Preparation and characterization of gelatin-based nanocomposite containing chitosan nanofiber and ZnO nanoparticles

Multifunctional palygorskite@ZnO nanorods enhance simultaneously mechanical strength and antibacterial properties of chitosan-based film

A general and effective strategy was developed for improving simultaneously the mechanical strength and antibacterial performance of biopolymer-based films. The well-dispersed zinc oxide (ZnO) nanoparticles were in-situ loaded on non-toxic natural palygorskite (PAL) nanorod to form an antibacterial PAL@ZnO composite nanorod, which can be embedded into chitosan/gelatin (CS/GL) film to produce the composite films with noticeably enhanced mechanical properties and antibacterial activity against S. aureus and E. coli bacteria (inhibition zones are 21.82 ± 0.95 mm and 16.36 ± 1.64 mm, respectively). The toughness of films enhances to 35.13 ± 0.95 MPa and the moisture uptake decreases to 23.74 ± 0.02% after embedding 3% and 9% of PAL@ZnO, respectively. In addition, incorporating PAL@ZnO nanorods also significantly enhanced the water resistance, and thermal stability of film. This work provides an alternative way for the development of antibacterial films with potential applications in many fields such as food packing.

Design and characterization of keratin/PVA-PLA nanofibers containing hybrids of nanofibrillated chitosan/ZnO nanoparticles

In this paper, designing electrospun composite nanofibers containing poly (lactic acid) (PLA) and keratin/poly (vinyl alcohol) (K/PVA) as the major components and natural nanofibrillated chitosan (CHNF)/ZnO nanoparticles (ZnONPs) (CSZ) combination as the nanofiller ingredient, has been investigated. PLA solution from one syringe and K/PVA from another one with incorporation of CHNF (CS), CSZ (2:1), (1:1) and (1:2) were electrospun and produced nanofibers were formed on the rotating collector. Addition of CHNF and ZnONPs amounts in CSZ combination resulted in reduction of the diameter of nanofibers. The highest hydrophilicity was reported for K/PVA/CS-PLA/CS sample with the contact angle of about 43 ± 3°. AFM results for K/PVA-PLA, K/PVA/CS-PLA/CS and K/PVA/CSZ(2:1)-PLA/CSZ(2:1), K/PVA/CSZ(1:2)-PLA/CSZ(1:2) samples indicated that the surface roughness factor for these nanofibers was about 708, 277, 378 and 658 nm, respectively. DSC analysis for K/PVA/CSZ(1:2)-PLA/CSZ(1:2) structure exhibited that the peaks related to the melting points of PLA and PVA shifted to higher temperatures. Overally, K/PVA/CSZ(2:1)-PLA/CSZ(2:1) nanofiber with diameter of 352.50 ± 31 nm, contact angle of 48 ± 3°, tensile strength of 0.96 ± 0.18 MPa is suggested as a proper wound healing scaffold that has highest antibacterial as well as potential to increase cell proliferation.

The regulating effect of trace elements Si, Zn and Sr on mineralization of gelatin-hydroxyapatite electrospun fiber

Biomineralization approaches have been increasingly adopted to synthesizing advanced materials with superior properties. Nevertheless, the potential influence of inorganic trace elements on the mineralization process of collagen has been rarely reported, despite of the significant progress achieved on exploiting the critical roles of organic polymers in regulating the collagen mineralization. To this aim, the potential roles of Si, Zn and Sr in regulating the mineralization of gelatin-hydroxyapatite (HA) composite fibers have been examined in this study. The results indicated that the incorporation of trace elements not only promoted the biomineralization of gelatin, but also led to drastic change in the mineralization behavior. In particular, the gelatin-SiHA sample showed uniform mineralization predominantly inside the fibers, with nucleation and growth directions along the c-axis of the gelatin fibers. On the contrary, the gelatin-HA sample showed nucleation outside the fibers and spherical mineral crystals on top of fibers, typical structure for heterogeneous nucleation. As the mineralization process proceeded, the gelatin-ZnHA and gelatin-SrHA samples evolved into having similar structure as the gelatin-SiHA sample, despite of showing totally different mineralization behaviors at early time. Overall, the incorporation of trace elements seemed to lower the nucleation barriers, led to a more homogeneous mineralization mode within the fiber region and formation of mineralized structures closer to those in natural bone. Moreover, mineralized samples with trace elements demonstrated improved adhesion and cytoskeleton organization of osteoblastic cells. Such finding would provide important insight for understanding the mineralization process and the optimal design of advanced biological materials.

