Azure A Research Articles

Exploration of the role of Hibiscus esculentus (okra) mucilage for the removal of phenothiazinium dyes from water body: Spectroscopic, thermodynamic and molecular modeling study

Environmental pollution poses a major problem now a day. Several dyes, in the form of industrial waste, pollute water body and may cause adverse effects to human health. In this paper ADME and toxicity of fives Phenothiazinium group of dyes Methylene blue (MB), Azure A (AA), Azure B (AB), Azure C (AC) and Toluidine Blue O (TBO) were predicted using Swiss ADME and Protox II tools. Results showed these dyes may herm for living organism due to their carcinogenic, mutagenic and hepatotoxic properties. Removal efficiency of these dyes using okra plant product were determined using spectroscopic, thermodynamic and molecular modeling study. It was revealed that these dyes adsorb on the surface of okra leaf mostly at pH 7.0 and the adsorption isotherms were found to fit in Langmuir and Freundlich isotherm model, while Temkin model fails to do this. Mucilage present in different parts of okra plant plays a significant role on removal of these dyes and is able to remove near about 71–92 % of dyes from water body by itself. As this process did not fit in any of above said adsorption isotherm model, it may be suggested that some other mechanism may happen. Further studies explore that these dyes bound to the hydrophobic pocket of mucilage with binding affinity in the order of 105 M−1 and the bindings were exothermic in nature with enthalpy change in the range of − 2.94 to − 4.28 kcal/mole. Molecular docking study validate all the experimental results obtained from spectroscopic and thermodynamic study and enlighten the role of structure of dyes on their binding affinity to mucilage. This paper will help to systematically understand the role of okra plant products on removal efficiency of Phenothiazinium group of dyes with their structural variations.

Sonodynamic inactivation of gram-negative and gram-positive bacteria in the presence of phenothiazine compounds toluidine blue and azurin A

BackgroundSonodynamic antimicrobial chemotherapy (SACT) is an effective antimicrobial treatment that can avoid the production of drug-resistant bacteria. Design and development of new high-efficiency sonosensitizers play a key role in the practical application of SACT. MethodsThe bacteriostatic effects of two phenothiazine compounds, toluidine blue (TB) and azure A (AA) combined with ultrasonic (US) on Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were studied, and the sonodynamic antibacterial activities of TB and AA were compared. The reactive oxygen species (ROS) and the types of ROS produced in the sonodynamic system were detected and the sonodynamic mechanisms of TB and AA were proposed. ResultsThe sonodynamic bacteriostasis mediated by TB and AA increased with the increasing concentration of sonosensitizer, the extension of sonication time and the increase of reaction temperature. The production of ROS was the main reason that TB and AA had excellent sonodynamic antibacterial performance. Singlet oxygen (1O2) and hydroxyl radical (•OH) were the main ROS types in the sonodynamic antibacterial system. The ROS produced by the combined action of AA and US was higher than that of TB. ConclusionBoth TB and AA displayed excellent sonodynamic antibacterial activities. Moreover, AA had a higher sonodynamic activity than TB. The electron donation effect and steric hindrance effect of the methyl group of phenothiazine parent nucleus of TB might be the cause of the decrease of its sonodynamic activity. These results would provide a valuable reference for the further study of phenothiazines sonosensitizers and their clinical application in SACT.

Bismuthene - Tetrahedral DNA nanobioconjugate for virus detection

In this work, we present an electrochemical sensor for fast, low-cost, and easy detection of the SARS-CoV-2 spike protein in infected patients. The sensor is based on a selected combination of nanomaterials with a specific purpose. A bioconjugate formed by Few-layer bismuthene nanosheets (FLB) and tetrahedral DNA nanostructures (TDNs) is immobilized on Carbon Screen-Printed Electrodes (CSPE). The TDNs contain on the top vertex an aptamer that specifically binds to the SARS-CoV-2 spike protein, and a thiol group at the three basal vertices to anchor to the FLB. The TDNs are also marked with a redox indicator, Azure A (AA), which allows the direct detection of SARS-CoV-2 spike protein through changes in the current intensity of its electrolysis before and after the biorecognition reaction. The developed sensor can detect SARS-CoV-2 spike protein with a detection limit of 1.74 fg mL−1 directly in nasopharyngeal swab human samples. Therefore, this study offers a new strategy for rapid virus detection since it is versatile enough for different viruses and pathogens.

