Search

Drug-loaded nanoscale cavitation agents, called nanodroplets, are an attractive solution to enhance and localize drug delivery, offering increased stability and prolonged half-life in circulation compared to microbubbles. However, the spatial precision with which drug can be released and delivered into brain tissue from such agents has not been directly mapped. Decafluorobutane lipid-shell droplets (206 +/− 6 nm) were loaded with a fluorescent blood-brain barrier (BBB)-penetrating dye (Nile Blue) and vaporized with ultrasound (1.66 MHz, 10 ms pulse length, 1 Hz pulse repetition frequency), generating transient echogenic microbubbles and delivering the encapsulated dye. The distribution and intensity of released fluorophore was mapped in a tissue-mimicking phantom, and in the brain of rats (Sprague Dawley, N = 4, n = 16). The release and distribution of dye was found to be pressure-dependent (0.2–3.5 MPa) and to occur only above the vaporization threshold of the nanodroplets (1.5 +/− 0.25 MPa in vitro, 2.4 +/− 0.05 MPa in vivo). Dye delivery was achieved with sub-millimetre spatial precision, covering an area of 0.4 to 1.5 mm in diameter, determined by the sonication pressure. The distribution and intensity of dye released at depth in the brain followed the axial pressure profile of the ultrasound beam. Nile Blue (354 Da, LogP 2.7) was compared to Nile Red (318 Da, LogP 3.8) and Quantum Dots (CdSe/ZnS, 5 nm diameter) to visualize the role of molecule size and lipophilicity in crossing the intact BBB following triggered release. Acoustic emissions were shown to predict the successful delivery of the BBB-penetrating dye and the extent of the distribution, demonstrating the theranostic capabilities of nanoscale droplets to precisely localize drug delivery in the brain.

Microwave catalysis is extremely lucrative due to prompt mineralization and superior efficiency. Ideal microwave catalysts should possess crystalline nature, large surface area, room temperature ferromagnetic, high dielectric properties apart from structural stability at elevated temperature. In the present article, the candidature of microwave synthesized strontium hexaferrite 2D sheets (2D SFO) has been explored as microwave catalysts for the degradation of a host of organic dyes and antibiotics. Malachite green (MG) and nile blue A (NB) in particular exhibited 99.8% and 97.6% degradation, respectively. Degradation reaction is established to follow pseudo-second-order kinetics. Total organic carbon (TOC) measurements hint at 52% and 60% mineralization for MG and NB, respectively. Liquid chromatography-mass spectroscopy (LCMS) measurements indicate the reaction pathways via intermediates and eventual mineralization to CO2 and H2O. Mott-Schottky measurements along with scavenger tests hint that both hydroxyl and superoxide radicals participate in the reaction. Having superior efficiency apart from the versatile nature of the 2D SFO microwave catalyst, the present research will guide to the emergence of microwave catalysis as a new technology.

[ES] La senescencia celular es un proceso que sufren las células mitóticamente competentes mediante el cual se produce el arresto del ciclo celular, y que puede ser activado de forma natural o inducida como respuesta al estrés u otros estímulos. Este proceso provoca cambios morfológicos y fenotípicos que impiden la proliferación celular. Entre estos cambios, la sobreexpresión de la enzima lisosomal β-galactosidasa es el marcador más empleado para la detección. En el presente trabajo nos basamos en este aspecto para el desarrollo de una sonda molecular que permita la detección de células senescentes in vivo. Dicha sonda molecular está constituida por el fluoróforo Azul de Nilo aceptado por la Food and Drugs Administration, accesible en formato comercial y cuya emisión de fluorescencia se encuentra en el infrarrojo cercano, y por una molécula de galactosa que actúa como unidad de reconocimiento. El enlace entre fluoróforo y unidad de reconocimiento provoca una disminución de la señal de fluorescencia. En presencia de la enzima β-Galactosidasa, se produce la hidrólisis del enlace y el subsiguiente aumento de la fluorescencia. De esta forma, se obtiene un método de análisis cualitativo, rápido y poco invasivo que permite llevar a cabo la detección directa de células senescentes en modelos in vivo., [EN] Cellular senescence is a process that occurs in mitotically competent cells that promote the arrest of the cell cycle and can be activated by natural way or induced as response to stress or other stimuli. This process generates morphological and phenotypic changes that stops cell proliferation. Among these changes, the most used detection marker is the overexpression of lysosomal β-galactosidase enzyme. In this work, we are based on this aspect for the development of a molecular probe in order to detect senescent cells in vivo. This molecular probe is based in Nile Blue fluorophore, accepted by the Food and Drugs Administration, accessible in commercial source and whose fluorescence emission is in the near infrared, and a galactose molecule that acts as recognition unit. The bond between fluorophore and recognition unit provokes the deactivation of fluorescence signal. In the presence of β-Galactosidase enzyme, bond was hydrolyzed and the activation of fluorescence takes place. In this way, is obtained a qualitative, fast, and minimally invasive analysis method that allows the direct detection of senescent cells in vivo models.

