Red Molecules Research Articles

Development of chitosan decorated Fe3O4 nanospheres for potential enhancement of photocatalytic degradation of Congo red dye molecules

Fe3O4 nanospheres (Nsps) and chitosan (Cts)/Fe3O4 Nsps were prepared using a one-pot hydrothermal method and subsequently used as photocatalysts against the degradation of Congo red (CR) dye molecules. The sphere-shaped Fe3O4 nanoparticles were heterogeneously decorated by the Cts matrix, which was confirmed by powder X-ray diffraction, scanning and transmission electron microscopies. The Cts/Fe3O4 Nsps demonstrated 98% efficient photocatalytic activity against CR dye molecules upon 60 min exposure to visible light compared to Fe3O4 Nsps (77% for 60 min). When compared to Fe3O4 Nsps, the visible light photocatalytic efficiency of Cts/Fe3O4 Nsps against CR dye molecules was significantly improved.

Experimentally and theoretically approaches for Congo red dye adsorption on novel kaolinite-alga nano-composite

ABSTRACT A comprehensive study combining experimental, computational, and field experiments was conducted to find out the most suitable catalysis method to assist industries using Congo red dye to get rid of this waste from industrial wastewater in Beni-Suef area. The adsorption potential of kaolinite, Liagora farinose (Egyptian marine macroalgae) and kaolinite modified by Liagora farinose macroalgae assessed for the removal of Congo red dye from aqueous solutions. The kaolinite/alga nano-composite with a crystal size of 40 nm was fabricated using a wet impregnation technique. Our results indicate that surface modification of kaolin with Liagora farinose results in an obvious increase in adsorption of toxic dye for nano-composite than individuals. Batch experiments were applied and both kinetics and isotherms of Congo red dye adsorption were also explored in order to find out the influence of different experimental factors. Congo red removal percentage is highly affected by adsorbent dose, working temperature, and pH value. The best temperature for Congo red adsorption onto kaolinite/alga nano-composite is 40°C at pH > 7. The maximum adsorption capacities were found to be 5.0, 7.0 and 10 mg/g for kaolinite, alga and kaolinite/alga nano-composite, respectively. Computational simulations studies have shown that the adsorption of the Congo red molecule on Kaolinite surfaces is exothermic, energetically favourable and spontaneous. Congo red adsorption on kaolinite/alga nano-composite is well handled with the first-order diffusion model, while kaolin and Liagora farinose follow two different kinetic adsorption models depending on the Congo red dye concentration. Finally, the field tests showed optimistic results with nearly 94% efficiency for kaolinite/alga nano-composite in removing mixed dyes from industrial wastewater, which in turn verified the foundation of new eco-friendly nano-adsorbents to help reuse industrial wastewater.

N-Phenylcarbazole substituted bis(hexylthiophen-2-yl)-benzothiadiazoles as deep red emitters for hole-transporting layer free solution-processed OLEDs

Two structural isomers of donor-π-acceptor-π-donor (D-π-A-π-D) type red light-emitting molecules (C3TBz and C4TBz), comprising N-phenylcarbazole as a donor, 2,1,3-benzothiadiazole as an acceptor, and either 3-hexylthiophene or 4-hexylthiophene as π-linkages, respectively, were designed and synthesized as hole-transporting emissive materials for OLEDs. C3TBz and C4TBz were chemically characterized, and their photoelectric properties were investigated by spectroscopy, electrochemical and theoretical studies. They showed strong D-A characteristics with intense deep red fluorescence in solutions, decent hole-transporting ability, good thermal and electrochemical stabilities. Both materials were successfully employed as emitters in the solution-processed double-layered OLEDs, which resulted in a pure red emission with promising device performance. Notably, the C3TBz-based device reached the best EL results with a maximum brightness of 2557 cd m−2, a maximum EQE of 3.08%, a maximum luminance efficiency of 4.87 cd A−1, and a low turn-on voltage of 3.2 V.