Prospects of Polymeric Nanofibers Loaded with Essential Oils for Biomedical and Food-Packaging Applications

Essential oils prevent superbug formation, which is mainly caused by the continuous use of synthetic drugs. This is a significant threat to health, the environment, and food safety. Plant extracts in the form of essential oils are good enough to destroy pests and fight bacterial infections in animals and humans. In this review article, different essential oils containing polymeric nanofibers fabricated by electrospinning are reviewed. These nanofibers containing essential oils have shown applications in biomedical applications and as food-packaging materials. This approach of delivering essential oils in nanoformulations has attracted considerable attention in the scientific community due to its low price, a considerable ratio of surface area to volume, versatility, and high yield. It is observed that the resulting nanofibers possess antimicrobial, anti-inflammatory, and antioxidant properties. Therefore, they can reduce the use of toxic synthetic drugs that are utilized in the cosmetics, medicine, and food industries. These nanofibers increase barrier properties against light, oxygen, and heat, thereby protecting and preserving the food from oxidative damage. Moreover, the nanofibers discussed are introduced with naturally derived chemical compounds in a controlled manner, which simultaneously prevents their degradation. The nanofibers loaded with different essential oils demonstrate an ability to increase the shelf-life of various food products while using them as active packaging materials.

Poly Lactic Acid (PLA) Nanocomposites: Effect of Inorganic Nanoparticles Reinforcement on Its Performance and Food Packaging Applications

Poly lactic acid (PLA) is a compostable, as well as recyclable, sustainable, versatile and environmentally friendly alternative, because the monomer of PLA-lactide (LA) is extracted from natural sources. PLA's techno-functional properties are fairly similar to fossil-based polymers; however, in pristine state, its brittleness and delicacy during processing pose challenges to its potential exploitation in diverse food packaging applications. PLA is, therefore, re-engineered to improve its thermal, rheological, barrier and mechanical properties through nanoparticle (NP) reinforcement. This review summarises the studies on PLA-based nanocomposites (PLA NCs) developed by reinforcing inorganic metal/metallic oxide, graphite and silica-based nanoparticles (NPs) that exhibit remarkable improvement in terms of storage modulus, tensile strength, crystallinity, glass transition temperature (Tg) value, antimicrobial property and a decrease in water vapour and oxygen permeability when compared with the pristine PLA films. This review has also discussed the regulations around the use of metal oxide-based NPs in food packaging, PLA NC biodegradability and their applications in food systems. The industrial acceptance of NCs shows highly promising perspectives for the replacement of traditional petrochemical-based polymers currently being used for food packaging.

Cellulose Nanofiber-Based Nanocomposite Films Reinforced with Zinc Oxide Nanorods and Grapefruit Seed Extract

Here, we report the fabrication and characterization of cellulose nanofiber (CNF)-based nanocomposite films reinforced with zinc oxide nanorods (ZnOs) and grapefruit seed extract (GSE). The CNF is isolated via a combination of chemical and physical methods, and the ZnO is prepared using a simple precipitation method. The ZnO and GSE are used as functional nanofillers to produce a CNF/ZnO/GSE film. Physical (morphology, chemical interactions, optical, mechanical, thermal stability, etc.) and functional (antimicrobial and antioxidant activities) film properties are tested. The incorporation of ZnO and GSE does not impact the crystalline structure, mechanical properties, or thermal stability of the CNF film. Nanocomposite films are highly transparent with improved ultraviolet blocking and vapor barrier properties. Moreover, the films exhibit effective antimicrobial and antioxidant actions. CNF/ZnO/GSE nanocomposite films with better quality and superior functional properties have many possibilities for active food packaging use.