Efficient Dye Extraction from Wastewater Using Indium-MOF-Immobilized Polyvinylidene Fluoride Membranes with Selective Filtration for Enhanced Remediation.

Industrial activities have led to releasing harmful substances into the environment, necessitating the elimination of these toxic compounds from wastewater. Organic dyes, commonly found in industrial effluents, pose a threat to ecosystems and human health. Conventional treatment methods often suffer from limitations such as high cost and poor efficiency. Metal-organic frameworks (MOFs) have emerged as promising materials for selective separation, including membrane filtration (MF). Mixed-matrix membranes (MMMs) combining MOFs with polymers offer improved filtration properties. In this study, MMMs were fabricated by incorporating synthesized In-MOF with a polyvinylidene fluoride (PVDF) polymer (In-MOF@PVDF MMMs) using the nonsolvent-induced phase separation process. The MMMs were evaluated for the MF of various organic dyes, achieving notable removal efficiencies. The membrane containing 20% In-MOF (M4) demonstrated exceptional performance, removing 99% of the methylene blue (MB) dye. Additionally, membrane M4 effectively filtered Azure A (AZA), Azure B (AZB), and toluidine blue O (TOLO) with a removal efficiency of 99%. However, for Rhodamine B (RHB) and methyl orange (MO), the removal efficiencies were slightly lower at 74 and 39%, respectively. Further, these membranes are utilized in selective dye filtration in the MB+/RHB+ and MB+/MO- systems, where the selectivity was found for MB. The isothermal and DFT studies revealed the membrane's behavior with dye mixtures, while water stability and regeneration studies confirmed its durability. Thus, these findings highlight the potential of In-MOF@PVDF MMMs for effective and selective dye removal in wastewater treatment applications.

Fate of Molecular Photon Emitters in Plasmonic Hot Spots in Air and a Vacuum

We report on the physicochemical behavior of molecular photon emitters in plasmonic hot spots by comparing the temporal evolution of the scattering signal in a vacuum and air of three chromophores, namely Methylene Blue (MB), Azure A (AzA), and Toluidine Blue O (TBO). The differences in behavior are studied by monitoring the surface-enhanced Raman scattering spectra of the adsorbates as a function of illumination time at 632.8 nm excitation wavelength that overlaps with the electronic transition energy of the chromophores. It is shown that the adsorbates are relatively stable in a vacuum, while they undergo N-demethylation when excited at ambient conditions. Comparison of the vacuum and ambient data suggests that the photochemical transformation is preceded by fluorescence quenching that involves intersystem crossing, energy transfer, and singlet oxygen generation. Generally, the plasmon-induced physicochemical behaviors of the three dyes are similar with some notable exceptions. The strongest signal fluctuation is observed for the N-demethylation product of MB due to most significant disruption of the adsorption geometry as four methyl groups are eliminated, leaving the product in the metastable state. On the other hand, TBO appears to be the most effective photosensitizer as evidenced by the most significant extent of N-demethylation within 0.5 s of exposure as well as through comparison of the N-demethylation signature in a vacuum due to a trace amount of oxygen. These results have important implications in the study of molecular polaritons in plasmonic nanocavities, where interpretation of strong coupling can be ambiguous due to competing excited state processes that lead to photochemical conversion of the emitters.

Application of chemometric method and computational analysis in the spectroscopic study of Azure A dimerization

