New and efficient NiO/chitosan/polyvinyl alcohol nanocomposites as antibacterial and dye adsorptive films

Programable sewage-cleaning technology: Regenerating chitosan biofilms with anti-bacterial capacity via self-purification of water pollutants

In this paper, a novel programable sewage-cleaning technology for the regeneration of antibacterial nanocomposites via the removal of wastewater pollutants is presented. Montmorillonite (MMT) was encapsulated in poly(vinyl alcohol) (PVA)-enhanced chitosan (CTS) hydrogels to form MMT-loaded nanocomposite biofilms (PCM). The PCM nanocomposite biofilms exhibited increased breaking strength and elongation at break, by factors of approximately 1.38 and 1.40, respectively, compared with those of the pure PVA/CTS biofilms. The maximum adsorption capacity of the PCM nanocomposite biofilms toward tetracycline and Ag(I) is 275.0 and 567.0 mg/g, respectively. The adsorbed nanocomposite biofilms exhibited excellent antibacterial properties against Staphylococcus aureus and Escherichia coli. Meanwhile, the nanocomposite also showed an effective adsorption capacity toward other toxic components, where the highest adsorption capacity is 2748.0 mg/g (for methyl blue). The simulation results indicated that the adsorption behaviors of the malachite green, neutral red, methyl blue, tetracycline, Cu(II), Zn(II), and Ag(I) by the PCM nanocomposite biofilms followed pseudo-second-order kinetic and Freundlich isotherm models. Furthermore, the PCM nanocomposite biofilms are stable in PBS solution but degradable in lysozyme-containing PBS solution, suggesting their potential application in the wastewater treatment as well as antibacterial fields.

Enhanced antibacterial properties of polyvinyl alcohol/starch/chitosan films with NiO-CuO nanoparticles for food packaging

Packaging is very important to maintain the quality of food and prevent the growth of microbes. Therefore, the use of food packaging with antimicrobial properties protects the food from the growth of microorganisms. In this study, antibacterial nanocomposite films of polyvinyl alcohol/starch/chitosan (PVA/ST/CS) together with nickel oxide-copper oxide nanoparticles (NiO-CuONPs) are prepared for food packaging. NiO-CuONPs were synthesized by the co-precipitation method, and structural characterization of nanoparticles (NPs) was carried out by XRD, FTIR, and SEM techniques. Composites of PVA/ST/CS, containing different percentages of NPs, were prepared by casting and characterized by FTIR and FESEM. The mechanical properties, diffusion barrier, and thermal stability were determined. The nanoparticles have a round structure with an average size of 6.7 ± 1.2 nm. The cross-section of PVA/ST/CS film is dense, uniform, and without cracks. In the mechanical tests, the addition of NPs up to 1% improved the mechanical properties (TS = 31.94 MPa), while 2% of NPs lowered TS to 14.76 MPa. The fibroblast cells toxicity and the films antibacterial activity were also examined. The films displayed stronger antibacterial effects against Gram-positive bacteria (Staphylococcus aureus) compared to Gram-negative bacteria (Escherichia coli). Furthermore, these films have no toxicity to fibroblast cells and the survival rate of these cells in contact with the films is more than 84%. Therefore, this film is recommended for food packaging due to its excellent mechanical and barrier properties, good antibacterial activity, and non-toxicity.

Low-cost and eco-friendly PVA/carrageenan membrane to efficiently remove cationic dyes from water: Isotherms, kinetics, thermodynamics, and regeneration study

Methylene blue (MB), a common dye in the textile industry, has a multitude of detrimental consequences on humans and the environment. Accordingly, it is necessary to remove dyes from water to guarantee our health and sustainable ecosystem. In this study, we developed polyvinyl alcohol (PVA)-based hydrogel adsorbents with high adsorption capacity by adding three types of carrageenan (kappa, iota, and lambda) to remove MB from water. Thanks to the functional groups, the PVA/carrageenan membranes dramatically increased the removal efficiency (kappa, 98.8%; iota, 97.0%; lambda, 95.4%) compared to the pure PVA membrane (6.3%). Among the three types of PVA/carrageenan membranes, the PVA/kappa-carrageenan membrane exhibited the best adsorption capacity of 147.8 mg/g. This result implies that steric hindrance was considerably significant, given that kappa carrageenan has only one sulfate group in the repeating unit, whereas iota and lambda carrageenan composite PVA membranes possess two and three sulfate groups. Apart from the maximum adsorption capacity, this study addressed a variety of characteristics of PVA/carrageenan membranes such as the effects of initial MB concentration, kappa carrageenan weight percentage, contact time, adsorbent dosage, and temperature on the adsorption performance. In addition, the kinetic and thermodynamic studies were also carried out. Lastly, the reusability of the PVA/carrageenan membrane was verified by the 98% removal efficiency maintained after five adsorption-desorption cycles.