Combinatorial therapy of chitosan hydrogel-based zinc oxide nanocomposite attenuates the virulence of Streptococcus mutans

Background

Biofilm formation is an important causative factor in the expansion of the carious lesions in the enamel. Hence, new approaches to efficient antibacterial agents are highly demanded. This study was conducted to evaluate the antimicrobial-biofilm activity of chitosan hydrogel (CS gel), zinc oxide/ zeolite nanocomposite (ZnONC) either separately or combined together [ZnONC / CS gel (ZnONC-CS)] against Streptococcus mutans biofilm.

Results

MTT assay demonstrated that the ZnONC-CS exhibits a non-cytotoxic effect (> 90% cell viability) toward human gingival fibroblast cells at different dosages (78.1–625 μg/mL) within 72 h. In comparison with CS gel and ZnONC, ZnONC-CS was superior at biofilm formation and metabolic activity reduction by 33 and 45%, respectively; (P < 0.05). The field emission scanning electron microscopy micrographs of the biofilms grown on the enamel slabs were largely in concordance with the quantitative biofilm assay results. Consistent with the reducing effect of ZnONC-CS on biofilm formation, the expression levels of gtfB, gtfC, and ftf significantly decreased.

Conclusions

Taken together, excellent compatibility coupled with an enhanced antimicrobial effect against S. mutans biofilm has equipped ZnONC-CS as a promising candidate for dental biofilm control.

Incorporation of ZnO Nanoparticles into Soy Protein-Based Bioplastics to Improve Their Functional Properties

The union of nanoscience (nanofertilization) with controlled release bioplastic systems could be a key factor for the improvement of fertilization in horticulture, avoiding excessive contamination and reducing the price of the products found in the current market. In this context, the objective of this work was to incorporate ZnO nanoparticles in soy protein-based bioplastic processed using injection moulding. Thus, the concentration of ZnO nanoparticles (0 wt%, 1.0 wt%, 2.0 wt%, 4.5 wt%) and mould temperature (70 °C, 90 °C and 110 °C) were evaluated through a mechanical (flexural and tensile properties), morphological (microstructure and nanoparticle distribution) and functional (water uptake capacity, micronutrient release and biodegradability) characterization. The results indicate that these parameters play an important role in the final characteristics of the bioplastics, being able to modify them. Ultimately, this study increases the versatility and functionality of the use of bioplastics and nanofertilization in horticulture, helping to prevent the greatest environmental impact caused.

A journey to the world of fascinating ZnO nanocomposites made of chitosan, starch, cellulose, and other biopolymers: Progress in recent achievements in eco-friendly food packaging, biomedical, and water remediation technologies

Green chemistry or in other words "green world" is referred to a sustainable environment using biocompatible, biodegradable, renewable, economical, and simple materials, and methods. Without any exaggeration, the exceptional chemical and physical properties of ZnO bionanocomposites beside various utilizations, make it vital materials in research and green chemistry field. Biocompatible ZnO nanoparticles with fascinating antimicrobial, physicochemical, as well as photocatalytic performance could be applied as a prominent candidate to reinforce diverse biopolymer matrixes, for instance, chitosan, starch, cellulose, gelatin, alginate, poly(hydroxyalkanoates), carrageenan, and so on. With a combination of advantageous properties of these materials, they could be illustrated specific utilizations in different areas. In this regard, the following context focuses on highlighting the recent achievements of this category of material on three important and widely used scopes: eco-friendly food packaging, biomedical specially wound dressings, and water remediation technologies.

