Surface functionalization of magnetic nanoparticles via palladium‐catalyzed Diels‐Alder approach

Fast synthesis of [1,2,3]-triazole derivatives on a Fe/Cu-embedded nano-catalytic substrate

Triazoles are biologically important compounds that play a crucial role in biomedical applications. In this study, we present an innovative and eco-friendly nanocatalyst system for synthesizing compounds via the click reaction. The system is composed of Arabic gum (AG), iron oxide magnetic nanoparticles (Fe3O4 MNPs), (3-chloropropyl) trimethoxysilane (CPTMS), 2-aminopyridine (AP), and Cu(i) ions. Using AP as an anchor for Cu(i) ions and Fe3O4 MNPs allows facile separation using an external magnet. The hydrophilic nature of the Fe3O4@AG/AP-Cu(i) nanocomposite makes it highly efficient in water as a green solvent. The highest reaction efficiency (95.0%) was achieved in H2O solvent with 50.0 mg of nanocatalyst for 60 min at room temperature. The reaction yield remained consistent for six runs, demonstrating the stability and effectiveness of the catalyst.

Silver-assisted reduction of nitroarenes by an Ag-embedded curcumin/melamine-functionalized magnetic nanocatalyst

In the current study, we introduce a hybrid magnetic nanocomposite comprised of curcumin (Cur), iron oxide magnetic nanoparticles (Fe₃O₄ MNPs), melamine linker (Mel), and silver nanoparticles (Ag NPs). Initially, a facile in situ route is administrated for preparing the Fe₃O₄@Cur/Mel-Ag effectual magnetic catalytic system. In addition, the advanced catalytic performance of the nanocomposite to reduce the nitrobenzene (NB) derivatives as hazardous chemical substances were assessed. Nevertheless, a high reaction yield of 98% has been achieved in short reaction times 10 min. Moreover, the Fe₃O₄@Cur/Mel-Ag magnetic nanocomposite was conveniently collected by an external magnet and recycled 5 times without a noticeable diminish in catalytic performance. Therefore, the prepared magnetic nanocomposite is a privileged substance for NB derivatives reduction since it achieved notable catalytic activity.

A magnetic X-band frequency microwave nanoabsorbent made of iron oxide/halloysite nanostructures combined with polystyrene

A novel nanocomposite has been designed and fabricated through an in situ polymerization process, based on iron oxide nanoparticles (Fe3O4 NPs), halloysite nanotubes (HNTs), and polystyrene (PS). The prepared nanocomposite (formulated as Fe3O4/HNT-PS) has been fully characterized through various methods, and its applicability in microwave absorption was investigated by using some single-layer and bilayer pellets containing nanocomposite and resin. The efficiency of the Fe3O4/HNT-PS composite with different weight ratios and pellets with the thickness of 3.0 and 4.0 mm were examined. Vector network analysis (VNA) revealed that the microwave (12 GHz) can be noticeably absorbed by Fe3O4/HNT-60% PS particles in a bilayer structure with 4.0 mm thickness and 85% resin of the pellets, resulting in a microwave absorption value of ca. -26.9 dB. The observed bandwidth (RL < -10 dB) was about 1.27 GHz, where ca. 95% of the radiated wave is absorbed. Ultimately, due to low-cost raw materials and high performance of the presented absorbent system, the Fe3O4/HNT-PS nanocomposite and the construction of the presented bilayer system can be subjected to further investigations to test and compare with other compounds for industrialization.

Vancomycin-Loaded Fe3O4/MOF-199 Core/Shell Cargo Encapsulated by Guanidylated-β-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.

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.

Pyrazolopyridines are common scaffolds in various bioactive compounds, which have several therapeutic effects and unique pharmacological properties.

Effects of morphology and size of nanoscale drug carriers on cellular uptake and internalization process: a review

In the field of targeted drug delivery, the effects of size and morphology of drug nanocarriers are of great importance and need to be discussed in depth. To be concise, among all the various shapes of nanocarriers, rods and tubes with a narrow cross-section are the most preferred shapes for the penetration of a cell membrane. In this regard, several studies have focused on methods to produce nanorods and nanotubes with controlled optimized size and aspect ratio (AR). Additionally, a non-spherical orientation could affect the cellular uptake process while a tangent angle of less than 45° is better at penetrating the membrane, and Ω = 90° is beneficial. Moreover, these nanocarriers show different behaviors when confronting diverse cells whose fields should be investigated in future studies. In this survey, a comprehensive classification based on carrier shape is first submitted. Then, the most commonly used methods for control over the size and shape of the carriers are reviewed. Finally, influential factors on the cellular uptake and internalization processes and related analytical methods for evaluating this process are discussed.

