CV). The detection is based on the peak current change of the modified electrode before and after the antigen–antibody reaction. Tests relating to the detection of AFP demonstrated that the immunosensor exhibited high sensitivity, wide linear range (0.05–2.00 ng mL −1), low detection limit (5.77 pg mL −1 based S/ N = 3) and good long-term stability. The reliability of the developed immunosensor has been proved by the detection of AFP in serum samples with satisfactory results.

Multifunctional mesoporous silica nanoparticles as labels for the preparation of ultrasensitive electrochemical immunosensors

Labels based on mesoporous silica nanoparticles (MSN) loaded with mediator thionine (TH), enzyme horseradish peroxidase (HRP) and secondary anti-human IgG antibody (Ab 2) were developed in order to improve the sensitivity and detection limit of an amperometric immunosensor. The sensitivity of the sandwich-type immunosensor using MSN–TH–HRP–Ab 2 as labels for human IgG detection was about 100 times higher than that using either MSN–TH–Ab 2 or MSN–HRP–Ab 2 as labels, indicating the high catalytic efficiency of HRP in the presence of mediator TH toward H 2O 2. The immunosensor using MSN–TH–Ab 2 as labels exhibited a high sensitivity and showed a linear response within the range of 0.01–10 ng/mL human IgG. It also showed good reproducibility and selectivity and acceptable stability. These labels for immunosensors may provide many potential applications for the detection of different biomolecules.

A novel sensing platform based on periodate-oxidized chitosan

A novel thionine (TH) sensing platform was proposed based on immobilization of TH on a periodate-oxidized chitosan (CS) modified glassy carbon electrode (GCE) surface. Oxidation of CS by periodate can lead to the cleavage of carbon–carbon bonds on the pyranosidic ring of CS, with the generation of dialdehyde groups. TH, an electroactive mediator, was selected as a model of amine compounds to react with the aldehyde group via Schiff-base reaction. Due to the resulting aldehyde-enriched surface and covalent immobilization of TH on periodate-oxidized CS, the CS-grafted-TH showed a pronounced electrochemical response with high stability. The application of the fabricated TH sensing platform as a hydrogen peroxide (H2O2) sensor was also investigated and it exhibited a rapid response to H2O2 within 4 s. The linear calibration ranged from 1.0 × 10−5 to 1.83 × 10−3 M with a detection limit of 4.0 × 10−6 M.

Acrylic Tanks for Stunning Chemical Demonstrations

We describe the use of acrylic tanks (400 x 450 x 27 mm) for visualization of chemical demonstrations in aqueous solutions. Examples of well-suited demonstrations are oscillating reactions, pH indicators, photochemical reduction of Lauth's violet, and chemoluminiscent reactions.

Controllable Adsorption and Ideal H-Aggregation Behaviors of Phenothiazine Dyes on the Tungsten Oxide Nanocolloid Surface

The monomer-aggregate equilibrium of four phenothiazine (PN) dyes, containing thionine (TH), methylene blue (MB), new methylene blue (NMB), and 1,9-dimethylmethylene blue (DMB), in the tungsten(VI) oxide (WO(3)) nanocolloid solution has been investigated by means of UV-vis spectroscopy. Addition of PN dye into the WO(3) nanocolloid solution brought about significant changes in the absorption spectrum, suggesting the formation of H-type (face-to-face fashion) trimer on the WO(3) nanocolloid surface. The adsorptivity of PN dyes onto the WO(3) nanocolloid surface was diminished by the raising the ionic strength, indicating the evidence of the electrostatic interaction between cationic PN dye and negatively charged WO(3) nanocolloids. The detail analysis of each spectral data provided insight into the effect of molecular structure of PN dyes on the adsorption and aggregation behaviors on the WO(3) nanocolloid surface. Moreover, in situ measurement of PN dye aggregation using the centrifugal liquid membrane (CLM) technique revealed that the aggregation of PN dyes on the WO(3) nanocolloid surface proceeded in a two-step three-stage (monomer --> dimer --> trimer) formation. The aggregation mechanism of PN dyes on the WO(3) nanocolloid surface was discussed on the basis of Kasha's exciton theory.