The lipid content of mammalian cells varies greatly between cell type. Current methods for analysing lipid components of cells are technically challenging and destructive. Here, we report a facile, inexpensive method to identify lipid content – intracellular flow cytometric lipid analysis (IFCLA). Distinct lipid classes can be distinguished by Nile Blue fluorescence, Nile Red fluorescence or violet autofluorescence. Nile Blue is fluorescent in the presence of unsaturated fatty acids with a carbon chain length greater than 16. Cis-configured fatty acids induce greater Nile Blue fluorescence than their trans-configured counterparts. In contrast, Nile Red exhibits greatest fluorescence in the presence of cholesterol, cholesteryl esters, some triglycerides and phospholipids. Multiparametric spanning-tree progression analysis for density-normalized events (SPADE) analysis of hepatic cellular lipid distribution, including vitamin A autofluorescence, is presented. This flow cytometric system allows for the rapid, inexpensive and non-destructive identification of lipid content, and highlights the differences in lipid biology between cell types by imaging and flow cytometry. This article has an associated First Person interview with the first author of the paper.

The highly sensitive and reliable detection, imaging, and monitoring of changes of intracellular caspase-3 are critical for understanding the cell apoptosis and studying the progression of caspase-3-related cervical cancer. Herein, we present a novel surface-enhanced Raman scattering (SERS) probe for the detection of caspase-3 during cervical cancer cell apoptosis, composed of Au nanoboxes modified with Nile blue A as a Raman reporter and a caspase-3-specified peptide as a molecular cross-linker. In the presence of caspase-3, the substrate peptides can be cleaved and the changed surface charge of the Au nanoboxes results in the Au nanoboxes-NBA-peptide assembling to form aggregates and a great enhancement of SERS signal. The finite-difference time-domain simulation showed that hot spots mainly located in the nanogaps of the aggregated Au nanoboxes, which in theory proved the rationality of this signal amplification method. The SERS probes exhibited excellent reproducibility and selectivity toward caspase-3. A detection limit of 0.127 fM was obtained for caspase-3, with a dynamic range from 1 fM to 1 nM. MTT assay demonstrated that the probes had no obvious cytotoxicity within a certain concentration range. HeLa cells were treated with doxorubicin to induce long-term apoptosis. Upon cellular uptake of these probes, the spatiotemporal dynamics of caspase-3 in apoptotic cells could be real-time monitored using SERS. The activity of caspase-3 increased with the prolongation of apoptosis time. The SERS results were in accordance with that of western blotting assay. This kind of probe can offer great potential for the determination of enzymatic activities in the physiological processes of cells.

Polyhydroxybutyrate (PHB) is the most widely studied biodegradable plastic that does not release any toxins or residues in the environment like petroleum based plastics. This work has been undertaken to screen PHB accumulating microorganisms from marine sponges and a total of sixteen isolates were collected and purified. Screening of isolated strains was done by Nile blue staining and observed under Leica LSCM to confirm the production of PHB. Yellow pigmented AB8a isolate from Oceanopia arenosa scored positive for PHB accumulation and subjected to morphological, biochemical and phylogenetic characterization. The biopolymer was extracted by dispersion of sodium hypochlorite and chloroform solution and characterized by FT-IR and 1H NMR for the confirmation as PHB. The highest PHB production (70.25%/100 ml) was achieved at pH 7.0 by applying dextrose as medium at incubation temperature 30°C and 150 rpm agitation speed. The FTIR spectrum of the PHB sample showed major peaks at 3457, 1692, 1550, 1454, 1420, 1190 and 1050 cm-1, whereas the remaining peaks are closely laid between 3450 cm-1 and 600 cm-1. 1H NMR spectrum of PHA isolated from dextrose media indicated characteristic signals of PHB. The spectrum also revealed the presence of three groups of signals characteristic of PHB by the doublet at 1.3 ppm attributed to the methyl group coupled to one proton; and the spectrum of the quadruplet at 2.57 ppm, the methylene group adjacent to an asymmetric carbon atom bearing a single proton and the multiplet at 5.28 ppm indicated signals of PHB. The PHB accumulated bacterium identified as Bacillus flexus strain based on characterization studies and 16S rRNA sequence analysis and confirmed the presence of intracellular accumulated polymer substantiated as PHB.

Benzophenoxazine fluorophores, including derivatives of Nile Blue, one of the best known in this family of compounds, have been used as histological stains due to their optical properties in the NIR region and stability. Given their potential, the synthesis of two new Nile Blue derivatives with different substituents on the amines of the positions 5 and 9 was performed, with the introduction of a sulfonamide group in one of the compounds. Photophysical properties of the compounds were evaluated in acidified ethanol and aqueous solution at physiological pH. The fluorescent staining capacity was evaluated by staining Saccharomyces cerevisiae with the compounds, followed by fluorescence microscopy.