Chitosan-derived mesoporous N-doped carbon catalyst embedded with NiO for highly selective benzyl alcohol oxidation

MOF-derived heteroatom-doped mesoporous carbons have gained the significant consideration in heterogenous catalytic reactions because of their multipurpose features. Especially, the high Specific Surface Area (SSA) of these materials provides abundant activated sites for the catalytic reactions, while the mesoporous structure allows for the effective mass transfer, enhancing the overall capability of the catalytic process. Herein, the efficient NiO/CN-T (T referred to the pyrolysis temperature) was prepared by facile pyrolysis of MOF/CS composite (Ni-MOF (74), Chitosan) in the presence of excess amount of starch as the carbon precursor. The NiO/CN-T as heterogenous catalyst has desired SSA varied from 1094 to 491 m2.g-1. The optimized catalyst (NiO/CN-600) possesses the superior catalytic activity toward the oxidation of the BnOHs due to its high SSA (1094 m2.g-1), which can notably rectify the mass transfer proficiency. Additionally, the NiO/CN-600 heterogenous catalyst also represents the acceptable chemical stability. So, it was demonstrated that such an innovative strategy can provide several versatile tunability insights for the preparation of MOF/biopolymer-derived heterogenous catalysts.

Preparation and characterization of gelatin/chitosan nanocomposite reinforced by NiO nanoparticles as an active food packaging

Food packaging with antibacterial properties has attracted much attention recently. In this study, nickel oxide nanoparticles (NiONPs) were synthesized by co-precipitation and then gelatin/chitosan polymer films (GEL/CS) with different percentages of NiONPs, bio-nanocomposites, were prepared by casting. Morphology, crystal microstructure, molecular interactions and thermal stabilities of the NPs and the composite films were characterized by FESEM, XRD, FTIR and TGA, respectively. The bio-nanocomposite films exhibited excellent barrier, thermal and mechanical properties by addition of an optimized content of NPs. For example, the tensile strength (TS) of the GEL/CS film without NPs was 23.83 MPa and increased to 30.13 MPa by incorporation of 1% NPs. The antibacterial properties and toxicity of the films were investigated. These films show good antibacterial behavior against Gram-positive (Staphylococcus aureus) bacteria compared to Gram-negative (Escherichia coli) bacteria. Furthermore, the films were found to be non-toxic to fibroblast cells that came into contact with the films, with a survival rate of more than 88%. Therefore, these films can be applied for food packaging due to their excellent mechanical, barrier, and antibacterial properties.

Chitosan-based supramolecular aerogel with "skeletal structure" constructed in natural deep eutectic solvents for medical dressings

Bacterial infection of wounds remains one of the major clinical challenges, calling for the urgent development of novel multifunctional biological dressings. In this study, we developed a chitosan-based supramolecular aerogel NADES/PVA/CS, constructed by hydrogen bonding between chitosan, a natural deep eutectic solvents and polyvinyl alcohol, as a novel wound dressing against bacterial infections. The effect of polyvinyl alcohol content and its incorporation within chitosan-based supramolecular aerogels were investigated. The results of antibacterial test and MTT assay showed that it has obvious inhibitory effect on Staphylococcus aureus and Escherichia coli, showing excellent biocompatibility and effectively promotes wound healing. The microstructure of chitosan-based supramolecular aerogel showed that by adjusting the addition amount of polyvinyl alcohol, it could exhibit a perfect skeleton-type 3D network structure, which also made it possess smaller density and larger porosity and exhibit excellent water absorption property, contributing to the wetting of wound surface. More importantly, chitosan-based supramolecular aerogel is an environment-friendly biomaterial, which has been verified by degradability experiment. In a word, these unique advantages provide a broad prospect for the medical application of chitosan-based supramolecular aerogel NADES/PVA/CS, and provide a new strategy for the construction of green polysaccharide medical materials.

