Cellulose nanofibrils and silver nanoparticles enhances the mechanical and antimicrobial properties of polyvinyl alcohol nanocomposite film

Preparation and assessment of polylactic acid-curcumin nanofibrous wound dressing containing silver nanoparticles for burn wound treatment

This study aims to produce and evaluate nanofibrous wound dressings through the electrospinning method, utilizing polylactic acid (PLA), curcumin (Cur), and silver nanoparticles (AgNPs). For this purpose, five types of wound dressings with PLA, PLA+Cur, PLA+Cur+ 1 %AgNPs, PLA+Cur+ 2 %AgNPs and PLA+Cur+ 3 %AgNPs were produced using the electrospinning method. Analysis of the Fourier transform infrared spectroscopy and scanning electron microscopic observations indicated successful fabrication, with nanometer diameters achieved in all electrospun samples. Examination of water absorption of wound dressings revealed that over 40 h the electrospun samples had variable water absorption between 0 % and 0.25 %. The results of the curcumin release test over one week showed that the nanofibers with PLA+Cur+ 2 %AgNPs exhibited the lowest release rate, while those with PLA+Cur+ 3 %AgNPs showed the highest release. Assessment of mechanical properties revealed that the tensile strength of the nanofibers increased by adding curcumin to polylactic acid, while the addition of a high content of AgNPs led to a decrease in tensile strength. Also, the PLA+Cur dressing demonstrated 84.06 % and the PLA+Cur+ 3 %AgNPs dressing exhibited 99.12 % antibacterial properties. The cell culture test demonstrated that the incorporation of curcumin and AgNPs increasedboth the growth and proliferation, as well as the adhesion on the nanofibrous wound dressing. Thus, the PLA+Cur+ 1 %AgNPs nanofibrous scaffold, as a multipurpose dressing, presented considerable promise for wound healing and burn treatment.

Ecofriendly synthesis of cellulose-silver nanocomposites and the evaluation of their antibacterial activity

The integration of nanotechnology with cellulose matrices has gained considerable attention due to the resulting enhanced mechanical, thermal, and antibacterial properties. This study introduces a facile and environment-friendly microwave-assisted method for synthesizing cellulose/Ag nanocomposites. Palm date wood extract was used as an efficient reductant for silver ions, facilitating their deposition onto cellulose surface. The cellulose-silver nanocomposite was synthesized by reducing silver in situ on the surface of cellulose extracted from date palm wood fibers. The extraction involved a series of specific chemical treatments, including alkalization and whitening. The resulting nanocomposite was subjected to various characterization techniques. FTIR spectra showed the elimination of non-cellulosic components post chemical treatments, while XRD affirmed the presence of cellulose peaks. Experimental results indicated that the palm date wood extract was an effective reductant for silver ions favoring the formation of silver with higher crystallinity and mass content in the nanocomposites. Silver nanoparticles were identified within the cellulose matrix through Scanning Electron Microscopy (SEM). The FTIR spectral characterization studies demonstrated the existence of silver in the cellulose nanocomposites. Additionally, the XRD analysis confirmed the formation of silver peaks within these composites. Qualitative antibacterial tests towards gram negative (Escherichia coli) and gram positive (Micrococcus luteus) bacteria were carried out and the results showed that the Ag-MFCs effectively inhibit the growth of both types of bacteria, with 9-13 mm of inhibition zone for both the bacteria. The ecofriendly synthesis method using cellulose as a stabilizing agent proved to be effective in producing well-dispersed spherical AgNPs. The synthesized cellulose silver nanocomposite demonstrated notable antibacterial properties, indicating their potential for applications in medical and environmental fields. This study highlights the feasibility of using green synthesis methods to develop nanocomposites with significant antibacterial activity.

Evaluation of the Food Barrier and Mechanical Properties of Carrageenan-Starch Composite Films

