In situ thermosensitive hybrid mesoporous silica: preparation and the catalytic activities for carbonyl compound reduction.

In this study, free-radical polymerisation inside MCM-41 mesopores was examined to expose a construction route for a temperature-responsive switchable polymer-silica nanohybrid material with well-defined porosity. Herein, we introduced a vinyl monomer (N-isopropyl acrylamide), a cross-linker, and an AIBN initiator into the palladium nanoparticle incorporated MCM-41 pore channels using the wet-impregnation method followed by in situ radical polymerisation. The structural properties of the synthesised PNIPAM-PdNP-MCM-41 catalyst were analysed by various sophisticated analytical techniques. The temperature switchable nanohybrid catalyst was used to reduce carbonyl compounds to their corresponding alcohols. The catalyst showed high catalytic efficiency and robustness in an aqueous medium at 25 °C. Moreover, the system's polymer layer remarkably boosted catalytic selectivity and activity for carbonyl compound reduction as compared to other controlled catalysts. The suggested switchable system can be employed as a temperature-controllable heterogeneous catalyst and highlights a substitute technique to counter the methodical insufficiency in switchable supported molecular catalytic system production.

Palladium nanoparticles-anchored dual-responsive SBA-15-PNIPAM/PMAA nanoreactor: a novel heterogeneous catalyst for a green Suzuki-Miyaura cross-coupling reaction.

To develop a sustainable and cost-effective catalyst for cross-coupling reactions, dual (temperature and pH)-responsive poly(N-isopropyl acrylamide-co-methacrylic acid) (PNIPAM/PMAA) functionalised SBA-15 was synthesised via free radical polymerisation using potassium persulfate as an initiator and decorated with palladium nanoparticles (PdNPs-SBA-15-PNIPAM/PMAA). The X-ray photoelectron spectroscopic analysis revealed that the Pd content in the zero oxidation state of the catalyst was 1.21 wt%. The dynamic light scattering studies showed that the catalyst exhibited swelling behaviours at low temperatures (<32 °C) and high pH (>4), but exhibited deswelling behaviours at high temperatures (>32 °C) and low pH (<4). To examine the performance of the catalyst, Suzuki-Miyaura cross-coupling (SMC) reaction was conducted under batch reaction conditions. The reaction conditions were optimised with various parameters using phenylboronic acid and bromobenzene as the model substrates. High conversions (>90%) were realized for the room-temperature SMC reaction in an aqueous medium for various substituted aryl halides, while the conversion was low at relatively high temperatures (>32 °C). The conversion was dependent on the different electronic effects between the electron-releasing and electron-withdrawing groups of the aryl halides. After the experiment, the catalyst was successfully recovered without any loss of heterogeneity and could be reused at least up to the fifth cycle.

Sulfamerazine Schiff-base complex intercalated layered double hydroxide: synthesis, characterization, and antimicrobial activity.

Cobalt (Co(II)) and copper (Cu(II)) complexes of sulfamerazine-salicylaldehyde (SS) ligand intercalated Mg/Al-layered double hydroxide [Co-SS-LDH/Cu-SS-LDH] were prepared for the antimicrobial application. Sulfamerazine and salicylaldehyde were mixed together and dissolved in methanol for the synthesis of SS ligand and modified further by the complexation with Co(II) and Cu(II) metal ions [Co-SS/Cu-SS]. The delaminating/restacking method was used to intercalate the Mg/Al-NO3-LDH with the metal complexed ligands (Co-SS/Cu-SS). The obtained materials were analyzed using different characterization techniques to prove their successful synthesis and preparation. The antibacterial activity of the synthesized Co-SS-LDH/Cu-SS-LDH were checked by the inhibition zone method. The prepared hybrid materials showed good antimicrobial activity against both gram negative (Escherichia coli, E. coli) and gram positive (Staphylococcus aureus, S. aureus) bacteria.

Tunable Intracellular Degradable Periodic Mesoporous Organosilica Hybrid Nanoparticles for Doxorubicin Drug Delivery in Cancer Cells.

In this work, a dual (pH and redox)-sensitive cystamine-integrated periodic mesoporous organosilica (Cys-PMO) hybrid nanoparticle has been developed and subsequently loaded with doxorubicin (Dox) as an anticancer drug for intracellular cancer drug delivery. The formation of Cys-PMO was confirmed by FTIR, 13C (CP-MAS), and 29Si MAS NMR spectroscopic techniques. X-ray diffraction and transmission electron microscopy confirmed that the Cys-PMO hybrid nanoparticles possessed mesoscopically ordered 2D hexagonal (P6mm) symmetry with cylindrical shape morphology. The N2 sorption isotherm showed that the Cys-PMO hybrid nanoparticles have a large surface area (691 m2 g-1), pore diameter (3.1 nm), and pore volume (0.59 cm3 g-1). As compared to conventional mesoporous silica materials and other PMO nanoparticles, the developed Cys-PMO hybrid nanoparticles have the capability of holding a high Dox content 50.6% (15.2 mg of Dox per 30 mg of Cys-PMO) at an optimized concentration (20 mg Dox) and avoid premature drug release under extracellular conditions. In vitro, the treatment of HeLa cells with Dox-encapsulated Cys-PMO hybrid nanoparticles results in a significantly greater cytotoxicity in response to intracellular acidic pH and a redox environment due to the degradation of disulfide bonds available in the framework of Cys-PMO hybrid nanoparticles. Further, confocal microscope images show the colocalization of Dox-loaded Cys-PMO hybrid nanoparticles inside the HeLa cells. Upon internalization inside HeLa Cells, the Cys-PMO use intracellular pH and redox environments to release Dox to the nucleus. Thus, the pH and reduction sensitivity of Cys-PMO hybrid nanoparticles make them suitable for intracellular drug delivery applications.