Synthesis, Characterization and Applications of Schiff Base Chemosensor for Determination of Cr(III) Ions.

The development of a highly sensitive, selective, and efficient sensor for the determination and detection of Cr(III) ions remains a great challenge. Recently, some fluorescent chemosensors have been developed for the recognition of Cr(III) ions. But, the main drawbacks of the reported fluorescent chemosensors are the lack of selectivity and interference of anions and other trivalent cations. Herein, we designed and synthesized a novel thiazole-based fluorescent and colorimetric Schiff base chemosensor SB2 for the detection of Cr(III) ion by chemodosimetric approach. Using different analytical techniques including UV-vis, 13C-NMR, 1H-NMR, and FT-IR analysis the chemosensor SB2 was structurally characterized. The fully characterized chemosensor SB2 was used for the spectrofluorimetric and colorimetric detection of Cr(III) ions. Interestingly, chemosensor SB2 upon interaction with various metal cations including Ni2+, Na+, Cd2+, Ag+, Mn2+, K+, Zn2+, Cu2+, Hg2+, Co2+, Pb2+, Mg2+, Sn2+, Al3+ and Cr3+ displays highly selective and sensitive fluorescent (turn-on) and colorimetric (yellow to colorless) response toward Cr(III) ions. The fluorescence and UV-vis techniques confirmed the selective hydrolysis of azomethine group (-C = N-) of Schiff base chemosensor SB2 by Cr(III) ions. As a result, the fluorescence enhancement was observed that is corresponding to 2-hydroxy-1-nepthaldehyde (fluorophore). The chemosensor SB2 exhibits high interference performance towards Cr(III) ions over other metal cations in a wide pH range. Mover, the quite low detection limit was calculated to be 0.027 µg ml-1 (0.5 µM) (3σ/slop), lower than the maximum tolerable limits of Cr(III ions (10 µM) in drinking water permitted by the United States Environmental Protection Agency (EPA). These results show that chemosensor SB2 has great potential to detect selectively Cr(III) ions in the agricultural, environmental and biological analysis system.

Utility of 4-chloro-7-nitrobenzofurazan for spectrofluorimetric and spectrophotometric determinations of the anti-hirsutism agent (α-difluoromethylornithine) in pharmaceutical cream samples.

α-Difluoromethylornithine is an effective medication for the treatment of African Trypanosomiasis and widely distributed for the treatment of hirsutism. This work provides an adequate analytical protocol for the spectrophotometric and the spectrofluorimetric determination of α-difluoromethylornithine through its interaction with 4-chloro-7-nitrobenzofurazan (NBD-chloride) reagent. After optimization of the reaction conditions (NBD-chloride volume, buffer volume, the best diluting solvent, heating time and temperature and pH of the medium) the reaction product was measured spectrophotometrically at λmax = 478 nm and spectrofluorimetrically at λemission = 540 nm after λexcitation = 475 nm. The proposed methods were linear over the ranges 5-30 µg ml-1 and 0.4-2 µg ml-1 for the spectrophotometric method and the spectrofluorimetric method, respectively. Moreover, the proposed work offers an adequate sensitive and selective determination for α-difluoromethylornithine where the detection limits were 0.90 µg ml-1 and 0.071 µg ml-1 for the spectrophotometric method and the spectrofluorimetric method, respectively. Furthermore, both methods were successfully applied for the quantification of α-difluoromethylornithine in the pharmaceutical cream samples with acceptable recovery results.

Applying different spectroscopic techniques for the selective determination of daclatasvir using merbromin as a probe: Applications on pharmaceutical analysis.