In this contribution we allied chemometric tools and theoretical calculus to comprehend the self-aggregation process of the phenothiazine Azure A (AA), a potential photosensitizer for Photodynamic Therapy. Firstly, due to the high spectral overlap between monomer and dimer, the MCR-ALS method successfully resolve AA's spectra, indicating the formation of a twisted sandwich-like dimer instead of pure H-type aggregate. This chemometric protocol helped not only in the resolution but also in more trustable values of KD. The difference between the KD values after the resolution of the curves was significant, which shows the importance of this procedure. The data extracted from experimental also converged with the informations retrieved from theoretical calculus. The optimization of the AA’s dimer showed the repulsion between the central nitrogen (and at the same time with the sulfur atoms) causes a slight distortion and displacement of one molecule in relation to the other, favoring dimAA-symTRANS, a twisted sandwich-like conformation.The studies also evaluated the impact of salts in the self-aggregation depicting that, besides the ionic strength, polarizable soft anions interact better with cationic species like AA. Thus, soft anions as iodide and bromine causes the most striking impact in self-aggregation. The present study shows the importance in resolve the spectra data set before calculate KD values, role succsesfull developed by MCR-ALS methodology. The approach used here can help in the investigation of others self-aggregation process of photosensitizers and active molecules.

The Biotransformation and Biodecolorization of Methylene Blue by Xenobiotic Bacterium <i>Ralstonia pickettii</i>

The biotransformation and biodecolorization of methylene blue (MB) dye using the bacterium Ralstonia pickettii was investigated. This experiment was conducted in a nutrient broth (NB) medium after adding MB at 100 mg L–1 concentration. Approximately 98.11% of MB was decolorized after 18 h of incubation. In addition, the metabolic products detected by LC-TOF/MS were Azure A (AA), thionine, leuco-MB, and glucose-MB, which indicated the MB degradation through a reductase that attacked the heterocyclic central chromophore group present in the structure. Moreover, azure A and thionine fragments resulted from the N-demethylase enzyme that attacked the auxochrome group. Thus, this research was assumed to be the first scientific report suggesting the potential to use R. pickettii in the biodecolorization and biotransformation of dye waste, particularly MB.

Determination of Methylene Blue and Its Metabolite Residues in Aquatic Products by High-Performance Liquid Chromatography-Tandem Mass Spectrometry.

A sensitive and reliable method was developed to determine methylene blue (MB) and its metabolite residues, including azure A (AZA), azure B (AZB), and azure C (AZC) in aquatic products by HPLC–MS/MS. The samples were extracted by acetonitrile and cleaned up by alumina-neutral (ALN) cartridges. The analytes were separated on a Sunfire C18 column (150 mm × 2.1 mm, 5 µm). The method was validated according to the European criteria of Commission Decision 2002/657/CE. Good linearity between 1–500 µg/L was obtained with correlation coefficients (R2) greater than 0.99. The limit of quantification (LOQ) was 1.0 µg/kg. The average recoveries at three levels of each compound (1, 5, and 10 µg/kg) were demonstrated to be in the range of 71.8–97.5%, with relative standard deviations (RSDs) from 1.05% to 8.63%. This method was suitable for the detection of methylene blue and its metabolite residues in aquatic products.

Covalent Immobilization of Organic Photosensitizers on the Glass Surface: Toward the Formation of the Light-Activated Antimicrobial Nanocoating

Two highly efficient commercial organic photosensitizers—azure A (AA) and 5-(4-aminophenyl)-10,15,20-(triphenyl)porphyrin (APTPP)—were covalently attached to the glass surface to form a photoactive monolayer. The proposed straightforward strategy consists of three steps, i.e., the initial chemical grafting of 3-aminopropyltriethoxysilane (APTES) followed by two chemical postmodification steps. The chemical structure of the resulting mixed monolayer (MIX_TC_APTES@glass) was widely characterized by X-ray photoelectron (XPS) and Raman spectroscopies, while its photoactive properties were investigated in situ by UV–Vis spectroscopy with α-terpinene as a chemical trap. It was shown that both photosensitizers retain their activity toward light-activated generation of reactive oxygen species (ROS) after immobilization on the glassy surface and that the resulting nanolayer shows high stability. Thanks to the complementarity of the spectral properties of AA and APTPP, the effectiveness of the ROS photogeneration under broadband illumination can be optimized. The reported light-activated nanocoating demonstrated promising antimicrobial activity toward Escherichia coli (E. coli), by reducing the number of adhered bacteria compared to the unmodified glass surface.

