The effect of Dunaliella salina extracts on the adhesion of Pseudomonas aeruginosa to 3D printed polyethylene terephthalate and polylactic acid.

Polyethylene terephthalate (PET) and polylactic acid (PLA) are among the polymers used in the food industry. In this study, crude extracts of Dunaliella salina were used to treat the surface of 3D printed materials studied, aiming to provide them with an anti-adhesive property against Pseudomonas aeruginosa. The hydrophobicity of treated and untreated surfaces was characterized using the contact angle method. Furthermore, the adhesive behavior of P. aeruginosa toward the substrata surfaces was also studied theoretically and experimentally. The results showed that the untreated PLA was hydrophobic, while the untreated PET was hydrophilic. It was also found that the treated materials became hydrophilic and electron-donating. The total energy of adhesion revealed that P. aeruginosa adhesion was theoretically favorable on untreated materials, while it was unfavorable on treated ones. Moreover, the experimental data proved that the adhesion to untreated substrata was obtained, while there was complete inhibition of adhesion to treated surfaces.

The combined effect of essential oils on wood physico-chemical properties and their antiadhesive activity against mold fungi: application of mixture design methodology.

In the heritage field, the microbial adhesion on wood, and consequently the formation of biofilm led to inestimable losses of historical and cultural monuments. Thereby, this study aimed to examine the combined effect of Thymus vulgaris, Myrtus communis, and Mentha pulegium essential oils on wood surface physico-chemical properties, and to elaborate the optimal mixture using the mixture design approach coupled to the contact angle method. It was found that both wood hydrophobicity and electron donor character increased significantly after treatment using an optimal mixture containing 57% and 43% of M. pulegium and M. communis essential oils, respectively. The theoretical and experimental fungal adhesion on untreated and treated wood were also investigated. The results showed that the adhesion was favorable on untreated wood and reduced using the optimal mixture. Moreover, the experimental data demonstrated that the same mixture exhibited an antiadhesive efficacy effect with a reduction of 36-75% in adhesion.

The theoretical adhesion of Staphylococcus aureus and Pseudomonas aeruginosa as nosocomial pathogens on 3D printing filament materials.

Microbial infections and nosocomial diseases associated with biomaterial have become a major problem of public health and largely lead to revision surgery, which is painful and quite expensive for patients. These infections are caused by formation of biofilm, which present a difficulty of treatment with conventional antibiotics. The aim of our study is to investigate the theoretical adhesion of Staphylococcus aureus and Pseudomonas aeruginosa on four 3-dimensional printing filament materials used in the manufacture of medical equipment. Thus, the physicochemical properties of these microorganisms and all filament materials were determined using the contact angle measurements. Our results indicated that bacterial surfaces were hydrophilic, strongly electron donating and weakly electron accepting. In contrast, nylon, acrylonitrile butadiene-styrene, polyethylene terephthalate, and polylactic acid surfaces were hydrophobic and more electron-donor than electron-acceptor. In addition, according to the values of total free interaction energy ΔGTotal, Staphylococcus aureus was found unable to adhere to the filament materials except polyethylene terephthalate surface. However, Pseudomonas aeruginosa showed adhesion capacity only for acrylonitrile butadiene-styrene and polyethylene terephthalate surfaces. These findings imply that the usage of these 3D printed materials in the medical area necessitates more research into enhancing their resistance to bacterial adherence.

The Effect of Different Vegetable Oils on Cedar Wood Surface Energy: Theoretical and Experimental Fungal Adhesion.

Despite having been used for ages to preserve wood against several effects (biological attack and moisture effects) that cause its degradation, the effect of vegetable oils on the cedar wood physicochemical properties is poorly known. Thus, in this study, the hydrophobicity, electron-acceptor (γ +), and electron-donor (γ -) properties of cedar wood before and after treatment with vegetable oils have been determined using contact angle measurement. The cedar wood has kept its hydrophobic character after treatment with the different vegetable oils. It has become more hydrophobic quantitatively with values of surface energy ranged from -25.84 to -43.45 mJ/m2 and more electron donors compared to the untreated sample. Moreover, the adhesion of four fungal strains (Penicillium commune (PDLd"), Thielavia hyalocarpa, Penicillium commune (PDLd10), and Aspergillus niger) on untreated and treated cedar wood was examined theoretically and experimentally. For untreated wood, the experimental adhesion showed a positive relationship with the results obtained by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) approach which found that all fungal strains could adhere strongly to the cedar wood material. In contrast, this relationship was not always positive after treatment. The Environmental Scanning Electron Microscopy (ESEM) has shown that P. commune (PDLd10) and A. niger were found unable to adhere to the wood surface after treatment with sunflower and rapeseed oils. In addition, the results showed that the four fungal strains' adhesion was decreased with olive and linseed oils treatment except that of P. commune (PDLd10) treated with linseed oil.

Effect of preconditioning cobalt and nickel based dental alloys with Bacillus sp. extract on their surface physicochemical properties and theoretical prediction of Candida albicans adhesion.