In this study, rapid resonance Rayleigh scattering (RRS), spectrophotometric, and spectrofluorimetric methods were performed for facile quantitation of daclatasvir dihydrochloride without interference from sofosbuvir (a co-formulated anti-hepatitis C virus drug). The proposed approaches were based on forming a binary complex between daclatasvir dihydrochloride and merbromin reagent at pH 4.1. The binary complex was measured spectrophotometrically at λmax = 544 nm. The spectrofluorimetric approach relied on the quenching effect of daclatasvir dihydrochloride on the fluorescence strength of merbromin at λEmission = 545 nm. The RRS approach depended on augmentation in the merbromin RRS spectrum at 363 nm upon addition of daclatasvir dihydrochloride. The presented methodologies were linear over the concentration ranges 2.5-15.0, 0.2-1.6 and 0.15-3.0 µg ml-1 with detection limits of 0.45, 0.046, and 0.036 µg ml-1 for the spectrophotometric approach, the spectrofluorometric approach, and RRS approach, respectively. Current approaches were validated in compliance with International Council for Harmonisation guidelines and utilized practically to estimate daclatasvir dihydrochloride either in binary mixtures with sofosbuvir or in its commercial tablet dosage form with good results. Moreover, the test for content uniformity was applied successfully on commercial tablets using the current spectroscopic approaches.

Resonance Rayleigh scattering and spectrofluorimetric approaches for the selective determination of rupatadine using erythrosin B as a probe: application to content uniformity test.

In this study, spectrofluorimetric and resonance Rayleigh scattering techniques were applied for the first time for determination of rupatadine through two validated methods. The proposed methods were based on a facile association complex formation between rupatadine and erythrosin B reagent in acidic medium. Spectrofluorimetric determination relied on the quenching effect of rupatadine on the fluorescence intensity of erythrosin B at 556 nm (excitation = 530 nm). Conversely, the resonance Rayleigh scattering (RRS) method relied on enhancement in the resonance Rayleigh scattering spectrum of erythrosin B at 344 nm after the addition of rupatadine. The developed methods produced linear results over ranges 0.15-2.0 µg/ml and 0.1-1.5 µg/ml, with detection limits of 0.030 µg/ml and 0.018 µg/ml for the spectrofluorimetric method and the RRS method, respectively. All reaction conditions for rupatadine-erythrosin B formation were optimized experimentally and both methods were validated according to International Council for Harmonisation guidelines. The developed methods were applied to estimate rupatadine content in its pharmaceutical tablet dosage form with acceptable recoveries. Furthermore, a content uniformity test for the commercial rupatadine tablets was successfully applied by the suggested spectroscopic methods according to United States Pharmacopeia guidelines.

Enhancing methyl violet 2B pollutant removal from wastewater using Al-MOF encapsulated with poly (itaconic acid) grafted crosslinked chitosan composite sponge: Synthesis, characterization, DFT calculation, adsorption optimization via Box-Behnken Design.

In this research, aluminum metal-organic framework encapsulated with poly (itaconic acid) grafted crosslinked chitosan composite sponge (Al-MOF@PIC) was prepared. SEM, FTIR, XPS, XRD, and BET techniques were employed to thoroughly characterize the synthesized material and establish its structure and characteristics. The study discovered that the Al-MOF@PIC is an efficient way to remove dyes, which constitute a significant number of contaminants in industrial wastewater. Subsequently the adsorption of methyl violet 2B (MV-2B) dye, the surface area, pore size, and pore volume of the adsorbent decreased from 1860.68 m2/g, 1.62 nm, and 1.52 cc/g to 1426.45 m2/g, 1.11 nm, and 0.92 cc/g, individually. This modification suggested that a portion of the MV-2B dye had been removed by adsorption over the adsorbent's pores. The excellent adsorption capacity of the material was further confirmed by batch adsorption tests, which displayed a maximum adsorption capability of 646.76 mg/g for the elimination of MV-2B dye. The high adsorption energy of 26.8 kJ/mol designates that chemisorption is primarily responsible for MV-2B dye adsorption against the sponge adsorbent. The Al-MOF@PIC composite sponge demonstrated exceptional reusability over six cycles, demonstrating its strength and durability. The Al-MOF@PIC composite sponge successfully removes MV-2B from water by pore filling, π-π stacking, hydrogen bonding, and electrostatic interactions, which are the key mechanisms behind the adsorption of the dye pollutant. Its potential for practical applications is further demonstrated using Box Behnken-design (BBD) to optimize the adsorption consequences.

Development of photoluminescent viscose fibers integrated with polymer containing lanthanide-doped phosphor.

