Inhibition Action Research Articles

Molecular Docking of Phytochemicals from Adhatoda vasica Against Caries, Periodontitis and Inflammatory Mediators – A Computational Study

Orthodontic treatment is associated with pain, difficulty in plaque control, caries incidence, and slow movement of teeth. Authors hypothesize that the answer to these questions may lie in phytochemicals which are a huge unexplored area. Due to previous reports on Adhathoda vasica about its anti-inflammatory and antimicrobial properties, its use in orthodontics is explored in the dry lab scenario. This can be considered as a preliminary step to study the herb in great detail for use in orthodontic therapy. Computational algorithms from Auto Dock version 4 were used in the study. Vasicine, Vasinone, Vasicoline and Anisotine were analysed against Glucosyltransferase (GFT) of Streptococcus mutans, Gingipain K - Porphyromonas gingivalis, FIM A of Porphyromonas gingivalis, TNF ALPHA and Prostaglandin H synthases. Compounds exerted promising inhibiting action against Streptococcus mutans, Gingipain K, FimA, TNF-alpha and prostaglandin E2. The said phytochemicals - Vasicine, Vasicinone, Vasicoline and Anisotine can further be explored for proper delivery to saliva, periodontal region and to bone for effective use during and after orthodontic treatment.

Invasive weed of Eupatorium Adenophora Spreng leaves extract as a novel efficient inhibitor for the corrosion of cold rolled steel in chloroacetic acid solution

Traditional inhibitors are restricted due to their high price and high toxicity. Plant extracts as green inhibitors can be used as an alternative to traditional inhibitors due to their merits of low price, eco-friendly, and rich resources. The inhibitive action and mechanism of Eupatorium Adenophora Spreng leaves extract (EASLE) on the corrosion of cold rolled steel (CRS) in chloroacetic acid (ClCH2COOH) medium was investigated for the first time. The maximum inhibition efficiency of EASLE is 94.9% even at higher temperature of 50 °C. The surface micro-topography of inhibited CRS is relatively flat from SEM, AFM and CLSM images, and C/N/O elements contained in EASLE can form coordinated bonds with Fe atoms, as observed through XPS and TOF-SIMS. The adsorption of EASLE mainly occurs through chemisorption and is consistent with Langmuir isotherm. EASLE acts as a hybrid inhibitor, and its inhibitive mechanism is consistent with “geometric blocking effect”. The charge-transfer resistance turns to be higher after adding EASLE, and there is a single time constant. All the main inhibiting components of o-cresol, erucamide, vanillin, 3-phenoxybenzoic acid, p-coumaric acid, and adenine in EASLE exhibit the inhibition efficiency of approximately 80% in ClCH2COOH. Theoretical calculations suggest that benzene rings, heterocycles, and carboxyl groups are derived from these active components can be used as both electron acceptors and provider. The hydrophilic group can actively adsorb to CRS surface through heteroatoms of erucamide, while the hydrophobic group with a long carbon chain extends to the aqueous phase to form a protective barrier. EASLE can be an excellent substitute for traditional inhibitors, which are of both economic and environmental values.

The Inhibition Action of Some Brij-Type Nonionic Surfactants on the Corrosion of OLC 45 in Various Aggressive Environments.

