In-Silico Design, Synthesis and Evaluation of a Nanostructured Hydrogel as a Dimethoate Removal Agent

Abstract

This study describes the in-silico design, synthesis, and evaluation of a cross-linked PVA hydrogel (CLPH) for the absorption of organophosphorus pesticide dimethoate from aqueous solutions. The crosslinking effectiveness of 14 dicarboxilic acids was evaluated through in-silico studies using semiempirical quantum mechanical calculations. According to the theoretical studies, the nanopore of PVA cross-linked with malic acid (CLPH-MA) showed the best interaction energy with dimethoate. Later, using all-atom molecular dynamics simulations, three hydrogels with different proportions of PVA:MA (10:2, 10:4, and 10:6) were used to evaluate their interactions with dimethoate. These results showed that the suitable crosslinking degree for improving the affinity for the pesticide was with 20% (W%) of the cross-linker. In the experimental absorption study, the synthesized CLPH-MA20 recovered 100% of dimethoate from aqueous solutions. Therefore, the theoretical data were correlated with the experimental studies. Surface morphology of CLPH-MA20 by Scanning Electron Microscopy (SEM) was analyzed. In conclusion, the ability of CLPH-MA20 to remove dimethoate could be used as a technological alternative for the treatment of contaminated water.

Rational Design, Synthesis and Evaluation of γ-CD-Containing Cross-Linked Polyvinyl Alcohol Hydrogel as a Prednisone Delivery Platform

“…A semi-empirical quantum mechanical strategy described in previous works [ 34 , 35 , 36 ] was used to calculate the interaction energy of molecule1–molecule2 complexes. Briefly, single-point energies (1SCF) for a specific molecular conformation (molecule1–molecule2 complex) and also from their isolated parts were calculated using Parameterized Method number 7 (PM7) [ 37 ] implemented in MOPAC2016 software version 16.111L (for LINUX), Colorado Springs, CO, USA [ 38 ].…”

“…A distance of at least 5 Å was used to separate each chain from each other. The LEAP module was used to perform the crosslinking procedure according the previous work [ 36 ], which was based on a cyclic iteration scheme. Briefly, two –OH groups of two different PVA chains (separated by no more than 10 Å) were randomly selected, then, these –OH groups were covalent bonding with the –COO − groups of SA, the geometry of the modified polymer system was formatted and optimized (in order to avoid steric hindrance) using the Antechamber software package version 1.27 (for Linux) [ 41 ] and the steepest descent algorithm and the Universal Force Field (UFF) implemented in Openbabel software version 2.3.1 (for Linux) [ 42 ].…”

Rational Development of a Novel Hydrogel as a pH-Sensitive Controlled Release System for Nifedipine

“…A methodology that involves a Monte Carlo sampling [30] and semi-empirical quantum mechanical (SQM) [31] calculations was used to obtain the interaction energy (Δ E ) for pair of molecules (Molecule 1–Molecule 2 complexes). The detail of the methodology was described in previous works [32,33,34]. Briefly, MOPAC2016 program version 16.111L for Linux, Colorado Springs, CO, USA [35] was used to obtain the Δ E through the following Equation (1):Δ E 1,2 = E (Molecule 1–Molecule 2) − ( E (Molecule 1) + E (Molecule 2) ) where “Molecule 1” represents the structural blocks (PVA chain + dicarboxilic acid + γ-CD) of 20 possible hydrogels and “Molecule 2” represents NFD.…”

“…To model the 10:2 proportion of PVA:MA, the polymer matrix built with the 28 PVA chains (considering a total of 952 PVA monomers) was crosslinked incorporating 190 MA into the polymer matrix, of which 150 were covalently bonded to the –OH groups of PVA chains. The crosslinking procedure was performed according to previous work described by Marican et al (2018) and Avila-Salas et al (2018) [17,34]. Subsequently, LEAP program was used to covalently bonding 16 γ-CD molecules to the MAs that were linked to the PVA only by one end.…”

“…Three MD simulations were carried out for about 50 ns each, all them considered the default relaxation protocol used by Desmond/Maestro software version 2017-4 academic release for Linux, DE Shaw Research, NY city, USA [38] to prepare the system before the simulation. Major details were described in previous work by Marican et al (2018) and Avila-Salas et al (2018) [17,34]. The first MD simulation was carried out for 50 ns considering the system inserted in a box of methanol.…”