Nanoparticles can be applied to the hair follicles, which can serve as reservoirs for triggered drug release. A valid measurement method for the determination of the pH within the hair follicle in vivo has not been shown yet. Here, melamine formaldehyde particles up to 9 µm in size were applied on 40 freshly plucked scalp hairs of eight individuals to determine the pH along the hair shaft down to the root area of the hair. For fluorescent pH indicators, pyranine and Nile blue were incorporated into the particles. Measurements were conducted using confocal laser scanning microscopy. A pH decay gradient could be found from the hair sheath towards the external hair shaft (p = 0.012) with pH values at the hair sheath of 6.63 ± 0.09, at the hair sheath end at 6.33 ± 0.11, and at the external hair shaft at 6.17 ± 0.09 (mean ± SE). The pH difference between the hair sheath end and the external hair shaft was found to be significant (p = 0.036). The results might be comparable with the pH within the hair follicle in vivo indicating a pH increase towards the hair root.

The present work focuses the investigation on fluorescence quenching of nile blue (NB) in presence of various substituted uracil molecules. UV–Visible absorption studies signify the possibility of ground state complex formation between NB and uracil molecules. The increase in concentration of quencher molecules greatly influences the emission spectra of NB. The bimolecular quenching rate constant (kq) were calculated and found to depend on the position and electronic properties of substituent in quencher molecules. Fluorescence quenching experiments were performed at different temperature to calculate the thermodynamic parameters. The fluorescence lifetime measurements show that the quenching process proceeds through static quenching. The mechanism of fluorescence quenching includes the possibility of proton transfer. The bond dissociation enthalpy (BDE) reveals the release of H from the quencher molecules. The quencher molecules possess antioxidant activity and identified using deoxyribose degradation assay. The position of substituent and its electronic property are key features to address the antioxidant activity of uracil molecules.

The determination of the adipogenic potential and behavior of adipose-derived mesenchymal stem/stromal cells (ASCs) is particularly relevant for their potential clinical application in regenerative medicine, especially when the regeneration processes is supported by biomaterials or scaffolds. Scaffolds should be able to induce tissue repair, limiting the undesired adipogenic differentiation. Depending on the scaffold, the determination of cell behavior may be hindered, due to material interference with staining limiting either cells identification or dye quantification. Collagen is a promising biomaterial in regenerative medicine, however histological analysis of cells cultured on collagen-based scaffolds is challenging. Herein we propose a new histological method, based on the combination of iron hematoxylin and Oil Red O (ORO) staining, for the determination of the adipogenic differentiation of ASCs cultivated on a collagen-based 2D scaffold. ASCs were seeded on collagen films or plastic, differentiated into adipocytes for 14 days, then stained either with ORO or with a combination of iron hematoxylin and ORO. As the collagen films highly absorb the ORO dye, conventional staining and quantification by dye extraction did not allow to discriminate between differentiated and undifferentiated cells on collagen films. On the contrary, iron hematoxylin-ORO combination allowed a quantitative and more reliable determination of adipocytes based on single cell count. The proposed method is particularly recommended for the determination of adipogenic differentiation potential of ASCs and other cell types when grown on highly absorptive materials that need to be validated for their potential use in bioengineering and regenerative medicine.

The hydrophobicity of nanoparticles (NPs) is a key property determining environmental fate, biological partitioning and toxicity. However, methods to characterize surface hydrophobicity are not uniformly applied to NPs and cannot quantify surface changes in complex environments. Existing methods designed to evaluate the hydrophobicity of bulk solids, chemicals, and proteins have significant limitations when applied to NPs. In this study, we modified and evaluated two methods to determine the hydrophobicity of NPs, hydrophobic interaction chromatography (HIC) and dye adsorption, and compared them to the standard octanol-water partitioning protocol for chemicals. Gold, copper oxide, silica, and amine-functionalized silica NPs were used to evaluate methods based on their applicability to NPs that agglomerate and have surface coatings. The octanol water partitioning and HIC methods both measured Au NPs as hydrophilic, but despite having a small size and stable suspension, NPs could not be fully recovered from the HIC column. For the dye adsorption method, hydrophobic (Rose Bengal) and hydrophilic (Nile Blue) dyes were adsorbed to the NP surface, and linear isotherm parameters were used as a metric for hydrophobicity. CuO was determined to be slightly hydrophilic, while SiO2 was hydrophilic and Ami-SiO2 was hydrophobic. The advantages and limitations of each method are discussed, and the dye adsorption method is recommended as the most suitable for application across broad classes of nanomaterials. The dye assay method was further used to measure changes in the surface hydrophobicity of TiO2 NPs after being suspended in natural water collected from the Alsea Rivers watershed in Oregon. TiO2 NPs adsorbed Rose Bengal when suspended in ultrapure water, but adsorbed Nile Blue after being incubated in natural water samples, demonstrating a shift from hydrophobic to hydrophilic properties on the outer surface. The dye adsorption method can be applied to characterize surface hydrophobicity of NPs and quantify environmental transformations, potentially improving environmental fate models.