The corrosion protection property of three Brij-type surfactants, namely, Brij 35, Brij 56 and Brij 58P, was considered on OLC 45 carbon steel in a 0.5 M H2SO4 medium. The efficacy for these organic compounds was examined using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods, scanning electron microscopy (SEM) procedures, and Fourier transform infrared (FT-IR) spectroscopy. We hypothesized that these surfactants hinder the corrosion for OLC 45 samples through a protecting mechanism owing to the adsorption of organic molecules that form an inhibitive film or through the formation of complex oxides. These surfactants exhibited an appreciable protective effect against OLC 45 corrosion, operating as mixed inhibitors, as could be demonstrated by their influence on the electrochemical characteristics of the metallic substrates. The adsorption of surfactants over the substrates zone conformed to the representation of the Langmuir isotherm. The effect of temperature on the electrochemical comportment of the OLC 45 specimens in H2SO4 without and with Brij at 800 ppm was examined in the temperature interval of 293 to 333 K. The negative estimate of thermodynamic attributed as Gibbs free energy of adsorption presented the spontaneity of the adsorption activity. The investigation with FT-IR and SEM established the adsorption of Brij and the constitution of the corrosive components on the OLC 45 surface. Electrochemical determinations of these surfactants indicated its anticorrosion inhibition performance and the highest inhibition of 96% was reached when the Brij 35 concentration was at 800 or 1000 ppm, while for Brij 56 and Brij 58P, the highest inhibition was obtained when their concentrations were 500, 800, or 1000 ppm.

Inhibition of mild steel corrosion by 4-[(benzylidene)-amino]-antipyrine

The inhibition effect of 4-[(benzylidene)-amino]-antipyrine (BAAP) on corrosion behaviour of mild steel in 1 M HCl solution was studied by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements. Polarization measurements indicate that BAAP acts as mixed type of inhibitor. The adsorption of BAAP on the mild steel surface follows Langmuir adsorption isotherm model. The thermodynamic parameters governing the adsorption process were determined and discussed. Also, quantum chemical parameters were calculated to provide further insight into the mechanism of inhibition action of BAAP.

Electrochemical investigation and surface interaction of thiophene based Chitosan Schiff base on mild steel surface in 1 M HCl

Environment friendly Chitosan Thiophene carboxaldehyde Schiff base, a biopolymer derivative was synthesized to examine the inhibitive action of mild steel corrosion in 1 M Hydrochloric acid. Chitosan Thiophene carboxaldehyde Schiff base was prepared by the modification of Chitosan with thiophene carboxaldehyde through condensation reaction. The effect of Chitosan Schiff base as corrosion inhibitor was investigated using electrochemical impedance spectroscopy at higher temperature differentials of 313–343 K. Chitosan Schiff base showed enhanced corrosion resistance in all the studied temperature range by the forming protective film on the metal surface. The preliminary information about the complex formation in the solution phase, protective layer formation on the metal surface was investigated by Atomic absorption spectroscopy and Ultraviolet spectroscopic studies. The surface interaction between inhibitor molecules and mild steel surface was examined by Fourier Transform Infrared Spectroscopy, scanning electron microscopy and Contact angle measurements. The adsorption of inhibitor layer on the metal was monitored by cyclic voltammetry studies. Quantum chemical results support the possibility of surface interaction between inhibitor and empty orbitals of metal surface.

PHYSICOCHEMICAL AND PHARMACOKINETIC ANALYSIS AND DOCKING OF DRUG REPOSITIONING AGAINST SARS-COV-2: AN IN SILICO STUDY

Studies on the development of effective and cost-effective oral drugs are the new priority of the pharmaceutical industry for the prevention and treatment of COVID-19. This work was based on the computational analysis of physicochemical parameters, pharmacokinetic and toxicological measurements, molecular docking and in silico measurement of the antiviral activity of 12 repositionable drugs. The Molinspiration platform (physical-chemical parameters), pkCSM® (absorption, distribution, metabolism and excretion), OSIRIS Property Explorer® (toxicological measurements), Seam® (Docking with the RdRp protein) and AVCpred server® (antiviral activity) were used. Considering the 12 selected repositionable drugs, molecular anchoring data with the RdRp protein, only the drug tilorone had lower binding energy than the control used in this study (Molnupiravir). Ledipasvir, daclatasvir and piperaquine showed the best percentage of antiviral inhibition considering the control pattern. ADMETox data showed that piperaquine has a high toxicological potential for mutagenesis, tumorigenesis and irritant effects. The findings of this study indicate that ledipasvir and daclatasvir showed greatest potential for inhibition RdRp and action against COVID-19.

