Self-Assembling Peptide-Based Magnetogels for the Removal of Heavy Metals from Water

Abstract

In this study, we present the synthesis of a novel peptide-based magnetogel obtained through the encapsulation of γ-Fe2O3-polyacrylic acid (PAA) nanoparticles (γ-Fe2O3NPs) into a hydrogel matrix, used for enhancing the ability of the hydrogel to remove Cr(III), Co(II), and Ni(II) pollutants from water. Fmoc-Phe (Fluorenylmethoxycarbonyl-Phenylalanine) and diphenylalanine (Phe2) were used as starting reagents for the hydrogelator (Fmoc-Phe3) synthesis via an enzymatic method. The PAA-coated magnetic nanoparticles were synthesized in a separate step, using the co-precipitation method, and encapsulated into the peptide-based hydrogel. The resulting organic/inorganic hybrid system (γ-Fe2O3NPs-peptide) was characterized with different techniques, including FT-IR, Raman, UV-Vis, DLS, ζ-potential, XPS, FESEM-EDS, swelling ability tests, and rheology. Regarding the application in heavy metals removal from aqueous solutions, the behavior of the obtained magnetogel was compared to its precursors and the effect of the magnetic field was assessed. Four different systems were studied for the separation of heavy metal ions from aqueous solutions, including (1) γ-Fe2O3NPs stabilized with PAA, (γ-Fe2O3NPs); (2) Fmoc-Phe3 hydrogel (HG); (3) γ-Fe2O3NPs embedded in peptide magnetogel (γ-Fe2O3NPs@HG); and (4) γ-Fe2O3NPs@HG in the presence of an external magnetic field. To quantify the removal efficiency of these four model systems, the UV-Vis technique was employed as a fast, cheap, and versatile method. The results demonstrate that both Fmoc-Phe3 hydrogel and γ-Fe2O3NPs peptide magnetogel can efficiently remove all the tested pollutants from water. Interestingly, due to the presence of magnetic γ-Fe2O3NPs inside the hydrogel, the removal efficiency can be enhanced by applying an external magnetic field. The proposed magnetogel represents a smart multifunctional nanosystem with improved absorption efficiency and synergic effect upon applying an external magnetic field. These results are promising for potential environmental applications of γ-Fe2O3NPs-peptide magnetogels to the removal of pollutants from aqueous media.

Peptide-Hydrogel Nanocomposites for Anti-Cancer Drug Delivery

“…To fabricate advanced hydrogel nanocomposites and obtain the desired properties, there are four main methods, including blending, grafting, in situ precipitation, and swelling [49]. Among these methods, the swelling strategy is an in situ methodology in which the hydrogel nanocomposites are synthesized in one step.…”

“…Peptide hydrogels are an interesting class of materials made from amino acid precursors. They are generally biocompatible and suitable for biological applications, including anticancer drug delivery [48,49]. Over the past decades, considerable developments in the synthesis and technology of non-peptide hydrogel nanocomposites have qualified them as promising candidates for designing controlled-release drug delivery systems.…”

Liposome–Hydrogel Composites for Controlled Drug Delivery Applications

“…Hydrogels are 3D cross-linked polymer networks with high water-absorbing abilities similarly to body tissues, which allows them to encapsulate drugs and protect them in physiological conditions [53][54][55][56][57][58][59][60][61][62]. Hydrogels can be classified based on their characteristics and structure, for instance (1) their charge (cationic, neutral, anionic or ampholytic hydrogels); (2) the nature of their side groups (e.g., charged or neutral); (3) their physical structural parameters (e.g., hydrogen-bonded structures, amorphous or semi-crystalline, supramolecular structures, hydrocolloidal aggregates); (4) the nature of cross-links (e.g., physical or chemical); (5) the preparation method (e.g., homo-or co-polymers); and (6) their origin (e.g., synthetic or natural) [63].…”

Biosynthesis of Peptide Hydrogel–Titania Nanoparticle Composites with Antibacterial Properties

“…Fmoc-Phe 3 self-assembling peptide and TiO 2 NPs were chosen to prepare hgel-TiO 2 NP composites. the biosynthesis of Fmoc-Ph 3 hydrogel using Fmoc-Phe and Phe 2 as starting reagents and a lipolytic enzyme (PFL) to catalyze the formation of a peptide bond between them was optimized in previous studies [41]. In the present work, this reaction was used to prepare hydrogels and impregnate them with different amounts of TiO 2 NPs.…”