Removal and Extraction of Carboxylic Acids and Non-ionic Compounds with Simple Hydroxides and Layered Double Hydroxides

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.

Nanoflakes of chloride zinc–iron–aluminum-based layered double hydroxides obtained from industrial waste: a green approach to mass-scale production

A greener technology aiming at a smarter industrial waste treatment is proposed to produce chloride iron–zinc–aluminum layered double hydroxides (LDHs). Waste Pickling Acid (WPA) and sodium aluminate (NaAlO₂) from secondary sources were meticulously mixed under mild experimental conditions using a sodium hydroxide solution as a pH-regulator. A set of characterization techniques (XRD, SEM, TGA, FTIR, AAS and adsorption–desorption of N₂) indicated the formation of highly-dispersed nanoflake crystallites with textural characteristics and thermal stability similar to syntheses with high-quality chemicals. An interesting discussion on chemical composition and M²⁺/M³⁺ molar ratio is presented. Although the co-precipitation synthesis was conducted without control of environmental CO₂, complete intercalation of the chloride anion was achieved, making these particles more favorable for further anion exchange applications. The experimental variables temperature of reaction and WPA/NaAlO₂ volume ratio showed the strongest influence on the LDHs crystallinity and porosity. LDHs architected with iron and zinc have the potential to be applied in systems for removing sulfur gases for cleaner energy production, e.g. in the refining process of biogas to produce biomethane.

A greener technology aiming at a smarter industrial waste treatment is proposed to produce chloride iron–zinc–aluminum layered double hydroxides (LDHs).