“Painted CNT”@Au nanoparticles: a nanohybrid electrocatalyst of direct methanol oxidation

In an era of global new energy rush, hybrid nanomaterials have raised huge interest as their components can synergistically improve the expected performances in terms of power. In this regard, direct methanol oxidation (DMO) is among the most investigated reactions for implementation in portable and other devices. Herein, we report on the design of gold-decorated multiwalled carbon nanotube-aryl nanohybrids as electrocatalyst of DMO. In a first step, Azure A (AA), Neutral Red (NR), and Congo Red (CR) dye diazonium salts were reacted with multiwalled carbon nanotubes (hereafter CNTs) to provide CNT-Dye nanoscale platforms for the immobilization of gold NPs. This step was conducted with CNT-Dye platforms evenly spread over glassy carbon (GC) electrodes. The CNT-Dye@Au nanohybrid electrode materials served for DMO electrocatalysis. Cyclic voltammograms show that bare CNT-Dye nanohybrids exhibit high electrocatalytic activity, particularly for the CNT-CR nanohybrid which returned a threefold improvement. With anchored Au NPs, a further 4 time remarkable increase in the oxidation peak intensity was achieved (i.e., about 12-fold the peak intensity recorded in the absence of any nanocatalyst). The forward to the backward anodic peak current density ratio Jf/Jb was found to be as high as is 1.68. This work provides an efficient approach for designing robust, nanohybrid electrocatalyst for DMO, based on the smart combination of CNTs, diazotized dyes, and gold NPs.Graphical abstract EMMA-D-20-00232R1

The photosensitiser azure A disrupts mitochondrial bioenergetics through intrinsic and photodynamic effects

Azure A (AA) is a cationic molecule of the class of phenothiazines that has been applied in vitro as a photosensitising agent in photodynamic antimicrobial chemotherapy. It is a di-demethylated analogue of methylene blue (MB), which has been demonstrated to be intrinsically and photodynamically highly active on mitochondrial bioenergetics. However, as far as we know, there are no studies about the photodynamic effects of AA on mammalian mitochondria. Therefore, this investigation aimed to characterise the intrinsic and photodynamic acute effects of AA (0.540 μM) on isolated rat liver mitochondria, isolated hepatocytes, and isolated perfused rat liver. The effects of AA were assessed by evaluating several parameters of mitochondrial bioenergetics, oxidative stress, cell viability, and hepatic energy metabolism. The photodynamic effects of AA were assessed under simulated hypoxic conditions, a suitable way for mimicking the microenvironment of hypoxic solid tumour cells. AA interacted with the mitochondria and, upon photostimulation (10 min of light exposure), produced toxic amounts of reactive oxygen species (ROS), which damaged the organelle, as demonstrated by the high levels of lipid peroxidation and protein carbonylation. The photostimulated AA also depleted the GSH pool, which could compromise the mitochondrial antioxidant defence. Bioenergetically, AA photoinactivated the complexes I, II, and IV of the mitochondrial respiratory chain and the F1FO–ATP synthase complex, sharply inhibiting the oxidative phosphorylation. Upon photostimulation (10 min of light exposure), AA reduced the efficiency of mitochondrial energy transduction and oxidatively damaged lipids in isolated hepatocytes but did not decrease the viability of cells. Despite the useful photobiological properties, AA presented noticeable dark toxicity on mitochondrial bioenergetics, functioning predominantly as an uncoupler of oxidative phosphorylation. This harmful effect of AA was evidenced in isolated hepatocytes, in which AA diminished the cellular ATP content. In this case, the cells exhibited signs of cell viability reduction in the presence of high AA concentrations, but only after a long time of incubation (at least 90 min). The impairments on mitochondrial bioenergetics were also clearly manifested in intact perfused rat liver, in which AA diminished the cellular ATP content and stimulated the oxygen uptake. Consequently, gluconeogenesis and ureogenesis were strongly inhibited, whereas glycogenolysis and glycolysis were stimulated. AA also promoted the release of cytosolic and mitochondrial enzymes into the perfusate concomitantly with inhibition of oxygen consumption. In general, the intrinsic and photodynamic effects of AA were similar to those of MB, but AA caused some distinct effects such as the photoinactivation of the complex IV of the mitochondrial respiratory chain and a diminution of the ATP levels in the liver. It is evident that AA has the potential to be used in mitochondria-targeted photodynamic therapy, even under low oxygen concentrations. However, the fact that AA directly disrupts mitochondrial bioenergetics and affects several hepatic pathways that are linked to ATP metabolism, along with its ability to perturb cellular membranes and its little potential to reduce cell viability, could result in significant adverse effects especially in long-term treatments.