Fabrication of Gelatin-ZnO Nanofibers for Antibacterial Applications

In this study, GNF@ZnO composites (gelatin nanofibers (GNF) with zinc oxide (ZnO) nanoparticles (NPs)) as a novel antibacterial agent were obtained using a wet chemistry approach. The physicochemical characterization of ZnO nanoparticles (NPs) and GNF@ZnO composites, as well as the evaluation of their antibacterial activity toward Gram-positive (Staphyloccocus aureus and Bacillus pumilus) and Gram-negative (Escherichia coli and Pseudomonas fluorescens) bacteria were performed. ZnO NPs were synthesized using a facile sol-gel approach. Gelatin nanofibers (GNF) were obtained by an electrospinning technique. GNF@ZnO composites were obtained by adding previously produced GNF into a Zn2+ methanol solution during ZnO NPs synthesis. Crystal structure, phase, and elemental compositions, morphology, as well as photoluminescent properties of pristine ZnO NPs, pristine GNF, and GNF@ZnO composites were characterized using powder X-ray diffraction (XRD), FTIR analysis, transmission and scanning electron microscopies (TEM/SEM), and photoluminescence spectroscopy. SEM, EDX, as well as FTIR analyses, confirmed the adsorption of ZnO NPs on the GNF surface. The pristine ZnO NPs were highly crystalline and monodispersed with a size of approximately 7 nm and had a high surface area (83 m2/g). The thickness of the pristine gelatin nanofiber was around 1 µm. The antibacterial properties of GNF@ZnO composites were investigated by a disk diffusion assay on agar plates. Results show that both pristine ZnO NPs and their GNF-based composites have the strongest antibacterial properties against Pseudomonas fluorescence and Staphylococcus aureus, with the zone of inhibition above 10 mm. Right behind them is Escherichia coli with slightly less inhibition of bacterial growth. These properties of GNF@ZnO composites suggest their suitability for a range of antimicrobial uses, such as in the food industry or in biomedical applications.

Gelatin: sources, preparation and application in food and biomedicine

Gelatin is a proteinaceous substance composed of all the essential amino acids (except tryptophan) and derived from collagen using a hydrolysis technique. Hydrogels and modified composites based on gelatin are widely used in the food industry, biomedicine, pharmaceutical industry and food packaging materials due to their biocompatibility, biodegradability, nonimmunogenicity and ability to stimulate cell adhesion and proliferation. Gelatin can absorb 5-10 times its weight of water and is the main ingredient of hard and soft capsules in pharmaceutical industry. It melts above 30°C and easily releases biologically active compounds, nutrients and drugs in human gastrointestinal tract. In addition, gelatin contains arginine-glycine-asparagine RGD-sequences in the polymer structure and contributes to various functions such as antioxidant, anti-hypertensive, anti-microbial, tissue regeneration, wound healing, enhances bone formation and anti-cancer therapy. This article reports a brief overview of gelatin sources, gelatin preparation processes and its physico-chemical properties, as well as advances in the preparation of gelatin-based composite materials and hydrogels for tissue engineering, drug delivery, wound dressings, active packaging using various cross-linking techniques.

Biodegradable Hybrid Nanocomposite of Chitosan/Gelatin and Green Synthesized Zinc Oxide Nanoparticles for Food Packaging

In the context of emerging global concerns with synthetic plastic packaging, alternative natural biodegradable packaging materials are gaining increasing attention for food packaging applications. In this study, chitosan and gelatin nanocomposite hybrid films containing green synthesized zinc oxide (ZnO) nanoparticles (NPs) were developed and microstructural properties were studied. Antimicrobial activity of the developed films was evaluated using both Gram negative (Escherichia coli) and Gram positive bacteria (Staphylococcus aureus). Green synthesis protocol was used for the precipitation of ZnO NPs using fruit extract of Cassia fistula. The as-synthesized polyhedral ZnO NPs were in the range of 20–40 nm (average size ≈29 nm). Reinforcement with ZnO NPs in the hybrid films lead to improved thermal stability, elongation-at-break (EAB), and compactness properties. The developed films with 2% and 4% ZnO NPs showed a smooth, compact, and heterogeneous surface morphology compared to the control (chitosan-gelatin hybrid) films. Disc diffusion assays showed that the nanocomposite film had significant antimicrobial activity against E. coli. The developed hybrid nanocomposite films have potential to be developed as biodegradable alternative for postharvest packaging of fresh fruits and vegetables.