Amperometric detection of hydrogen peroxide at nano-nickel oxide/thionine and celestine blue nanocomposite-modified glassy carbon electrodes

Abstract A simple procedure was developed to prepare a glassy carbon (GC) electrode modified with nickel oxide (NiOx) nanoparticles and water-soluble dyes. By immersing the GC/NiOx modified electrode into thionine (TH) or celestine blue (CB) solutions for a short period of time (5–120 s), a thin film of the proposed molecules was immobilized onto the electrode surface. The modified electrodes showed stable and a well-defined redox couples at a wide pH range (2–12), with surface confined characteristics. In comparison to usual methods for the immobilization of dye molecules, such as electropolymerization or adsorption on the surface of preanodized electrodes, the electrochemical reversibility and stability of these modified electrodes have been improved. The surface coverage and heterogeneous electron transfer rate constants (ks) of thionin and celestin blue immobilized on a NiOx-GC electrode were approximately 3.5 × 10−10 mol cm−2, 6.12 s−1, 5.9 × 10−10 mol cm−2 and 6.58 s−1, respectively. The results clearly show the high loading ability of the NiOx nanoparticles and great facilitation of the electron transfer between the immobilized TH, CB and NiOx nanoparticles. The modified electrodes show excellent electrocatalytic activity toward hydrogen peroxide reduction at a reduced overpotential. The catalytic rate constants for hydrogen peroxide reduction at GC/NiOx/CB and GC/NiOx/TH were 7.96 (±0.2) × 103 M−1 s−1 and 5.5 (±0.2) × 103 M−1 s−1, respectively. The detection limit, sensitivity and linear concentration range for hydrogen peroxide detection were 1.67 μM, 4.14 nA μM−1 nA μM−1 and 5 μM to 20 mM, and 0.36 μM, 7.62 nA μM−1, and 1 μM to 10 mM for the GC/NiOx/TH and GC/NiOx/CB modified electrodes, respectively. Compared to other modified electrodes, these modified electrodes have many advantages, such as remarkable catalytic activity, good reproducibility, simple preparation procedures and long-term stabilities of signal responses during hydrogen peroxide reduction.

Homogenous Thionine-SiO<SUB>2</SUB> Nanocomposite Spheres: Sonochemical Preparation, Characterization, and Application in H<SUB>2</SUB>O<SUB>2</SUB> Biosensor

The electrochemical properties of new homogenous thionine (TH)-doped silica nanoparticles as a mediator were studied. The nanocomposites were synthesized by using sonochemical method. The sonication induced the strong combination between dye molecules and silica in the construction of the composites. By controlling reaction condition, face rougher uniform spheres could be achieved. The as-prepared nanocomposites can be used as the mediator to construct the biosensors with horseradish peroxidase coimmobilized in the gelatine matrix and cross-linked with formaldehyde. The described experimental evidences show the different ratio of ethanol to water can induce the changes in their diameters. As a consequence, the resulting biosensors exhibited amperometric response decreased with the increase of the spherical size. The resulting biosensor mediated by the 100 nm diameter of TH-doped silica nanoparticles exhibited very fast amperometric response, good stability and could be effectively used for the study of the electrocatalytic properties.