Towards analytical application of electrochromic polypyrrole layers modified by phenothiazine derivatives

Electrochromism is the phenomenon, which is based on the change of material color when particular voltage is applied to electrochemical system. This feature is of high importance for a wide range of actuating devices such as smart windows, screens, thermal modulators and various sensors. During this research we have formed and investigated polypyrrole (Ppy) based layers, which were electrochemically deposited on the indium tin oxide coated glass in the presence of three phenothiazine (PT) derivatives - methylene blue (MB), azure A (AA), and thionine (TH). The surface morphology of the coatings was determined by atomic force microscopy (AFM) and scanning electron microscopy (SEM). It was found that the thickness of the surface irregularities ranged from 1 to 3 µm. The reflection absorption infrared spectroscopy (RAIRS) was chosen for the evaluation of the layer due to the possibility to measure reflection spectra of thin layers avoiding influence of the glass substrate present under the ITO layer. Polypyrrole and poly(Azure A) (Ppy-PAA) layer was the thickest one and non-translucent, therefore, it was not suitable for optical evaluation. The polypyrrole and poly(methylene blue) (Ppy-PMB) and polypyrrole and polythionine (Ppy-PTH) layers also were analyzed by cyclic voltammetry and chronoamperometry methods. The applicability of Ppy-PMB, Ppy-PAA, and Ppy-PTH in chemical sensing was evaluated. The investigated polymeric coatings exhibited electrochromic properties (color change at different potential), reacted to pH changes and to ascorbic acid concentration.

Electropolymerization of Azure A and pH Sensing Using Poly(azure A)-modified Electrodes.

A modified electrode was developed by immobilizing poly(azure A) (pAA) onto the surface of a glassy carbon electrode via the electropolymerization of azure A (AA). The pAA immobilized on the electrode exhibited redox response during cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The redox reaction obeyed the Nernst equation because of the involvement of H+ ions. In addition, the peak potential was shifted according to the solution pH. The shifts of the oxidation peak potential could be more easily observed using DPV than when using CV, indicating that the developed electrode could be useful as a pH sensor. This pH measurement method can be successfully applied in the pH range of 1 to 10 and can be successfully repeated more than 50 times.

Effective electrochemical detection of riboflavin and butylated hydroxy anisole based on azure A and nickel hexacyanoferrate framework on graphite electrode

A highly stable and layered combination of Azure A (AZA) and Nickel hexacyanoferrate (NiHCF) grafted on graphite electrode was used as selective sensor for the determination of Riboflavin and Butylated hydroxy anisole. The surface of modified electrode was analysed and confirmed by scanning electron microscopy, EDS and Confocal Raman spectroscopy studies. Cyclic voltammetry analysis exhibited redox peaks for NiHCF in NaNO3 solution (0.1 M) and AZA in PBS solution (0.1 M) with formal potential as 0.32 V and -0.39 V at a scan rate 50 mV/s. The AZA/NiHCF modified electrode exhibited remarkable electrocatalytic performance for BHA oxidation by the NiHCF system and reduction of RF by AZA system with the detection limit as 2.22 × 10−6 M and 1.45 × 10−6 M respectively. The sensitivity was calculated as 0.1234 µA/µM for BHA and as 0.1352 µA/µM for RF. Finally, the proposed sensor was applied to estimate BHA in biscuit and RF in pharmaceutical samples successfully.