Molecular design strategy for orange-red thermally activated delayed fluorescence emitters via intramolecular energy transfer and their application in solution processable organic light-emitting diodes

Realizing effective orange-red/red emission is still far behind blue and green emission in thermally activated delayed fluorescence (TADF) materials. In this context, a novel strategy for achieving efficient orange-red/red TADF emitters is proposed via intramolecular energy transfer by encapsulating the red-emitting core with a blue emitting chromophore. Two novel compounds called TS-1 and TS-2 were prepared and characterized, in which two blue TADF emitting units are used as the end groups and a red TADF emitter as the molecular core (TA). Both compounds show clear TADF character with red emission at 655 nm in a neat film, suggesting an effective intramolecular energy transfer from the blue chromophores to the red one. Both TS-1 and TS-2 present higher photoluminescence quantum yields (70–90%) than the TA core (42%) due to the encapsulation and energy transfer. Solution-processable organic light-emitting diodes (OLEDs) exhibit a maximum external quantum efficiency of ∼13% for compound TS-1, much higher than that of TA-based OLEDs (2.3%). This research is the first example for red TADF emitter via intramolecular energy transfer, which clearly provides an effective method for designing highly efficient red TADF molecules.

Electrophoretic mobility shift as a molecular beacon-based readout for miRNA detection

MicroRNAs are short, non-coding RNA sequences involved in gene expression regulation. Quantification of miRNAs in biological fluids involves time consuming and laborious methods such as Northern blotting or PCR-based techniques. Molecular beacons (MB) are an attractive means for rapid detection of miRNAs, although the need for sophisticated readout methods limits their use in research and clinical settings. Here, we introduce a novel method based on delayed electrophoretic mobility, as a quantitative means for detection of miRNAs-MB hybridization. Upon hybridization with the target miRNAs, MB form a fluorescent duplex with reduced electrophoretic mobility, thus bypassing the need for additional staining. In addition to emission of light, the location of the fluorescent band on the gel acts as an orthogonal validation of the target identity, further confirming the specificity of binding. The limit of detection of this approach is approximately 100 pM, depending on the MB sequence. The method is sensitive enough to detect specific red blood cell miRNAs molecules in total RNA, with single nucleotide specificity. Altogether, we describe a rapid and affordable method that offers sensitive detection of single-stranded small DNA and RNA sequences.

Label-Free Ratiometric Upconversion Nanoprobe for Spatiotemporal pH Mapping in Living Cells.

Sensing and imaging pH inside living cells are of paramount importance for better penetrating cellular functions and disease diagnostics. Herein, we engineered an original pH sensor by a simple one-step self-assembly of poly(ethylene glycol) (PEG)ylated phospholipid (DSPE-PEG) and a phenol red small molecule on the surface of upconversion nanoparticles (UCNPs) to form a phospholipid monolayer for sensing and imaging the change of intracellular pH. The sensor showed excellent reversibility and rapid response to the pH variations. Furthermore, this pH sensing system could measure spatial and temporal pH changes during endocytosis and interrogate the pH fluctuations inside cells under external stimuli. Our experimental results revealed that the pH sensor was able to map spatial and temporal pH fluctuations inside living cells, showing its potential application in diagnostics and pH-related study of cell biology.

Quantum chemical studies and electrochemical investigations of pyrogallol red modified carbon paste electrode fabrication for sensor application

In order to develop a sensing platform, it is very important to understand the sensing mechanism of the modified electrode by locating the redox reactive sites of the modifier, for this better understanding we used the density functional theory (DFT)-based quantum chemical modelling to explain the redox reactive sites of the pyrogallol red molecule. The pyrogallol red was later used to modify the carbon paste electrode by electropolymerisation technique for sensing applications. The real analytical applicability of the proposed sensor was evaluated by employing it to the analysis of pharmaceutical sample and a good recovery results were obtained. According to the experimental results, a high reactivity performance is observed at the fabricated electrode for the paracetamol (PRM) electro-oxidation involving the transfer of identical number of electrons and protons. The lower limit of detection (LOD) was 0.11 μM by differential pulse voltammetric (DPV) method in the linear range of 5.0 µM − 45.0 µM was obtained. The real analytical applicability of the proposed method is valid for the pharmaceutical analysis in presence of possible excipients suggested that the fabricated electrode is a promising sensing platform. The methodology adopted in the present work can be extended to construct the electrochemical sensor for other electroactive molecules also.

