Optical properties of novel luminescent nacre-like epoxy/graphene nanocomposite coating integrated with lanthanide-activated aluminate nanoparticles.

Nacre structure has aragonite polygonal tablets, tessellated to generate separate layers, and exhibits adjacent layers and tablets within a layer bonded by a biopolymer. Here, we report the development of a nacre-like organic/inorganic hybrid nanocomposite coating consisting of epoxy tablets as well as rare-earth-activated aluminate and graphene oxide tablet/tablet interfaces. The lanthanide-activated aluminate was prepared using a high temperature solid-state approach followed by top-down technology to provide the phosphor nanoparticles (PNPs). Graphene oxide nanosheets were prepared from graphite. The prepared epoxy/graphene/phosphor nanocomposites were applied onto mild steel. Covalent bonds were formed between epoxy polymer chains resin and the graphene oxide nanosheets. These interface interactions resulted in a tough surface, high tensile strength, and excellent durability. The use of phosphor in the nanoparticle form guaranteed that no agglomerations were produced throughout the hardening procedure by allowing better distribution of PNPs in the nacre-like matrix. The generated nacre-like substrates displayed reversible fluorescence. The excitation of the white coloured nacre-like coats at 367 nm resulted in a green emission band at 518 nm as designated by the Commission Internationale de l'éclairage (CIE) Laboratory and photoluminescence spectra. Various analysis methods were utilized to inspect the surface structure and elemental composition of the nacre-like coats. An improved hydrophobicity and mechanical characteristics were detected when increasing the phosphor concentration. Due to the astonishing characteristics of the prepared nacre-like composite paint, both ceramics and metals can benefit from the current simple strategy.

Preparation of transparent photoluminescence smart window by integration of rare-earth aluminate nanoparticles into recycled polyethylene waste.

Novel photoluminescent nanocomposite sheets were prepared for simple commercial manufacturing of transparent and luminous photochromic smart windows. A simple physical integration of lanthanide-doped strontium aluminium oxide (LdSAO) nanoparticles into recycled polyethylene (PE) waste produced a smart nanocomposite with persistent phosphorescence and photochromic properties. Because the nanoparticle form of LdSAO is important for developing transparent materials, LdSAO nanoparticles were well dispersed in the PE matrix. Both the morphologies and chemical compositions of the LdSAO nanoparticles and LdSAO-containing luminescent PE sheets were investigated. Both LdSAO-free and photoluminescent PE sheets were colourless in normal daylight. However the LdSAO-containing PE luminescent samples only exhibited a brilliant green colour under ultraviolet (UV) light and a greenish-yellow colour in the dark as verified by Commission Internationale de l'éclairage laboratory parameters. Both absorbance and emission bands were monitored at 377 and 436/517 nm, respectively. The LdSAO-containing PE luminescent sheets were compared with the LdSAO-free sample using both photoluminescence spectroscopy and for their mechanical properties and were found to have improved scratch resistance, UV protection, and superhydrophobic activity. Due to the added LdSAO, photoluminescence, decay, and lifetime spectral tests confirmed its photochromic fluorescence and long-lasting phosphorescence characteristics. The PE@LdSAO nanocomposite sheets displayed UV protection, photostability, hydrophobicity, and excellent durability compared with the blank LdSAO-free PE sheet.

Development of silica-coated rare-earth doped strontium aluminate toward superhydrophobic, anti-corrosive and long-persistent photoluminescent epoxy coating.

Long-persistent phosphorescent smart paints have the ability to continue glowing in the dark for a prolonged time period to function as energy-saving products. Herein, new epoxy/silica nanocomposite paints were prepared with different concentrations of lanthanide-doped aluminate nanoparticles (LAN; SrAl2 O4 :Eu2+ ,Dy3+ ). The LAN pigment was firstly coated with silicon dioxide (SiO2 ) utilizing the heterogeneous precipitation technique to provide LAN-encapsulated between SiO2 nanoparticles (LAN@SiO2 ). The epoxy/silica/lanthanide-doped aluminate nanoparticles (ESLAN) nanocomposite paints were coated on steel. The prepared ESLAN paints were studied by transmission electron microscopy (TEM), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray fluorescence (XRF) analysis, and energy-dispersive X-ray spectroscopy (EDS). The transparency and coloration properties of the nanocomposite coated films were explored by CIE Lab parameters and photoluminescence spectra. The ultraviolet-induced luminescence properties of the transparent coated films demonstrated greenish phosphorescence at 518 nm upon excitation at 368 nm. Both hardness and hydrophobic activities were investigated. The anticorrosion activity of the nanocomposite films coated onto mild steel substrates immersed in aqueous sodium chloride (NaCl(aq) ) (3.5%) was studied by electrochemical impedance spectroscopy (EIS). The silica-containing coatings were monitored to exhibit anticorrosion properties. Additionally, the nanocomposite films with LAN@SiO2 (25%) exhibited the optimized long-lasting luminescence properties in the dark for 90 min. The nanocomposite films showed highly reversible and durable long-lived phosphorescence.