Activated Complex Approach to Describe Bovine Serum Albumin-Azure A and Bovine Serum Albumin-Azure B Intermolecular Interactions

Azure A (AZA) and azure B (AZB) phenothiazine dyes are used for clinical and medical purposes, and their functions can be altered via interactions with proteins. However, no kinetics information on the interactions between phenothiazine dyes and bovine serum albumin (BSA) is available. Surface plasmon resonance was used to determine the energetic and dynamic of the BSA-AZA and BSA-AZB complexes formation at pH 7.4. At temperature ≤ 16 °C, the formation of activated (DH‡a,12°C,AZA= -310.57 kJ mol-1 and DH‡a,12 °C,AZB= -256.37 kJ mol-1) and thermodynamically stable (DH°12°C,AZA= -314.56 kJ mol-1 and DH°12°C,AZB= -265.73 kJ mol-1) complexes was driven by enthalpy, while at temperature ≥ 20 °C, by entropy, (TDS‡a,28°C,AZA= 207.49 and TDS‡a,28°C,AZB= 190.69; TDS°28°C,AZA= 277.50 and TDS°28°C,AZB= 257.26 kJ mol-1). Hydrophobic interactions were fundamental to the complex stability and the increase in number of -CH3 groups in the dyes do not affect kinetic and thermodynamic parameters. Our results could help optimize the medical and pharmaceutical applications of phenothiazine dyes.

Lactoferrin-phenothiazine dye interactions: Thermodynamic and kinetic approach

Life manifestation is mainly based on biopolymer-ligand molecular recognition; therefore, the elucidation of energy and speed associated with protein-ligand binding is strategic in understanding and modulating biological systems. In this study, the interactions between methylene blue (MB) or azure A (AZA) dyes and bovine lactoferrin (BLF) were investigated by surface plasmon resonance, fluorescence spectroscopy, and isothermal titration microcalorimetry. Despite the molecular similarities between the dyes, the BLF-AZA binding thermodynamic parameters (ΔGAZAo = −30.50 and ΔHAZAo = 10.8 (kJ·mol−1)) were higher in magnitude than those of the BLF-MB systems (ΔGMBo = −27.3 and ΔHMBo = 5.72 (kJ·mol−1)). To increase the systems' entropy (TΔSAZAo = 41.3 and TΔSMBo = 33.0 (kJ·mol−1)), the hydrophobic interactions must outweigh the electrostatic repulsion, thereby promoting BLF-dye binding. The activation complex formation (Eac, aMB = 33, Eac, aAZA = 32, ∆Ha, MB‡ = 31, ∆Ha, AZA‡ = 30, ∆Ga, MB‡ = 51.84, ∆Ga, AZA‡ = 50.7, T∆Sa, MB‡ = −21, T∆Sa, AZA‡ = −21 (kJ·mol−1)), owing to free BLF and MB (or AZA) associations, was not affected by the dye chemical structure, while for the thermodynamically stable BLF-dye complex dissociation, the same energetic parameters (Eac, dMB = 16, Eac, dAZA = 6.4, ∆Hd, MB‡ = 14, ∆Hd, AZA‡ = 3.9, ∆Gd, MB‡ = 81.4, ∆Gd, AZA‡ = 74.93, T∆Sd, MB‡ = −68, T∆Sd, AZA‡ = −71.0 (kJ·mol−1)) were considerably affected by the number of methyl groups. Our results may be very useful to determine binding processes controlled by kinetic parameters, as well as to optimize the application of these photosensitive dyes in biological systems.

Photophysical insights and in vitro cytotoxicity of dyes-gold nanostars system towards MCF-7 and A-549 cancer cells

In this paper, the interaction of phenothiazine (PHZ) dyes (Azure A (AZA) and thionine (TH)) with gold nanostars (Au NSs) were studied using absorption spectroscopy, steady state emission spectroscopy, high resolution transmission electron microscopy (HR-TEM), dynamic light scattering (DLS), Zetapotential measurements and Fourier transform infrared (FT-IR) spectroscopy. Absorption spectral studies of Au NSs in the presence of dyes resulted in a slight red shift on the surface plasmon resonance band (SPR) of Au NSs, suggesting the changes in the Au NSs surface owing to the adsorption of dyes. The phenomena of hypochromism and the appearance of coupled localized surface plasmon resonance (LSPR) bands in the absorption spectral studies of the AZA-Au NSs and TH–Au NSs systems suggested the vital role of electrostatic interactions between PHZ dyes and Au NSs. The formation of the ground state complex between dyes and Au NSs were evident from the outcome of the steady-state emission titration experiments of the dyes-Au NSs system. Further, the cytotoxic activity of AZA, TH, AZA-Au NSs and TH-Au NSs complexes on breast cancer (MCF-7) and A-549 cell lines were also investigated. These studies revealed that AZA-Au NSs, TH-Au NSs complexes showed the higher level of cytotoxicity than PHZ dyes treated cells.