Utilization of Ag2O–Al2O3–ZrO2 decorated onto rGO as adsorbent for the removal of Congo red from aqueous solution

The water resources contamination in an alarming concern for sustainable environment. This has led to development of new technologies and materials for waste water detoxification. In the present study, we have fabricated novel trimetallic based mixed oxides decorated reduced graphene oxide (rGO) composite using facile microwave method and utilized it as an adsorbent for the removal of congo red dye from aqueous solution. The final composite showed highly agglomerated metal oxides present on the rGO surface. The high surface area and activity of the synthesized adsorbent resulted in its high adsorption capacity of 333.32 mg/g for congo red. The Langmuir model better explained the isotherm data indicating the monolayer adsorption of congo red molecules onto Ag2O–Al2O3–ZrO2/rGO surface. The grander adsorption ability of Ag2O–Al2O3–ZrO2/rGO towards organic dye indicate its probable utilization in the removal of other dyes also from wastewater.

Computational modeling – an approach to the development of blood grouping reagents

ABSTRACT Introduction: Blood group antigens are defined by an immune response that generates antibodies against a red blood cell molecule. Antibodies against these antigens can be associated with hemolytic transfusion reactions. However, difficulties can arise when developing antibodies against antigens through the use of peptide sequences alone. Three-dimensional representations (models) of the molecular structure of antigen-bearing proteins can provide valuable insights into tertiary structures and their consequent antigenicity. This can be achieved through predictive computational modeling to produce both structural and molecular dynamics models of blood group proteins. Areas covered: Authors discuss the use of molecular dynamic simulations on existing structures, as well as the use of computational modeling techniques in the development of protein models lacking preexisting data. Finally, the authors discuss specific examples of the use of computationally derived models of the MNS blood group system and its use in attempts to produce antibodies against MNS proteins. Expert opinion: Although in silico techniques have limitations, computer-based predictive models can inform the direction of research into blood group proteins. It is to be expected that as computer-based techniques grow more powerful these contributions will be even more significant.

Optical Sensor-Based Molecular Imprinted Poly(Hydroxyethyl Methacrylate-N-Methacryloyl-(L)-Histidine Methyl ester) Thin Films for Determination of Tartrazine in Fruit Juice

In this study, a selective, rapid and sensitive surface plasmon resonance (SPR) sensor is prepared for real time detection of tartrazine in fruit juice. Tartrazine imprinted and non-imprinted poly(hydroxyethylmethacrylate-N-methacryloyl-(L)-histidine methyl ester) thin films are synthesized onto SPR chip surface using ultraviolet polymerization. The characterization studies of tartrazine imprinted and non-imprinted SPR sensors are performed with contact angle measurements, atomic force microscopy and ellipsometry. Then, kinetic studies for tartrazine are carried out in the concentration range of 0.5-100.0 μM. The response time for adsorption, desorption and regeneration cycles is approximately about 15 min for the optical sensor system. The limit of detection and quantification are obtained as 0.0076 μM and 0.0252 μM, respectively. The selectivity studies of the tartrazine imprinted and non-imprinted SPR sensors are determined in the presence of allura red and sunset yellow molecules. In order to demonstrate the applicability, validation studies of tartrazine imprinted SPR sensor are performed by liquid chromatography-tandem mass spectrometry (LC-MS).

Microfluidic Integrated Organic Electrochemical Transistor with a Nanoporous Membrane for Amyloid-β Detection.