Enhancing wheat crop production with eco-friendly chitosan encapsulated nickel oxide nanocomposites: A safe and sustainable solution for higher yield

In this work, we looked at using nickel oxide (NiO) nanocomposites with chitosan encapsulation as a nano-primer to improve wheat crop output. A straightforward green precipitation procedure was used to create the nanocomposites, and they were then characterized using several methods. According to the findings, the chitosan-encapsulated NiO nanocomposites possessed a large surface area and were resilient to changes in pH. Following this, wheat seeds were primed with the nanocomposites, and under greenhouse circumstances, the impact on crop growth was assessed. The findings demonstrated that, in comparison to the control group, nanocomposites priming considerably enhanced wheat growth and germination rate up to 99 %. In comparison to untreated plants, the wheat plants treated with the nanocomposites primer had greater plant height i.e. shoot length (11.4 cm) and root length (10.3 cm), leaf area, and biomass accumulation. Further research into the mechanism underlying the priming effect of nanocomposites on wheat growth revealed that the nanocomposites enhanced nutrient absorption, photosynthesis, and stress tolerance in wheat plants. In conclusion, our research shows that chitosan-encapsulated NiO nanocomposites have the potential to improve wheat crop productivity in an environmentally benign and long-term manner, offering a viable strategy for sustainable farming.

Adsorption of methyl orange by porous membranes prepared from deep eutectic supramolecular polymer-modified chitosan

The fabrication of an adsorbent with excellent performance has been a focus of attention because of the toxicity, mutagenicity and carcinogenicity of methyl orange (MO)-containing wastewater discharged from the textile, tannery and pharmaceutical industries. In this study, chitosan (CS) membranes were modified with a deep eutectic supramolecular polymer (DESP), and adsorbent membranes with porous structures were prepared with polyethylene glycol (PEG). Microstructural characterization of the CS-DESP-PEG composite membranes with FT-IR, XRD and SEM showed that the membranes had amorphous crystalline structures and that hydrogen bonding interactions weakened the crystallinity and formed loose porous structures. Optimization of the chitosan to β-cyclodextrin ratio, pH, PEG proportion, MO concentration and adsorbent dose significantly improved the adsorption efficiencies of the membranes. The adsorption behaviours of the membranes were fit with pseudo-second-order adsorption kinetics and the Freundlich adsorption isotherm model. Regeneration experiments showed that the membranes were reusable multiple times and maintained good adsorption capacities.

Green nanocoating-based polysaccharides decorated with ZnONPs doped Egyptian kaolinite for antimicrobial coating paper

Paper coating plays an important role in the paper properties, printability and application. The nanocoating is a multifunction layer that provides the paper with unique features. In this work, nanocoating formulas were prepared using a green method and component. The nanocoating formulas were based on biopolymers nanostarch NSt and nanochitosan NCh (NCS) decorated with Egyptian kaolinite Ka doped with zinc nanoparticles NCS@xka/ZnONPs (x represents different ratios) support for multifunctional uses. The nanocoating formulas were characterized using a physiochemical analysis as well as a topographical study. FTIR, XRD, SEM and TEM techniques were used. Additionally, the antimicrobial activity of the tested samples was assessed against six microorganisms including Gram-negative and Gram-positive bacteria. The prepared nanocoating formulas affirmed excellent antimicrobial activity as a broad-spectrum antimicrobial active agent with excellent activity against all representative microbial communities. The nanocoating with the highest ratio of Ka/ZnONPs (NCS@40 ka/ZnONPs) showed excellent antimicrobial activity with an inhibition percentage of more than 70% versus all microorganisms presented. The paper was coated with the prepared suspensions and characterized concerning optical, mechanical and physical properties. When Ka/ZnONPs were loaded into NCS in a variety of ratios, the characteristics of coated paper were enhanced compared to blank paper. The sample NCS@40 ka/ZnONPs increased tensile strength by 11%, reduced light scattering by 12%, and improved brightness and whiteness by 1%. Paper coated with NCh suspension had 35.32% less roughness and 188.6% less porosity. When coated with the sample NCS@10 ka/ZnONPs, the coated paper's porosity was reduced by 94% and its roughness was reduced by 10.85%. The greatest reduction in water absorptivity was attained by coating with the same sample, with a reduction percentage of 132%.