High-Sensitive Glutamate Biosensor Based on NADH at Lauth’s Violet/Multiwalled Carbon Nanotubes Composite Film on Gold Substrates

A highly sensitive amperometric L-glutamate biosensor based on the electrocatalytic oxidation of reduced nicotinamide adenine dinucleotide has been developed on Lauth's Violet (known as thionine)/multiwalled carbon nanotubes (Th-MWCNTs) composite film, which is used as a mediator and an enzyme immobilization matrix. The glutamate biosensor, which is fabricated by immobilizing glutamate dehydrogenase (GLDH) on the surface of Th-MWCNTs, displayed a precipitous response (ca. 3 s), a low detection limit (15.9 nM), a wide linear dynamic range (0.1 to 500 microM), and high sensitivity of 281.6 microAmM(-1) cm(-2), higher biological affinity, as well as good stability and repeatability. Interferences from other biological compounds were also studied for the fabricated sensor. The Th-MWCNTs system exemplifies a simple and efficient approach to the assimilation of GLDH and electrodes, which can provide analytical access to a large group of enzymes for wide range of bioelectrochemical applications in health care fields.

Monitoring of redox state in a dechlorinating culture with immobilized redox indicators

During the dechlorination of tetrachloroethene (PCE) to ethene (ETH) in a microcosm bottle containing an enriched chlororespiring culture, redox conditions were spectrophotometrically monitored with the redox indicators thionine (THI) and cresyl violet (CV) immobilized on transparent films. Measurements were taken with a unique flow redox monitoring system based on circulating solution from the bottle through a specially constructed flow cell and returning it to the bottle. An enclosure for a peristaltic pump was constructed to minimize contamination of the solution with atmospheric O(2). The redox monitoring instrumentation was shown to be an excellent tool to evaluate the ability of an enclosure for anoxic samples to prevent diffusion of very small amounts of oxygen from the atmosphere into the sample. With careful design of the apparatus, the O(2) permeation rate into a solution of THI in a microcosm bottle during redox monitoring was reduced to less than 40 nmol h(-1). When monitoring a dechlorinating culture, dechlorination was not observed until immobilized THI was completely reduced and vinyl chloride was not produced until partial reduction of CV.

Adsorption and photocatalysed destruction of cationic and anionic dyes on mesoporous titania films: Reactions at the air–solid interface

Cationic dyes, such as methylene blue (MB), Thionine (TH) and Basic Fuschin (BF), but not anionic dyes, such as Acid Orange 7 (AO7), Acid Blue 9 (AB9) and Acid Fuschin (AF), are readily adsorbed onto mesoporous titania films at high pH (pH 11), i.e. well above the pzc of titania (pH 6.5), due to electrostatic forces of attraction and repulsion, respectively. The same anionic dyes, but not the cationic dyes, are readily adsorbed on the same titania films at low pH (pH 3), i.e. well below titania's pzc. MB appears to adsorb on mesoporous titania films at pH 11 as the trimer (λmax=570nm) but, upon drying, although the trimer still dominates, there is an absorption peak at 665nm, especially notable at low [MB], which may be due to the monomer, but more likely MB J-aggregates. In contrast, the absorption spectrum of AO7 adsorbed onto the mesoporous titania film at low pH is very similar to the dye monomer. For both MB and AO7 the kinetics of adsorption are first order and yield high rate constants (3.71 and 1.48lg−1min−1), indicative of a strong adsorption process. Indeed, both MB and AO7 stained films retained much of their colour when left overnight in dye-free pH 11 and 3 solutions, respectively, indicating the strong nature of the adsorption. The kinetics of the photocatalytic bleaching of the MB–titania films at high pH are complex and not well-described by the Julson–Ollis kinetic model [A.J. Julson, D.F. Ollis, Appl. Catal. B. 65 (2006) 315]. Instead, there appears to be an initial fast but not simple demethylation step, followed by a zero-order bleaching and further demethylation steps. In contrast, the kinetics of photocatalytic bleaching of the AO7–titania film give a good fit to the Julson–Ollis kinetic model, yielding values for the various fitting parameters not too dissimilar to those reported for AO7 adsorbed on P25 titania powder.

