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The aim of the present study was to prepare and characterize nanocomposite films to improve the treatment of skin wounds by applying the film as a bandage. To modify chitosan (Cs) and to prepare nanocomposites, a mixture between titanium dioxide nanoparticles (TiO 2 NPs) was performed at different concentrations (2, 5, 10 and 15 wt%) and oleic acid (OA). The thin nanocomposite films were prepared by using casting method. The prepared films (Cs, Cs/TiO 2 NPs, Cs/OA and Cs/OA/TiO 2 NPs) were described by water absorption (swelling study) and biological degradation. Physico-chemical characterizations of Cs, Cs/OA, Cs/TiO 2 NPs and Cs/OA/TiO 2 NPs (with only 15 wt% TiO 2 NPs) films were determined by X-ray diffraction, transmission high-resolution electron microscopy, field emission scanning electron microscopy, thermal analysis and Fourier transform infrared spectroscopy as well as their mechanical properties. Antimicrobial activity against microorganisms has been studied to assess activity against bacteria. The prepared nanocomposite films showed good antimicrobial activity for both Gram-positive and Gram-negative bacteria. The therapeutic effects of Cs-TiO 2 NPs-oleic acid nanocomposites on healing excision wounds were studied in rat animal model. The data obtained revealed that groups treated with nanocomposites showed enhancement wound closure and speed up wound healing time. K E Y W O R D S antimicrobial activity, chitosan and oleic acid, chitosan and titanium dioxide nanoparticles, nanocomposites films, wound healing 1 | INTRODUCTION Bionanocomposites are beneficial and have been used in a wide range of applications in many fields such as physical, biological, biomedical and pharmaceutical applications (Díez-Pascual, 2019; Loureiro, Azoia, Gomes, & Cavaco-Paulo, 2016; Nikalje, 2015). Nanoparticles are an important component of many classes of biopolymers and bionanocomposites (Lenart & Hore, 2018). Numerous research has stated that TiO 2 nanoparticles at a low content (1-5%) may improve the physical-thermal properties of biocomposite films (Oleyaei, Almasi, Ghanbarzadeh, & Moayedi, 2016; Zhang et al., 2017). Khan and his colleagues reviewed a detailed overview of the properties, and applications of nanoparticles (NPs) present in various forms (Khan, Saeed, & Khan, 2019). Wound dressings develop according to the cause of different wounds. Various types of wound dressings, for example, xerogels, charcoal, alginate, chitosan, and hydrogel, have been introduced for this purpose (Abbasalipour, Mirjalili, Khajavi, & Majidi, 2014).

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Enzyme cost and stability are the main problems facing industrial applications. Consequently, Aspergillus nigerNRC1ami was isolated from rotten orange and recorded a promising pectinase activity (13.8 U/ml). The enzyme was optimized using citrus peel pectin as the sole carbon source and recorded (40 U/ml). It was purified by two steps purifications and recorded 632 purification folds. The pure enzyme showed 14.7% carbohydrate content and consists of 15 amino acids. Glutamic acid was the major (22%) followed by leucine (10.67%) and threonine was the minor (2.70%). A. niger NRC1ami pectinase was conjugated by covalent coupling to sodium periodate (NaIO4) activated polysaccharides. Galactomannan showed the highest recovered activity (85%) and 94.34% reduction in viscosity. The optimum temperature for the pure enzyme shifted from 40 to 45 °C after the conjugation process. Also, the free enzyme showed its optimum activity at pH 5 compared to pH 4, 5 in the conjugated form case. The thermal stability of the free enzyme greatly improved after the modification process. The conjugated process reduced the activation energy to 36%, prolonged the enzyme half-life 5.6-fold at 60 °C, and increase the deactivation energy (Ed) by about 19% in comparison to the free form. The D value of the conjugated enzyme increased to 13.2-fold at 50 °C compared to the free form. Gibbs's free energy (ΔG) of the enzyme increased after the modification process, while the enthalpy (ΔH) and entropy (ΔS) decreased. Na+ and Zn2+ had a stimulating effect on both enzyme forms. Graphical Abstract

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Continue to hypothesize that honey is a storehouse of beneficial bacteria, and the majority of these isolates are levansucrase producers. Accordingly, ten bacterial strains were isolated from different honey sources. Four honey isolates that had the highest levansucrase production and levan yield were identified by the partial sequencing of the 16S rRNA gene as Achromobacter sp. (10A), Bacillus paralicheniformis (2M), Bacillus subtilis (9A), and Bacillus paranthracis (13M). The cytotoxicity of the selected isolates showed negative blood hemolysis. Also, they are sensitive to the tested antibiotics (Amoxicillin + Flucloxacillin, Ampicillin, Gentamicin, Benzathine benzylpenicillin, Epicephin, Vancomycin, Amikacin, and Zinol). The isolates had strong alkaline stability (pHs 9, 11) and were resistant to severe acidic conditions (29–100 percent). The tested isolates recorded complete tolerance to both H2O2 and the bile salt (0.3% Oxgall powder) after 24 h incubation. The cell-free supernatant of the examined strains had antifungal activities against C. Albicans with varying degrees. Also, isolates 2M and 13M showed strong activities against S. aureus. The isolates showed strong adhesion and auto-aggregation capacity. Isolate 10A showed the highest antioxidant activity (91.45%) followed by 2M (47.37%). The isolates recorded different catalase and protease activity. All isolates produced cholesterol oxidase and lipase with different levels. Besides, the four isolates reduced LDL (low-density lipoprotein) to different significant values. The cholesterol-reducing ability varied not only for strains but also for the time of incubation. The previous results recommended these isolates be used safely in solving the LDL problem.