Silver sulfadiazine-loaded electrospun ethyl cellulose/polylactic acid/collagen nanofibrous mats with antibacterial properties for wound healing

Recently, the electrospun nanofiber mats with appropriate properties for applications in the biomedical area has been more considered. In this regard, we successfully fabricated a novel antibacterial nanofiber mat (ethyl cellulose/poly lactic acid/collagen) (EC/PLA/collagen) incorporated with silver sulfadiazine (AgSD) and then analyzed with the required tests. AgSD was loaded in the developed mats with different contents (0.25%, 0.5% and 0.75%) and then electrospun to prepare nanofiber mats. To check the chemical structure of the developed mat, Fourier transform infrared spectroscopy (FTIR) was assessed. Surface morphological studies were performed by Scanning Electron Microscopy (SEM), which displayed uniform nanofiber mats without any bead formation. When the hydrophilicity was enhanced by decreasing the blending ratios of EC/PLA, the thermal stability of the nanofibers was reduced. The water contact angle (WCA) of NFs enhanced by decreasing the blending ratios of EC/PLA. The antibacterial properties showed the inhibition activity against Bacillus (9.71 ± 1.15 mm) and E. coli (12.46 ± 1.31 mm) bacteria. Besides, nanofibers have improved cell proliferation and adhesion with any cytotoxic effect on NIH 3T3 fibroblast cells. According these results, it seems that the developed mats would be effective scaffold for application in wound dressings.

Chitosan based ZnO nanoparticles loaded gallic-acid films for active food packaging

Chitosan (Ch) and zinc oxide nanoparticles loaded gallic-acid films, (Ch-ZnO@gal) have been prepared aiming for their exploitation as environmentally benign food packaging material. The chitosan films with varying quantities of zinc oxide nanoparticles loaded gallic-acid (ZnO@gal) content were synthesized in order to evaluate the effect of ZnO@gal on their optimum mechanical and biological potential. The characteristic results have shown that the incorporation of ZnO@gal into chitosan films remarkably enhanced the desired mechanical property of the chitosan films. Other noticeable physical properties such as oxygen and water vapor permeability (WVP), swelling, water solubility and UV-vis light transmittance have also been found to improve positively. SEM analysis of the films indicates a good material compatibility between chitosan and ZnO@gal matrices. Ch-ZnO@gal films possess significant antibacterial potential and strong antioxidant behavior compared to pristine chitosan. The overall results suggested that the prepared biocomposite chitosan films may be considered for active food packaging applications.

Facile synthesis of Ag nanoparticles-loaded chitosan antibacterial nanocomposite and its application in polypropylene

The development of environmental-friendly antibacterial agents with high efficiency and low cost has become the focus of attention. In this work, the Ag nanoparticles doped into chitosan (Ag NPs-CS) were synthesized by a green and facile method, and the samples were characterized by UV-Vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The antibacterial tests implied that Ag NPs-CS obtained from glucose (G-Ag NPs-CS) exhibited the excellent antimicrobial activities against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) microbes. Besides, the utilization of antibacterial agents in polymeric materials plays an significant role in healthy living. The aim is to impart the antibacterial properties and maintain/improve the mechanical properties. Therefore, the G-Ag NPs-CS with 5 wt% Ag was chosen as the optimal additive to endow polypropylene with antimicrobial activity via a simple melt blending method. The results demonstrated that the suppression of bacteria proliferation was enhanced with increasing the amount of antibacterial agent, and the microorganisms were almost killed when the content reached to 8 wt%. Meanwhile, the considerable improvement in elastic modulus and impact strength along with a slight decrease of elongation at break provided the evidence that Ag NPs-CS/PP nanocomposites were the promising candidate for practical applications.