[EN] In vivo detection of cellular senescence is accomplished by using mesoporous silica nanoparticles loaded with the NIR-FDA approved Nile blue (NB) dye and capped with a galactohexasaccharide (S3). NB emission at 672 nm is highly quenched inside S3, yet a remarkable emission enhancement is observed upon cap hydrolysis in the presence of beta-galactosidase and dye release. The efficacy of the probe to detect cellular senescence is tested in vitro in melanoma SK-Mel-103 and breast cancer 4T1 cells and in vivo in palbociclib-treated BALB/cByJ mice bearing breast cancer tumor., R.M. thanks financial support from the Spanish Government (RTI2018-100910-B-C41 and RTI2018-101599-B-C22 (MCUI/AEI/FEDER, UE)) and the Generalitat Valenciana (PROMETEO 2018/024). M.O. thanks the financial support from SAF2017-84689-R project and MINECO/AEI/FEDER, UE and the Generalitat Valenciana (PROMETEO/2019/065). B.L.-T. is grateful to the Spanish Ministry of Economy for her PhD grant. I.G. thanks her contract from IDM. J.F.-B. and M.A. thank the UPV for their postdoctoral fellowship.

Light-harvesting systems are an important way for capturing, transferring and utilizing light energy. It remains a key challenge to develop highly efficient artificial light-harvesting systems. Herein, we report a supramolecular co-assembly based on lower-rim dodecyl-modified sulfonatocalix[4]arene (SC4AD) and naphthyl-1,8-diphenyl pyridinium derivative (NPS) as a light-harvesting platform. NPS as a donor shows significant aggregation induced emission enhancement (AIEE) after assembling with SC4AD. Upon introduction of Nile blue (NiB) as an acceptor into the NPS-SC4AD co-assembly, the light-harvesting system becomes near-infrared (NIR) emissive (675 nm). Importantly, the NIR emitting NPS-SC4AD-NiB system exhibits an ultrahigh antenna effect (33.1) at a high donor/acceptor ratio (250:1). By co-staining PC-3 cells with a Golgi staining reagent, NBD C6 -ceramide, NIR imaging in the Golgi apparatus has been demonstrated using these NIR emissive nanoparticles.

Nanoparticle (NP)-loaded filter paper (FP)-based surface-enhanced Raman scattering (SERS) substrates have been prepared using differently shaped gold (Au) NPs. The shape of Au NPs plays a significant role in the amplification of SERS signal. Here, two differently shaped Au NPs were synthesized using two different techniques: (a) femtosecond (fs) laser ablation in liquid and (b) chemical method. Spherical shaped Au NPs were obtained using fs ablation of a bulk Au target in distilled water and Au nanostars (NSs) were achieved through chemical process utilizing N-vinyl-2-pyrrolidone as a reducing/capping agent. The size and shapes of these synthesized NPs and NSs were investigated meticulously using different characterization techniques such as transmission electron microscopy, field emission scanning electron microscopy and X-ray diffraction. Both the NPs and NSs were subsequently loaded onto commercially available FP by simple drop casting method. To achieve higher number of hot spots, the aggregated spherical NPs were obtained by addition of NaCl. The non-aggregated spherical, aggregated spherical, and star Au NPs loaded on FP were used for the detection of a dye (Nile blue) and an explosive molecule (Picric acid).

Four new benzo [a] phenoxazinium chlorides with combinations of chloride, ethyl ester and methyl as terminals of the amino substituents were synthesized. These compounds were characterized and their optical properties were studied in absolute dry ethanol and water. Their antiproliferative activity was tested against Saccharomyces cerevisiae in a broth microdilution assay, along with an array of 36 other benzo[a]phenoxazinium chlorides. Minimum Inhibitory Concentration (MIC) values between 1.56 and > 200 tM were observed. Fluorescence microscopy studies, used to assess the intracellular distribution of the dyes, showed that these benzo[a]phenoxazinium chlorides function as efficient and site specific probes for the detection of the vacuole membrane. The added advantage of some of the compounds, that displayed the lower MIC values, was the simultaneous staining of both the vacuole membrane and the perinuclear membrane of endoplasmic reticulum (ER). Molecular docking studies were performed on the human membrane protein oxidosqualene cyclase (OSC), using the crystal structure available on PDB (code 1W6K). The results showed that these most active compounds accommodated better in the active sites of ER enzyme OSC suggesting this enzyme as a potential target. As a whole, the results demonstrate that the benzo [a] phenoxazinium chlorides are interesting alternatives to the available commercial dyes. Changes in the substituents of these compounds can tailor both their staining specificity and antimicrobial activity., Thanks are due to the Fundacao para a Ciencia e Tecnologia (FCT, Portugal) for financial support to the NMR portuguese network (PTNMR, Bruker Avance III 400-Univ. Minho), FCT and FEDER (European Fund for Regional Development)-COMPETE-QREN-EU for financial support to Research Centres CQ/UM [PEst-C/QUI/UI0686/2013 (FCOMP-01-0124-FEDER-037302)], CBMA (project PEst-OE/BIA/UI4050/2014, and UID/BIA/04050/2019) and CFUM [PEst-C/FIS/UI0607/2011(F-COMP-01-0124-FEDER-022711)]. Post-doctoral grant to B. R. Raju (SFRH/BPD/62881/2009) is also acknowledged to FCT, POPH-QREN, FSE. We are also thankful to J. Nosek from the Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Slovakia, for giving the strain S. cerevisiae W303-1A-pDF01-VBA1-YEGFP. To B. Westermann from Department of Biology, Faculty of Biology, Chemistry and Earth Sciences, University of Bayreuth, Germany, for the strain S. cerevisiae W303-1B-pYX232mtGFP. By providing the strain S. cerevisiae BY4741-SEC66-GFP we are thankful to E. O'Shea from Department of Molecular and Cellular Biology, Faculty of Arts and Sciences, Harvard University, Massachusetts, U.S.A. Finally, we would like to acknowledge to P. Coutinho from the Department of Physics, School of Sciences, University of Minho, Portugal, for kindly provide the salmon sperm DNA used in this work.

