Novel nano composites from Citrus limon and Citrullus colocynthis agricultural wastes for biomedical applications.

In recent years, academic and industrial research has focused on using agro-waste for energy and new material production to promote sustainable development and lessen environmental issues. In this study, new nanocomposites based on polyvinyl alcohol (PVA)-Starch using two affordable agricultural wastes, Citrus limon peels (LP) and Citrullus colocynthis (Cc) shells and seeds powders with different concentrations (2, 5, 10, and 15 wt%) as bio-fillers were prepared. The nanocomposites were characterized by Dielectric Spectroscopy, Fourier-Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and water swelling ratio. The antimicrobial properties of the nanocomposites against Escherichia coli, Staphylococcus aureus, and Candida albicans were examined to investigate the possibility of using such composites in biomedical applications. Additionally, the biocompatibility of the composites on human normal fibroblast cell lines (HFB4) was tested using MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. The results demonstrate that the filler type and concentration strongly affect the film's properties. The permittivity ε', dielectric loss ε″ and conductivity σdc increased by increasing filler content but still in the insulators range that recommend such composites to be used in the insulation purposes. Both bio fillers control the water uptake, and the samples filled with LP were more water resistant. The polyvinyl alcohol/starch incorporated with 5 wt% LP and Cc have antimicrobial effects against all the tested microorganisms. Increasing the filler content has a negative impact on cell viability.

Production of eco composites based on natural rubber and recycled sugarcane bagasse waste to be utilised as a type of food contact.

Natural fibres are abundant, renewable, and biodegradable, which has inspired numerous academics worldwide to investigate their possible applications in various industrial fields. The food packaging sector is seeking bio-based and biodegradable substitutes to increase sustainability. In this study, new composites were prepared from natural rubber (NR) and sugarcane bagasse fibres (SCB) with different concentrations of SCB (0, 2.5, 5, 10 &20 phr). The effect of SCB on the properties of natural rubber was studied before and after the alkaline treatment of the fibres. The biocomposites are characterized using Fourier transmission infrared spectroscopy, thermogravimetric analysis, scanning electron microscope, transmission electron microscope, and dielectric measurements in addition to rheological and mechanical analysis. The overall migration test for biocomposites loaded with 20phr SCB was performed to assess the biocomposite's safety as food contact materials. The study's results indicated that, adding SCB improved the conductivity, tensile strength, and elongation at break of natural rubber. Alkaline treatment strengthened the bonding between the filler and matrix and improved biocomposites' thermal dielectric and mechanical properties. The overall migration test indicated that the alkaline treatment increased the overall migration to simulants. Accordingly, alkaline-treated NR-SCB biocomposites are effective eco-friendly food packaging candidates for certain types of food such as aqueous non-acidic products.

Dielectric properties and in vitro hemocompatibility of Nd:YAG laser-irradiated polyethylene terephthalate.

Surface properties and morphology of the biomaterial play an essential role in the polymer-material interaction. In this work, laser surface modification of polyethylene terephthalate as a polymer with distinguished mechanical properties was carried out using (neodymium-doped yttrium aluminum garnet) Nd:YAG laser (1.064 µm) with different output power (0.3, 3, and 6 W). The structural, surface, and dielectric properties of PET before and after laser irradiation have been studied using attenuation total reflection-Fourier transform infrared (ATR-FTIR), dielectric spectroscopy (DS), scanning electron microscope (SEM), and contact angle measurements. Moreover, the anticoagulant properties of the laser-irradiated PET was determined through measuring the prothrombin time (PT), partial thromboplastin time (PTT), and international normalized ratio (INR). In vitro platelet adhesion test was used to assess the platelets adhered to the surface of the samples; in addition to hematological study. It was found that contact angle (θ) measurements of laser-irradiated PET samples decreased compared to the unirradiated PET. The irradiated samples at 0.3 W have the lowest contact angle which is a clear indication that surface treatment with Nd:YAG laser brought about improving the wettability of the polymer. From the dielectric measurements, both values of permittivity and dielectric loss decrease by increasing the laser power. The electrical conductivity decreases with increasing laser power, but still in the same order 10-14 S/cm. The decrease in electrical conductivity σ may be due to the cross-linking of the polymeric matrix which led to a decrease in the total polarity and consequently decrease in electrical conductivity. The magnitude of σ obtained is highly recommended to be used for insulator purposes in addition to the main purpose that is blood contact.

Preparation and characterization of polyethylene terephthalate-chamomile oil blends with enhanced hydrophilicity and anticoagulant properties.

New blend films based on polyethylene terephthalate (PET) with different concentrations (50, 100 and 200 µL) of chamomile oil (CAO) were prepared. The effect of oil on the dielectric properties, structural and surface properties of PET was studied. The wettability of the blend films was evaluated by contact angle measurements. In vitro platelet adhesion on the surface and coagulation assessment were conducted to evaluate the behavior of the new blends for blood contact applications. Results of the study indicate that the wettability of PET-CAO blends up to 100 µL has been enhanced relative to the pure PET as indicated by the decrease in contact angle measurements. The attenuation total reflection-Fourier transform infrared spectra of the blends confirmed the presence of chamomile oil in the polymer matrix and suggested the presence of interaction between them. The permittivity ε' values decreased by increasing oil content upto 100 µL. On the other hand, the values of dielectric loss ε″ were found to increase by increasing oil content to 100 µL after which it decreased. The delay in partial thromboplastin time (PTT) of the blood would validate the anti-coagulant property of PET-CAO blends. The results demonstrated that the PET-CAO blends with concentration of 100 µL could be considered as a promising candidate material in blood contact application.

Chitosan/banana peel powder nanocomposites for wound dressing application: Preparation and characterization.

Wound infection is a serious infection has been spread worldwide. In order to provide fast aid treatments for such infection, banana peels have been incorporated within chitosan as wound dressing. Banana was collected from Egyptian markets peeled and the dried peels were grounded to powder, Incorporated as nano fillers within chitosan matrix with different concentrations (0, 2, 5 and 10wt%). Glycerol was added as plasticizer and crosslinker to the membranes. The banana peel powder (BPP) particle shape and size were determined using Transmission Electron Microscope (TEM), The homogeneity and distribution of BPP in the membranes were investigated through Scanning Electron Microscope (SEM). The interaction between BPP and chitosan was characterized by Fourier Transform Infrared (FTIR). The dielectric properties of chitosan and BPP-chitosan membranes studied via dielectric constant, dielectric loss and conductivity measurements over a frequency range 100Hz up to 100kHz. The curves relating ε″ and the applied frequency are broad enough reflecting more than one relaxation process. These processes may be attributed to the relaxation processes of the main chain and its related motions. The higher values of ε″ at low frequency range may be a combination of the losses due to the electrical conductivity and the interfacial polarization process called "Maxwell Wagner Sillers" effect. By increasing BPP content in the sample a pronounced shift towards lower frequency was noticed. This shift may be due to some sort of polymer/filler interaction which causes an increase in the relaxed units and consequently the relaxation time. The addition of BPP decreases the swelling degree of chitosan matrix. The antimicrobial properties of the membranes were done against Gram positive, Gram negative bacteria and yeast. The results showed that chitosan/BPP membranes have a synergistic action with the highest activity at 10wt%. Moreover, Candida albicans was the most sensitive strain recorded for these membranes.