Effective intercalation of zein into Na-montmorillonite: role of the protein components and use of the developed biointerfaces

Magnetite-sepiolite nanoarchitectonics for improving zein-based bionanocomposite foams

Magnetic nanoarchitectures have been used to introduce multifunctionality in biopolymeric matrices. Bionanocomposite foams based on the corn protein zein were prepared for the first time using the hydrophobic properties of zein in a sequential treatment consisting of the removal of ethanol-soluble fractions, followed by the water swelling of the remaining phase and a further freeze-drying process. When this protocol is applied to zein pellets, they can be consolidated as porous monoliths. Moreover, it is possible to incorporate diverse types of inorganic nanoparticles in the starting pellet to produce the bionanocomposite foams. In particular, the preparation of superparamagnetic foams has been explored using two approaches: the direct incorporation of magnetite nanoparticles in a ferrofluid by impregnation in the foams, and the application of the foaming process to mixtures of zein with magnetite nanoparticles alone or previously assembled into sepiolite clay fibers. The first methodology leads to the production of inhomogeneous foams, while the use of magnetite nanoparticles and better Fe3O4-sepiolite nanoarchitectured materials as fillers results in more homogeneous materials with improved water stability and mechanical properties, offering superparamagnetic behavior. The resulting multifunctional foams have been tested in adsorption processes using the herbicide 4-chloro-2-methylphenoxyacetic acid as a model pollutant, confirming their potential utility in decontamination applications in open waters as they can be easily recovered from the aqueous medium using a magnet.

Facile synthesis and physicochemical characterization of κ-Carrageenan-silver-bentonite based nanocatalytic platform for efficient degradation of anionic azo dyes

Water pollution due to textile industry effluents is a global concern that warrants versatile research solutions for degrading them, and for a sustainable environment. In the present work, by using the imperative role of nanotechnology, a facile one-pot synthesis has been devised to generate κ-carrageenan capped silver nanocatalyst (CSNC), and was immobilized on 2D bentonite (BT) sheets to generate nanocatalytic platform (BTCSNC) for the degradation of anionic azo dyes. The nanocomposite(s) were physicochemically characterized using UV-Vis, DLS, TEM, FESEM, PXRD, ATR-FTIR, TGA, BET and XPS etc., to obtain insights into the nanocomposite composition, structure, stability, morphology and mechanism of interaction. The obtained CNSC are monodispersed, spherical with a size of 4 ± 2 nm, and were stabilized by the functional groups (-OH, COO‾, and SO3‾) of κ-Crg. The broadening of peak corresponding to basal plane (001) of BT montmorillonite in PXRD spectra established its exfoliation upon addition of CSNC. XPS and ATR-FTIR data evidenced the absence of covalent interactions between CSNC and BT. The catalytic efficiency of CSNC and BTCSNC composites were compared for the degradation of methyl orange (MO) and congo red (CR). The reaction followed a pseudo first order kinetics, and immobilization of CSNC on BT resulted in a 3-4 fold enhancement in degradation rates. The rates achieved for the degradation kinetics are: MO degradation within 14 s (Ka 9.86 ± 2.00 min-1), and CR degradation within 120 s (Ka of 1.24 ± 0.13 min-1). Further, a degradation mechanism has been proposed by analyzing the products identified through LC-MS. The reusability studies of the BTCSNC evidenced the complete activity of the nanocatalytic platform for six cycles, and gravitational separation method for catalyst recycling. In a nutshell, the current study provided an environmentally friendly, sizable, and sustainable nano catalytic platform" for the remediation of industrial wastewater contaminated with hazardous azo dyes".

Zein-layered hydroxide biohybrids: strategies of synthesis and characterization

This work constitutes a basic study about the first exploration on the preparation of biohybrids based on the corn protein zein and layered metal hydroxides, such as layered double hydroxides (LDH) and layered single hydroxides (LSHs). For this purpose, MgAl layered double hydroxide and the Co₂(OH)₃ layered single hydroxide were selected as hosts, and various synthetic approaches were explored to achieve the formation of the zein-layered hydroxide biohybrids, profiting from the presence of negatively charged groups in zein in basic medium. Zein-based layered hydroxide biohybrids were characterized by diverse physicochemical techniques such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis/differential thermal analysis (TG/DTA), solid state ¹³C cross-polarization magical angle spinning nuclear magnetic resonance (CP-MAS NMR), field emission-scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), etc., which suggest that the different synthesis procedures employed and the anion located in the interlayer region of the inorganic host material seem to have a strong influence on the final features of the biohybrids, resulting in mixed, single intercalated, or highly exfoliated intercalated phases. Thus, the resulting biohybrids based on zein and layered hydroxides could have interest in applications in biomedicine, biosensing, materials for electronic devices, catalysis, and photocatalysis.

Functional Carboxymethylcellulose/Zein Bionanocomposite Films Based on Neomycin Supported on Sepiolite or Montmorillonite Clays

The present work introduces new functional bionanocomposite materials based on layered montmorillonite and fibrous sepiolite clays and two biopolymers (carboxymethylcellulose polysaccharide and zein protein) to produce drug-loaded bionanocomposite films for antibiotic topical delivery. Neomycin, an antibiotic indicated for wound infections, was employed as the model drug in this study. The physical properties and the antimicrobial activity of these materials were evaluated as a function of the type of hybrid and the amount of zein protein incorporated in the bionanocomposite films. In addition, the interfacial and physicochemical properties of these new clay-drug hybrids have been studied through a combination of experimental and computational methodologies, where the computational studies confirm the intercalation of neomycin into the montmorillonite layers and the possible penetration of the drug in the tunnels of sepiolite, as pointed out by N2 adsorption and X-ray diffraction techniques. The antimicrobial activity of these bionanocomposite materials show that the films based on montmorillonite-neomycin display a more pronounced inhibitory effect of the bacterial growth than those prepared with the sepiolite-neomycin hybrid. Such effect can be related to the difficult release of neomycin adsorbed on sepiolite due to a strong interaction between both components.