Surface-Enhanced Raman Scattering (SERS) performance of filter paper (FP) loaded with gold nanoparticles (Au NPs) of three different size/shapes (spherical, triangular and star) were investigated. Spherical Au NPs were synthesized using femtosecond laser ablation of Au target in distilled water and other two anisotropic (triangular and star-shaped) Au NPs were prepared by colloidal chemical methods. COMSOL Multiphysics simulations were performed to investigate near field distributions of these Au NPs and as expected, the strongly enhanced near-field intensity at the sharp features was observed. The SERS performance [using the dye molecule Nile Blue (NB)] of star-shaped Au NPs loaded FP was superior compared to the triangle and spherical Au NPs loaded FP due to the presence of sharp tips and thus it was proved to be capable of detecting 10 pM NB concentration with an estimated enhancement factor of ∼3.7×1010.

Nanostructured hybrid thin films of crystalline CuSCN and fluorescent cationic dyes; Rhodamine B (RB), Nile Blue A (NB) and 4-(N,N-dimethylamino)-4'-(N'-methyl)stilbazolium (DAS) were obtained by electrochemical self-assembly from a single pot containing all the chemical ingredients. Concerted functionalities achieved by the intimate interaction between CuSCN and dye was studied for photoluminescence (PL) behavior between 77 and 298 K. PL from RB and NB was totally quenched when they were hybridized with CuSCN, due to hole transfer from the dye excited state to the valence band of CuSCN, potentially indicating their use as light absorber in solar cells and photodiodes. On the contrary, that of DAS was not quenched despite of its favorable HOMO position for the hole transfer. Crystalline DAS salt with tosylate (DAST) exhibited a strong exciton-phonon coupling to weaken, broaden and red-shift PL at room temperature, so that it inversely is strongly enhanced, sharpened and blue-shifted at 77 K. The PL of the same chromophore in the hybrid thin film, however, shows a slight red-shift and only moderate enhancement at reduced temperature, due to exciton stabilization and energy transfer from CuSCN to DAS luminophore, making it a unique nearly temperature-independent luminescent material.

Halophilic microorganisms thrive at elevated concentrations of sodium chloride up to saturation and are capable of growing on a wide variety of carbon sources. Hence, the biotechnological application of these microorganisms can cover many aspects one of these is bioplastic production. Biodegradable plastics are plastics that are decomposed by the action of living organisms using bacteria. Biodegradable plastic is a renewable biopolymers synthesized in bacteria having similar characteristics of plastics produced from petroleum character. In the following work preisolated halophilic strains were screened for PHB production. The positive strains were subjected to PHB production. Estimation of PHB was done by using UV spectrophotometer and FTIR. Highest PHB producing strain was further used for optimization of different parameters for PHB production.

Aims (i) To analyse the increase in calcium ion uptake caused by several cationic dyes on Candida albicans, (ii) to postulate a mechanism, (iii) to define the effects of Zn ions on the phenomenon, and (iv) to propose the use of the dyes or their derivatives against C. albicans. Methods and results Cells were grown in yeast peptone dextrose medium and starved. We measured the hydrophobic solvent/water partition coefficients and the dyes uptake by the cells and found no correlation with their hydrophobicity. Most of the dyes caused an increase in K+ efflux (in correlation with a decrease in 86 Rb+ uptake), and a raise in Ca2+ uptake except for those used as Zn salts, but not of their HCl salts. Respiration and acidification of the medium were modified only with few dyes and interestingly, when exposing cultures to nile blue, neutral red and toluidine blue ZnCl2 a decrease in C. albicans growth was observed. Conclusions We propose a general mechanism for the stimulation of Ca2+ uptake by the dyes used. Some of the dyes tested might be used as agents against C. albicans, probably combined with other agents. Moreover, the effects of Zn ions on Ca2+ uptake and on cell growth open possibilities of further studies, not only of their effects, but also of the mechanism of Ca2+ transport in C. albicans and other yeasts. Significance and impact of the study This study, in conjunction with previously published results, contribute to the basic research regarding ion transport in C. albicans and the role of zinc in this process. Besides, suggests the additional use of dyes, along with other antifungals agents, as combined therapy against candidiasis. Derived dyes from those used also might be possible therapeutic agents against this disease.

