Utilizing magnetic xanthan gum nanocatalyst for the synthesis of acridindion derivatives via functionalized macrocycle Thiacalix[4]arene.

An effective method for synthesizing acridinedione derivatives using a xanthan gum (XG), Thiacalix[4]arene (TC4A), and iron oxide nanoparticles (IONP) have been employed to construct a stable composition, which is named Thiacalix[4]arene-Xanthan Gum@ Iron Oxide Nanoparticles (TC4A-XG@IONP). The process used to fabricate this nanocatalyst includes the in-situ magnetization of XG, its amine modification by APTES to get NH2-XG@IONP hydrogel, the synthesis of TC4A, its functionalization with epichlorohydrine, and eventually its covalent attachment onto the NH2-XG@IONP hydrogel. The structure of the TC4A-XG@IONP was characterized by different analytical methods including Fourier-transform infrared spectroscopy, X-Ray diffraction analysis (XRD), Energy Dispersive X-Ray, Thermal Gravimetry analysis, Brunauer-Emmett-Teller, Field Emission Scanning Electron Microscope and Vibration Sample Magnetomete. With magnetic saturation of 9.10 emu g-1 and ~ 73% char yields, the TC4As-XG@IONP catalytic system demonstrated superparamagnetic property and high thermal stability. The magnetic properties of the TC4A-XG@IONP nanocatalyst system imparted by IONP enable it to be conveniently isolated from the reaction mixture by using an external magnet. In the XRD pattern of the TC4As-XG@IONP nanocatalyst, characteristic peaks were observed. This nanocatalyst is used as an eco-friendly, heterogeneous, and green magnetic catalyst in the synthesis of acridinedione derivatives through the one-pot pseudo-four component reaction of dimedone, various aromatic aldehydes, and ammonium acetate or aniline/substituted aniline. A combination of 10 mg of catalyst (TC4A-XG@IONP), 2 mmol of dimedone, and 1 mmol of aldehyde at 80 °C in a ethanol at 25 mL round bottom flask, the greatest output of acridinedione was 92% in 20 min.This can be attributed to using TC4A-XG@IONP catalyst with several merits as follows: high porosity (pore volume 0.038 cm3 g-1 and Pore size 9.309 nm), large surface area (17.306 m2 g-1), three dimensional structures, and many catalytic sites to active the reactants. Additionally, the presented catalyst could be reused at least four times (92-71%) with little activity loss, suggesting its excellent stability in this multicomponent reaction. Nanocatalysts based on natural biopolymers in combination with magnetic nanoparticles and macrocycles may open up new horizons for researchers in the field.

Magnetic xanthan gum-silk fibroin hydrogel: A nanocomposite for biological and hyperthermia applications.

A magnetic xanthan hydrogel/silk fibroin nanobiocomposite (XG hydrogel/SF/Fe3O4) was designed, fabricated, and characterized using analyzing methods such as FT-IR, EDX, FE-SEM, XRD, TGA, and VSM to evaluate the exact structure of product nanobiocomposite. The FE-SEM images reveal the presence of spherical shapes exhibiting a narrow size range and homogeneous distribution, measuring between 30 and 35 nm in diameter. The VSM analysis demonstrates the superparamagnetic properties of the XG hydrogel/SF/Fe3O4 nanobiocomposite, exhibiting a magnetic saturation of 54 emu/g at room temperature. The biological response of the nanobiocomposite scaffolds was assessed through cell viability and red blood cell hemolytic assays. MCF10A cells were exposed to a concentration of 1.75 mg/mL of the nanobiocomposite, and after 2 and 3 days, the cell viability was found to be 96.95 % and 97.02 %, respectively. The hemolytic effect was nearly 0 % even at higher concentrations (2 mg/mL). Furthermore, the magnetic nanobiocomposite showed excellent potential for hyperthermia applications, with a maximum specific absorption rate of 7 W/g for 1 mg/mL of the sample under a magnetic field in different frequencies (100, 200, 300, and 400 MHz) and 5 to 20 min time intervals.

Enhancement of adsorption efficiency of crystal violet and chlorpyrifos onto pectin hydrogel@Fe3O4-bentonite as a versatile nanoadsorbent.