Novel Deliberately Sensitive and Selective Tetrahydrozoline Voltammetric Sensors Integrated with a Copper Oxide Nanoparticle/Zeolite Platform.

The present study introduced a novel disposable screen-printed carbon electrodes (SPCEs) modified with copper oxide/zeolite nanostructures for eco-friendly selective differential pulse voltammetric quantification of tetrahydrozoline (THZ) in eyedrop samples and biological fluids. Modification of the electrode matrix with copper oxide nanoparticles/zeolite nanostructures (CuONPs/ZY) with their effective and synergistic electrocatalytic activity enhanced the electrode performance against electrooxidation of THZ at 0.960 V in BR at pH 9.0 with a diffusion-controlled reaction mechanism. The tentative oxidation mechanism based on molecular orbital calculations postulates the oxidation of THZ molecules through oxidation of a nitrogen atom five-membered ring and the participation of two electrons/protons in the electrode reaction. Linear calibration curves were illustrated within a wide THZ concentration range from 0.24 to 57.2 µg mL-1 recording a limit of detection (LOD) value of 0.0799 µg mL-1. The CuONPs/ZY/SPEs exhibited improved performance compared with the sole reported THZ sensor-based gold film-plated carbon paste electrodes, in addition to their high reproducibility of fabrication and measurement and prolonged shelf lifetime. Tetrahydrozoline was successfully assayed in the presence of excipients, degradation products, and chloramphenicol. The presented voltammetric sensor can be considered as an eco-friendly and reliable analytical approach for monitoring THZ residues in eye drop samples and biological fluids with high recovery compared with the official pharmacopeial analytical protocol. The presented sensors were assessed according to an EcoScale tool and also compared with the reported THZ sensor.

Facile synthesis of new metal-organic framework/chitosan composite sponge for Hg(II) removal: Characterization, adsorption efficiency, and optimization using Box-Behnken design.

The objective of this research was to develop a novel adsorbent to eliminate mercury (Hg(II)) from water. A unique citrate-crosslinked La-MOF/citrate crosslinked chitosan composite sponge (La-MOF@CSC composite sponge) was successfully synthesized in an acidic environment using a one-step technique. Modifying the composition of adsorbent materials is a commonly employed strategy to enhance adsorption capacity, particularly for materials composed of metal-organic frameworks. The study investigated the impact of the composite sponge on the adsorption and removal of Hg(II). The composite sponge exhibited a maximum adsorption capacity (qmax) for Hg(II) at 765.22 mg/g and an impressive high surface area of 1208 m2/g. Various factors influencing the adsorption capacity were taken into account in this study. The adsorption isotherm and kinetics were modeled using Langmuir and pseudo-second-order equations, respectively. Consistent with thermodynamics, the adsorption process was identified as spontaneous and endothermic. The quantities of adsorbed substances increased with rising temperature. The La-MOF@CSC composite sponge demonstrated the ability to be reused up to five times with satisfactory efficiency, retaining its chemical composition and exhibiting similar XRD and XPS data before and after each reuse. The interaction between heavy metals and the La-MOF/CSC composite sponge was examined. Optimization of the adsorption outcomes was conducted using the Box-Behnken design (BBD).

Development of green and sustainable smart biochromic and therapeutic bandage using red cabbage (Brassica oleracea L. Var. capitata) extract encapsulated into alginate nanoparticles.