An effective antimicrobial complex of nanoscale β-cyclodextrin and ciprofloxacin conjugated to a cell adhesive dipeptide

Today, various drug delivery systems (DDS) are utilized to carry and deliver the desired drugs to the targeted action area to reduce potential side effects and negative interactions. Nanomaterials are an excellent candidate for the delivery of potent drugs, as they enhance pharmacokinetic and pharmacodynamic properties. Herein, we present a new ciprofloxacin (CPFX) delivery system based on a polymeric nanocarrier (β-cyclodextrin) conjugated to a cell-adhesive dipeptide structure. Cyclodextrin (CD) is an inexpensive, easily accessible, biodegradable, and biocompatible material. Also, the conjugation of cysteine-arginine (CR) dipeptide to the CPFX/β-CD particles is carried out to enhance cell adhesion growth. Through accurate analysis, the drug content and release for a final product have been estimated to be ca. 32%. Overall, the antimicrobial effects of CPFX were considerably raised through a low dose of CPFX. The growth zone inhibition of CPFX/β-CD-CR particles on the staphylococcus aureus and the Escherichia coli bacterial cells was 5.5 ± 0.2 cm and 3.5 ± 0.2 cm, respectively. Hence, this therapeutic nano bioconjugate is an excellent candidate to be applied in antimicrobial applications with the minimum incorporated CPFX.

Efficient Photodegradation of Eriochrome Black-T by a Trimetallic Magnetic Self-Synthesized Nanophotocatalyst Based on Zn/Au/Fe-Embedded Poly(vinyl alcohol)

This study presents a novel photocatalytic system for photocatalytic degradation of Eriochrome black-T (EBT) dye via green light-emitting diode (LED) light exposure. This photocatalyst is comprised of nanoscale components, i.e., poly(vinyl alcohol) (PVA), magnetic iron oxide nanoparticles (Fe₃O₄ NPs), gold NPs (Au NPs), and zinc oxide nanorods (ZnO NRs), rendering an active high surface area. The most highlighted property from the structural facet is the superparamagnetic behavior of Fe₃O₄ NPs, which provides a facile collection of magnetic photocatalyst NPs from the reaction flask and is successfully recycled eight times without considerable reduction in catalytic behavior. Briefly, the photocatalytic degradation at its highest efficiency reached 51.4% (10 ppm dye solution, 5.0 mL) and 64.75% (8 ppm dye solution, 5.0 mL) utilizing 10 mg of the designed photocatalyst (formulated as Fe₃O₄@PVA-Au/ZnO), a magnetic photocatalytic system under green LED light (7 W, 526 nm) exposure for 60 min. Besides, the photocatalytic degradation mechanism of the EBT dye by the as-prepared photocatalyst was proposed. Based on the obtained results, the presented photocatalytic method was recommended for scaling up and large-scale exploitation for the purification of the water resources.

Synergies in antimicrobial treatment by a levofloxacin-loaded halloysite and gold nanoparticles with a conjugation to a cell-penetrating peptide

Herein, a novel designed antimicrobial therapeutic drug delivery system is presented, in which halloysite nanotubes (HNTs) encapsulate a determined dosage of levofloxacin (lvx). Moreover, gold nanoparticles (AuNPs) have been embedded into the structure for plasmonic heating under irradiation of the green LED light (7 W, 526 nm). It was revealed that the plasmonic heating of the AuNPs leads to a controlled trend in the lvx release process. Also, a synergistic effect on the antimicrobial activity of the prepared therapeutic system has been observed through photothermal heating of the structure. To enhance the cell adhesion, a cell-penetrating peptide sequence (CPP) is conjugated to the surfaces. This CPP has led to quick co-localization of the prepared nano-cargo (denoted as lvx@HNT/Au-CPP) with the bacterial living cells and further attachment (confirmed by confocal microscopy). Concisely, the structure of the designed nano-cargo has been investigated by various methods, and the in vitro cellular experiments (zone of inhibition and colony-counting) have disclosed that the antimicrobial activity of the lvx is significantly enhanced through incorporation into the HNT/Au-CPP delivery system (drug content: 16 wt%), in comparison with the individual lvx with the same dosage. Hence, it can be stated that the bacterial resistance against antibiotics and the toxic effects of the chemical medications are reduced through the application of the presented strategy.

A magnetic antibody-conjugated nano-system for selective delivery of Ca(OH)2 and taxotere in ovarian cancer cells

An efficient strategy for cancer therapy is presented, in which a tumor mass is initially pretreated with calcium hydroxide, then treated with Taxotere (TXT). In this regard, an advanced delivery system based on iron oxide nanoparticles has been designed. The surface of nanoparticles was functionalized with sortilin (SORT-1, a human IgG1 monoclonal antibody) that specifically encodes caov-4 ovarian cancerous cells. Plasmonic heating of the incorporated gold nanoparticles in polyvinyl alcohol (PVA) has been exploited to control the release process of TXT. The in vitro, ex vivo and in vivo experiments have exhibited high efficacy of a seven-day pretreatment by Ca(OH)₂ plus 14 days treatment program by Ca(OH)₂@Fe₃O₄/PVA/Au-SORT nano-therapeutics, where more penetration ratio resulted in tumor growth inhibition by ca. 78.3%. As a result, due to showing high values of the anti-tumor properties and biosafety, the presented pretreatment strategy is suggested for more effective treatment on the aged tumors.

A magnetic drug delivery system containing polyvinyl alcohol, gold nanoparticles, and sortilin antibody followed by the plasmonic photothermal heating strategy for the controlled drug release is proposed, with use in ovarian cancer demonstrated.