The magnetic mesoporous hydrogel-based nanoadsornet was prepared by adding the ex situ prepared Fe3O4 magnetic nanoparticles (MNPs) and bentonite clay into the three-dimentional (3D) cross-linked pectin hydrogel substrate for the adsorption of organophosphorus chlorpyrifos (CPF) pesticide and crystal violet (CV) organic dye. Different analytical methods were utilized to confirm the structural features. Based on the obtained data, the zeta potential of the nanoadsorbent in deionized water with a pH of 7 was - 34.1 mV, and the surface area was measured to be 68.90 m2/g. The prepared hydrogel nanoadsorbent novelty owes to possessing a reactive functional group containing a heteroatom, a porous and cross-linked structure that aids convenient contaminants molecules diffusion and interactions between the nanoadsorbent and contaminants, viz., CPF and CV. The main driving forces in the adsorption by the Pectin hydrogel@Fe3O4-bentonite adsorbent are electrostatic and hydrogen-bond interactions, which resulted in a great adsorption capacity. To determine optimum adsorption conditions, effective factors on the adsorption capacity of the CV and CPF, including solution pH, adsorbent dosage, contact time, and initial concentration of pollutants, have been experimentally investigated. Thus, in optimum conditions, i.e., contact time (20 and 15 min), pH 7 and 8, adsorbent dosage (0.005 g), initial concentration (50 mg/L), T (298 K) for CPF and CV, respectively, the CPF and CV adsorption capacity were 833.333 mg/g and 909.091 mg/g. The prepared pectin hydrogel@Fe3O4-bentonite magnetic nanoadsorbent presented high porosity, enhanced surface area, and numerous reactive sites and was prepared using inexpensive and available materials. Moreover, the Freundlich isotherm has described the adsorption procedure, and the pseudo-second-order model explained the adsorption kinetics. The prepared novel nanoadsorbent was magnetically isolated and reused for three successive adsorption-desorption runs without a specific reduction in the adsorption efficiency. Therefore, the pectin hydrogel@Fe3O4-bentonite magnetic nanoadsorbent is a promising adsorption system for eliminating organophosphorus pesticides and organic dyes due to its remarkable adsorption capacity amounts.

In situ preparation of MOF-199 into the carrageenan-grafted-polyacrylamide@Fe3O4 matrix for enhanced adsorption of levofloxacin and cefixime antibiotics from water.

In this research study, a novel method, an in-situ growth approach, to incorporate metal-organic framework (MOF) into carrageenan-grafted- polyacrylamide-Fe3O4 substrate was introduced. Carrageenan-grafted-polyacrylamide-Fe3O4/MOF nanocomposite (kC-g-PAAm@Fe3O4-MOF-199) was fabricated utilizing three stages. In this way, the polyacrylamide (PAAm) was grafted onto the carrageenan (kC) backbone via free radical polymerization in the presence of methylene bisacrylamide (MBA) as cross-linker and Fe3O4 magnetic nanoparticles. Next, the kC-g-PAAm@Fe3O4 was modified by MOF-199 via an in-situ solvothermal approach. Several analyses such as Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-Dispersive X-ray Spectroscopy (EDX), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), Brunauer-Emmett-Teller (BET) demonstrated the successful synthesis of kC-g-PAAm@Fe3O4-MOF-199 magnetic hydrogel nanocomposite. The XRD pattern of magnetic hydrogel nanocomposite illustrated characteristic peaks of Fe3O4, neat kC, and MOF-199 with enhanced crystallinity in comparison with kC-g-PAAm@Fe3O4. TGA showed it has a char yield of 24 wt% at 800 °C. VSM confirmed its superparamagnetic behavior (with Ms of 8.04 emu g-1), and the BET surface area of kC-g-PAAm@Fe3O4-MOF-199 was measured at 64.864 m2 g-1, which was higher than that of kC-g-PAAm@Fe3O4 due to the highly porous MOF-199 incorporation with a BET surface area of 905.12 m2 g-1). The adsorption effectiveness of kC-g-PAAm@Fe3O4-MOF-199 for eliminating cephalosporin and quinolones antibiotics, i.e., Cefixime (CFX) and Levofloxacin (LEV) from the aquatic area was considered. Several experimental setups were used to evaluate the efficacy of adsorption, such as solution pH, amount of adsorbent, contact duration, and initial concentration. The maximum adsorption capacity (Qmax) of the prepared magnetic hydrogel nanocomposite was found to be 2000 and 1666.667 mg-1 for LEV and CFX using employing 0.0025 g of adsorbent. The Freundlich isotherm model well described the experimental adsorption data with R2CFX = 0.9986, and R2LEV = 0.9939. And the adsorption kinetic data were successfully represented by the pseudo-second-order model with R2LEV = 0.9949 and R2CFX = 0.9906. Hydrogen bonding, π-π interaction, diffusion, and entrapment in the hydrogel network all contributed to the successful adsorption of both antibiotics onto the kC-g-PAAm@Fe3O4-MOF-199 adsorbent. Other notable physicochemical properties include the three-dimensional structure and availability of the reactive adsorption sites. Moreover, the adsorption/desorption efficacy of magnetic hydrogel nanocomposites was not significantly diminished after four cycles of recovery.