Novel multifunctional wound dressing with the ability to protect, cure and sense the healing process, was developed. Red-cabbage extract has been reported to exhibit bioactive compounds with the ability to function as antioxidant, antiinflammatory, anticancer, antibacterial, antifungal, and antiviral agent, as well as a natural pH-sensory chromophoric material. An anthocyanin extract was prepared from Red-cabbage (Brassica oleracea L. Var. capitata). The anthocyanins extract was encapsulated into calcium alginate in the presence of potash alum mordant, which was then applied to the surface of the cotton gauze. Red-cabbage based anthocyanin chromophoric extract was encapsulated at different concentrations into alginate-based hydrogel and immobilized into cotton gauze to provide a smart therapeutic pH-responsive wound dress to function as an antimicrobial and biochromic matrix providing a comfortable dress sensor to monitor the wound status. Decreasing the pH of a wound mimic solution caused a blue shift from 579 to 437 nm. The anthocyanin spectroscopic probe's halochromic activity demonstrated a colorimetric change from purple to pink, which was critical to the dyed cotton diagnostic assay's biochromic performance. The colorimetric parameters of the prepared dressing sensor were proved by UV-Vis absorbance and CIE Lab coordinates. Both mechanical and morphological properties of the prepared dressing were studied using different analytical methods. The effect of anthocyanin concentration on the mechanical, water vapor permeability, water absorption and morphological properties of the wound dressing were investigated. No substantial flaws in air-permeability or bend length were detected after dyeing. The colored cotton gauze samples were tested for their high colorfastness. The cytotoxicity and antimicrobial activity of the prepared biochromic cotton gauze were explored. The dyed cotton samples exhibited no cytotoxicity and improved antimicrobial activity with increasing the anthocyanin ratio on cotton surface.

Development of photoluminescent artificial nacre-like nanocomposite from polyester resin and graphene oxide.

Long-lasting phosphorescent nacre-like material was simply prepared from a nanocomposite of inorganic and organic materials. Low molecular weight unsaturated polyester (PET), graphene oxide (GO), and nanoparticles of rare-earth activated aluminate pigment were used in the preparation process of an organic/inorganic hybrid nanocomposite. Using methylethylketone peroxide (MEKP) as a hardener, we were able to develop a fluid solution that hardens within minutes at room temperature. Covalent and hydrogen bonds were introduced between the polyester resin and graphene oxide nanosheets. The interface interactions of those bonds resulted in toughness, excellent tensile strength, and high durability. The produced nacre substrates demonstrated long-persistent and reversible luminescence. The excitation of the produced nacre substrates at 365 nm resulted in a 524 nm emission. After being exposed to UV light, the photoluminescent nacre substrates became green. The increased superhydrophobic activity of the produced nacre substrates was achieved without affecting their physico-mechanical properties. HIGHLIGHTS: Colorless photoluminescent smart nacre-like nanocomposites were prepared. Graphene oxide and polyester were mixed with phosphor nanoparticles at 25°C. Photostable long-persistent phosphorescence lighting was observed in the dark. Photochromic change to green emission was detected under ultraviolet light. The nacre-like composites exhibit improved hardness and hydrophobicity.

Optical Detection of Acetone Using "Turn-Off" Fluorescent Rice Straw Based Cellulose Carbon Dots Imprinted onto Paper Dipstick for Diabetes Monitoring.

Persistent bad breath has been reported as a sign of serious diabetes health conditions. If an individual's breath has a strong odor of acetone, it may indicate high levels of ketones in the blood owing to diabetic ketoacidosis. Thus, acetone gas in the breath of patients with diabetes can be detected using the current easy-to-use fluorescent test dipstick. In another vein, rice straw waste is the most well-known solid pollutant worldwide. Thus, finding a simple technique to change rice straw into a valuable material is highly important. A straightforward and environmentally friendly approach for reprocessing rice straw as a starting material for the creation of fluorescent nitrogen-doped carbon dots (NCDs) has been established. The preparation process of NCDs was carried out via one-pot hydrothermal carbonization using NH4OH as a passivation substance. A testing strip was developed on the basis of cellulose CD nanoparticles (NPs) immobilized onto cellulose paper assay. The NCDs demonstrated a quantum yield of 23.76%. A fluorescence wavelength was detected at 443 nm upon applying an excitation wavelength of 354 nm. NCDs demonstrated remarkable selectivity for acetone gas as their fluorescence was definitely exposed to quenching by acetone as a consequence of the inner filter effect. A linear correlation was observed across the concentration range of 0.5-150 mM. To detect and measure acetone gas, the present cellulose paper strip has a "switch off" fluorescent signal. A readout limit was accomplished for an aqueous solution of acetone as low as 0.5 mM under ambient conditions. The chromogenic fluorescence of the cellulose assay responsiveness depends on the fluorescence quenching characteristic of the cellulose carbon dots in acetone. A thin fluorescent cellulose carbon dot layer was deposited onto the surface of cellulose strips by a simple impregnation process. CDs were made using NP morphology and analyzed using infrared spectroscopy and transmission electron microscopy. The carbon dot distribution on the paper strip was evaluated by scanning electron microscope and energy-dispersive X-ray analysis. The absorption and fluorescence spectral analyses were investigated. The paper sheets' mechanical qualities were also examined.