A diselenobis-functionalized magnetic catalyst based on iron oxide/silica nanoparticles suggested for amidation reactions

In this study, a new heterogeneous magnetic catalytic system based on selenium-functionalized iron oxide nanoparticles is presented and suggested for facilitating amide/peptide bonds formation. The prepared nanocatalyst, entitled as "Fe3O4/SiO2-DSBA" (DSBA stands for 2,2'-diselanediylbis benzamide), has been precisely characterized for identifying its physicochemical properties. As the most brilliant point, the catalytic performance of the designed system can be mentioned, where only a small amount of Fe3O4/SiO2-DSBA (0.25 mol%) has resulted in 89% reaction yield, under a mild condition. Also, given high importance of green chemistry, convenient catalyst particles separation from the reaction medium through its paramagnetic property (ca. 30 emu·g-1) should be noticed. This particular property provided a substantial opportunity to recover the catalyst particles and successfully reuse them for at least three successive times. Moreover, due to showing other excellences, such as economic benefits and nontoxicity, the presented catalytic system is recommended to be scaled up and exploited in the industrial applications.

Fe3O4@SiO2-PMA-Cu magnetic nanoparticles as a novel catalyst for green synthesis of β-thiol-1,4-disubstituted-1,2,3-triazoles

The magnetic nanoparticles of Fe₃O₄ were synthesized through a solid-state reaction of hydrated iron (III) chloride, hydrated iron (II) chloride and NaOH, and then purified by calcination at high temperature. In order to protect ferrite nanoparticles from oxidation and agglomeration, and to manufacture a novel catalytic system of anchored copper on the magnetic substrate, the Fe₃O₄ was core-shelled by adding tetraethyl orthosilicate. Next, the prepared Fe₃O₄@SiO₂ was supported by phosphomolybdic acid (PMA) as the second layer of nanocomposite at 80 °C in 30 h. Eventually, the new nanocomposite of Fe₃O₄@SiO₂-PMA-Cu was successfully synthesized by adding copper (II) chloride solution and solid potassium borohydride. The structure of magnetic nanocatalyst was acknowledged through different techniques such as EDS, VSM, XRD, TEM, FT-IR, XPS, TGA, BET and FESEM. The synthesis of β-thiolo/benzyl-1,2,3-triazoles from various thiiranes, terminal alkynes and sodium azide was catalyzed by Fe₃O₄@SiO₂-PMA-Cu nanocomposite in aqueous medium. In order to obtain the optimum condition, the effects of reaction time, temperature, catalyst amount and solvent were gauged. The recycled catalyst was used for several consecutive runs without any loss of activity.

Nanoscale bioconjugates: A review of the structural attributes of drug-loaded nanocarrier conjugates for selective cancer therapy

Nanobioconjugates are nanoscale drug delivery vehicles that have been conjugated to or decorated with biologically active targeting ligands. These targeting ligands can be antibodies, peptides, aptamers, or small molecules such as vitamins or hormones. Most research studies in this field have been devoted to targeting cancer. Moreover, the nanostructures can be designed with an additional level of targeting by being designed to be stimulus-responsive or "smart" by a judicious choice of materials to be incorporated into the hybrid nanostructures. This stimulus could be an acidic pH, raised temperature, enzyme, ultrasound, redox potential, an externally applied magnetic field, or laser irradiation. In this case, the smart capability can increase the accumulation at the tumor site or the on-demand drug release, while the ligand ensures selective binding to the tumor cells. The present review highlights some interesting studies classified according to the nanostructure material. These materials include natural substances (polysaccharides), multi-walled carbon nanotubes (and halloysite nanotubes), metal-organic frameworks and covalent-organic frameworks, metal nanoparticles (gold and silver), and polymeric micelles.

Functionalized hybrid magnetic catalytic systems on micro- and nanoscale utilized in organic synthesis and degradation of dyes

Herein, a concise review of the latest developments in catalytic processes involving organic reactions is presented, focusing on magnetic catalytic systems (MCSs). In recent years, various micro- and nanoscale magnetic catalysts have been prepared through different methods based on optimized reaction conditions and utilized in complex organic synthesis or degradation reactions of pharmaceutical compounds. These biodegradable, biocompatible and eco-benign MCSs have achieved the principles of green chemistry, and thus their usage is highly advocated. In addition, MCSs can shorten the reaction time, effectively accelerate reactions, and significantly upgrade both pharmaceutical synthesis and degradation mechanisms by preventing unwanted side reactions. Moreover, the other significant benefits of MCSs include their convenient magnetic separation, high stability and reusability, inexpensive raw materials, facile preparation routes, and surface functionalization. In this review, our aim is to present at the recent improvements in the structure of versatile MCSs and their characteristics, i.e., magnetization, recyclability, structural stability, turnover number (TON), and turnover frequency (TOF). Concisely, different hybrid and multifunctional MCSs are discussed. Additionally, the applications of MCSs for the synthesis of different pharmaceutical ingredients and degradation of organic wastewater contaminants such as toxic dyes and drugs are demonstrated.

Cefixime-Containing Silica Nanoseeds Coated by a Hybrid PVA-Gold Network with a Cys-Arg Dipeptide Conjugation: Enhanced Antimicrobial and Drug Release Properties

Therapeutic nano-bioconjugates (TNBCs) as an advanced class of drug delivery systems have attracted much attention due to more efficacy than the individual medications. Hence, in this study, a novel anti-infection TNBC system is designed based on highly porous silica nanoparticles, gold nanoparticles (AuNPs), and hybridized polyvinyl alcohol (PVA) for the efficient delivery of cefixime (CFM). Furthermore, a conjugation of cysteine-arginine (CR) dipeptide is made onto the surfaces for the enhancement of cell adhesion. Concisely, the AuNPs incorporated inside the PVA network play the key role in the controlled release process triggered by localized surface plasmon resonance (LSPR) heating. The drug content of the CFM-containing cargo (named as CFM@SiO₂/PVA/Au-CR) and related release profile have been precisely studied by the confirmed analytical methods. Eventually, confocal microscopy on the stained cells has revealed that the TNBC particles are capable of entering the Escherichia coli (E. coli) and Klebsiella pneumoniae (K. pneumoniae) bacterial cells better than the individual CFM. Also, optical density experiments (OD₆₀₀) have corroborated that the prepared CFM@SiO₂/PVA/Au-CR TNBC includes a high antimicrobial effect on K. pneumoniae and E. coli cells with (93.0 ± 1.5) % and (86.8 ± 1.0) % success rates, respectively, whereas the same dosage of the individual CFM has shown a lower effect on the cell growth rate. Also, estimation of minimum inhibitory/bactericidal concentrations (MIC/MBC) confirmed the enhanced antibacterial property of the CFM through the presented delivery method. Overall, this product is suggested to be clinically administrated instead of the individual CFM due to its high efficacy and containing lower dosage of the antibiotic drug.

Enhanced antimicrobial treatment by a clay-based drug nanocarrier conjugated to a guanidine-rich cell penetrating peptide

In this study, a novel and efficient drug delivery system is proposed for the enhancement of antimicrobial properties of antibiotic medications such as vancomycin (VCM) and levofloxacin (OFX). The architecture of the designed drug carrier is based on halloysite nanotubes (HNTs) with a rolled-laminate shape, suitable for the encapsulation of drug and further release. In order to make them capable for magnetic direction to the target tissue, the exterior surface of the tubes is composed of iron oxide nanoparticles (Fe₃O₄ NPs), via an in situ process. The main role in the antimicrobial activity enhancement is played by a cell-penetrating peptide (CPP) sequence synthesized in the solid phase, which contains three arginine–tryptophan blocks plus a cysteine as the terminal amino acid (C(WR)₃). The drug content values for the prepared nanocargoes named as VCM@Fe₃O₄/HNT–C(WR)₃ and OFX@Fe₃O₄/HNT–C(WR)₃, have been estimated at ca. 10 wt% and 12 wt%, respectively. Also, the drug release investigations have shown that above 90% of the encapsulated drug is released in acetate buffer (pH = 4.6), during a 90 minutes process. Confocal microscopy has corroborated good adhesion and co-localization of the particles and the stained living cells. Moreover, in vitro antimicrobial assessments (optical density, zone of inhibition, and minimum inhibitory concentration) have revealed that the bacterial cell growth rate is significantly inhibited by suggested nanocargoes, in comparison with the individual drugs in the same dosage. Hence, administration of the presented nanocargoes is recommended for the clinical treatment of the infected target organ.

A novel anti-infection therapeutic nano-bioconjugate based on magnetized halloysite nanotubes and a CPP is presented. High levels of bactericidal effects have been obtained with the designed nanocargo in comparison with the individual drugs.

Magnetic Particle Spectroscopy with One-Stage Lock-In Implementation for Magnetic Bioassays with Improved Sensitivities

In recent years, magnetic particle spectroscopy (MPS) has become a highly sensitive and versatile sensing technique for quantitative bioassays. It relies on the dynamic magnetic responses of magnetic nanoparticles (MNPs) for the detection of target analytes in the liquid phase. There are many research studies reporting the application of MPS for detecting a variety of analytes including viruses, toxins, nucleic acids, and so forth. Herein, we report a modified version of the MPS platform with the addition of a one-stage lock-in design to remove the feedthrough signals induced by external driving magnetic fields, thus capturing only MNP responses for improved system sensitivity. This one-stage lock-in MPS system is able to detect as low as 781 ng multi-core Nanomag50 iron oxide MNPs (micromod Partikeltechnologie GmbH) and 78 ng single-core SHB30 iron oxide MNPs (Ocean NanoTech). We first demonstrated the performance of this MPS system for bioassay-related applications. Using the SARS-CoV-2 spike protein as a model, we have achieved a detection limit of 125 nM (equal to 5 pmole) for detecting spike protein molecules in the liquid phase. In addition, using a streptavidin-biotin binding system as a proof-of-concept, we show that these single-core SHB30 MNPs can be used for Brownian relaxation-based bioassays while the multi-core Nanomag50 cannot be used. The effects of MNP amount on the concentration-dependent response profiles for detecting streptavidin were also investigated. Results show that by using a lower concentration/ amount of MNPs, concentration-response curves shift to a lower concentration/amount of target analytes. This lower concentration-response indicates the possibility of improved bioassay sensitivities by using lower amounts of MNPs.

Highly porous copper-supported magnetic nanocatalysts: made of volcanic pumice textured by cellulose and applied for the reduction of nitrobenzene derivatives

Herein, a novel designed heterogeneous catalytic system constructed of volcanic pumice magnetic particles (VPMPs), cellulose (CLS) as a natural polymeric matrix, and copper nanoparticles (Cu NPs) is presented. Also, to enhance the inherent magnetic property of VPMP, iron oxide (Fe3O4) nanoparticles have been prepared and incorporated in the structure via an in situ process. As its first and foremost excellent property, the designed composite is in great accordance with green chemistry principles because it contains natural ingredients. Another brilliant point in the architecture of the designed composite is the noticeable porosity of VPMP as the core of the composite structure (surface area: 84.473 m2 g-1). This great porosity leads to the use of a small amount (0.05 g) of the particles for catalytic purposes. However, the main characterization methods, such as Fourier-transform infrared and energy-dispersive X-ray spectroscopy, thermogravimetric analysis, and electron microscopy, revealed that the spherical metallic particles (Fe and Cu oxides) were successfully distributed onto the surface of the VPMP and CLS matrices. Further, vibrating-sample magnetometer analysis confirmed the enhancement of the magnetic property (1.5 emu g-1) of the composite through the addition of Fe3O4 nanoparticles. Further, the prepared (Fe3O4@VPMP/CLS-Cu) nanocomposite has been applied to facilitate the reduction reaction of hazardous nitrobenzene derivatives (NBDs) to their aniline analogs, with 98% conversion efficiency in eight minutes under mild conditions. Moreover, the good reusability of the catalytic system has been verified after recycling it ten times without any significant decrease in the performance.

Bifunctional PVA/ZnO/AgI/Chlorophyll Nanocomposite Film: Enhanced Photocatalytic Activity for Degradation of Pollutants and Antimicrobial Property under Visible-Light Irradiation

Here, poly(vinyl alcohol) (PVA) with numerous hydroxyl groups has been applied as a suitable substrate for efficient formation of zinc oxide (ZnO) nanoparticles with a flower shape (confirmed by electron-scanning microscopy), silver iodide (AgI) nanoparticles, and chlorophyll (Chl), as a natural-based photocatalyst (PVA/ZnO/AgI/Chl). First, an efficient preparation route for the PVA/ZnO/AgI/Chl nanophotocatalyst is presented starting from the extraction of Chl from fresh spinach. Then, the catalytic role of the prepared composite is precisely investigated in degradation of methylene blue (MB). The effects of visible-light irradiation, different contact times, and the employed ingredients on the architecture of the PVA/ZnO/AgI/Chl are screened in the degradation process of MB. It is demonstrated that the best result (MB removal efficiency ca. 95.5%) is achieved by applying the visible-light irradiation using a LED lamp (70 W, λ = 425 nm) for a 60 min duration. Moreover, the photocatalytic performance of PVA/ZnO/AgI/Chl has been further confirmed by degradation of Congo red (CR) (ca. 92%, in 150 min) and 4-chlorophenol (4-CP) (88%, in 270 min), as well. As another function of the prepared PVA/ZnO/AgI/Chl composite, a substantial antibacterial property against human bacterial pathogens such as Staphylococcus aureus and Escherichia coli as Gram-positive and Gram-negative bacteria has been noticed, studied by agar diffusion cup plate and colony methods. The zones of inhibition have been evaluated ca. 20 and 12 mm for the S. aureus and E. coli cell lines, respectively. Finally, a great synergy between the prepared composite and the visible light has been observed through the examination of the live bacteria: 99.6% for S. aureus and 99.8% for E. coli in the presence of visible light, after the subjection of PVA/ZnO/AgI/Chl particles to the bacteria, verified by the colony counter method.

Reversible Diels-Alder Reactions with a Fluorescent Dye on the Surface of Magnetite Nanoparticles

Diels–Alder reactions on the surface of nanoparticles allow a thermoreversible functionalization of the nanosized building blocks. We report the synthesis of well-defined magnetite nanoparticles by thermal decomposition reaction and their functionalization with maleimide groups. Attachment of these dienophiles was realized by the synthesis of organophosphonate coupling agents and a partial ligand exchange of the original carboxylic acid groups. The functionalized iron oxide particles allow a covalent surface attachment of a furfuryl-functionalized rhodamine B dye by a Diels–Alder reaction at 60 °C. The resulting particles showed the typical fluorescence of rhodamine B. The dye can be cleaved off the particle surface by a retro-Diels–Alder reaction. The study showed that organic functions can be thermoreversibly attached onto inorganic nanoparticles.

Magnetic nanocatalysts utilized in the synthesis of aromatic pharmaceutical ingredients

This review covers recent developments in nanoscale magnetic catalytic systems and their applications in facilitating organic synthetic reactions of aromatic pharmaceutical ingredients.

Convenient conversion of hazardous nitrobenzene derivatives to aniline analogues by Ag nanoparticles, stabilized on a naturally magnetic pumice/chitosan substrate

Herein, silver nanoparticles (Ag NPs), as an effective catalyst for the reduction process of nitrobenzene derivatives to non-hazardous and useful aniline derivatives, are conveniently synthesized on an inherently magnetic substrate. For this purpose, an efficient combination of volcanic pumice (VP), which is an extremely porous igneous rock, and a chitosan (CTS) polymeric network is prepared and suitably used for the stabilization of the Ag NPs. High magnetic properties of the fabricated Ag@VP/CTS composite, which have been confirmed via vibrating-sample magnetometer (VSM) analysis, are the first and foremost advantage of the introduced catalytic system since it gives us the opportunity to easily separate the particles and perform purification processes. Briefly, higher yields were obtained in the reduction reactions of nitrobenzenes (NBs) under very mild conditions in a short reaction time. Also, along with the natural biocompatible ingredients (VP and CTS) in the structure, excellent recyclability has been observed for the fabricated Ag@VP/CTS catalytic system, which convinces us to do scaling-up and suggests the presented system can be used for industrial applications.

Facile route to synthesize Fe3O4@acacia-SO3H nanocomposite as a heterogeneous magnetic system for catalytic applications

In this work, a novel catalytic system for facilitating the organic multicomponent synthesis of 9-phenyl hexahydroacridine pharmaceutical derivatives is reported. Concisely, this catalyst was constructed from acacia gum (gum arabic) as a natural polymeric base, iron oxide magnetic nanoparticles (Fe3O4 NPs), and sulfone functional groups on the surface as the main active catalytic sites. Herein, a convenient preparation method for this nanoscale composite is introduced. Then, essential characterization methods such as various spectroscopic analyses and electron microscopy (EM) were performed on the fabricated nano-powder. The thermal stability and magnetic properties were also precisely monitored via thermogravimetric analysis (TGA) and vibrating-sample magnetometry (VSM) methods. Then, the performance of the presented catalytic system (Fe3O4@acacia-SO3H) was further investigated in the referred organic reaction by using various derivatives of the components involved in the reaction. Optimization, mechanistic studies, and reusability screening were carried out for this efficient catalyst as well. Overall, remarkable reaction yields (94%) were obtained for the various produced derivatives of 9-phenyl hexahydroacridine in the indicated optimal conditions.

Multi-Stimuli Nanocomposite Therapeutic: Docetaxel Targeted Delivery and Synergies in Treatment of Human Breast Cancer Tumor

A versatile breast cancer-targeting nanocomposite therapeutic combining docetaxel (DXL), polyvinyl alcohol (PVA) network for controlled release, and silica-protected magnetic iron oxide nanoparticles (Fe3 O4 NPs) for targeted delivery and gold nanoparticles (AuNPs) for plasmonic photothermal therapy (PPTT) is presented in this work. First, the designed nanocomposite is magnetically directed for cancer-targeted therapy confirmed by computerized tomography (CT) scans. Second, 10% DXL by mass is loaded into PVA, a pH and temperature responsive gel, for controlled release. Third, PPTT is confirmed with Au/Fe3 O4 /PVA-10%DXL using a prototype circulation system and then for tumor treatment in vivo; Au/Fe3 O4 /PVA-10%DXL is conveniently directed and the entrapped DXL is selectively released (≈96%) via the interaction of green and near-infrared (NIR) light with the localized surface plasmon resonance of AuNPs. A 75% cell death is reported from in vitro studies with DXL doses as low as 20 µg mL-1 of Au/Fe3 O4 /PVA-10%DXL, and a 70% tumor growth inhibition is demonstrated by in vivo experiments with the biosafety studies confirming minimal side effects to other organs. Overall, the developed Au/Fe3 O4 /PVA-10%DXL has a strong potential to simultaneously enhance CT imaging contrast together with the targeted delivery of DXL.

Synthesis and characterization of a supported Pd complex on volcanic pumice laminates textured by cellulose for facilitating Suzuki-Miyaura cross-coupling reactions

Herein, a novel high-performance heterogeneous catalytic system made of volcanic pumice magnetic particles (VPMP), cellulose (CLS) natural polymeric texture, and palladium nanoparticles (Pd NPs) is presented. The introduced VPMP@CLS-Pd composite has been designed based on the principles of green chemistry, and suitably applied in the Suzuki-Miyaura cross-coupling reactions, as an efficient heterogeneous catalytic system. Concisely, the inherent magnetic property of VPMP (30 emu g-1) provides a great possibility for separation of the catalyst particles from the reaction mixture with great ease. In addition, high heterogeneity and high structural stability are obtained by this composition resulting in remarkable recyclability (ten times successive use). As the main catalytic sites, palladium nanoparticles (Pd NPs) are finely distributed onto the VPMP@CLS structure. To catalyze the Suzuki-Miyaura cross-coupling reactions producing biphenyl pharmaceutical derivatives, the present Pd NPs were reduced from chemical state Pd2+ to Pd0. In this regard, a plausible mechanism is submitted in the context as well. As the main result of the performed analytical methods (including FT-IR, EDX, VSM, TGA, FESEM, TEM, BTE, and XPS), it is shown that the spherical-shaped nanoscale Pd particles have been well distributed onto the surfaces of the porous laminate-shaped VPMP. However, the novel designed VPMP@CLS-Pd catalyst is used for facilitating the synthetic reactions of biphenyls, and high reaction yields (∼98%) are obtained in a short reaction time (10 min) by using a small amount of catalytic system (0.01 g), under mild conditions (room temperature).

Design and Fabrication of a Magnetite-based Polymer-supported Hybrid Nanocomposite: A Promising Heterogeneous Catalytic System Utilized in Known Palladium-assisted Coupling Reactions

Objective:

Herein, a novel heterogeneous catalytic system constructed of iron oxide and palladium nanoparticles is presented. Firstly, a convenient synthetic pathway for the preparation of this catalytic system is introduced, then the application of the fabricated nanocomposite in the Pd-catalyzed C─C coupling reactions is monitored. High reaction yields (98%) have been obtained in short reaction time, by using this catalytic system.

Materials and Methods:

Fe3O4/P4VP-Pd catalytic system was fabricated via an in situ method by 4- vinylpyridine (4-VP). In this regard, all the essential structural analyses such as FT-IR, EDX, VSM, and TGA have been performed on the Fe3O4/P4VP-Pd catalytic system to investigate its properties. The spherical morphology of the NPs and their uniform size have also been studied by the SEM method. Further, the reaction progress was controlled by thin-layer chromatography. Finally, NMR analysis was used to identify the synthesized biphenyl pharmaceutical derivatives.

Results:

High efficiency of this catalytic system has been precisely investigated and the optimal conditions were determined. The catalytic process is carried out in 20 min, under mild conditions (room temperature). Then, the purification process is easily performed via magnetic separation of the catalyst NPs. After completion of the synthesis reaction, the NPs were collected, washed, and reused several times.

Conclusion:

Among recently reported heterogeneous catalytic systems, Fe3O4/P4VP-Pd is recommended due to its high catalytic performance, convenience of the preparation process, excellent biocompatibility, economic benefits, and well reusability. Overall, in order to save time in the complex synthetic processes and also prevent using so many chemical reagents and solvents for the purification process, the presented catalytic system could be suitable for scaling up and applying for the industrial applications.

Cellulose-Supported Sulfonated Magnetic Nanoparticles: Utilized for One-pot Synthesis of α-Iminonitrile Derivatives

ntroduction: An instrumental strategy for α-iminonitrile derivatives preparation by Fe3O4@cellulose-OSO3H (MCSA) as an eco-friendly nanocatalyst and oxidative agent in aerobic condition, is presented.

MATERIALS AND METHODS

Through this method, a one-pot three-component condensation reaction of various aldehydes, primary amines and trimethylsilylcyanide (TMSCN) were applied to synthesize the desired products. It was performed in absolute ethanol and under a mild condition by using the presented nanocatalyst. High reaction yields were obtained through using the presented magnetic agent, as well. Moreover, the threecomponent reactions were executed using accessible and economical precursors. The convenient separation and recyclability of the used nanocatalyst were also precisely investigated.

RESULTS AND DISCUSSION

In this research, we identified novel α-iminonitrile derivatives using 1H NMR, 13C NMR, CHN, and FT-IR analyses, as well. In order to determine the well-known derivatives, we used FT-IR method as well as comparing their melting points with those of reported.

CONCLUSION

In summary, an extremely efficient method was used for the environmentally-friendly synthesis of α-iminonitrile derivatives that are important bioactive substances. The catalytic oxidative coupling reaction afforded the products via a one-pot three-component condensation reaction of various aldehydes, primary amines and TMSCN with great reaction yields, in ethanol under mild conditions.

High-performance sono/nano-catalytic system: Fe3O4@Pd/CaCO3-DTT core/shell nanostructures, a suitable alternative for traditional reducing agents for antibodies

Herein, a novel heterogeneous nanoscale reducing agent for antibody cleavage, made of iron oxide nanoparticles, silica network, palladium on calcium carbonate (10%), and dithiothreitol (Fe₃O₄@Pd/CaCO₃-DTT), is presented as a substantial alternative for traditional homogeneous analogues. Conventionally, antibody fragmentation is accomplished using reducing agents and proteases that digest or cleave certain portions of the immunoglobulin protein structure to provide active thiol sites for drug tagging aims. Then, dialysis process is needed to separate excess chemical structures and purify the reduced antibody. In this work, we have made an effort to design a suitable heterogeneous tool for protein cleavage and skip the dialysis process for purification of the reduced antibody. In this regard, firstly, various preparation methods including microwave irradiation, reflux and ultrasonication have been precisely compared, and it has been proven that the best result is obtained through 10 min ultrasound (US) irradiation using an US bath with 50 KHz frequency and 200 W L^-1 power density. Then, all the necessary structural analyses have been done and thoroughly interpreted for the final product. Afterward, the catalytic performance of Fe₃O₄@Pd/CaCO₃-DTT nanoscale system in the presence of US waves (50 KHz, 200 W) has been monitored using some disulphide derivatives. The NPs could be conveniently separated from the mixture through their substantial paramagnetic property. Thus, dialysis process in which various types of membranes are used is practically jumped after the reduction process. In this work, this is clearly demonstrated that there is a constructive synergistic effect between US waves and prepared Fe₃O₄@Pd/CaCO₃-DTT nanoscale reducing agent. Ultimately, trastuzumab (anti HER-2) antibody has been used to test the performance of the prepared Fe₃O₄@Pd/CaCO₃-DTT NPs in a real protein reduction reaction.

Reversible Covalent Assembly of Nanoparticles through On-Surface Diels-Alder Reaction

We demonstrate here a controlled assembly of individual nanoscale building blocks into defined architectures based on chemospecific covalent bonding interactions. For this purpose, α-Fe₂O₃, γ-Fe₂O₃, and SiO₂ nanoparticles decorated with surface-conjugated organic ligands were used for performing on-surface Diels-Alder reactions. Driven through their chemical affinity and surface-grafted complementary functionalities, nanoparticles underwent click-reactions to produce covalently organized nanostructures. An advantage of using the Diels-Alder reaction is its reversible nature, which was used to click and unclick the nanoparticles on demand. The efficiency and chemical specificity of this approach opens up another synthetic access to unify materials with complementary properties, where the thermoresponsive nature of particle assemblies imparts to them a fully reversible character. The covalent conjugation strategies demonstrated in this work potentially allow the use of a diverse range of particles and ligands for their applications in different disciplines such as medicine, optics, or photonics. The nanoparticles morphology and crystalline nature were investigated by TEM and XRD analysis, while the presence of surface attached groups was verified by NMR, FTIR, UV-vis, and ζ potential measurements.

Ultrasound-assisted diversion of nitrobenzene derivatives to their aniline equivalents through a heterogeneous magnetic Ag/Fe3O4-IT nanocomposite catalyst

A heterogeneous magnetic catalytic system is fabricated and suitably applied for the fast and direct conversion of nitrobenzene (NB) derivatives to their aniline forms.

Enhanced activity of vancomycin by encapsulation in hybrid magnetic nanoparticles conjugated to a cell-penetrating peptide

We describe a novel antibiotic delivery system based on magnetic nanoparticles (NPs) conjugated to a cell-penetrating peptide (CPP).

High-performance sono/nano-catalytic system: CTSN/Fe3O4-Cu nanocomposite, a promising heterogeneous catalyst for the synthesis of N-arylimidazoles

Herein, a promising heterogeneous nanoscale catalytic system constructed of chitosan (CTSN, as a polymeric basis), iron oxide nanoparticles (Fe3O4 NPs, as the magnetic agent), and copper oxide nanoparticles (CuO NPs, as the main catalytic active site) is presented. Firstly, a convenient synthetic route for preparation of this novel nanocatalyst (CTSN/Fe3O4-Cu) is presented. Further, the synergistic catalytic effect between the novel-designed catalyst and ultrasound waves (USW) in N-arylation coupling reactions of the imidazole derivatives (using various aryl halides) is precisely discussed. Concisely, high reaction yields (98%) have been obtained in short reaction time (10 min) through applying a partial amount (0.01 g) of this nanocatalyst. As the main reason for high catalytic activity of CTSN/Fe3O4-Cu, nanosized cluster-shaped morphology, which provides a wide surface active area, can be expressed. However, as the most distinguished properties of CTSN/Fe3O4-Cu catalytic system, high convenience in separation and excellent reusability could be mentioned. CTSN/Fe3O4-Cu nanocomposite can be easily recovered by using an external magnet and reused at least for eight times with no significant decline in the catalytic activity. Structural characterizations of this novel system have been done by various analytical methods and the obtained results have been well interpreted in the context.

Synergistic catalytic effect between ultrasound waves and pyrimidine-2,4-diamine-functionalized magnetic nanoparticles: Applied for synthesis of 1,4-dihydropyridine pharmaceutical derivatives

A convenient strategy for synthesis of the various derivatives of 1,4-dihydropyridine (1,4-DHP), as one of the most important pharmaceutical compounds, is presented in this study. For this purpose, firstly, magnetic iron oxide nanoparticles (Fe₃O₄ NPs) were fabricated and suitably coated by silica network (SiO₂) and trimethoxy vinylsilane (TMVS). Then, their surfaces were well functionalized with pyrimidine-2,4-diamine (PDA) as the main active sites for catalyzing the synthesis reactions. In this regard, the performance of three different methods including reflux, microwave (MW) and ultrasound wave (USW) irradiations have been comparatively monitored via studying various analyses on the fabricated nanocatalyst (Fe₃O₄/SiO₂-PDA). Concisely, high efficiency of the USW irradiation (in an ultrasound cleaning bath with a frequency of 50 kHz and power of 250 W/L) has been well proven through the investigation of the main factors such as excellent surface-functionalization, core/shell structure conservation, particle uniformity, close size distribution of the particles, and great inhibition of the particle aggregation. Then, the effectiveness of the USW irradiation as a promising co-catalyst agent has been clearly demonstrated in the 1,4-DHP synthesis reactions. It has been concluded that the USW could provide more appropriate conditions for activation of the catalytic sites of Fe₃O₄/SiO₂-PDA NPs. However, high reaction yields (89%) have been obtained in the short reaction times (10 min) due to the substantial synergistic effect between the presented nanocatalyst and USW.

A brief survey on the advanced brain drug administration by nanoscale carriers: With a particular focus on AChE reactivators

Obviously, delivery of the medications to the brain is more difficult than other tissues due to the existence of a strong obstacle, which is called blood-brain barrier (BBB). Because of the lipophilic nature of this barrier, it would be a complex (and in many cases impossible) process to cross the medications with hydrophilic behavior from BBB and deliver them to the brain. Thus, novel intricate drug-carriers in nano scales have been recently developed and suitably applied for this purpose. One of the most important categories of these hydrophilic medications, are reactivators for acetyl cholinesterase (AChE) enzyme that facilitates the breakdown of acetylcholine (as a neurotransmitter). The AChE function is inhibited by organophosphorus (OP) nerve agents that are extremely used in military conflicts. In this review, the abilities of the nanosized drug delivery systems to perform as suitable vehicles for AChE reactivators are comprehensively discussed.