Biofilm formation on dental biomaterials is implicated in various oral health problems. Thus the challenge is to prevent the formation of this consortium of microorganisms using a safe approach such as antimicrobial and anti-adhesive natural products. Indeed, in the present study, the effects of an antifungal extract of Bacillus sp., isolated from plant rhizosphere, on the surface physicochemical properties of cobalt and nickel based dental alloys were studied using the contact angle measurements. Furthermore, in order to predict the adhesion of Candida albicans to the treated and untreated dental alloys, the total free energy of adhesion was calculated based on the extended Derjaguin-Landau-Verwey-Overbeek approach. Results showed hydrophobic and weak electron-donor and electron-acceptor characteristics of both untreated dental alloys. After treatment with the antifungal extract, the surface free energy of both dental alloys was influenced significantly, mostly for cobalt based alloy. In fact, treated cobalt based alloy became hydrophilic and predominantly electron donating. Those effects were time-dependent. Consequently, the total free energy of adhesion of C. albicans to this alloy became unfavorable after treatment with the investigated microbial extract. A linear relationship between the electron-donor property and the total free energy of adhesion has been found for both dental alloys. Also, a linear relationship has been found between this latter and the hydrophobicity for the cobalt based alloy. However, the exposure of nickel based alloy to the antifungal extract failed to produce the same effect.

Delivery system for berberine chloride based on the nanocarrier ZnAl-layered double hydroxide: Physicochemical characterization, release behavior and evaluation of anti-bacterial potential.

Layered double hydroxide (LDH) has attracted major interest as one of the most versatile drug delivery systems especially for adsorption capacity and/or controlled delivery property of bioactive agents owing to their combining features of biohybrid. ZnAl synthesized layered double hydroxide can offer a platform to immobilize various types of bioactive compounds, particularly berberine chloride (BBC). However, the immobilization reaction of berberine chloride into ZnAl-LDH was performed by direct co-precipitation method at different ratios of BBC/LDH. BBC-ZnAl-LDH biohybrids were characterized in terms of structure, surface morphology, in vitro drug release profile and antibacterial assay against various bacterial cells. The BBC biomolecules were attached by coordinate bond. Structural and microstructural characterization confirms that interaction of BBC with ZnAl-LDH occurs by adsorption rather than intercalation of BBC within LDH layers. The BBC release profiles from BBC-ZnAl-LDH had a longer release duration compared to the physical mixture, and the drug release seemed faster with the low ratio of BBC/LDH. BBC-ZnAl-LDH can be internalized into bacterial cells. In vitro experiments in PBS medium showed that BBC-ZnAl-LDH biohybrid had higher cytotoxicity and inhibitory effects against three pathogenic bacteria; Staphylococcus aureus CIP 543154, Pseudomonas aeruginosa A22 and Bacillus subtilus ILP 1428B upon the drug release profiles and its destructive potential depends on the loading BBC on the LDH layers. Nonetheless these results prove that the prepared BBC-ZnAl-LDH biohybrids retain the anti-bacterial character of the BBC molecules and are therefore potential modified drug delivery system (DDS).

Preparation and optimization of a drug delivery system based on berberine chloride-immobilized MgAl hydrotalcite.

Hydrotalcite (HT), also known as a layered double hydroxide (LDH) compound, has been widely used in past years in the formulation of drugs due to its specific properties including good biocompatibility, null toxicity, high chemical stability and pH-dependent solubility which aid in drug controlled release. In this work, berberine chloride (BBC) class antibacterial agent was immobilized into magnesium-aluminum LDH in order to improve the drug efficiency as well as to achieve the controlled release property. BBC molecules were immobilized into MgAl LDH through a conventional ion exchange reaction and co-precipitation method. The ion-exchange experiments of BBC on MgAl LDH were investigated with particular attention paid to the influence of the layer charge, the nature of the intercalated anion and the morphology. The immobilization efficiency was dependent upon the LDH properties and the immobilization process. Characterization by powder x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and contact angle measurements revealed that the interaction of BBC with MgAl LDH occurs by adsorption rather than intercalation of BBC within LDH layers. In vitro anti-bacterial tests were carried out using disc diffusion assay to prove the effectiveness of these novel biohybrid beads as a controlled drug delivery method. Consequently, the BBC-LDH co-precipitated formulation revealed an enhanced anti-bacterial activity compared to the ion-exchanged formulation not only due to an improvement of chemical stability and retained amount of BBC molecules but also due to the release property.

Methods for in vitro evaluating antimicrobial activity: A review.

In recent years, there has been a growing interest in researching and developing new antimicrobial agents from various sources to combat microbial resistance. Therefore, a greater attention has been paid to antimicrobial activity screening and evaluating methods. Several bioassays such as disk-diffusion, well diffusion and broth or agar dilution are well known and commonly used, but others such as flow cytofluorometric and bioluminescent methods are not widely used because they require specified equipment and further evaluation for reproducibility and standardization, even if they can provide rapid results of the antimicrobial agent's effects and a better understanding of their impact on the viability and cell damage inflicted to the tested microorganism. In this review article, an exhaustive list of in vitro antimicrobial susceptibility testing methods and detailed information on their advantages and limitations are reported.