Antimicrobial Activity Of Coatings Research Articles

Extension of ultrafiltered cheese shelf life using edible coatings containing supercritical rosemary, thyme and coriander extracts as antimicrobial agents

Currently, supercritical extraction allows for the “green” isolation of plant antimicrobial components and their subsequent use in the food industry. The study aims to extend the shelf life of ultrafiltered cheese by using edible coatings containing supercritical fluid extracts (SFEs) of Rosmarinus officinalis L., Thymus vulgaris and Coriandrum sativum L. The SFEs chemical profiling was studied using GC-MS. Ten emulsion coating formulations were prepared using whey protein concentrate and the SFEs. The antimicrobial activity of coatings was assessed using well diffusion assay. Their effect on shelf life, physicochemical and sensory characteristics of the ultrafiltered cheese samples was investigated. GC/MS analysis of Rosmarinus officinalis L., Thymus vulgaris and Coriandrum sativum L. showed that 1,8-Cineol, m-Cymene, and Linalool are the major compounds with 35.4, 41.6, and 61.3 % respectively. The particle size of all formulations ranged from 157.3 to 453.7 nm and had a broad size distribution with a low Polydispersity Index values ranging from 0.35 to 0.49. The obtained Zeta potential values from −27.8 to −36.0 mV indicate the stability of the SFE-emulsion formulations. The antimicrobial trials showed that formulations, that mainly contained Thymus vulgaris, demonstrated more inhibition effect against all tested strains than other formulas with inhibition zone diameter ranged between 10.7 and 16.3 mm and followed by formulations, that mainly contained Rosmarinus officinalis L., with inhibition zones diameter between 6.7 and 11.7 mm depending on microbial type. Combining rosemary and coriander extracts synergistically enhanced their antimicrobial effect and extended the shelf life of cheese beyond 40 days.

Characteristics and Antibacterial Effect of Chitosan Coating Nanoemulsion Containing Zataria multiflora and Bunium persicum Essential Oils Against Listeria monocytogenes

Background: Nowadays, finding natural compounds with antimicrobial properties against pathogens is very important, especially for the food and drug industries. Objectives: The antibacterial activity of chitosan coatings nanoemulsion (NE) containing Zataria multiflora and Bunium persicum essential oils (EOs) was evaluated in a food model (chicken breast fillets) during 15 days of refrigerated storage. Methods: The chicken breast fillets were divided into seven groups: control, chitosan 2%, sonicated chitosan 2%, chitosan NE coating containing Z. muitiflora EO (ZMEO, 0.5%, and 1 %) and chitosan NE coating containing B. persicum EO (BPEO, 0.5%, and 1 %). Characteristics of chitosan NE coatings containing EOs were analyzed. Moreover, the antimicrobial activity of coatings against Listeria monocytogenes was investigated. Results: The results showed good properties of the NE coatings. The analysis of EOs revealed that the major components for ZMEO were carvacrol (51.55%) and thymol (25.49%). In addition, the main components of BPEO were p-cumic aldehyde (38.39%) and p-cymene (18.36%). All treatments exhibited antimicrobial properties; however, the best result was recorded for chitosan NE coating containing 1% ZMEO, which was the lowest amount of L. monocytogenes (7.61 Log CFU/g). Moreover, L. monocytogenes analysis for chitosan NE coating containing 1% BPEO samples was 7.73 Log CFU/g. Conclusions: Therefore, based on the results of this study, chitosan NE coating containing ZMEO and BPEO as natural preservatives can be recommended for meat products, especially chicken meats.

Synthesis, Modification and Characterization of Antimicrobial Textile Surface Containing ZnO Nanoparticles.

In this research, a textile surface was modified by the sol–gel methodology with a new antimicrobial coating containing nanoparticles active against bacteria resistant to antibiotics. The effect of ultrasonic irradiation power (40 to 90 kHz), the concentration of reagents (nanoparticles, precursor and acids) and time (15 to 72 min) were investigated in relation to the structure, morphology and antimicrobial activity of coatings with zinc oxide nanoparticles. The relationship between the sonocatalytic performance and structure of the resultant modification was established by using various techniques, such as FTIR spectroscopy (FTIR) and scanning electron microscopy with an EDX detector (SEM-EDX), thin-layer chromatography (TLC) and antimicrobial effects were determined on selected model microorganisms. The homogeneity of layers with ZnO nanoparticles on samples was increased by increasing the ultrasonic irradiation power and time. The ultrasonic irradiation unify did not only unify both the structure and the morphology of samples, it also prevented the agglomeration of the nanoparticles. Moreover, under optimal conditions, an antimicrobial coating with ZnO nanoparticles, active against bacterial species S. aureus and E. coli was efficiently prepared. Results of the Time-kill methodology revieled excellent results starting after 6 hours of exposal to antimicrobialy functionalized cellulose polymer.