We report on the improved stability and yield of silver nanorods with well controlled aspect ratios synthesized using a modified seed mediated approach conducted at room temperature. It is found that the longitudinal surface plasmon resonance of these nanoparticles can be tuned in the spectral range 400–700 nm by varying the concentration of seed particles. The surface enhanced Raman scattering (SERS) activity of these nanorods with varying aspect ratios was tested with four dye molecules viz., crystal violet, malachite green, nile blue chloride and rhodamine-6G, using visible and near-infrared laser excitation sources viz., 514.4 and 784.8 nm, respectively. The mechanism of enhancement for the dye molecules adsorbed on these nanorods was investigated in detail. A maximum enhancement factor in the order of 108 was obtained when factors such as the peak wavelength corresponding to the plasmon of the nanorods, the absorption of dye and the excitation line were in close approximation. The linearity obtained in the calibration curves drawn for intense Raman peaks in the SERS spectra of different dye molecules indicated that these substrates are suitable for applications such as biosensing. Keywords: Silver nanorods, Seed mediated synthesis, Surface enhanced Raman scattering, Crystal violet, Malachite green, Nile blue chloride, Rhodamine 6G

Azo dyes and herbicides are significant environmental contaminants which are characterized by the presence of one or more azo bonds (−N=N−) and aromatic species in their structure. The aim of present work is to use inexpensive and environmentally friendly nanocomposite as an adsorbent. Double-oxidized graphene oxide (GO) sheets are coated by polydopamine to adsorb the studied pollutants Nile blue (NB) and Paraquat (PQ) from wastewater. Characterizations of the synthesized GO coated with polydopamine were investigated by several techniques such as FT-IR, FE-SEM, XRD, adsorption isotherm. The effect of solution initial pH, initial concentration, and contact time was investigated. Results indicate that adsorption capacity in ambient temperature could reach 131.58, 101.01 mg/g for Nile blue and Paraquat, respectively. The efficiency of Langmuir isotherm model for these pollutants was acquired from the equilibrium adsorption data. Indeed, based on the experimental results, the possible adsorption mechanism was also suggested.

Rice husk was utilized as a silica source for the synthesis of mesoporous silica (MS), which was further used for the surface modification of iron oxide nanoparticles (IO-NPs) to form mesoporous silica-modified iron oxide nanoparticles (MSIO-NPs). IO-NPs and MSIO-NPs were characterized using FT-IR, XRD, X-ray photoelectron spectroscopy, vibrating sample magnetometry, nitrogen adsorption–desorption, TEM and dynamic light scattering analysis. The catalytic activity of MSIO-NPs was tested for degradation and mineralization of Nile blue sulphate dye (NBS) in Fenton-like oxidation process. The degradation efficiency and total organic carbon (TOC) removal of NBS dye onto MSIO-NPs was found to be 92.46 and 66.58%, respectively, after 20 min of reaction time using 5 mM of H2O2 concentration. Modified generalized kinetic model was developed for TOC removal of dye degradation onto MSIO-NPs, to account for oxidizable compounds, non-oxidizable compounds, and intermediate organic compounds. The intermediate products formed during degradation of NBS dye were detected by LC–MS experiment and ten fragments were identified based on mass to charge ratio (m/z). The mechanistic pathway for degradation of NBS dye onto MSIO-NPs has been proposed.

The formation of silver nanostructures (AgNSs) with different crystals morphology in porous SiO2/p-Si templates by the electroless wetchemical method at temperatures between 20 and 50 °C and surface-enhanced Raman scattering (SERS) was investigated. It was found that optimized dendritic silver architectures contain a significant number of localized “hot spots.” We show that well-reproducible AgNSs provide a significantly enhanced Raman signal of Nile blue dye molecules up to 10−6 M by using different excitation wavelengths (473, 532, and 633 nm). Based on our observations, the well-organized AgNSs can act as efficient surfaces for SERS as well as (bio)-sensor applications.

A microspheres-based microbial optosensor for NO 2 − ion quantitation was constructed by using immobilized Raoutella planticola ( R. planticola ), the bacterium expressing NAD(P)H nitrite reductase (NiR) enzyme, which was isolated from local edible bird’s nest (EBN) via microbial technique. The whole cells and the lipophilic Nile Blue chromoionophore (NBC) were physically adsorbed on the self-adhesive photocurable poly( n -butyl acrylate-co- N -acryloxysuccinimide) [poly(nBA-NAS)] microspheres, whilst the reduced co-enzyme NAD(P)H was covalently immobilized on the succinimide-functionalized acrylic microspheres via peptide link to produce a reagentless nitrite biosensing system. As the microbial bio-optode responded to nitrite through colour change from blue to pink, a facile reflectometric approach was adopted to measure reflectance intensity at 639 nm, before and after reaction with nitrite at optimum pH 8. The optosensor could quantify NO 2 − ion concentration within a dynamic linear response range of 0.5–400 mg L −1 with a limit of detection (LOD) of 0.2 mg L −1 . The large surface area to volume ratio of the acrylic microspheres allowed solid-state diffusional mass transfer of the substrate to occur at micro-bio-optode surface, and an equilibrium response was achieved within 5 min. The practical feasibility of using the bio-optode for nitrite assay in food matrix sample showed good agreement with standard ion chromatography method.