Alzheimer’s disease (AD) is a neurodegenerative disorder associated with a severe loss in thinking, learning, and memory functions of the brain. To date, no specific treatment has been proven to cure AD, with the early diagnosis being vital for mitigating symptoms. A common pathological change found in AD-affected brains is the accumulation of a protein named amyloid-β (Aβ) into plaques. In this work, we developed a micron-scale organic electrochemical transistor (OECT) integrated with a microfluidic platform for the label-free detection of Aβ aggregates in human serum. The OECT channel–electrolyte interface was covered with a nanoporous membrane functionalized with Congo red (CR) molecules showing a strong affinity for Aβ aggregates. Each aggregate binding to the CR-membrane modulated the vertical ion flow toward the channel, changing the transistor characteristics. Thus, the device performance was not limited by the solution ionic strength nor did it rely on Faradaic reactions or conformational changes of bioreceptors. The high transconductance of the OECT, the precise porosity of the membrane, and the compactness endowed by the microfluidic enabled the Aβ aggregate detection over eight orders of magnitude wide concentration range (femtomolar–nanomolar) in 1 μL of human serum samples. We expanded the operation modes of our transistors using different channel materials and found that the accumulation-mode OECTs displayed the lowest power consumption and highest sensitivities. Ultimately, these robust, low-power, sensitive, and miniaturized microfluidic sensors helped to develop point-of-care tools for the early diagnosis of AD.

Structure and Location of Protein Sites Binding Self-Associated Congo Red Molecules with Intercalated Drugs as Compact Ligands-Theoretical Studies.

In the search for new carriers capable of transporting toxic drugs to a target, particular attention has been devoted to supramolecular systems with a ribbon-like micellar structure of which Congo red is an example. A special promise of the possible use of such systems for directing drugs to a target emerges from their particular affinity to immune complexes and as an independent property, binding many organic compounds including drugs by intercalation. Serum albumin also appeared able to bind micellar particles of such systems. It may protect them against dilution in transport. The mathematical tool, which relies on analysis of the distribution of polarity and hydrophobicity in protein molecules (fuzzy oil drop model), has been used to find the location of binding area in albumin as well as anchorage site for Congo red in heated IgG light chain used as a model presenting immunoglobulin-like structures. Results confirm the suggested formerly binding site of Congo red in V domain of IgG light chain and indicated the cleft between pseudo-symmetric domains of albumin as the area of attachment for the dye.

Effective and selective removal of organic pollutants from aqueous solutions using 1D hydroxyapatite-decorated 2D reduced graphene oxide nanocomposite

The efficient and selective removal of toxic dye molecules from water/surface water remains a problematic task, owing to their high water solubility and low biodegradability. We fabricated the hydroxyapatite-decorated reduced graphene oxide (HA@rGO) nanocomposites via a simple hydrothermal process and used them as efficient adsorbents for the diazo dyes removal. In the batch experiments, the resultant HA@rGO nanocomposites exhibited fast and excellent removal performance for Trypan blue and Congo red dye molecules in a wide pH range and the maximum adsorption efficiencies of 146.51 and 150.09 mg/g, respectively. Several characterization analysis results demonstrated that the removal performance of the HA@rGO nanocomposites for the toxic dyes was mainly driven by electrostatic, hydrophobic, π–π interactions, and H-bonding between the adsorbents and dye molecules in the aqueous solution. Ubiquitous co-anions have significant influence on the dye removal performance of the HA@rGO nanocomposites because of the higher ionic radius and electronegativity. After adsorption, the exhausted HA@rGO nanocomposites could be regenerated in alkaline solution and reused throughout five successive adsorption–desorption cycles. We believe that the adsorbent fabricated in this work can be effectively used to remove toxic diazo dye molecules from aqueous media.

