Microencapsulation of benzalkonium chloride enhanced its antibacterial and antibiofilm activities against Listeria monocytogenes and Escherichia coli.

AIMS: In this study, benzalkonium chloride (BAC) microcapsules were developed for surface disinfection purpose and were evaluated against Listeria monocytogenes and Escherichia coli biofilms. METHODS AND RESULTS: Microcapsules were prepared with two different strategies: uncomplexed BAC-microcapsules (UBM) containing BAC and maltodextrins, and complexed BAC-microcapsules (CBM) containing BAC complexed by pectin and maltodextrins. The minimum inhibitory concentrations (MICs) of free and microencapsulated BAC were investigated against two food pathogens: L. monocytogenes and E. coli. The antibiofilm activities of UBM and CBM against L. monocytogenes and E. coli biofilms formed on stainless steel at 37°C were evaluated and compared to BAC used under its free form. MICs of encapsulated BAC were up to fourfold lower than those of free BAC. The UBM and CBM showed higher antibiofilm effect when compared to the free BAC. CONCLUSIONS: Overall, results demonstrated that microencapsulation enhanced the antibacterial activity of BAC against L. monocytogenes and E. coli biofilms. SIGNIFICANCE AND IMPACT OF THE STUDY: The application of such BAC microcapsule-based delivery systems can improve surface disinfection procedures and reduce the required BAC concentrations and the related cytotoxicity of this antimicrobial compound.

Sargassum muticum extract based on alginate biopolymer as a new efficient biological corrosion inhibitor for carbon steel in hydrochloric acid pickling environment: Gravimetric, electrochemical and surface studies.

The inhibition effect of the invasive brown seaweed Sargassum muticum extract (ESM), harvested from the Atlantic coast of Morocco, against the corrosion of carbon steel (CS) in 1 M HCl medium was studied for the first time using gravimetric, electrochemical and surface techniques. The methanolic crude extract of Sargassum muticum (ESM) is rich in alginate biopolymer. The evaluation corrosion tests showed that this algal extract acts as a good mixed corrosion inhibitor for CS substrate in 1 M HCl since inhibition efficiency of 97% was reached with 1 g/L of ESM at 303 K. AC impedance findings showed that the seaweed extract adding in the corrosive electrolyte increases the polarization resistance and conversely decreases the charge capacitance at the interface. Adsorption of ESM on the substrate surface followed the Langmuir adsorption isotherm. X-ray photoelectron spectroscopy analyses (XPS) demonstrated that the corrosion inhibition mechanism of CS substrate in 1 M HCl environment by the investigated algal extract is typical of the chemisorption process and the protective barrier is mainly formed by the adsorbed biological macromolecules.

Corrosion inhibition performance of newly synthesized 5-alkoxymethyl-8-hydroxyquinoline derivatives for carbon steel in 1 M HCl solution: experimental, DFT and Monte Carlo simulation studies.

Three new organic compounds primarily based on 8-hydroxyquinoline have been successfully synthesized and characterized via different spectroscopic methods (FTIR, 1H, and 13C NMR). The synthesized compounds, namely 5-propoxymethyl-8-hydroxyquinoline (PMHQ), 5-methoxymethyl-8-hydroxyquinoline (MMHQ) and 5-hydroxymethyl-8-hydroxyquinoline (HMHQ), were evaluated as corrosion inhibitors for carbon steel in 1 M HCl solution using electrochemical impedance spectroscopy, potentiodynamic polarization and weight loss measurements at 298 K. Electrochemical measurements confirmed that the newly synthesized 5-alkoxymethyl-8-hydroxyquinoline derivatives are mixed type corrosion inhibitors and confirmed maximum protection efficiencies of 94, 89 and 81% for PMHQ, MMHQ, and HMHQ, respectively, at the optimum concentration of 10-3 M. The EIS spectra confirmed a slightly depressed semi-circle profile with a single time constant in Bode diagrams for the three organic compounds over the whole concentration and temperature ranges studied. The adsorption of PMHQ, MMHQ, and HMHQ on the carbon steel surface followed the Langmuir adsorption isotherm. In addition, the kinetic and thermodynamic parameters for carbon steel corrosion and inhibitor adsorption, respectively, were determined and discussed. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) analyses supported the formation of a protective film on carbon steel in the presence of PMHQ, MMHQ, and HMHQ. Density functional theory calculations (DFT) showed that the effectiveness of the inhibitive actions of the studied compounds correlates well with their electron donating ability, whilst Monte Carlo simulations revealed that the extent and favourability of adsorption of inhibitor molecules on the carbon steel surface establish their corrosion inhibition performances.