Facile synthesis of pyrazolopyridine pharmaceuticals under mild conditions using an algin-functionalized silica-based magnetic nanocatalyst (Alg@SBA-15/Fe3O4).

Pyrazolopyridines are common scaffolds in various bioactive compounds, which have several therapeutic effects and unique pharmacological properties. In this study, we fabricated a novel environmentally friendly silica-based nanocomposite as a multifunctional catalytic system for the synthesis of pyrazolopyridine derivatives. This novel heterogeneous nanocomposite named Alg@SBA-15/Fe3O4 (Alg stands for alginic acid), was prepared in several steps. In this regard, SBA-15 was synthesized by the hydrothermal method. Next, it was magnetized by Fe3O4 nanoparticles via an in situ co-precipitation process. Then, SBA-15/Fe3O4 particles were functionalized with 3-minopropyltriethoxysilane (APTES). Afterward, Alg@SBA-15/Fe3O4 was obtained by a nucleophilic substitution reaction between SBA-15/Fe3O4-NH2 and an as-synthesized methyl-esterified alginic. Different analyses such as Fourier-transform infrared (FTIR), energy-dispersive X-ray (EDX) spectroscopy, field-emission scanning-electron microscopy (FESEM), vibrating-sample magnetometer (VSM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and BET (Brunauer-Emmett-Teller) have been used to confirm the structure of the fabricated catalyst. The magnetic properties of the Alg@SBA-15/Fe3O4 catalytic system imparted by Fe3O4 MNPs enable it to be conveniently isolated from the reaction mixture by using an external magnet. According to the obtained results, the prepared nanocatalyst has high thermal stability and it lost approximately 26% of its weight up to 800 °C. Interestingly, a small amount of prepared nanocatalyst (0.02 g) has shown excellent catalytic performance in the synthesis of pyrazolopyridine derivatives (90-97%) in a short reaction time (20-30 min) at room temperature which can be attributed to its porous structure and large surface area, and the presence of many acidic and basic functional groups. In general, it can be argued that the Alg@SBA-15/Fe3O4 nanocomposite deserves more attention due to its non-toxicity, ease of preparation, good recyclability, and its high catalytic efficiency.

Vancomycin-Loaded Fe3O4/MOF-199 Core/Shell Cargo Encapsulated by Guanidylated-ß-Cyclodextrine: An Effective Antimicrobial Nanotherapeutic.

This study describes an efficient antimicrobial drug delivery system composed of iron oxide magnetic nanoparticles (Fe3O4 NPs) coated by an MOF-199 network. Then, the prepared vancomycin (VAN)-loaded carrier was fully packed in a lattice of beta-cyclodextrin (BCD). For cell adhesion, beta-cyclodextrin has been functionalized with guanidine (Gn) groups within in situ synthetic processes. Afterward, drug loading efficiency and the release patterns were investigated through precise analytical methods. Confocal microscopy has shown that the prepared cargo (formulated as [VAN@Fe3O4/MOF-199]BCD-Gn) could be attached to the Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacterial cells in a higher rate than the individual VAN. The presented system considerably increased the antibacterial effects of the VAN with a lower dosage of drug. The cellular experiments such as the zone of inhibition and optical density (OD600) have confirmed the enhanced antibacterial effect of the designed cargo. In addition, the MIC/MBC (minimum inhibitory and bactericidal concentrations) values have been estimated for the prepared cargo compared to the individual VAN, revealing high antimicrobial potency of the VAN@Fe3O4/MOF-199]BCD-Gn cargo.

Arabic Gum-Grafted-Hydrolyzed Polyacrylonitrile@ZnFe2O4 as a Magnetic Adsorbent for Remediation of Levofloxacin Antibiotic from Aqueous Solutions.