Smart clothing refers to textiles that can sense an external stimulus by changing their physical properties such as colorimetric and fluorescent fabrics. The pad-dry-curing coloration approach was used to apply a luminous and hydrophobic composite coating onto cellulose-based materials. This novel method includes incorporating phosphor nanoparticles made from lanthanide-doped strontium aluminum oxide (LSAO) into room temperature vulcanizing silicone rubber (RTV). The LSAO nano-sized particles (3-8 nm) must be mixed evenly throughout RTV without aggregation to allow for the formation of a colorless layer onto viscose surface. Pad-dry-curing the film onto viscose cloth worked well at room temperature. The contact angles of the luminous fibers enhanced from 138.6° to 158.2° as the LSAO ratio increased. The antimicrobial and ultraviolet (UV) protection of the LSAO-finished viscose were investigated. The transparent fluorescent film on viscose surface was excited at 367 nm to display an emission peak at 518 nm. According to CIE Lab coordinates and luminescence analyses, the fluorescent viscose fibers showed various colors, including white under visible light, intense green beneath UV device, and greenish-yellow under darkness. The comfort properties of the LSAO-finished viscose were assessed by measuring their bend length and permeability to air. Transmission electron microscopic analysis of LSAO nanoparticles was explored. Energy dispersive x-ray, x-ray fluorescence, and scanning electron microscopy were utilized to describe the spectroscopic outcomes of the treated textiles. The colorfastness of the LSAO-finished viscose fabrics was examined. The coated fabrics exhibited a non-fatigable reversible luminous photochromism in response to UV illumination. RESEARCH HIGHLIGHTS: Multifunctional LSAO@RTV nanocomposite was pad-dry-cured onto viscose textile. Photochromism to green under UV light and greenish-yellow in the dark was detected. Efficient antimicrobial, UV protective, and superhydrophobic activity were observed. The antimicrobial properties were maintained for 24 washing cycles. Pad-dry-cured viscose showed good comfortability and photostability.

Multifunctional Lipophobic Polymer Dots from Cyclodextrin: Antimicrobial/Anticancer Laborers and Silver Ions Chemo-Sensor.

ß-Cyclodextrin (CD) is currently exploited for the implantation of lipophobic polymer dots (PDs) for antimicrobial and anticancer laborers. Moreover, the PDs were investigated to act as a chemo-sensor for metal detection. The data revealed that under basic conditions, photoluminescent PDs (5.1 nm) were successively clustered with a controllable size at 190 °C, whereas under acidic conditions, smaller-sized non-photoluminescent carbon nanoparticles (2.9 nm) were obtained. The fluorescence intensity of synthesized PDs under basic conditions was affected by pH, and such an intensity was significantly higher compared to that prepared under acidic conditions. The PDs were exploited as florescent detectors in estimation of Ag+ ions in aquatic streams. Treatment of Ag+ ion colloids with PDs resulted in fluorescence quenching attributing to the production of AgNPs that approved by spectral studies. The cell viability percent was estimated for Escherichia coli, Staphylococcus aureus, and Candida albicans after incubation with PDs implanted under basic conditions for 24 h. The cell mortality percent was estimated for breast cancer (MCF-7) after incubation with different concentrations of PDs that were implanted under acidic versus basic conditions to show that treatment of the tested cells with 1000 µg/mL PDs prepared under basic (IC50 232.5 µg/mL) and acidic (IC50 88.6 µg/mL) conditions resulted in cell mortality percentages of 70 and 90%, respectively.

Optimisation and Stability of Rh Particles on Noble Metal Films Immobilised on H+ Conducting Solid Polymer Electrolyte in Attaining Efficient Nitrate Removal.