Single use plastics are a leading source of microplastics that have been detected along the food chain. This study evaluated the potential of starch (ST) and carrageenan (CRG) in packaging film formulation. CRG isolated from the seaweed (SW) Eucheuma denticulatam was blended with starch and cast to obtain films whose moisture content (MC), total soluble matter (TSM), degree of solubility (DS), water vapor permeability (WVP), opacity (O), contact angles (CA), moisture absorption (MA), and percent elongation (PE) were evaluated. The films' morphology, crystallinity, opacity, thermal profile, and functional groups were then studied by scanning electron microscopy, powder diffraction, UV-Vis, thermal gravimetry, and infrared spectroscopy. From the results obtained, the SWF films exhibited a higher MC, DS, and TSM than CRG and CRG-ST films but lower DC values. The PE of CRG films was lower than that of SWF (30%) though incorporation of ST increased the PE of CRG-ST. However, SWF films had WVP of 2.25 × 10-7 gs-1m-1Pa-1, compared to 3.65 × 10-7 gs-1m-1Pa-1 of CRG, 2.73 × 10-7 gs-1m-1Pa-1 of CRG-ST and a moisture absorption of 29.29 ± 3.5 as compared to 17.29 ± 0.87 of CRG and 23.80% ± 4.12% of CRG-ST. The opacities were found to be 41.02, 79.89, and 42.23 for SWF, CRG, CRG-ST while the contact angles were found to be 72.86, 80.93, 65.57 for SWF, CRG, and CRG-ST, respectively. Moreover, the films were impermeable to vegetable oil, had carbohydrate functional groups, good thermal stabilities, and trace micronutrients. In conclusion, this study formulated packaging films with enhanced food barrier and mechanical properties that can potentially replace single use packaging films.

Fabrication of Silver Nanoparticle Loaded into Nanocellulose Derived from Hemp and Poly(vinyl alcohol)-Based Composite as an Electrode for Electrochemical Sensors for Lactate Determination

Nanocellulose derived from hemp (HNC) with the addition of silver nanoparticles (AgNPs) is utilized for improving the electrochemical sensing performances for lactate detection. Initially, HNC is chemically extracted and purified by using alkali treatment and acid hydrolysis. Then, AgNPs are nucleated in situ by the self-reduction process prior to forming a composite with poly(vinyl alcohol) (PVA). This nanocomposite significantly improves the electrochemical properties of the electrode, including electrochemical conductivity and electrocatalysis. The morphologies and chemical alterations of the HNC/AgNPs-PVA nanocomposite are investigated by field emission scanning electron microscopy. It demonstrates a three-dimensional network with random orientation of the nanocellulose fiber. The AgNPs are well-dispersed in the nanocomposite. Moreover, the nanocomposite provides high thermal stability up to 450 °C. Then, it is remarkably noted that 10 wt % HNC/AgNPs-PVA modified on the electrode provides the highest current responses, with a standard redox couple [(Fe(CN)6]3-/4-]. For lactate detection, this modified screen-printed graphene electrode with nonimmobilized lactate oxidase exhibits an increase in the current signal with the increment of lactate concentration and offered a linear range of 0-25 mM, covering a cutoff value (12.5 mM) for muscle fatigue indication. Eventually, this sensor is successfully applied for lactate detection with high potential for a wearable lactate sensor.

Nanotechnology in wood science: Innovations and applications

Application of nanomaterials is gaining tremendous interest in the field of wood science and technology for value addition and enhancing performance of wood and wood-based composites. This review focuses on the use of nanomaterials in improving the properties of wood and wood-based materials and protecting them from weathering, biodegradation, and other deteriorating agents. UV-resistant, self-cleaning (superhydrophobic) surfaces with anti-microbial properties have been developed using the extraordinary features of nanomaterials. Scratch-resistant nano-coatings also improve durability and aesthetic appeal of wood. Moreover, nanomaterials have been used as wood preservatives for increasing the resistance against wood deteriorating agents such as fungi, termites and borers. Wood can be made more resistant to ignition and slower to burn by introducing nano-clays or nanoparticles of metal-oxides. The use of nanocellulose and lignin nanoparticles in wood-based products has attracted huge interest in developing novel materials with improved properties. Nanocellulose and lignin nanoparticles derived/synthesized from woody biomass can enhance the mechanical properties such as strength and stiffness and impart additional functionalities to wood-based products. Cellulose nano-fibres/crystals find application in wide areas of materials science like reinforcement for composites. Incorporation of nanomaterials in resin has been used to enhance specific properties of wood-based composites. This review paper highlights some of the advancements in the use of nanotechnology in wood science, and its potential impact on the industry.

Nanocellulose Composite Films in Food Packaging Materials: A Review

Owing to the environmental pollution caused by petroleum-based packaging materials, there is an imminent need to develop novel food packaging materials. Nanocellulose, which is a one-dimensional structure, has excellent physical and chemical properties, such as renewability, degradability, sound mechanical properties, and good biocompatibility, indicating promising applications in modern industry, particularly in food packaging. This article introduces nanocellulose, followed by its extraction methods and the preparation of relevant composite films. Meanwhile, the performances of nanocellulose composite films in improving the mechanical, barrier (oxygen, water vapor, ultraviolet) and thermal properties of food packaging materials and the development of biodegradable or edible packaging materials in the food industry are elaborated. In addition, the excellent performances of nanocellulose composites for the packaging and preservation of various food categories are outlined. This study provides a theoretical framework for the development and utilization of nanocellulose composite films in the food packaging industry.