The Arabic gum-grafted-hydrolyzed polyacrylonitrile/ZnFe2O4 (AG-g-HPAN@ZnFe2O4) as organic/inorganic adsorbent was obtained in three steps using grafted PAN onto Arabic gum in the presence of ZnFe2O4 magnetic nanoparticles and then hydrolysis by alkaline solution. Fourier transform infrared (FT-IR), energy-dispersive X-ray analysis (EDX), field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), and the Brunauer-Emmett-Teller (BET) analysis analyses were used to characterize the chemical, morphological, thermal, magnetic, and textural properties of the hydrogel nanocomposite. The obtained result demonstrated that the AG-g-HPAN@ZnFe2O4 adsorbent showed acceptable thermal stability with 58% char yields and superparamagnetic property with magnetic saturation (Ms) of 24 emu g-1. The XRD pattern showed that the semicrystalline structure with the presence of ZnFe2O4 has distinct peaks which displayed that the addition of zinc ferrite nanospheres to amorphous AG-g-HPAN increased its crystallinity. The AG-g-HPAN@ZnFe2O4 surface morphology exhibits uniform dispersion of zinc ferrite nanospheres throughout the smooth surface of the hydrogel matrix, and its BET surface area was measured at 6.86 m2/g, which was higher than that of AG-g-HPAN as a result of zinc ferrite nanosphere incorporation. The adsorption effectiveness of AG-g-HPAN@ZnFe2O4 for eliminating a quinolone antibiotic (levofloxacin) from aqueous solutions was investigated. The effectiveness of adsorption was assessed under several experimental conditions, including solution pH (2-10), adsorbent dose (0.0015-0.02 g) contact duration (10-60 min), and initial concentration (50-500 mg/L). The maximum adsorption capacity (Q max) of the produced adsorbent for levofloxacin was found to be 1428.57 mg/g (at 298 k), and the experimental adsorption data were well explained by the Freundlich isotherm model. The pseudo-second-order model satisfactorily described the adsorption kinetic data. The levofloxacin was mostly adsorbed onto the AG-g-HPAN@ZnFe2O4 adsorbent via electrostatic contact and hydrogen bonding. Adsorption-desorption studies demonstrated that the adsorbent could be efficiently recovered and reused after four consecutive runs with no significant loss in adsorption performance.

Assessment of catalytic and antibacterial activity of biocompatible agar supported ZnS/CuFe2O4 magnetic nanotubes.

The tubular magnetic agar supported ZnS/CuFe2O4 nanocomposite was fabricated via a simple procedure. Next, various properties of this nanocomposite were studied by employing multiple characterization techniques including FT-IR, EDX, SEM, TEM,VSM, XRD, and TGA. Then, the catalytic and antibacterial applications were evaluated for the fabricated nanocomposite. Based on the experimental result, the nanocomposite showed excellent catalytic activity to promote the multicomponent reaction between ethyl acetoacetate, hydrazine hydrate, aromatic aldehydes, and malononitrile to synthesize a variety of dihydropyrano[2,3-c]pyrazole derivatives with high yields (89-95%) in acceptable reaction times (20-40 min) under mild reaction conditions. It can be efficiently recycled and re-work in six consequent runs without notable reduction in catalytic productiveness. Furthermore, its antibacterial activity was assessed against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) bacteria by the agar diffusion and plate-count methods. These results indicate that the width of the inhibition zone around the S. aureus (G+ bacterium) is more than that of E. coli (G- bacterium). Moreover, the agar supported ZnS/CuFe2O4 nanocomposite exhibited strong prevention of the bacterial colonies' growth.

Efficient remediation of chlorpyrifos pesticide from contaminated water by superparamagnetic adsorbent based on Arabic gum-grafted-polyamidoxime.

A novel organic/inorganic biosorbent hydrogel nanocomposite based on Arabic Gum-grafted-polyamidoxime and CuFe2O4 magnetic nanoparticles (AG-g-PAO/CuFe2O4) was prepared in three steps. The prepared hydrogel nanocomposite was well characterized using Fourier transform infrared (FT-IR), energy-dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), CHN, zeta potential, and Brunauer-Emmett-Teller (BET) analyses. The adsorption efficiency of the AG-g-PAO/CuFe2O4 for removing an organophosphorus pesticide (OPP) (chlorpyrifos) from aqueous solutions was studied. Effect of different experimental conditions such as the pH of the solution, adsorbent dosage, contact time, initial concentration on adsorption efficiency was evaluated. The experimental adsorption data described well by the Langmuir isotherm model and the maximum adsorption capacity (Qmax) of the prepared biosorbent for chlorpyrifos was found 769.23 mg/g. The adsorption kinetic data were well fitted by the pseudo-second-order model. It was suggested that the chlorpyrifos was adsorbed onto AG-g-PAO/CuFe2O4 hydrogel biosorbent mainly through electrostatic interaction and hydrogen bonding. The result of adsorption-desorption experiments revealed that the AG-g-PAO/CuFe2O4 can be excellently regenerated and reused after three sequential runs without a considerable decline in its adsorption performance.