During the electrocatalytic reduction of nitrate, nitrite is often evolved as a product along with ammonia due to the sluggish nitrite-to-ammonia conversion process compared to the nitrate-to-nitrite conversion step. Rhodium metal has been proven to enhance nitrite-to-ammonia conversion rates, yielding ammonia as the only final product. In the present article, we have shown how effectively Rh nanoparticles immobilized on Pt and Pd films deposited on H+ conducting Nafion-117 membranes eliminate intermediate nitrite ions during the progress of the nitrate reduction reaction in a flow type reactor. In this research, we also demonstrated the optimization of Rh nanoparticles on the cathode surface to attain effective nitrate reduction along with a reproducibility check. The dissolution of loosely held Rh nanoparticles on the cathodic surface was observed, which tends to be redeposited during cathodic electrolysis, causing stable performance. Finally, Tafel analysis was performed to show the relative kinetic feasibility of the Rh-modified Pt and Pd electrodes in attaining nitrate reduction reactions in neutral medium.

A specific turn-on fluorescence probe for determination of nitazoxanide based on feasible oxidation reaction with hypochlorite: Applying cobalt ferrite nanoparticles for pre-concentration and extraction of its metabolite from real urine samples.

Nitazoxanide is an antimicrobial compound that was originally developed as an antiprotozoal drug. Recently nitazoxanide has been identified as broad-spectrum antiviral agent and redirected for the remediation of some respiratory tract viral infections. In this study, the spectrofluorimetric technique has been applied to determine Nitazoxanide (NTX) in tablets or its metabolite, tizoxanide (TZD), in human urine samples. The developed methodology is based on oxidizing NTX (non-fluorescence) into a highly fluorescent product by sodium hypochlorite. The fluorescence emission intensity was measured at 436.5 nm after fluorescence excitation at 362.5 nm. After optimizing all conditions, the analytical procedures and bio-analytical steps were evaluated and validated using ICH and FDA criteria, respectively. The method linearity, LOQ, and LOD values of NTX were 1.0-5.0 µg/mL, 0.434, and 0.143 µg/mL, respectively. The other novelty side of the presented work is the application of cobalt ferrite (CoFe2O4) nanoparticles (NPs) as a magnetic solid-phase for the pre-concentration and extraction process. The synthesized magnetic nanoparticles were characterized by scanning electron microscope and zeta sizer techniques. Finally, the utilized magnetic nanoparticles exhibited good recovery results for pre-concentration and extraction of NTX or its metabolite from spiked and real human urine samples, respectively.

Development of Thermochromic Ink Using the Anthocyanidin-Based Red-Cabbage Extract for Anticounterfeiting Applications.

Temperature-driven colorful switching inks have been an interesting security encoding method to improve the anticounterfeiting properties of commercially available merchandise. Recently, thermochromic inks have faced many disadvantages, such as low efficiency, high cost, and low durability. In the current study, we developed self-healable ink from poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA) integrated with the anthocyanidin(ACY)-based red-cabbage extract in the presence of ferrous sulfate for authentication purposes. Self-healable inks have been able to guarantee durability and thermal stability. Environmentally friendly, ACY-based chromophore was extracted from Brassica oleracea L. var. Capitata (red-cabbage) to serve as a spectroscopic probe immobilized into PAMPSA. The prepared self-healable nanocomposite ink (PAMPSA-ACY) displayed temperature-induced chromism with high reversibility and thermal stability. Different self-healable nanocomposite inks of thermochromic features were prepared employing different ratios of the ACY-based red-cabbage extract. As described by Commission Internationale de L'éclairage Lab coordinates, homogeneous films were stamped on the paper surface to show a purple color (631 nm) able to switch color into red (458 nm) with the increase in temperature from 25 to 65 °C, respectively. Transmission electron microscopy, infrared spectra (FT-IR), energy-dispersive X-ray, and scanning electron microscopy were utilized to inspect the morphological behavior and chemical compositions of thermochromic prints. Both mechanical and rheological properties of ink-printed paper substrates and ink solution were also investigated. Both of antimicrobial activity and cytotoxicity study of the nanocomposite ink (PAMPSA-ACY) were also evaluated. Various industries can take the advantage of the current ink as a competent approach for anticounterfeiting purposes.

Synthesis and Self-assembly of Novel Nanofeather-like Fluorescent Alkyloxy-Containing Diphenyl Ether Organogelators.