Application of cationic-nonionic surfactant based nanostructured dye carriers: Mixed micellar solubilization

Most of organic compounds being hydrophobic in nature are insoluble or sparingly soluble in water. The improvement in solubility is one of the major challenges in their industrial applications. Said issue can be addressed using micellar solutions of surfactants. Surfactants, owing to their inherent amphiphilic nature, have invited the interest of many researchers. It has, however, been observed that the stability and solubilizing capability of a single surfactant-based colloidal system is not up to the mark. To overcome this problem, we have formulated and applied composite micelles of CTAB/TX-100 and CPC/TX-100 as carriers of direct red 28 molecules to aid dispersion, solubility and stability of the dye in aqueous medium. Herein, thermodynamics of micellization and degree of the dye partitioning have been quantified conductometrically and spectroscopically. Results suggest that blend of different surfactants act synergistically to augment the dye partitioning. Furthermore, it has also been noted that micellization of surfactants, counterion binding and the dye partitioning are spontaneous processes.

Multiscale structure enabled effective plasmon coupling and molecular enriching for SERS detection

Surface enhanced Raman scattering (SERS), as a molecular-specific spectroscopy method using plasmonic nanostructures to significantly enhance Raman spectroscopy, has broad application prospects in various fileds. In our work, the Ag/CuO nanowires (NWs)/pyramidal PDMS multiscale structure were rationally fabricated as a multi-dimensional plasmon coupling SERS substrate with molecular enrichment effect. CuO NWs were grown in the pyramid cavity by alkaline etching and formed micro-nano multiscale strucure. The Ag film was decorated on the nano-micro multiscale structure by physical vapor deposition method, endowing the SERS activity. The subwavelength-size Ag/CuO NWs can also provide a rough enough surface to separate the droplets from the air, reduce the surface energy, and achieve a hydrophobic effect. To demonstrate the SERS activity, the proposed multiscale micro-nano structure has been successfully applied to sensitively detect Rhodamine 6G (R6G) at low concentration. Interestingly, we also demonstrate that the Ag/CuO NWs/pyramidal PDMS multiscale structure has excellent molecular adsorption for practical application detection. We successfully achieve the detection for the mixture of R6G, Crystal Violet (CV) and Congo Red (CR) molecule under turbid and different PH environment, which demonstrates its great potential for in-situ detection of chemical dye molecules in complex environments.

Managing Locally Excited and Charge-Transfer Triplet States to Facilitate Up-Conversion in Red TADF Emitters That Are Available for Both Vacuum- and Solution-Processes.

Developing red thermally activated delayed fluorescence (TADF) emitters for high-performance OLEDs is still facing great challenge. Herein, three red TADF emitters, pDBBPZ-DPXZ, pDTBPZ-DPXZ, and oDTBPZ-DPXZ, are designed and synthesized with same donor-acceptor (D-A) backbone with different peripheral groups attaching on the A moieties. Their lowest triplet states change from locally excited to charge transfer character leading to significantly enhance reverse intersystem crossing process. In particular, oDTBPZ-DPXZ exhibits efficient TADF feature and exciton utilization. It not only achieves an external quantum efficiency (EQE) of 20.1 % in red vacuum-processed OLED, but also realize a high EQE of 18.5 % in a solution-processed OLED, which is among the best results in solution-processed red TADF OLEDs. This work provides an effective strategy for designing red TADF molecules by managing energy level alignments to facilitate the up-conversion process and thus enhance exciton harvesting.

Managing Locally Excited and Charge‐Transfer Triplet States to Facilitate Up‐Conversion in Red TADF Emitters That Are Available for Both Vacuum‐ and Solution‐Processes

AbstractDeveloping red thermally activated delayed fluorescence (TADF) emitters for high‐performance OLEDs is still facing great challenge. Herein, three red TADF emitters, pDBBPZ‐DPXZ, pDTBPZ‐DPXZ, and oDTBPZ‐DPXZ, are designed and synthesized with same donor–acceptor (D‐A) backbone with different peripheral groups attaching on the A moieties. Their lowest triplet states change from locally excited to charge transfer character leading to significantly enhance reverse intersystem crossing process. In particular, oDTBPZ‐DPXZ exhibits efficient TADF feature and exciton utilization. It not only achieves an external quantum efficiency (EQE) of 20.1 % in red vacuum‐processed OLED, but also realize a high EQE of 18.5 % in a solution‐processed OLED, which is among the best results in solution‐processed red TADF OLEDs. This work provides an effective strategy for designing red TADF molecules by managing energy level alignments to facilitate the up‐conversion process and thus enhance exciton harvesting.