Temperature-Controlled Photooxygenation with Polymer Nanocapsules Encapsulating an Organic Photosensitizer

A cross-linked poly- N-isopropylacrylamide (polyNIPAM) nanocapsule, TH@PC, containing thionine (TH), an organic photosensitizer, has been synthesized. This capsulated polymeric photosensitizer promotes a singlet oxygen oxygenation ( (1)O 2) accurately controlled by temperature: it shows high oxygenation activity at low temperature, but shows activity decrease with a rise in temperature, resulting in almost zero activity at >40 degrees C. The clear on-off activity control is driven by a heat-induced structure change of the capsule from the swollen single capsule to contracted state, and then to aggregate, behaving as an intelligent (1)O 2 filter. At low temperature, the capsule exists as the swollen single capsule, which allows (1)O 2 diffusion to bulk water, resulting in high oxygenation activity. A rise in temperature leads to contraction of the capsule, reducing the mesh size of the capsule wall. This suppresses (1)O 2 diffusion to bulk water and shows decreased activity. Intercapsule aggregation at >30 degrees C further suppresses (1)O 2 diffusion and shows almost no activity. The capsule promotes reversible activity control regardless of the heating/cooling process and can be reused with a simple recovery process.

Amperometric determination of H 2O 2 at nano-TiO 2/DNA/thionin nanocomposite modified electrode

We report electrochemical preparation and characterization of a new biosensor made of nanostructured titanium dioxide (nano-TiO 2) particles and deoxyribonucleic acid (DNA). Thionin (TN) redox mediator was electrochemically deposited onto DNA/nano-TiO 2 modified glassy carbon electrode (GCE). The X-ray diffraction analysis, atomic force microscope (AFM) and scanning electron microscope (SEM) were used for surface analysis of TN/DNA/nano-TiO 2 film. In neutral buffer solution, TN/DNA/nano-TiO 2/GCE biosensor exhibited excellent electrocatalytic activity towards the reduction of hydrogen peroxide (H 2O 2) and oxygen (O 2). The biosensor shows excellent analytical performance for amperometric determination of H 2O 2, at reduced overpotential (−0.2 V). The detection limit and liner calibration range were found to be 0.05 mM (S/N = 3) and 0.05–22.3 mM, respectively. In addition, determination of H 2O 2 in real samples was carried out using the new biosensor with satisfactory results. The TN/DNA/nano-TiO 2/GCE showed stable and reproducible analytical performance towards the reduction of H 2O 2. This biosensor can be used as an amperometric biosensor for the determination of H 2O 2 in real samples.

A new composite sorbent for water and dye uptake: Highly swollen acrylamide/2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid/clay hydrogels crosslinked by 1,4‐butanediol dimethacrylate

AbstractA novel type of highly swollen hydrogels based on acrylamide (AAm) with 2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid (AMPS) and clay such as bentonite (Bent) crosslinked by 1,4‐butanediol dimethacrylate (BDMA) was prepared by free radical solution polymerization in aqueous media. Water uptake and dye sorption properties of polyelectrolyte AAm/AMPS hydrogels and AAm/AMPS/Bent composite hydrogels were investigated as a function of composition to find materials with swelling and sorption properties. FTIR analyses were made. Swelling experiments were performed in water and dye solution at 25°C, gravimetrically. Highly swollen AAm/AMPS and AAm/AMPS/Bent hydrogels were used in experiments on sorption of water‐soluble monovalent cationic dye such as Lauths violet “LV, (Thionin).” Swelling of AAm/AMPS hydrogels was increased up to 1,920–9,222% in water and 867–4,644% in LV solutions, while AAm hydrogels swelled 905% in water and swelling of AAm/AMPS/Bent hydrogels was increased up to 2,756–10,422% in water and 1,200–3,332% in LV solutions, while AAm/Bent hydrogels swelled 849% in water. Some swelling kinetic and diffusional parameters were found. Water and LV diffusion into hydrogels was found to be non‐Fickian in character. For sorption of cationic dye, LV into AAm/AMPS and AAm/AMPS/Bent hydrogel was studied by batch sorption technique at 25°C. The amount of the dye sorbed per unit mass removal effiency and partition coefficient of the hydrogels was investigated. The influence of AMPS content in the hydrogels to sorption was examined. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers