Tetramethylguanidine-functionalized silica-coated iron oxide magnetic nanoparticles catalyzed one-pot three-component synthesis of furanone derivatives

pH-responsive magnetic CuFe2O4-PMAA nanogel conjugated with amino-modified lignin for controlled breast cancer drug delivery

In this study, a novel magnetic and pH-responsive nanocarrier was developed, incorporating both natural and synthetic polymers, for delivering curcumin (CUR) to breast cancer cells. For this purpose, CuFe2O4@poly(methacrylic acid) (CuFe2O4@PMAA) nanogel was developed and conjugated with amino-modified lignin (Lignin-adipic acid dihydrazide conjugate, Lig-ADH) to achieve the CuFe2O4@PMAA@Lig-ADH nanocarrier. The morphology, structure, and physical properties of the synthesized nanomaterials were examined using a range of techniques, including transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray (EDX), and vibrating sample magnetometer (VSM). The synthesized nanocarrier exhibited a spherical shape, with an average diameter of approximately 15 nm, and demonstrated good magnetic responsiveness. Moreover, the in vitro drug release was found to be pH-dependent, with an increased release rate in acidic conditions. To evaluate cytotoxicity, the survival of MCF-7 cells was measured using the MTT assay for 24 h. Notably, the synthesized CuFe2O4@PMAA@Lig-ADH@CUR and CUR exhibited significant cytotoxic effects, effectively eliminating MCF-7 cells with IC50 values of 39.80 µg/mL and 4.27 µg/mL, respectively. Also, the significant intracellular uptake of NPs was confirmed by FITC and DAPI staining after 4 h. This research highlighted the potential of CuFe2O4@PMAA@Lig-ADH@CUR as a highly effective nano-delivery system and demonstrated a straightforward method for utilizing renewable lignin.

Tubular electrosynthesis of silica-coated magnetite and evaluation of magnetic nanobiocatalyst efficacy during biomass hydrolysis

Magnetic nanobiocatalysts (MNBCs) are a promising immobilization approach to ease enzyme recovery during bioprocessing. However, industrial adoption of MNBCs is unfeasible because MNBC-synthesis involves complex and potentially expensive processing steps including synthesis of silica-coated superparamagnetic iron oxide nanoparticles (Si-SPIONs). We developed a single-step process for Si-SPION synthesis using a tubular electrochemical system (TES) and investigated the effect of concentration of the Na₂SiO₃ coating agent on Si-SPION properties. The Si-SPIONs were used as a support for attachment of polymer-cellulase conjugate to make MNBCs. The spherical Si-SPIONs were 8-12 nm in diameter including a 2-nm silica coating. Na₂SiO₃ concentration in the reactor did not affect Si-SPION morphology, but increasing Na₂SiO₃ concentration reduced SPION productivity in the reactor. Protective properties of the SPION silica coatings were demonstrated by showing that they prevented dissolution of SPIONs in an acid solution for 48 h. Enzyme attachment was quantified as protein adsorption on Si-SPIONs which reached 55 μg/mg Si-SPION. The MNBCs were recovered and reused four times. The use of TES for Si-SPION synthesis is promising to reduce MNBC production complexity.

Enhancement of the brain delivery of methotrexate with administration of mid-chain ester prodrugs: In vitro and in vivo studies

In the present study, with the aim of improving the permeability of methotrexate (MTX) to the brain, the lipophilic MTX prodrugs containing the ester functional moiety were synthesized. The chemical structure of synthesized prodrugs was characterized and confirmed by FT-IR, NMR and mass spectral studies. Based on the results of in vitro cytotoxic studies, all of the synthesized prodrugs led to decrease in the IC50 in 72 h on U87 cancer cell line and the best result was observed for dihexyl methotrexate (MTX-DH) in comparison with free MTX, which led to decrease the IC50 amount up to 6 folds. In addition, in vivo toxicity on Artemia salina (A. salina) showed that the lipophilic MTX prodrugs have been able to partially mask the toxic profile of free MTX, at the same concentrations. These findings were also in compliance with hemolysis assay results, which confirm that the conjugates has not made the drug more toxic. Furthermore, in vivo study in rat model, was employed to determine the simultaneous drug concentration in brain and plasma. According to the obtained results, the brain-to-plasma concentration ratios (Kp values) of MTX-DH and dioctyl methotrexate (MTX-DO) groups were significantly higher compared with free MTX. Moreover, the uptake clearance of MTX by brain parenchyma increased significantly (3.85 and 9.08-time increased for MTX-DH and MTX-DO prodrugs, respectively). These findings indicate that the synthesized lipophilic MTX prodrugs are non-toxic and able to enhance brain penetration of MTX.

Modern Catalysts in A3- Coupling Reactions

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Propargylamines are an important constituent of diverse, biologically active and industrially valuable compounds. These useful, convenient and effective compounds can be synthesized via the A3-coupling reactions between an aldehyde, amine, and alkyne in the presence of a catalyst. In the past years, most of the catalysts containing transition metals were applied in these reactions, but today, various heterogeneous catalysts, especially nanocatalysts are used. The purpose of this review was to introduce some modern catalysts for the A3-coupling reaction.

Functionalized Silicas for Metal-Free and Metal-Based Catalytic Applications: A Review in Perspective of Green Chemistry

Heterogeneous catalysis plays a key role in promoting green chemistry through many routes. The functionalizable reactive silanols highlight silica as a beguiling support for the preparation of heterogeneous catalysts. Metal active sites anchored on functionalized silica (FS) usually demonstrate the better dispersion and stability due to their firm chemical interaction with FSs. Having certain functional groups in structure, FSs can act as the useful catalysts for few organic reactions even without the need of metal active sites which are termed as the covetous reusable organocatalysts. Magnetic FSs have laid the platform where the effortless recovery of catalysts is realized just using an external magnet, resulting in the simplified reaction procedure. Using FSs of multiple functional groups, we can envisage the shortened reaction pathway and, reduced chemical uses and chemical wastes. Unstable bio-molecules like enzymes have been stabilized when they get chemically anchored on FSs. The resultant solid bio-catalysts exhibited very good reusability in many catalytic reactions. Getting provoked from the green chemistry aspects and benefits of FS-based catalysts, we confer the recent literature and progress focusing on the significance of FSs in heterogeneous catalysis. This review covers the preparative methods, types and catalytic applications of FSs. A special emphasis is given to the metal-free FS catalysts, multiple FS-based catalysts and magnetic FSs. Through this review, we presume that the contribution of FSs to green chemistry can be well understood. The future perspective of FSs and the improvements still required for implementing FS-based catalysts in practical applications have been narrated at the end of this review.

Zeolite-Based Catalysts: A Valuable Approach toward Ester Bond Formation

Zeolite-based catalysts are versatile catalytic systems for a wide range of laboratory studies and industrial scale processes. The chemical composition, ion exchange, and pore size structure attributes of zeolites are responsible for their extensive catalytic applications. Esterification is one of the most important and routinely processes in diverse fields of organic synthesis. It has a long history in both industrial processes and laboratory work due to its versatility. This review intends to give a detailed insight into the significance of zeolite-based catalysts for ester bond formation