Mild and Effective Polymerization of Dopamine on Keratin Films for Innovative Photoactivable and Biocompatible Coated Materials

AbstractMussel‐inspired polydopamine (PD) coating represents a promising route for constructing functional materials and finely tuning or completely changing their surface properties. In this work, a mild and effective method to realize the deposition of PD on keratin‐based films is reported. Reactive oxygen species (ROS), generated by keratin films doped with a photosensitizer, e.g., Azure A (AzA), upon UV–vis and vis‐near IR irradiation, are exploited to obtain the PD coating. Interestingly, the use of vis‐near IR irradiation leads to an increased production of ROS by AzA resulting in a greater PD deposition. Compared to uncoated keratin films, the PD‐keratin coated materials show a granular but homogeneous surface and an increased hydrophilicity, maintaining the ROS generation ability of AzA. This work demonstrates a useful method to effectively and rapidly functionalize with PD materials that are sensitive to temperature, pH and UV light, such as keratin. The proposed strategy allows obtaining new multifunctional biomaterials of potential interest in tissue engineering and drug delivery; in particular, the use of PD‐keratin films for near IR laser bonding of ophthalmic tissue, which is a representative case in wound healing purpose, is shown.

Exploring the interaction of Azure dyes with t-RNA by hybrid spectroscopic and computational approaches and its applications toward human lung cancer cell line

In the present study, in depth characterization of binding aspects of Azure A (AZA) and Azure B (AZB) with transfer Ribonucleic acid (t-RNA) from Escherichia coli (E.coli) is investigated using spectroscopic techniques. The absorbance and fluorescence properties of these dyes have been remarkably changed upon binding with t-RNA. Significant changes in the absorption maxima of the dyes evidence the t-RNA induced metachromasy and the binding clearly revealed the high affinity of AZA and AZB to t-RNA. Strong emission polarization of the bound dyes and strong energy transfer from the guanine base pairs of t-RNA suggested intercalative binding interaction. The stoichiometry of AZA and AZB with t-RNA complexes are determined by the Benesi-Hildebrand plot from emission data. The negative values of free energy change indicated the involvement of hydrophobic forces and noncovalent interactions in the complexation of both the dyes with t-RNA. The 3-(4,5- dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay in A-549 human lung cancer cell lines reveals that binding of t-RNA reduces the toxicity of AZA and AZB. The utility of the present work explores the potential binding applicability of these dyes to t-RNA for their development as effective therapeutic agents and its target at molecular level for the treatment of diseases like cancer.

Adsorption Kinetic and Isotherm Studies of Azure-A on Various Activated Carbons Derived from Low Cost Agricultural Wastes

The present study narrates the eminent role of agricultural wastes as adsorbents viz., Sorghum Vulgare Carbon (SVC), Zea Mays Carbon (ZMC), Sorghum Vulgare Varity Carbon (SVVC), Ceiba Peutandra Carbon (CPC), Projobis Juliflora Carbon (PJC) for the removal of Azure-A (AA) dye from waste water. Experimental parameters such an effect of initialconcentration, contact time, dose, pH and particle size have been analyzed. The experimental results are there analyzed using Freundlich, Langmuir, Temkin, Redlich–Peterson and Dubinin–Radushkevich isotherm models. Multiple kinetic equations (first order, pseudo first order and pseudo second order) were applied to the adsorption kinetics of AA on various activated carbons. Surface morphology of the adsorbents before and after adsorption is studied by Scanning Electron Microscopy (SEM-Edax). FT-IR analyses revealed the presence of functional groups of dye on the adsorbents. It is inferred from the experimental result that the activated carbons (SVC, ZMC, SVVC, CPC and PJC) from agricultural wastes can be applied as an adsorbent in the removal of AA dye from waste water.