z. ebadi

Recent research has shown that chitosan has good moisture-absorbing properties at the micro and nanoscale, and seems to be a good candidate for the production of biodegradable moisture-absorbing films.

The aim of this study was to evaluate the properties and antibacterial activity of starch-based microchitosan (MCH) films impregnated with two essential oils (EOs).

MCH films with varying thicknesses were made from cornstarch (6%), microchitosan (1%), glycerol (2.25%), and/or EOs (2%), and their characteristics, including swelling degree (SD), tensile strength (TS), and elongation at break (EB%), were examined. The film structures were confirmed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). To determine the antibacterial activity against Escherichia coli and Staphylococcus aureus, two EOs of Shirazi thyme, garlic, and a mixture of them were used in the experimentation.

The EB% and TS had a linear relationship with the thickness of samples and improved by increasing the thickness of films. The XRD pattern showed that the MCH films had an amorphous structure. SEM of the films showed a homogeneous dispersion of MCH in the starch matrix without any porosity. The AFM images showed a simultaneous increase in the thickness of the MCH films and surface roughness. The film was able to absorb water up to 15.78 times its weight in 48 h. The inhibition zone of films containing 2% thyme EO was 42.0 mm for S. aureus and 12.3 mm for E. coli (P<0.05).

MCH film containing Shirazi thyme can be described as a moisture-absorbing antibacterial pad and is a new idea for active food packaging to increase the shelf life of foods with fully degradable properties.

The effect of nanoparticle diamond incorporated in an experimental dentaladhesive formulation is evaluated by examining the mechanical propertiesand shear bond strength of the system. Diamond nanoparticles were incorporatedinto the dentin adhesive system in different concentrations of 0, 0.05, 0.1,0.2, 0.5, and 1.0 weight percentages. The suspensions were ultrasonicated to facilitatethe nano-particle dispersion in an adhesive solution containing ethanol, bis-GMA,UDMA, TMPTMA, HEMA and photo-initiator system. Diametral tensile strength,flexural strength, flexural modulus, depth of cure and microshear bond strength of theadhesive system were measured. The adhesive-dentin interface was then observed byscanning electron microscopy. The results were analyzed using one-way ANOVA ata significant level of P>0.05. No significant difference was observed between the diametral tensile strength of the adhesive. At nanoparticle content level of 0.1% (by wt),however, 85% increase in flexural strength and 13% enhancement in flexural moduluswere observed. Microshear bond strength test revealed 70% and 79% improvementsof adhesion force in systems containing 0.1% and 0.2% nanoparticles, respectively.Although the neat diamond nanoparticles revealed antibacterial activity, the adhesivecontaining different percentages of the nano particles did not show any antibacterialactivities when tested against, Staphilococcus Aureus, Staphilococcus Streptococcus,Staphilococcus ephidermidis, Saprophyticus, Enterococcus faecalis bacteries