In this study, novel fluorescent low molecular-weight organogelators are derived from diphenyl ethers and substituted with para-alkoxy groups of different aliphatic chain lengths. The present research promotes the preparation of innovative nanofeather-like assemblies from the synthesized diphenyl ether-derived organogelators. The gelation performance of the prepared alkoxy-substituted diphenyl ethers was reported. The synthesis procedure was achieved by using a base-catalyzed reaction of hydroxyl-substituted diphenyl with various alcohols of different aliphatic chain lengths. The chemical structures of the synthesized diphenyl ether derivatives were studied by 1H/13C NMR and infrared spectroscopy. Fluorescence and UV-vis absorption spectral analyses showed solvatochromism. The diphenyl ether derivatives with longer alkoxy terminal substituents showed enhanced thermoreversible gelation activity as compared to the diphenyl ether derivatives with shorter alkoxy terminal substituents. The morphological properties of the self-assembled diphenyl ethers were studied by transmission electron microscopy and scanning electron microscopy, which showed supramolecular architectures of highly ordered nanofeathers, enforced by van der Waals interactions and π-stacks. Depending on the length of the aliphatic tail, different morphologies were detected, including nanofeathers, nanofibers, and nanosheets. The antimicrobial and cytotoxic properties of the prepared diphenyl ether-derived organogelators were examined to confirm their possible use in various fields like drug delivery systems.

Application of Hantzsch reaction for sensitive determination of eflornithine in cream, plasma and urine samples.

Eflornithine (EFN) is an anti-Trypanosoma brucei agent for the medication of sleeping sickness and widely distributed for the treatment of hirsutism (unwanted facial hair in women). The presented work demonstrates a comprehensive analytical approach for the spectrofluorometric determination of EFN in commercial cream samples and various biological samples. The proposed method is based on the formation of a highly yellow-green fluorescence dihydropyridine derivative after the interaction between EFN and acetylacetone/formaldehyde reagent in a slightly acidic medium. Furthermore, the optimal variables such as reagent volumes, pH of the medium, heating time, buffer volume, heating temperature and diluting solvent were carefully selected to achieve the maximum fluorescence activity. The fluorescence activity for the formed derivative was measured at λ emission = 477 nm after λ excitation = 418 nm. Concerning linearity, accuracy, sensitivity, precision and robustness, the presented method was validated and verified according to ICH guidelines. Moreover, the proposed work offered a selective determination for EFN in various brands of pharmaceutical cream without any interference from excipients. Eventually, the current approach was assured to be successful in the estimation of EFN in urine and plasma samples with acceptable recovery results.

Micellar sensitized Resonance Rayleigh Scattering and spectrofluorometric methods based on isoindole formation for determination of Eflornithine in cream and biological samples.

α-Difluoromethylornithine or Eflornithine is an FDA-approved drug used for the treatment of Sleeping Sickness (as vials dosage form) and also used for diminishing the unwanted excess facial hair in the hirsutism (as creams dosage form). The proposed work is based on the condensation interaction between the amino moiety of Eflornithine and O-phthalaldehyde/2-mercaptoethanol to form a highly fluorescent isoindole derivative. The fluorescence and the Resonance Rayleigh Scattering (RRS) intensities of the reaction product were greatly augmented upon the addition of hexadecyl-trimethyl ammonium bromide by 153% and 250%, respectively. After optimization of the reaction conditions, the formed isoindole derivative was measured fluorometrically at λemission= 429 nm after λexcitation= 337 nm. Moreover, the significant augmentation in the RRS intensity of the formed product was measured at λmax= 422 nm. In regards to accuracy, sensitivity, robustness and precision, the proposed methods were validated according to ICH guidelines. Furthermore, the proposed methods were successfully applied for the assay of Eflornithine in various commercial brands of the pharmaceutical cream samples with good recovery. In addition to the current fluorometric method was confirmed to be effective in the assaying of Eflornithine in spiked plasma and urine specimens with good recovery.

Effects of sonochemical approach and induced contraction of core-shell bismuth sulfide/graphitic carbon nitride as an efficient electrode materials for electrocatalytic detection of antibiotic drug in foodstuffs.