Present communication reports the effect of amphiphilic matrices and nano-clay platelets on the aggregation properties of a water soluble cationic fluorescent dye Nile Blue Chloride (NBC) in Langmuir-Blodgett (LB) films. In-situ Brewster Angle Microscopic (BAM) studies showed distinct domain structures of complex and hybrid Langmuir monolayer at the air-water interface. UV–vis absorption spectra showed non-fluorescent H-dimeric band in concentrated aqueous solution of NBC and in complex LB film of NBC with stearic acid. By changing various parameters, a great control over H-dimeric states has been achieved in clay incorporated hybrid LB films. These films can act as efficient fluorescence probe.

An efficient SERS substrate composed of gold nanocone arrays with abundant sharp tips directly grown on 3D porous Ni foam (AuNCA@Ni foam) was developed for sensitive detection of aromatic dyes. The AuNCA@Ni foam was prepared by a facile galvanic replacement reaction between Ni foam and HAuCl4 in the presence of cetyltrimethylammonium bromide (CTAB). The concentration of CTAB played an important role in determining the morphology of the product. Without CTAB or replacing CTAB with other surfactants, no AuNCA could be obtained. Thanks to the abundant uniform sharp tips and 3D porous structure, the AuNCA@Ni foam displayed much stronger SERS enhancement ability and higher reproducibility for aromatic dye detection compared with substrates prepared in the absence of CTAB or in the presence of other surfactants. Moreover, the AuNCA@Ni foam with the robust integrated structure also avoided the tedious operation of assembly and centrifugation. The SERS application of the AuNCA@Ni foam was tested by the detection of aromatic dyes crystal violet (CV) and Nile blue (NB), which achieved a detection limit (LOD) of 0.03 nM and 0.5 nM in standard solution, respectively, and an LOD of 3 nM for determining CV in real water samples.

The synthesis and characterisation of a novel dual stimuli-responsive nanogel, based on thermoresponsive N-n-propylacrylamide and an L-proline based monomer acting as a pH-switcher, is reported here. The effect of the crosslinker/co-monomer ratios was studied to demonstrate the relationship between the chemical structure, degree of hydrophobicity and physico-chemical characteristics of the nanogels. Tailoring of the thermoresponsive properties was achieved by altering crosslinker N,N′-methylenebis(acrylamide) content between 10 and 50 mol%, in combination with three thermoresponsive monomers N-n-isopropylacrylamide, N-n-propylacrylamide and N-acryloylpyrrolidine. A library of 25 different combinations of monomers and crosslinkers was obtained and characterised by dynamic light scattering and UV-Vis spectroscopy. The nanogel based on N-n-propylacrylamide and 10 mol% crosslinker was then co-polymerised with an L-proline based monomer to introduce a pH-switch. This nanogel was obtained with

The focus of the present work is to investigate the interaction of NBC with DNA and also to study the control of aggregation of NBC in solution as well as in LBL film by incorporating DNA. Nile Blue, a benzophenoxazine class of dye, is a well-known DNA binding probe. DNA can organize various organic molecules because it has a characteristic structure, such as the double strand with hydrogen bondings and molecules can intercalate into the stacking base pairs. On the other hand benzophenoxazine class of dyes exhibit relatively low systemic toxicity and some of them retard tumour growth. Compared to other conventional intercalators, the use of NBC has a merit of having low toxicity and comparable sensitivity for DNA quantification. UV-Vis absorption spectroscopic and fluorescence spectroscopic techniques have been employed to study the formation and control of aggregation in ultrathin films.

In this work, a sensitive three-signal assay of perfluorooctanesulfonic acid (PFOS) was proposed. In pH 3.3 Britton–Robinson (BR) buffer solution, perfluorooctane sulfonate anions can react with Nile blue A (NBA) through electrostatic attraction and hydrophobic force to form 1 : 1 ion-association complexes resulting in intensity changes in the fluorescence, UV-vis absorption and resonance light scattering (RLS). There was found to be a certain relationship between the three signal changes dependent upon the concentration of PFOS. The change of absorption of NBA is proportional to the logarithm of the concentration of PFOS in the range of 0.1–4.0 μmol L−1 with a limit of detection (LOD) of 14.8 nmol L−1, and RLS intensity change is proportional to the concentration of PFOS in the range of 2.0–12.0 μmol L−1 with a LOD of 119.5 nmol L−1 and the change in the fluorescence is proportional to the logarithm of the concentration of PFOS in the range of 0.05–4.0 μmol L−1 with a LOD of 3.2 nmol L−1. Scanning electron microscopy (SEM) and zeta potential measurements were recorded in order to study the mechanism. This simple, sensitive and cost-effective fluorescence method was successfully applied in the determination of PFOS in real water samples with RSD values of ≤2.14%.