Effect of the molar ratio of (Ni2+ and Fe3+) on the magnetic, optical and antibacterial properties of ternary metal oxide CdO-NiO-Fe2O3 nanocomposites

In this work, the effect of the molar ratio of (Ni²⁺ and Fe³⁺) on the properties of CdO-NiO-Fe₂O₃ nanocomposites was investigated. The synthesis of CdO-NiO-Fe₂O₃ nanocomposites was carried out by self-combustion. XRD, UV-Vis, PL and VSM were used to describe the physical properties of the materials. The results showed significant progress in structural and optical properties supporting antibacterial activity. For all samples, the particle size decreased from 28.96 to 24.95 nm with increasing Ni²⁺ content and decreasing Fe³⁺ content, as shown by the XRD pattern, which also shows the crystal structure of cubic CdO, cubic NiO, and cubic γ-Fe₂O₃ spinel. The Ni²⁺ and Fe³⁺ contents in the CdO-NiO-Fe₂O₃ nanocomposites have also been shown to enhance the ferromagnetic properties. Due to the significant coupling between Fe₂O₃ and NiO, the coercivity H_c values of the samples increase from 66.4 to 266 Oe. The potential of the nanocomposites for antibacterial activity was investigated against Gram-positive (Staphylococcus aureus) and Gram-negative (Pseudomonas aeruginosa, Escherichia coli, and Moraxella catarrhalis) bacteria. Comparison of P. aeruginosa with E. coli, S. aureus and M. catarrhalis showed that it has a stronger antibacterial activity with a ZOI of 25 mm.

Combination mechanism of the ternary composite based on Fe3O4-chitosan-graphene oxide prepared by solvothermal method

Magnetic nanohybrid combining chitosan and graphene have demonstrated promising application in environmental remediation. Herein, ternary composite MCG based on Fe₃O₄, chitosan (CS) and graphene oxide (GO) was facilely prepared via solvothermal method. The as prepared composite was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman, Brunauer/Emmett/Teller-Barret/Joyner/Halenda (BET-BJH) and thermo gravimetric-differential thermal analysis (TG-DTA). The combination mechanism of MCG was unveiled via employing the hard-soft acid-base (HSAB) theory and spectroscopic investigations including X-ray photoelectron spectroscopy (XPS), Ultraviolet-visible (UV-Vis) and fluorescent emission spectra. Particularly, combination mechanism of MCG was elucidated by the probable site to site interaction of the couplet components in MCG, as follows. (1) CS-Fe₃O₄. The primary interaction is N(NH₂)-Fe(III), electron donates from N to Fe, transforming one half of the amino groups of chitosan into positive N⁺. (2) GO-CS. Amidation reaction is the primary interaction form, converting the other half of the amino groups of chitosan into -C(O)NH-. (3) GO-Fe₃O₄. Dominant interactions are those of epoxy, hydroxyl and aromatic ring with Fe(III). Moreover, MCG exhibits fair adsorption performance on divalent heavy metals in six consecutive cycles. These explorations may shed light on the design of efficient adsorbent based on Fe₃O₄-chitosan-graphene architecture.

Synthesis, characterization and application of chitosan/graphene oxide/copper ferrite nanocomposite for the adsorptive removal of anionic and cationic dyes from wastewater

The increased discharge of water pollutants drives the development of new and effective wastewater remediation methods. Herein, a magnetic nanocomposite of chitosan-graphene oxide (GO) decorated with copper ferrite (MCSGO) was synthesized under ultrasound agitation and applied to the effective removal of Safranin O (SAF) and indigo carmine (IC) dyes from wastewater. The structural, magnetic, and physicochemical features of the as-prepared MCSGO nanocomposite have been thoroughly investigated using various characterization techniques. The operational parameters such as MCSGO mass, contact time, pH, and initial dye concentration were investigated. The effects of diverse coexisting species on both dye elimination processes were examined. The experimental results demonstrated that the adsorption capacity of MCSGO nanocomposite for IC and SAF was 112.6 and 66.15 mg g^-1, respectively. Five different adsorption isotherms were investigated using two-parameter (Langmuir, Tekman, and Freundlich) and three-parameter (Sips, and Redlich-Peterson) models. Thermodynamic studies revealed that the elimination of both dyes on MCSGO nanocomposite was endothermic and spontaneous, with anionic and cationic dye molecules randomly arranged onto the adsorbent nanoparticles. Moreover, the mechanism of dye elimination was deduced. Furthermore, even after five cycles of adsorption and desorption, the as-prepared nanocomposite showed no significant loss in the dye removal efficiency, indicating that it has superior stability and recycling potential.