Guanidinylated SBA-15/Fe3O4 mesoporous nanocomposite as an efficient catalyst for the synthesis of pyranopyrazole derivatives.

In this study, a novel mesoporous nanocomposite was fabricated in several steps. In this regard, SBA-15 was prepared by the hydrothermal method, next it was magnetized by in-situ preparation of Fe3O4 MNPs. After that, the as-prepared SBA-15/Fe3O4 functionalized with 3-minopropyltriethoxysilane (APTES) via post-synthesis approach. Then, the guanidinylated SBA-15/Fe3O4 was obtained by nucleophilic addition of APTES@SBA-15/Fe3O4 to cyanimide. The prepared nanocomposite exhibited excellent catalytic activity in the synthesis of dihydropyrano[2,3-c]pyrazole derivatives which can be related to its physicochemical features such as strong basic sites (presented in guanidine group), Lewis acid site (presented in Fe3O4), high porous structure, and high surface area. The characterization of the prepared mesoporous nanocomposite was well accomplished by different techniques such as FT-IR, EDX, FESEM, TEM, VSM, TGA, XRD and BET. Furthermore, the magnetic catalyst was reused at least six consequent runs without considerable reduction in its catalytic activity.

Magnetic dextrin nanobiomaterial: An organic-inorganic hybrid catalyst for the synthesis of biologically active polyhydroquinoline derivatives by asymmetric Hantzsch reaction.

Dextrin is a low molecular weight polysaccharide obtained from natural resources. Due to exceptional properties such as chemical structure, having extreme reactive functional groups, low cost, commercial availability, non-toxicity and biocompatibility, it can be introduced as a green organocatalyst. The fabrication of hybrid materials from natural polymers and synthetic inorganic materials constructs compounds with new features, abilities and applications. Therefore, magnetic dextrin nanobiocomposite was prepared using a simple chemical co-precipitation. Then, it was characterized by Fourier transform infrared (FT-IR) spectroscopy, energy-dispersive X-ray (EDX) analysis, vibrating sample magnetometer (VSM) curve, scanning electron microscopy (SEM) image, X-ray diffraction (XRD) pattern, thermogravimetric analysis (TGA) and inductively-coupled plasma atomic emission spectroscopy (ICP-AES) analysis. Subsequently, to evaluate the catalytic performance of the synthetic hybrid catalyst, it was tested for the synthesis of biologically active polyhydroquinoline derivatives by four-component condensation reactions of aromatic aldehyde, ethyl acetoacetate, dimedone, ammonium acetate in ethanol under refluxing conditions. Experimental observations indicated some advantages of the present method, such as the use of green and biopolymer-based catalyst, simple procedure, mild reaction conditions, short reaction times (15-45 min), appropriate yield of products (70-95%) and catalyst reusability after five consecutive runs without considerable catalytic performance decrease.

Cu(ii) immobilized on Fe3O4@HNTs-tetrazole (CFHT) nanocomposite: synthesis, characterization, investigation of its catalytic role for the 1,3 dipolar cycloaddition reaction, and antibacterial activity.

In the present study, Cu(ii) immobilized on an Fe3O4@HNTs-tetrazole (CFHT) nanocomposite was designed and prepared. For this, halloysite nanotubes (HNTs) as natural mesoporous substances were modified during several chemical reactions. The synthesis of the CFHT nanocomposite was investigated step by step with the required physicochemical techniques such as FT-IR, EDX, SEM, TEM, XRD, VSM, TGA and CHNS analyses. After ensuring that the nanocomposite was successfully prepared, its catalytic application in the synthesis of the 5-substituted 1H-tetrazole derivatives via multicomponent reactions (MCRs) between aromatic aldehydes, malononitrile, and sodium azide was assessed. According to the experimental results, the prepared nanocomposite exhibited excellent capability for conducting this MCR reaction. All desired products were obtained in a short reaction time (30-40 min) with high productivity (90-97%) and without a complicated workup procedure. Furthermore, the magnetic property of the synthesized heterogeneous nanocomposite empowers it to be recovered and reused in five times successive reactions without any significant reduction in reaction efficiency. Moreover, the remarkable antibacterial activity of the nanocomposite against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was evaluated by agar diffusion and plate-count methods. The zones of inhibition were around 16 and 20 mm for E. coli and S. aureus bacteria, respectively. Also, colony analysis confirms the killing of bacteria by using the CFHT nanocomposite.