Synthesis, Characterization, Docking Studies and in vitro Response of New Camptothecin Derivatives towards Oral Squamous Cell Carcinoma

Evidence suggests heterocyclic rings as the essential component of various available chemotherapeutics. Present study was aimed to carry out the molecular docking, synthesis, characterization and response of new camptothecin derivatives (NCDs) towards OSCC cell lines. To achieve the aim of the study, new camptothecin derivatives were designed to perform molecular docking against the target protein Human DNA Topoisomerase-1 (1T8I). Molecules 2 and 3 with high docking scores were subjected to synthesis. In current investigation, NCDs were synthesized by cyclization of imino analogue (2) into a new azetidinone derivative (3) on treatment with triethylamine and chloroacetyl chloride. Synthesized NCDs were characterized using IR, NMR and mass analysis. The NCDs were further subjected to antiproliferation study using CAL-27 (OSCC), followed by in vitro DNA relaxation assay and cell cycle analysis. The results of the docking of CPT-11 against Human DNA Topoisomerase-1 Duplex (PDB ID: 1T8I) in present study revealed compound 2 and 3 exhibited high docking score among all camptothecin analogues. Present study successfully synthesized and elucidated the structures of NCD 2 and 3. The antiproliferation study results revealed that NCD 2 and NCD 3 offered an IC50 of 34.73 µg/mL and 62.5 µg/mL, respectively. The DNA relaxation assay exhibited the inhibition action of synthesized NCDs (IC50 concentration) against topoisomerase enzyme. Moreover, the cell cycle analysis revealed that both NCDs arrested cancer cells in ‘S’ phase. Though the present study highlights the potential of NCDs against oral squamous cell carcinoma, however, the present study also recommends that the synthesized NCDs must be further evaluated for preclinical and clinical significance.

Inhibitive Action of Sulfide Ions on Corrosion and Enhancing Charge‐Discharge Efficiency of Zinc and Zinc‐Indium Alloy as Anode for Alkaline Batteries

AbstractThe obtained data reveal that the coverage of surface (θ) and protection efficiency (η%) for the studied electrodes increases gradually as the inhibitor concentration increases. Tafel plot is carried out at variant temperatures in the investigated basic electrolyte containing 1×10−1 M of S ions. This study reveals that the activation energy barrier of the studied alloy is higher than that of pristine zinc anode at a fixed inhibitor concentration. It is observed that ▵Goads. and η% values rise with rising solution temperature, indicating that S ions adsorption on the studied electrode surfaces occurs by a chemisorption mechanism. Other calculations are made for the additional thermodynamic parameters such as ▵Hoadsand ▵Soads. The zinc anodes get more efficient when S ions are added to the solution, considerably decreasing electrochemical polarization. In addition, the presence of indium sulfide improves the exposed surface area of the alloy, supplying additional improvement in charge‐discharge efficiency. Density functional theory (DFT) is utilized to extract the quantum data to acquire a deeper understanding of the chemical processes between sulfide ions at the interface.

Fabrication of second auxiliary ligand-induced copper-based coordination polymers as urease inhibitors

Urease inhibitors (UIs) can improve soil nutrients, reduce soil nitrogen loss, increase nitrate nitrogen content, and help soil maintain nutrients. Because the already available inhibitors were harmful and inefficient, it was critical to develop and manufacture a new family of UIs with high efficiency. In this paper, two copper-based coordination polymers (Cu-CPs) were prepared and served as UIs, which showed that the Cu-CPs had good inhibitory effects on urease and the inhibitory rates were 0.83 ± 0.01 μM and 4.22 ± 0.51 μM. The kinetics of the UIs were determined that the Cu-CPs were anti-competitive inhibition modes with corresponding dissociation constants Ki of 1.52 μM and 5.32 μM. The results of molecular docking show that the two series of active compounds have obvious binding effect on the active site of urease. Furthermore, the oxygen atoms of –COO and μ2-OH groups play critical roles in urease inhibition action.