Red Algal Molecules - Synthesis of Methyl Neo-β-carrabioside and Its S-Linked Variant via Two Synthetic Routes: A Late Stage Ring Closure and Using a 3,6-Anhydro-d-galactosyl Donor.

Methyl neo-β-carrabioside has been synthesized for the first time, employing either a late stage ring closure to install the required 3,6-anhydro-bridge or a suitable 3,6-anhydro-galactosyl donor to form the unfavored 1,2-cis-equatorial α-linkage. Using the late stage ring closure approach, an S-linked analogue of methyl neo-β-carrabioside was also realized. These compounds have applications in the identification and characterization of marine bacterial exo-α-3,6-anhydro-d-galactosidases that have specific activity on red algal neo-carrageenan oligosaccharides, such as those found in both family 127 and 129 of the glycoside hydrolases. In addition a biochemical assay using the synthesized methyl neo-β-carrabioside and the marine bacterial exo-α-3,6-anhydro-d-galactosidase ZgGH129 demonstrates that the minimum substrate unit for the enzyme is neo-β-carrabiose.

Biosynthesis of zinc oxide nanoparticles using leaf extracts of Alchornea laxiflora and its tyrosinase inhibition and catalytic studies

Zinc oxide nanoparticles (ZnO-NPs) were synthesized using a simple, low cost and safe method involving aqueous leaf extracts of Alchornea laxiflora and a zinc precursor salt. The nanoparticles were characterized by ultraviolet-visible (UV–vis), Fourier transform (FT-IR) spectroscopy, Energy dispersive X-ray (EDX), X-ray diffraction (XRD) and Scanning electron microscope (SEM). They were evaluated for their potentials as tyrosinase inhibitors and as catalysts in the degradation of Congo red dye. The UV–vis spectra gave characteristic surface Plasmon bands within the range 276−456 nm. The band gap energies of the ZnO-NPs were of the range, 2.50–3.67 ev. The SEM results showed average sizes of 29 nm and 38 nm for particles obtained using 1 mL and 2 mL of the plant extracts respectively. EDX plot showed the elemental compositions of the nanoparticles with zinc and oxygen being pronounced. The ZnO nanoparticles exhibited good photocatalytic efficiency of 87 % degradation of Congo red (CR) dye molecules in 60 min, They also showed good anti-tyrosinase ability with an IC50 of 66.28 μg/mL. Overall the biogenic ZnO nanoparticles are promising materials for dual applications as photocatalysts in the degradation of Congo red dye and as tyrosinase inhibitors.

Polarizable Density Embedding for Large Biomolecular Systems.

We present an efficient and robust fragment-based quantum-classical embedding model capable of accurately capturing effects from complex environments such as proteins and nucleic acids. This is realized by combining the molecular fractionation with conjugate caps (MFCC) procedure with the polarizable density embedding (PDE) model at the level of Fock matrix construction. The PDE contributions to the Fock matrix of the core region are constructed using the local molecular basis of the individual fragments rather than the supermolecular basis of the entire system. Thereby, we avoid complications associated with the application of the MFCC procedure on environment quantities such as electronic densities and molecular-orbital energies. Moreover, the computational cost associated with solving self-consistent field (SCF) equations of the core region remains unchanged from that of purely classical polarized embedding models. We analyze the performance of the resulting model in terms of the reproduction of the electrostatic potential of an insulin monomer protein and further in the context of solving problems related to electron spill-out. Finally, we showcase the model for the calculation of one- and two-photon properties of the Nile red molecule in a protein environment. Based on our analyses, we find that the combination of the MFCC approach with the PDE model is an efficient, yet accurate approach for calculating molecular properties of molecules embedded in structured biomolecular environments.