Encapsulation of AgNPs in a Lignin Isocyanate Film: Characterization and Antimicrobial Properties

Lignin isolated from agricultural residues is a promising alternative for petroleum-based polymers as feedstocks in development of antimicrobial materials. A polymer blend based on silver nanoparticles and lignin-toluene diisocyanate film (AgNPs-Lg-TDIs) was generated from organosolv lignin and silver nanoparticles (AgNPs). Lignin was isolated from Parthenium hysterophorus using acidified methanol and used to synthesize lignin capped silver nanoparticles. Lignin-toluene diisocyanate film (Lg-TDI) was prepared by treating lignin (Lg) with toluene diisocyanate (TDI) followed by solvent casting to form films. Functional groups present and thermal properties of the films were evaluated using Fourier-transform infrared spectrophotometry (FT-IR), thermal gravimetry (TGA), and differential scanning calorimetry (DSC). Scanning electron microscopy (SEM), UV-visible spectrophotometry (UV-Vis), and Powder X-ray diffractometry (XRD) were used to assess the morphology, optical properties, and crystallinity of the films. Embedding AgNPs in the Lg-TDI films increased the thermal stability and the residual ash during thermal analysis, and the presence of powder diffraction peaks at 2θ = 20, 38, 44, 55, and 58⁰ in the films correspond to lignin and silver crystal planes (111). SEM micrographs of the films revealed the presence of AgNPs in the TDI matrix with variable sizes of between 50 to 250 nm. The doped films had a UV radiation cut-off at 400 nm as compared to that of undoped films, but they did not exhibit significant antimicrobial activity against selected microorganisms.

Essential characteristics improvement of metallic nanoparticles loaded carbohydrate polymeric films - A review

Petroleum-based films have contributed immensely to various environmental issues. Developing green-based films from carbohydrate polymers is crucial for addressing the harms encountered. However, some limitations exist on their property, processibility, and applicability that prohibit their processing for further developments. This review discusses the potential carbohydrate polymers and their sources, film preparation methods, such as solvent-casting, tape-casting, extrusion, and thermo-mechanical compressions for green-based films using various biological polymers with their merits and demerits. Research outcomes revealed that the essential characteristics improvement achieved by incorporating different metallic nanoparticles has significantly reformed the properties of biofilms, including crystallization, mechanical stability, thermal stability, barrier function, and antimicrobial activity. The property-enhanced bio-based films made with nanoparticles are potentially interested in replacing fossil-based films in various areas, including food-packaging applications. The review paves a new way for the commercial use of numerous carbohydrate polymers to help maintain a sustainable green environment.

Stimuli-Responsive and Antibacterial Cellulose-Chitosan Hydrogels Containing Polydiacetylene Nanosheets

Herein, we report a stimuli-responsive hydrogel with inhibitory activity against Escherichia coli prepared by chemical crosslinking of carboxymethyl chitosan (CMCs) and hydroxyethyl cellulose (HEC). The hydrogels were prepared by esterification of chitosan (Cs) with monochloroacetic acid to produce CMCs which were then chemically crosslinked to HEC using citric acid as the crosslinking agent. To impart a stimuli responsiveness property to the hydrogels, polydiacetylene-zinc oxide (PDA-ZnO) nanosheets were synthesized in situ during the crosslinking reaction followed by photopolymerization of the resultant composite. To achieve this, ZnO was anchored on carboxylic groups in 10,12-pentacosadiynoic acid (PCDA) layers to restrict the movement of the alkyl portion of PCDA during crosslinking CMCs and HEC hydrogels. This was followed by irradiating the composite with UV radiation to photopolymerize the PCDA to PDA within the hydrogel matrix so as to impart thermal and pH responsiveness to the hydrogel. From the results obtained, the prepared hydrogel had a pH-dependent swelling capacity as it absorbed more water in acidic media as compared to basic media. The incorporation of PDA-ZnO resulted in a thermochromic composite responsive to pH evidenced by a visible colour transition from pale purple to pale pink. Upon swelling, PDA-ZnO-CMCs-HEC hydrogels had significant inhibitory activity against E. coli attributed to the slow release of the ZnO nanoparticles as compared to CMCs-HEC hydrogels. In conclusion, the developed hydrogel was found to have stimuli-responsive properties and inhibitory activity against E. coli attributed to zinc nanoparticles.