Friedländer reactions for novel annulated pyridotriazolothiazolopyridines: Synthetic approaches and antimicrobial evaluation

o-Aminoaldehyde 1 was employed as starting precursor for construction of some linear heterocyclic compounds. o-Aminoaldehyde 1 was permitted to undergo Friedländer reaction with some acyclic and cyclic methylene ketones giving the novel annulated heterocyclic systems 2-10. Moreover, the reactivity of o-aminoaldehyde 1 was examined toward some cyclic enamines and enols producing the corresponding annulated heterocyclic systems. The prepared compounds were investigated for their antimicrobial efficiency displaying different inhibition action toward the tested microorganisms. Based on analytical spectral and results, structures of the produced compounds were established.

Experimental and Quantum Chemical Investigation of Corrosion Inhibitive Action of Sertraline on Mild Steel in Acidic Medium

Experimental and Quantum Chemical Investigation of Corrosion Inhibitive Action of Sertraline on Mild Steel in Acidic Medium

Synthesis of iron oxide nanoparticles using orange fruit peel extract for efficient remediation of dye pollutant in wastewater.

The removal of color-causing compounds from wastewater is a significant challenge that industries encounter due to their toxic, carcinogenic, and harmful properties. Despite the extensive research and development of various techniques with the objective of effectively degrading color pollutants, the challenge still persists. This paper introduces a simple technique for producing iron oxide nanoparticles (Fe2O3 NPs) using orange fruit peel for sustainable dye degradation in aqueous environment. The observation of color change and the measurement of UV-visible absorbance at 240nm provided a confirmation for the development of Fe2O3 NPs. Transmission electron microscopy examination demonstrated that the Fe2O3 NPshave an agglomerated distribution and forming spherical structures with size ranging from 25-80nm. Energy-dispersive X-ray spectroscopy analysis supported the existence of Fe and O. Fourier transform infrared spectroscopy conducted to investigate the involvement of orange peel extract in the reduction, capping, and synthesis of Fe2O3 NPs from the precursor salt. Fe2O3 NPs showed a photocatalytic remediation of 97%, for methylene blue under visible light irradiation. Additionally, prepared NPs exhibited concentration depended biofilm inhibition action against E. coli and S. aureus. In conclusion, Fe2O3 NPs can efficiently purify water and suppress pathogens due to their strong degrading activity, reusability, and biofilm inhibitionproperty.

Bimetallic bis-Aroyldihydrazone-Isatin Complexes of High O=V(IV) and Low Cu(II) Valent Ions as Effective Biological Reagents for Antimicrobial and Anticancer Assays.

Due to the versatile bioreactivity of aroyldihydrazone complexes as cost-effective alternatives with different transition metals, two novel bimetallic homo-complexes (VOLph and CuLph) were prepared via the coordination of a terephthalic dihydrazone diisatin ligand (H2Lph) with VO2+ and Cu2+ ions, respectively. The structure elucidation was confirmed by alternative spectral methods. Biologically, the H2Lph ligand and its MLph complexes (M2+ = VO2+ or Cu2+) were investigated as antimicrobial and anticancer agents. Their biochemical activities towards ctDNA (calf thymus DNA) were estimated using measurable titration viscometrically and spectrophotometrically, as well as the gel electrophoresis technique. The growth inhibition of both VOLph and CuLph complexes against microbial and cancer cells was measured, and the inhibition action, MIC, and IC50 were compared to the inhibition action of the free H2Lph ligand. Both VOLph and CuLph showed remarkable interactive binding with ctDNA compared to the free ligand H2Lph, based on Kb = 16.31, 16.04 and 12.41 × 107 mol-1 dm3 and ΔGb≠ = 47.11, -46.89, and -44.05 kJ mol-1 for VOLph, CuLph, and H2Lph, respectively, due to the central metal ion (VIVO and CuII ions). VOLph (with a higher oxidation state of the V4+ ion and oxo-ligand) exhibited enhanced interaction with the ctDNA molecule compared to CuLph, demonstrating the role and type of the central metal ion within the performed electronegative and electrophilic characters.