Preparation, characterization, and antibacterial effect of bio-based modified starch films

There are several problems with common starch films, including strong water absorption and poor mechanical properties. To create a better starch film, octenyl succinate cassava starch ester (OSCS) was first blended with chitosan and nano ZnO to prepare an OSCS/CS/ZnO film. Then, the film was supplemented with different concentrations of ε-PL as a bacteriostatic agent to prepare a film that would resist bacterial invasion. The mechanical properties, barrier properties, optical properties, and color of the modified starch antibacterial films were investigated, and finally the antibacterial properties and cytotoxicity were tested. The results demonstrated that the modified starch antibacterial film had good mechanical properties, improved surface hydrophobicity, and had a UV-blocking effect. The modified starch antibacterial film with ε-PL of 8% had stable and long-lasting antibacterial properties, stable release, and good cytocompatibility. An active packaging material was successfully prepared using ε-PL and had a strong preservative effect on food.

Development of functional hydroxyethyl cellulose-based composite films for food packaging applications

Cellulose-based functional composite films can be a good substitute for conventional plastic packaging to ensure food safety. In this study, the semi-transparent, mechanical strengthened, UV-shielding, antibacterial and biocompatible films were developed from hydroxyethyl cellulose Polyvinyl alcohol (PVA) and ε-polylysine (ε-PL) were respectively used as reinforcing agent and antibacterial agent, and chemical cross-linking among these three components were constructed using epichlorohydrin The maximum tensile strength and elongation at break were 95.9 ± 4.1 MPa and 148.8 ± 2.6%, respectively. TG-FTIR and XRD analyses indicated that chemical structure of the composite films could be well controlled by varying component proportion. From UV-Vis analysis, the optimum values of the percentage of blocking from UV-A and UV-B and ultraviolet protection factor values were 98.35%, 99.99% and 60.25, respectively. Additionally, the composite films exhibited good water vapor permeability, swelling behavior, antibacterial activity and biocompatibility. In terms of these properties, the shelf life of grapes could be extended to 6 days after packing with the composite film.

Hollow mesoporous silica nanoparticles-loaded ion-crosslinked bilayer films with excellent mechanical properties and high bioavailability for buccal delivery

Mucoadhesive buccal films (MBFs) become the most promising buccal mucosal delivery system duo to its advantageous properties, including simple preparation technique and better patient compliance. The mechanical properties and mucoadhesion of MBFs are crucial in their successful performance as well as manufacturing and administration. In this study, we prepared hollow mesoporous silica nanoparticles-loaded ion-crosslinked bilayer films (CCS-PVA-TPP-FSM@HMSNs) using carboxymethyl chitosan (CCS) and polyvinyl alcohol (PVA) for buccal delivery of furosemide (FSM). The FSM-loaded hollow mesoporous silica nanoparticles (FSM@HMSNs) were firstly characterized by SEM, TEM, and nitrogen adsorption/desorption. Then, we constructed an ion-crosslinked network using CCS and PVA employed with the solution casting method, and sodium tripolyphosphate (TPP) was used as a hydrogen bond crosslinking agent. The formulation was optimized through Box-Behnken design, where the impact of the proportion of the ingredients on the quality of the films was evaluated entirely. Herein, folding endurance, swelling, tensile strength, and adhesion force were selected as response variables. Morphology, mechanical, spectroscopic, thermal, and safety of CCS-PVA-TPP-FSM@HMSNs films were also investigated. The release and permeability behaviors of CCS-PVA-TPP-FSM@HMSNs films were evaluated by in vitro drug release, across isolated porcine buccal and TR146 cell model. The CCS-PVA-TPP-FSM@HMSNs films showed outstanding mechanical properties, suitable bioadhesion, high drug loading, significant sustained-release properties, and improved permeability. In pharmacokinetic study with golden hamster models, the relative bioavailability was increased by 191.54%, and the absolute bioavailability was 82.20%. In summary, this study provides evidence that this innovative CCS-PVA-TPP-FSM@HMSNs films could be a promising and industrialized buccal drug delivery system.