Ultrasonic-enhanced surface-active bismuth trisulfide based core-shell nanomaterials were developed and used as an efficient modified electrode material to construct a highly sensitive antibiotic sensor. The core-shell Bi2S3@GCN electrode material was directly synthesized by in-situ growth of GCN on Bi2S3 to form core-shell like nanostar (Ti-horn, 30 kHz, and 70 W/cm2). The electrocatalyst of Bi2S3@GCN nanocomposites was efficaciously broadened towards electrochemical applications. As synthesized Bi2S3@GCN promoted the catalytic ability and electrons of GCN to transfer to Bi2S3. The single-crystalline GCN layers were uniformly grown on the surface of the Bi2S3 nanostars. Under the optimal conditions of electrochemical analysis, the CPL sensor exhibited responses directly proportional to concentrations (toxic chemical) over a range of 0.02-374.4 µM, with a nanomolar detection limit of 1.2 nM (signal-to-noise ratio S/N = 3). In addition, the modified sensor has exhibited outstanding selectivity under high concentrations of interfering chemicals and biomolecules. The satisfactory CPL recoveries in milk product illustrated the credible real-time application of the proposed Bi2S3@GCN sensors for real samples, indicating promising potential in food safety department and control. Additionally, the proposed electrochemical antibiotic sensor exhibited outstanding performance of anti-interfering ability, high stability and reproducibility.

Innovative Thin-Layer Chromatography/Fluorescence Detection Approach for Sensitive and Specific Determination of Ledipasvir in Rats' Feces and Pharmaceutical Dosage Form.

An innovative thin-layer chromatography method coupled with the fluorescence detection was developed for a specific estimation of ledipasvir. The separation was achieved on plates of silica gel 60 F254 using ethylacetate: hexane: acetonitrile: triethylamine; (6: 3.5: 1.5: 0.5, $\mathrm{v}/\mathrm{v}/\mathrm{v}/\mathrm{v}$) as a mobile phase system. The method involved the exposure of the developed thin-layer chromatography plate of ledipasvir to strong ultraviolet irradiation, resulting in a great enhancement in the fluorescence properties of ledipasvir. The irradiated plates were scanned after the excitation at 315 $\mathrm{nm}$. The method provided a sufficient separation of ledipasvir from sofosbuvir with ${R}_F$values of 0.28 and 0.36 for ledipasvir and sofosbuvir, respectively. The developed procedures were validated based on guidelines from the International Conference on Harmonization and Food and Drug Administration guidelines. The calibration curve was linear over the range of 5-50 $\mathrm{ng}/\mathrm{band}$. The excellent analytical features of the proposed method allow to the specific determination of ledipasvir in pharmaceutical tablets without interference from sofosbuvir or excipients. As the main elimination route for ledipasvir is via the fecal excretion (86%), the method was applied for the estimation of ledipasvir in fecal specimens with adequate recovery. In addition, the proposed method was applied for testing the content uniformity of ledipasvir in the pharmaceutical tablets.

Investigating the interaction of terbinafine with xanthenes dye for its feasible determination applying the resonance Rayleigh scattering technique.

Terbinafine hydrochloride is a potent antifungal drug indicated for oral and topical treatment of mycoses. A resonance Rayleigh scattering (RRS) method was developed for the determination of terbinafine hydrochloride through a feasible complexation reaction with erythrosine B. In a weakly acidic medium (acetate buffer, pH 5.0), terbinafine hydrochloride can react with erythrosine B through the electrostatic attraction and virtue of hydrophobic force to form an ion-association complex. The reaction resulted in the appearance of a new RRS peak at 369 nm. The RRS peak was increased by increasing the concentration of terbinafine hydrochloride in the linear range of 0.1-1.5 µg ml-1. All the reaction conditions (erythrosine B concentration, buffer volume, diluting solvent and pH) were optimized. The detection limit was 0.029 µg ml-1 while the quantitation limit was 0.089 µg ml-1. The suggested method after its validation was successfully applied for the determination of terbinafine hydrochloride in different pharmaceutical formulations (tablets and cream) with sufficient recovery.