Lonicera japonica protects Pelodiscus sinensis by inhibiting the biofilm formation of Aeromonas hydrophila.

Aquaculture has suffered significant financial losses as a result of the infection of zoonotic Aeromonas hydrophila, which has a high level of resistance to classic antibiotics. In this study, we isolated an A. hydrophila strain B3 from diseased soft-shelled turtle (Pelodiscus sinensis), which is one of the most commercially significant freshwater farmed reptiles in East Asia, and found that A. hydrophila was its dominant pathogen. To better understand the inhibition effect and action mechanism of Chinese herbs on A. hydrophila, we conducted Chinese herbs screening and found that Lonicera japonica had a significant antibacterial effect on A. hydrophila B3. Experimental therapeutics of L. japonica on soft-shelled turtle showed that the supplement of 1% L. japonica to diet could significantly upregulate the immunity-related gene expression of soft-shelled turtle and protect soft-shelled turtle against A. hydrophila infection. Histopathological section results validated the protective effect of L. japonica. As the major effective component of L. japonica, chlorogenic acid demonstrated significant inhibitory effect on the growth of A. hydrophila with MIC at 6.4 mg/mL. The in vitro assay suggested that chlorogenic acid could inhibit the hemolysin/protease production and biofilm formation of A. hydrophila and significantly decrease the expression of quorum sensing, biofilm formation, and hemolysin-related genes in A. hydrophila. Our results showed that the Chinese herb L. japonica would be a promising candidate for the treatment of A. hydrophila infections in aquaculture, and it not only improves the immune response of aquatic animals but also inhibits the virulence factor (such as biofilm formation) expression of A. hydrophila. KEY POINTS: • A. hydrophila was the dominant pathogen of the diseased soft-shelled turtle. • L. japonica can protect soft-shelled turtle against A. hydrophila infection. • Chlorogenic acid inhibits the growth and biofilm formation of A. hydrophila.

Environmentally Benign Grape Seed Oil for Corrosion Inhibition: Cutting-Edge Computational Modeling Techniques Revealing the Intermolecular and Intramolecular Synergistic Inhibition Action

The growing interest in eco-friendly alternatives has sparked research into essential oils as corrosion inhibitors, offering an innovative approach. Investigating their unique properties, researchers aim to advance corrosion engineering for a sustainable future. Despite promising lab results, the exact mechanism of their action in corrosion engineering is not fully understood, highlighting the need for further exploration. Using computational modeling, we explored how grape seed oil (GSO) compounds interact with carbon steel (C38) surfaces, unraveling the inhibitive properties against corrosion. Employing various simulation methods, such as density functional theory (DFT), density functional-based tight-binding (DFTB), and molecular dynamics (MD), this study validates experimental findings and unveils novel insights into the underlying mechanisms of these interactions. Quantitative analysis quantifies the inter- and intramolecular synergistic effect and suggests that the LA@OA promotes the charge-transfer process. DFTB calculations reveal that the synergistic action in the parallel adsorption configuration of LA and OA molecules is sufficiently strong to form a stable adsorption layer on the Fe surface with a large negative value of Eads (6.74 eV). Experimental results demonstrated that the inhibition performance of GSO extract exhibited a notable increase with increasing concentrations, reaching a higher efficiency of 79% at 0.5 g/L of GSO. EIS results demonstrated that the existence of the GSO inhibitor film increases the resistance of the charge transfer (about 80 Ω cm2 at 0.5 g/L), indicating the superior barrier anticorrosion properties of the formed film. The theoretical results validate the exceptional anticorrosion performance and provide compelling evidence of the remarkable ability to prevent corrosion of C38 substrate. The findings offer potential pathways for the development of eco-friendly alternatives and interestingly provide a foundation understanding in the field.