Recent advances in biobased and biodegradable polymer nanocomposites, nanoparticles, and natural antioxidants for antibacterial and antioxidant food packaging applications

Inorganic nanoparticles (NPs) and natural antioxidant compounds are an emerging trend in the food industry. Incorporating these substances in biobased and biodegradable matrices as polysaccharides (e.g., starch, cellulose, and chitosan) and proteins has highlighted the potential in active food packaging applications due to more significant antimicrobial, antioxidant, UV blocking, oxygen scavenging, water vapor permeability effects, and low environmental impact. In recent years, the migration of metal NPs and metal oxides in food contact packaging and their toxicological potential have raised concerns about the safety of the nanomaterials. In this review, we provide a comprehensive overview of the main biobased and biodegradable polymer nanocomposites, inorganic NPs, natural antioxidants, and their potential use in active food packaging. The intrinsic properties of NPs and natural antioxidant actives in packaging materials are evaluated to extend shelf-life, safety, and food quality. Toxicological and safety aspects of inorganic NPs are highlighted to understand the current controversy on applying some nanomaterials in food packaging. The synergism of inorganic NPs and plant-derived natural antioxidant actives (e.g., vitamins, polyphenols, and carotenoids) and essential oils (EOs) potentiated the antibacterial and antioxidant properties of biodegradable nanocomposite films. Biodegradable packaging films based on green NPs-this is biosynthesized from plant extracts-showed suitable mechanical and barrier properties and had a lower environmental impact and offered efficient food protection. Furthermore, AgNPs and TiO₂ NPs released metal ions from packaging into contents insufficiently to cause harm to human cells, which could be helpful to understanding critical gaps and provide progress in the packaging field.

Honeycomb-like V2O5 Based Films: Synthesis, Structural, Thermal, and Optical Properties for Environmental Applications

In the present study, new composite films consisting of hierarchical nanobelt V2O5 and polymer mixture were prepared via a simple casting method. The incorporation of 30 wt.% of V2O5 into the polymer matrix yielded a honeycomb like structure with abundant micro-voids (5.5 μm), higher roughness average by 45.8%, and a higher root mean square roughness by 52%, which are beneficial for the enhancement of active surface area for dye adsorption. Furthermore, optical property studies have shown that the incorporation of V2O5 has made the nanocomposite film a suitable UV–visible light-sensitive material, and thus the application of films can be expanded towards photocatalytic degradation of various toxic pollutants such as nitrophenol, Cr(VI), antibiotects, and so on. Finally, the composite film exhibited enhanced thermostability in comparison to unmodified film, as confirmed by TGA and DSC analysis. The optimal film showed 96.3% removal efficiency and 27.02 mg/g adsorption capacity. The dye sorption performance of V2O5 based films is studied at various times, dosages, and initial dye concentrations. The experimental data more closely fit the Langmuir isotherm model (R2 = 0.997) than the Freundlich, Temkin, and Dubinin–Radushkevich isotherm models, demonstrating a monolayer adsorption mechanism. The MB adsorption process on V2O5 film was controlled by the chemical adsorption step, which was evidenced by the good-fitting of kinetic adsorption results to the pseudo second order model (R2 = 0.991). The obtained results indicated that the V2O5 based films in this work are hopeful candidates for environmental applications.