Polyhydroxyalkanoates (PHAs) are the most promising alternatives to petroleum-derived polymers. The present study focuses on PHA synthesis by a new wild-type bacterial strain using lactose as a carbon source. Staining microbial cells with Sudan Black B (SBB) and Nile Blue A (NBA) yielded positive PHA granules. Bacillus tequilensis ARY86 was identified using 16S rRNA gene sequence analysis and deposited in the NCBI GenBank database. ARY86 showed a maximum yield of PHA 62% (w/w) by using 2% lactose and 0.5% nitrogen (C/N ratio of 8:1) at 30 °C and pH 7 as optimal conditions. The extracted polymer was characterized using FTIR and GC–MS to observe the functional groups in PHA. The DSC and XRD analysis to investigate thermal properties and crystalline nature of PHA respectively. The melting point was found to be 174.5 °C while the degree of crystallinity was 43.7%–45.7%, indicating the Scl-co-mcl PHA structure that offers a wide range of applications.

Artificially mimicking ageing of an equilibrium catalyst (ECAT) is an effective strategy to model the deactivation of a Fluid Catalytic Cracking (FCC) catalyst during refinery operations. Herein, we have used a correlative microscopy approach to unravel inter-particle spatial heterogeneities in artificially deactivated catalysts (DCATs) and compared them with a real-life ECAT containing on average 3800 ppm of Ni and 2300 ppm of V, and a set of density separated ECAT fractions. By doing so we could rationalize the effect of metal contaminants on catalyst acidity and pore accessibility. More specifically, the Fe, Ni, and V distributions were obtained using X-Ray Fluorescence (XRF), while Confocal Fluorescence Microscopy (CFM) after thiophene and Nile Blue A staining, respectively provided a visualization of Bronsted acid sites and accessibility distribution. We found that not only the metal poisons distribution, but also hydrothermal degradation, that affects ECATs dealumination and related acidity drop, need to be properly reproduced by artificial catalyst deactivation protocols. Fe contamination must also be taken into account since it affects matrix accessibility.

High Lactate Dehydrogenase (LDH) activity, a distinct feature of cancer cells, is a possible causative factor for cancer cells to metastasize, infiltrate, invade, and deteriorate. The exploration of upconversion hybrid nano fluorescent sensor (HNFS) with the capability of evaluation the LDH inhibitors efficacy will be useful to accelerate the development of anti-cancer drugs from LDH inhibitors. Herein, we design an HNFS that can evaluate the inhibitors efficacy in vitro from the changes of the upconversion luminescence in the red-light region. HNFS is composed of two components: a Nile Blue A derivative (CPNB) that detects LDH activity, and tailored manganese doped upconverting nanoparticles that produce bright red emission which absorbs by CPNB via Forster resonance energy transfer. The cytotoxicity of HNFS in living cells (HeLa, A549 and Ges-1) was investigated by using the CCK-8 assay, which showed that HNFS possesses excellent biocompatibility. After incubating HNFS with three types of cells (A549, HeLa, and Ges-1), the mean fluorescence intensities of confocal images in vitro can illustrate the efficacy of LDH inhibitors to different cancer cells and distinguish healthy cells (Ges-1) from cancer cells (A549 and HeLa). Therefore, the systematic study of HNFS in vitro does encourage the potential applications of evaluating the LDH inhibitors efficacy in cancer cells.

Cationic dyes are widely used colorants in textile and other related industries. These dyes are highly toxic for marine life and make a major fraction of the industrial effluents. In this study, we report the synthesis of ester derivative of calix[4]arene (EDC) impregnated polymer inclusion membrane (PIM) and employed it for the transfer of cationic dyes between two aqueous phases. EDC forms inclusion complex with cationic dyes having 1:1 M ratio as revealed by the Job’s plot, the log/log plot, and the Benesi-Hildebrand methods while using methylene blue (MB) as a model cationic dye. EDC was used as carrier with cellulose triacetate (CTA) as a base polymer, and 2-nitrophenyl octyl ether (2-NPOE) as a plasticizer for the synthesis of EDC-PIM. Membranes were characterized by Fourier Transform Infrared spectroscopy (FT-IR), Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET), and Barrett-Joyner-Halenda (BJH) analysis. The extraction performance of the synthesized PIM was optimized by varying different external parameters including pH of the donor and the acceptor phases, temperature, stirring speed, and concentration of EDC and dye while using MB as a model cationic dye. More than 90% extraction was achieved under optimized conditions which is 4.5-fold more than EDC-free-PIM. The extraction efficiency of the EDC-PIM remained similar after ten consecutive cycles that demonstrates its reusability potential in context of economical industrial applications. Finally, the synthesized EDC-PIM was used for selective extraction of other cationic dyes (basic red and nile blue) at the optimized conditions from the real industrial effluents. The extraction efficiency of the EDC-PIM was reproducible in all cases. The reusability and robustness of the EDC-PIM makes it an excellent candidate for retrieving cationic dyes from the industrial effluents.