Authentication of documents using polypropylene immobilized with rare-earth doped aluminate nanoparticles.

Anticounterfeiting of commercial products has been improved using photochromism as an intriguing approach. In order to develop a mechanically reliable nanocomposite, the engineering procedure of the anticounterfeiting nanocomposite must be improved. Rare-earth doped aluminate/polypropylene (REA/PP) hybrid nanofibers were successfully made by electrospinning, and they were shown to be mechanically stable and highly photoluminescent, making them ideal for anticounterfeiting applications. UV-induced photochromic anticounterfeiting properties were monitored in the synthesized nanocomposite films. In order to ensure that the REA-PP film is completely transparent, REA must be embedded into the polypropylene nanofibers in nano-sized particle shape to facilitate a better dispersion without agglomeration of REA particles in polypropylene matrix. The morphology and structure of REA were studied by transmission electron microscopy and X-ray diffraction. The morphologies and chemical contents of the polypropylene nanofibrous films were studied by scanning electron microscopy, X-ray fluorescence, and energy-dispersive X-ray spectroscopy. The REA-PP nanofibrous film showed absorbance and emission maxima at 365 and 517 nm, respectively. When exposed to UV light, the photochromic activity of the transparent nanofibrous substrates to greenish-yellow was rapid and reversible without fatigue. Hydrophobicity of REA-PP films increased without affecting their original look or mechanical properties, while increasing the REA content. It was possible to produce ultraviolet-induced photochromic nanofibrous films that were transparent, flexible, and cost-effective. As a result of this method, numerous anticounterfeiting materials could be developed toward a better marketplace with both economy and community values. HIGHLIGHTS: Rare-earth aluminate/polypropylene (REA/PP) electrospun nanofibers were prepared. The photochromic transparent nanofibers displayed green emission under UV light. The nanofibrous films were flexible, mechanically stable and highly luminescent. Films showed absorbance and emission maxima at 365 and 517 nm, respectively. Hydrophobicity was improved without affecting the films original properties.

Solution blowing spinning of polylactate/polyvinyl alcohol/ZnO nanocomposite toward green and sustainable preparation of wound dressing nanofibrous films.

The outstanding biodegradability, biocompatibility, affordability, and renewability of polylactic acid have made it a prominent biomaterial. Herein, an innovative, easy, and eco-friendly technique is used to prepare sodium polylactate (SP)-based nanofibers. Solution blowing spinning (SBS) was used to create fibrous mats of SP and polyvinyl alcohol (PVA). SBS's SP nanfibers were crosslinked using an aqueous solution of calcium chloride to produce moisture-resistant calcium polylactate nanofibrous spun mats. Both of UV-visible absorption spectra and transmission electron microscopy were utilized to study the produced zinc oxide (ZnO) nanoparticles (NPs) to indicate a diameter of around 15-23 nm with a high intensity absorption intensity at 370 nm. New polylactate copolymer was synthesized and characterized by infrared and NMR spectroscopic techniques. In order to prepare SP/PVA/ZnO nanocomposite nanofibers, various ZnO ratios were used. The morphologies of the composite nanofibers were investigated by infrared spectroscopy (FTIR), energy-dispersive X-ray analyzer, and scanning electron microscopy. The cytotoxicity tests of the prepared mat were studied by conducting experiments with L-929 cells at various time intervals. The prepared composite SP/PVA/ZnO nanofibers were subjected to cytotoxicity tests to determine their cytocompatibility. Results showed that those with ZnO concentrations between 0.5% and 2% were found to be less harmful than those with higher concentrations. A variety of bacterial species, including Bacillus pumilus and Staphylococcus aureus, as well as Klebseilla pneumoniae and Escherichia coli, were used to test the antibacterial properties of SP/PVA/ZnO spun mats. The ZnO NPs integrated in the SP/PVA fibrous mats were responsible for their antibacterial properties. After finding the appropriate concentration of ZnO that is least harmful while yet giving a satisfactory antibacterial activity, this biomaterial might be perfect for wound dressing applications. HIGHLIGHTS: New eco-friendly biodegradable sodium polylactate (SP) copolymer was synthesized. Zinc oxide nanoparticles (ZnO NPs) with a diameter of 15-23 nm were prepared. High antibacterial SP/PVA/ZnO fibers were prepared by solution blowing spinning. SP/PVA/ZnO nanofibers (180-220 nm) with various ratios of ZnO were presented. Cytotoxicity results showed that the cell viability decreases with increasing ZnO.