Antimicrobial and antifungal properties of NiCu-PANI/PVA quaternary nanocomposite synthesized by chemical oxidative polymerization of polyaniline

Increasing antimicrobial resistance has led to use of novel technologies such as nanomaterials and nanocomposites that have shown effective antimicrobial and/or antifungal activities against several gram-positive and gram-negative bacteria. There have been limited studies on antimicrobial properties of the combined polymer nanocomposites with transitional bimetallic nanoparticles such as nickel (Ni) and copper (Cu). Thus, the main objective of this study was to synthesis, characterize and investigate the antibacterial and antifungal properties of NiCu-PANI/PVA nanocomposite. The nanocomposite films with different amount of Ni and Cu salts were synthesized by chemical oxidative polymerization of polyaniline using HCl as oxidant and PVA as a stabilizer. Optical, chemical composition, and morphological characteristics as well as thermal stability were evaluated using UV-Visible, FTIR, SEM-EDX, and TGA analyses. Antimicrobial properties were then determined using the disc diffusion assay against gram-negative bacteria (i.e., Escherichia coli ATCC 25922, Klebsiella pneumonia ATCC 700603, Proteus sp.,) and gram-positive bacteria (i.e., Staphylococcus aureus ATCC 2593). Fungal plant pathogens including Aspergillus niger and Fusarium oxysporum f. sp. pisi were also evaluated for determination of antifungal activity of NiCu-PANI/PVA films. Among the synthesized films, Ni₆₅Cu₃₅-PANI/PVA showed excellent antibacterial activity against all the bacteria strains examined in this study. The diameters of inhibition zones for Escherichia coli ATCC 25922, Klebsiella pneumoniae ATCC 700603, Proteus sp., and Staphylococcus aureus ATCC 2593 were 23, 23, 17, and 18 mm, respectively indicating good antibacterial activities. Additionally, NiCu-PANI/PVA, particularly the films with higher Cu intake, showed better antifungal activity against Fusarium oxysporum f. sp. pisi. However, NiCu-PANI/PVA was ineffective against Aspergillus niger.

Facile synthesis and characterization of chitosan/zinc oxide nanocomposite for enhanced antibacterial and photocatalytic activity

In this report, chitosan/zinc oxide (CS/ZnO) nanocomposite was synthesized using Sida acuta and assessed their antibacterial and photocatalytic properties. The formation of CS/ZnO nanocomposite was preliminary confirmed by colour change and UV-visible spectroscopy. The crystalline peaks related to CS and ZnO in CS/ZnO nanocomposite were demonstrated by XRD. Morphological analysis through FE-SEM and TEM showed a rod like appearance for ZnO NPs and agglomerated grains with rod shaped morphology was observed for the CS/ZnO nanocomposite. The peaks around 400-800 cm^-1 in the IR spectrum of nanocomposite indicated the vibrations of metal-oxygen (ZnO), whereas bands at 1659 cm^-1 and 1546 cm^-1 indicated the presence of amine groups, which confirms the CS in the synthesized CS/ZnO nanocomposite. The CS/ZnO nanocomposite exhibited remarkable growth inhibition activity against B. subtilis and E. coli with 22 ± 0.3 and 16.5 ± 0.5 mm zone of inhibitions. In addition, CS/ZnO nanocomposite treated cotton fabrics also exhibited antibacterial activity against B. subtilis and E. coli. Furthermore, the ZnO NPs and nanocomposite showed time depended photodegradation activity and revealed 76% and 91% decomposition of CR under sunlight irradiation. In conclusion, our study revealed that the functionalization of biopolymer CS to the inorganic ZnO enhances the bio and catalytic properties.

Chitosan-based nanocomposite films incorporated with NiO nanoparticles: Physicochemical, photocatalytic and antimicrobial properties

The aim of this research was to fabricate active nanocomposite films by incorporation of nickel oxide nanoparticles (NiONPs) (3, 6 and 9% w/w) into the chitosan-based films. The NiONPs were synthesized by solution combustion method and the films were prepared by solvent casting method. The formation of new interactions and increasing of films' crystallinity were confirmed by FT-IR and XRD analyses. Uniform dispersion of NiONPs at lower concentrations and their aggregation at level of 9% was confirmed by FE-SEM observations. Water barrier properties, tensile strength, thermal properties and surface hydrophobicity of films enhanced by addition of 6% NiONPs. Photocatalytic activity of nanocomposites was confirmed by absorption of 72% of methyl orange during 270 min under UV irradiation. The nanocomposite films exhibited good antibacterial activity against gram-positive (S. aureus) and gram-negative (S. typhimurium) bacteria. Therefore, the chitosan-NiONPs nanocomposite films could be used for active food packaging applications and photodecolorization purposes.