Effect of 2-aminobenzothiazole on antimicrobial activity of waterborne polyurethane dispersions (WPUDs)

Antimicrobial coating, which has myriad applications in food industries, health authorities, veterinary care, cleansing, milk parlors, etc., has been produced in this research work. Polyol was synthesized by the condensation reaction of itaconic acid and 1,6-hexanediol. This polyol was then used for the synthesis of waterborne polyurethane dispersion (WPUDs), in which polyol was reacted with dimethylol propionic acid and isophoronediisocyanate to form a prepolymer. The prepolymer obtained was neutralized with triethylamine and 1,4-butanediol was used as a chain extender, followed by the addition of appropriate amount of water, as in a typical acetone process. 2-Aminobenzothiazole (ABT) was incorporated in the backbone along with the chain extender as an antimicrobial agent, and the effect of concentration of ABT on antimicrobial activity of coatings was studied. The obtained WPUDs were analyzed by Fourier transform infrared spectroscopy, particle size and zeta potential. Cured films were characterized for thermal, mechanical and antimicrobial properties. WPUD with 20% ABT content showed increased thermal properties with the highest Tg of 71.48 °C and good antimicrobial activity with an approximate 60% inhibition rate.

Toward Infection-Resistant Surfaces: Achieving High Antimicrobial Peptide Potency by Modulating the Functionality of Polymer Brush and Peptide.

Bacterial infection associated with indwelling medical devices and implants is a major clinical issue, and the prevention or treatment of such infections is challenging. Antimicrobial coatings offer a significant step toward addressing this important clinical problem. Antimicrobial coatings based on tethered antimicrobial peptides (AMPs) on hydrophilic polymer brushes have been shown to be one of the most promising strategies to avoid bacterial colonization and have demonstrated broad spectrum activity. Optimal combinations of the functionality of the polymer-brush-tethered AMPs are essential to maintaining long-term AMP activity on the surface. However, there is limited knowledge currently available on this topic. Here we report the development of potent antimicrobial coatings on implant surfaces by elucidating the roles of polymer brush chemistry and peptide structure on the overall antimicrobial activity of the coatings. We screened several combinations of polymer brush coatings and AMPs constructed on nanoparticles, titanium surfaces, and quartz slides on their antimicrobial activity and bacterial adhesion against Gram-positive and Gram-negative bacteria. Highly efficient killing of planktonic bacteria by the antimicrobial coatings on nanoparticle surfaces, as well as potent killing of adhered bacteria in the case of coatings on titanium surfaces, was observed. Remarkably, the antimicrobial activity of AMP-conjugated brush coatings demonstrated a clear dependence on the polymer brush chemistry and peptide structure, and optimization of these parameters is critical to achieving infection-resistant surfaces. By analyzing the interaction of polymer-brush-tethered AMPs with model lipid membranes using circular dichroism spectroscopy, we determined that the polymer brush chemistry has an influence on the extent of secondary structure change of tethered peptides before and after interaction with biomembranes. The peptide structure also has an influence on the density of conjugated peptides on polymer brush coatings and the resultant wettability of the coatings, and both of these factors contributed to the antimicrobial activity and bacterial adhesion of the coatings. Overall, this work highlights the importance of optimizing the functionality of the polymer brush to achieve infection-resistant surfaces and presents important insight into the design criteria for the selection of polymers and AMPs toward the development of potent antimicrobial coating on implants.

Antimicrobial activity of polysiloxane coatings containing quaternary ammonium-functionalized polyhedral oligomeric silsesquioxane

An array of quaternary ammonium functionalized-polyhedral oligomeric silsesquioxane (Q-POSS) compounds with different alkyl chain lengths and counter ions were synthesized using a two-step process. First, octasilane POSS was functionalized with dimethylamino groups by hydrosilylation with allyldimethylamine. Next, partial quaternization of the tertiaryamino-functional POSS was achieved using an alkyl halide to produce the Q-POSS. Alkyl chain length of the Q-POSS compounds varied from –C12H25 to –C18H37 and the counter ions varied between chlorine, bromine, and iodine. Moisture-cured polysiloxane coatings were prepared by dispersing Q-POSS molecules into a solution blend of silanol-terminated polydimethylsiloxane, methylacetoxysilane, and a catalyst. To evaluate the utility of the Q-POSS molecules as a broad-spectrum antimicrobial additive, the antimicrobial activity of the coatings toward the Gram-negative bacterium, Escherichia coli, the Gram-positive bacterium, Staphylococcus aureus, and the opportunistic fungal pathogen, Candida albicans, was determined using an agar plating method. The results obtained showed that both the composition of the Q-POSS and the composition of the polysiloxane matrix affected antimicrobial properties. Compositions were identified that inhibited the growth of all three microorganisms on the coating surface. Surface Raman spectroscopic analysis was performed on selected set of coatings to understand the relative concentration of Q-POSS molecules at the coating surface.