Preparation of photoluminescent nanocomposite ink for detection and mapping of fingermarks.

Simple and efficient detection and mapping method based on a strong turn-on fluorescent pigment was developed for fingerprint analysis. We present a phosphor powder characterized by strong emission which is useful to achieve better fingerprint detection on multicolored or photoluminescent surfaces, such as currency notes characterized by optically changeable inks and highly fluorescent positions, because it offers better contrast and reduce the difficulty of background interference. Novel photochromic ink was prepared to establish a fingerprinted colorless film onto cellulose documents with green emission for anticounterfeiting applications as illustrated by photoluminescence spectra. Inorganic/organic nanoscale composite ink was prepared from rare-earth doped aluminate phosphor nanoparticles (PNPs; 27-49 nm) dispersed in a polyacrylic acid binding agent. PNPs were dispersed efficiently in polyacrylic acid to generate a colorless mark. The produced photochromic inks were spray-coated onto off-white paper sheets enclosing invisible fingermarks, and then exposed to thermofixation. Photochromic film was detected on paper surface presenting a transparent appearance under visible daylight and switchable to green under UV light. The CIE Lab parameters and photoluminescence spectra were studied under visible light and ultraviolet irradiation. The fingerprinted sheets showed fluorescence band at 517 nm upon excitation at 366 nm, showing a bathochromic shift and reversible photochromism without fatigue. The morphologies of pigment phosphor particles and fingerprinted sheets were inspected. The rheological properties of ink and mechanical behavior of the fingerprinted paper samples were explored. HIGHLIGHTS: Novel smart ink with alkaline-earth aluminate and polyacrylic acid was developed. Dual-mode fluorescent photochromism was presented for latent fingerprint analysis. Off-white fingerprinted films under daylight showed color change to green under UV. Fluorescence band monitored at 517 nm upon excitation at 366 nm. Fluorescent fingermark on paper sheets demonstrated good photostability.

Preparation of photoluminescent and anticorrosive epoxy paints immobilized with nanoscale graphene from sugarcane bagasse agricultural waste.

Sugarcane bagasse agricultural waste has been one of the most common solid pollutants worldwide. Thus, introducing a simple method to convert sugarcane bagasse into value-added materials has been highly significant. Herein, we develop a simple and green strategy to reprocess sugarcane bagasse as a starting material for the preparation of graphene oxide nanosheets toward the preparation of novel photoluminescent, hydrophobic, and anticorrosive epoxy nanocomposite coatings integrated with lanthanide-doped aluminate nanoparticles. Environmentally friendly graphene oxide (GO) nanostructures were provided by a single-step preparation procedure from sugarcane bagasse (SCB) agricultural waste using ferrocene-based oxidation under muffled conditions. The oxidized SCB nanostructures were applied as a drier, anticorrosion, and crosslinking agent for epoxy coatings. Different concentrations of pigment phosphor were applied onto the epoxy coating. The generated epoxy-graphene-aluminate (EGA) paints were then coated onto mild steel. The hydrophobic properties and hardness as well as resistance to scratch of the EGA paints were examined. The transparency and colorimetric screening of the EGA nanocomposite paints were determined by the absorption spectral analysis and CIE Lab parameters. The luminescent translucent paints demonstrated a bright green emission at 520 nm when excited at 372 nm. The anticorrosion properties of the painted steel submerged in NaCl(aq) were inspected by the electrochemical impedance spectral (EIS) method. The EGA paints with phosphor (11% w/w) exhibited the most distinct anti-corrosion properties and long-persistent luminescence. The produced paints displayed high durability and photostability.