Mechanism of montelukast on autophagy and apoptosis of airway epithelial cells through STAT3-RORγt-IL-17/IL-23 signaling pathway

This study investigates the mechanism of montelukast intervention on autophagy and apoptosis of airway epithelial cells. Construction of HBE cell building model, which were intervened by montelukast. The proliferation of human 16HBE cells was detected using MTT method and β-catenin level was detected. The cellular cycle distribution, autophagy and apoptosis were detected using flow cytometry. And expressions of Transcriptional activator 3 (STAT3)-Retinoic acid-associated nuclear orphan receptor (RORγt)-interleukin 17 (IL-17)/interleukin 23 (IL-23) signaling related proteins were measured using Western blot. Montelukast inhibited the proliferation of human 16HBE cells and its inhibition rate and action concentration showed time and dose dependence. The half maximal inhibitory concentrations (IC50) were (12.8±0.67) μmol/L at 24 h, (8.8±0.43) μmol/L at 48 h and (6.6±0.42) μmol/L at 72 h, respectively. Montelukast induced 16HBE cellular cycle to arrest in G2/M phase dose-dependently (5, 10 and 20 μmol/L) (P <0.05) and simultaneously increased apoptosis rate (P < 0.05). 40 μL montelukast had a protective effect on 16HBE cells. In addition, montelukast reduced β-catenin level, which suggested that STAT3-RORγt-IL-17/IL-23 signaling pathway might be inhibited. Meanwhile, montelukast reduced the expressions of STAT3, P-STAT3, RORγt (RORβ), c-myc and survivin and increased protein expressions of GSK-3 (RORα) and Th17, but had no effect on the total RORγt level. Montelukast may effectively promote the apoptosis of 16HBE airway epithelial cells via inhibition of STAT3-RORγt-IL-17/IL-23 signaling.

Synthesis, antitumor activity, antimicrobial evaluation and molecular docking studies of some hydrazone, 1,3,4-oxadiazole, 1,2,4-triazole and pyrazole derivatives bearing nicotinoyl moiety

In this study, we synthesized a number of new intriguing azoles bearing nicotinoyl moiety, their antimicrobial and antitumor activities were investigated as well. We succeeded to prepare sequence of hydrazones 2,4, 1,3,4-oxadiazoles 5, 6, 11, 12, 1,2,4-triazole 8, pyrazoles 9, 10, 13, 14, 16, 18, 20, 22, 25 and pyrazolo[3,4-d]pyrimidines 15, 23, and 24. Most of the synthesized compounds were tested against strains of fungus and bacteria. Some compounds that demonstrated significant biological activity were selected to test for their activity against cancer cells. It is interesting to note that, some of the tested compounds showed moderate to potent antibacterial activity. Strong antibacterial activity was demonstrated by compounds 16 and 23 (MIC = 2.5–5 µg/mL) against most of the microorganisms. Compounds 24 and 4a demonstrated a reasonable response to the microorganisms. Compound 2 explained a weak activity towards one of the tested microorganisms. Also, it was found that at a given concentration (3.16 µg/mL) the amino nitrile 9 exhibited strong cell-growth inhibiting action (>50 %). Based on these findings, compound 9 and 23 seems like good lead candidates to investigate further as potential anticancer and antibacterial agent respectively.

Biofabrication of Nanosilver From Punica granatum Peel Extract and Their Anticoagulant Applications.

For utilizing biodegradable waste as a natural source for nanofabrication, this study was designed to highlight a simple, sustainable, safe, environmentally friendly, and energy consumption reduction waste management approach using hot aqueous extract of Punica granatum (pomegranate) peel waste (PPE) to biosynthesize silver nanoparticles (PPE-AgNPs). The fabrication of biosynthesized nanosilver was confirmed by UV-visible spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), and atomic force microscope (AFM). The initial pale brown color change upon adding silver nitrate to PPE confirmed bioreduction. For PPE, the absorption spectrum for UV-vis spectroscopy in the visible light region was 230-290 nm, while for PPE-AgNPs, the graph shows that surface plasmon resonance (SPR) spectrum for nanosilver at 360-460 nm. The XRD analysis proved that the PPE-AgNPs were crystalline in nature. The SEM micrograph revealed that silver nanoparticles were sphere-shaped, homogenous accumulations with particle size in the range of 21.63-30.97 ± 0.4 nm. The EDX data analysis also proved the presence of a sharp peak of silver element with 8.83% weight at 3 keV. The 3D AFM images of Ag nanoparticles illustrated that the diameter is around 7.20-14.80 nm with a median of 7.16 ± 1.3 nm and the root mean square (RMS) value corresponds to 1.40 ± 0.4 nm. The PPE-AgNPs efficiently exhibited a potent antioxidant and dose-dependent DPPH inhibition action. Visual and microscopic observations of fresh human blood when treated with 25, 50, 75, and 100 μg/mL of PPE-AgNPs were proven to be biocompatible with no morphological changes and no coagulation. This study predicts that PPE can be utilized to synthesize biocompatible nanosilver.

A comparison of the corrosion inhibition on 1060 aluminum in HCl solution between water and alcoholic extracts of Mikania micrantha

A detailed comparison of the corrosion inhibitory effect of water extract of Mikania micrantha (MME (H2O)) and 40% ethanol extract (MME (40% C2H5OH)) was conducted on 1060 aluminum in 1.0 M HCl by gravimetric, electrochemical and surface analysis techniques. The results show that two extracts have excellent inhibition performance, MME (H2O) (97.0%) surpasses MME (40% C2H5OH) (93.6%) in terms of maximum inhibition efficiency. MME (H2O) is a mixed-type inhibitor, whereas MME (40% C2H5OH) is mainly a cathodic inhibitor. Salicylic acid, isochlorogenic acid C, sucrose, succinic acid, valine and guanine in MME contribute on the inhibitive action.

Fabricating epoxy composite coating having self-healing/barrier anti-corrosion functions utilizing ion-exchange/pH-sensitive phosphate-doped ZIF8 MOF decorated Zn-Al-LDH nano-layers

Recently, the development of epoxy composite coatings with smart anti-corrosion features has been considered in many studies. Using inhibitor-loaded nanocarriers, i.e., layered double hydroxides (LDH) and metal-organic frameworks (MOFs) has attracted recent attention. In this work, the hybrid LDH@ZIF8 was constructed and applied in the epoxy coating as a dual-functional nanocarrier.In this study, firstly, LDH nano-size lamellar was synthesized followed by surface modification with nano-porous ZIF8 3D structures. Afterward, to provide further corrosion inhibition properties, phosphate ions were doped and the resultant particles were introduced into the epoxy coating. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscope (SEM), and X-ray diffraction (XRD) analysis were utilized to characterize the nanoparticles and they were a good indicator to prove the successful surface modification. Via inductively coupled plasma (ICP), the inhibitor pH/ion-responsive release (i.e., PO43− anions, Zn2+ cations) ability at various pHs was screened. Electrochemical measurements proved the inhibitive action of the phosphate-doped LDH@ZIF8 structures in the solution state (75.99 % inhibition index). EIS results revealed that after incorporating the phosphate-doped LDH@ZIF8 nano-hybrid into the epoxy coating its barrier properties were significantly improved (impedance values>1010 Ω.cm2). Besides, the phosphate-doped LDH@ZIF8 filled epoxy (with artificial scratch) showed about 57 % self-healing index. The adhesion bond durability was significantly improved after the addition of phosphate-doped LDH@ZIF8. About 69 % improvement in the wet adhesion (pull-off test) and 73 % reduction of cathodic delamination diameter (CD test) were recorded for the epoxy coating loaded with phosphate-doped LDH@ZIF8 compared to the blank epoxy. Generally, using phosphate-doped LDH@ZIF8, both barrier and active corrosion protection properties of the epoxy coating were significantly improved, and compared to similar works reported in literature better anti-corrosion durability was reached.