Polysaccharide and Protein Films with Antimicrobial/Antioxidant Activity in the Food Industry: A Review

From an economic point of view, the spoilage of food products during processing and distribution has a negative impact on the food industry. Lipid oxidation and deterioration caused by the growth of microorganisms are the main problems during storage of food products. In order to reduce losses and extend the shelf-life of food products, the food industry has designed active packaging as an alternative to the traditional type. In the review, the benefits of active packaging materials containing biopolymers (polysaccharides and/or proteins) and active compounds (plant extracts, essential oils, nanofillers, etc.) are highlighted. The antioxidant and antimicrobial activity of this type of film has also been highlighted. In addition, the impact of active packaging on the quality and durability of food products during storage has been described.

Development and characterization of carboxymethyl cellulose based probiotic nanocomposite film containing cellulose nanofiber and inulin for chicken fillet shelf life extension

Bioactive packaging is an alternative new technology for preserving the quality and safety of food products with providing health benefits. In this way, the Lactobacillus plantarum, cellulose nanofiber (CNF) and inulin incorporated carboxymethyl cellulose (CMC) based probiotic nanocomposite film was prepared. The fabricated film samples were characterized by FTIR, FE-SEM, XRD and DSC analyses, that the obtained results indicated the good compatibility between CMC, CNF, and inulin. As a result, the CMC-based probiotic films containing CNF and inulin exhibited satisfactory water barrier and mechanical properties. Additionally, the viability of probiotic bacteria in the CMC-based films was significantly (p < 0.05) increased (36%) by addition of inulin as a prebiotic ingredient during storage time. Probiotic film sample showed antibacterial activity against nine pathogens and also extended the chicken fillet shelf life when wrapped on the meat. In conclusion, the application of CNF and inulin incorporated CMC-based probiotic nanocomposite film as a bioactive food packaging system opens up a new horizon for improving the shelf life of food products and providing the health benefits for consumers.

Multifunctional betanin nanoliposomes-incorporated gelatin/chitosan nanofiber/ZnO nanoparticles nanocomposite film for fresh beef preservation

The objective of this study was to fabricate betanin nanoliposomes incorporated gelatin/chitosan nanofiber/ZnO nanoparticles bionanocomposite film (G/CH NF/ZnO NPs/B NLPs) and investigate its effects on the preservation of fresh beef. The scanning electron microscopy image of nanocomposite film displayed a good inter-connective porous morphology. Fourier transform infrared and X-ray diffraction analysis confirmed the formation of new hydrogen bonds and enhanced crystallinity through the addition of CH NF, ZnO NPs, and B NLPs. The G/CH NF/ZnO NPs/B NLPs film exhibited satisfactory mechanical properties and high surface hydrophobicity (water contact angle = 92.49 ± 3.71°). The incorporation of ZnO NPs and B NLPs in the nanocomposite film provided high antibacterial activity and DPPH inhibition activity (53.02 ± 3.26%). The growth of inoculated bacteria, lipid oxidation, and the changes in the pH and color quality of the beef samples were controlled by packaging with the fabricated film. In conclusion, the G/CH NF/ZnO NPs/B NLPs nanocomposite has a high potential for meat preservation.

Development of emulsion films based on bovine gelatin-nano chitin-nano ZnO for cake packaging

This research extends the effect of packaging with bovine gelatin, gelatin nanocomposite (GN), gelatin emulsion (GE), two layers gelatin nanocomposite and gelatin emulsion (GNE), and polyethylene (PE) films on sponge cake properties during storage at 25°C and 55 ± 2% RH. In this regard, water vapor permeability (WVP) and oxygen permeability (OP) of films were compared. Then, moisture content, acidity, peroxide value, texture profile, organoleptic properties, and fungal growth of packed cakes were determined. Results showed that the addition of nanoparticles could reduce the water vapor permeability from 9.680 ± 0.460 × 10-10 (g m/sm-2Pa-1) for net gelatin film to 6.067 ± 0.337 × 10-10 (g m/sm-2 Pa-1) for gelatin nanocomposite film and oxygen permeability from 39.262 (cm3μm/ m2dkPa) for net gelatin film to 29.645 (cm3μm m-2 dkPa) for nanocomposite film. However, GNE films had the highest barrier properties. Results of acidity and peroxide values of cakes admitted the sufficiency of GNE films for sponge cakes packaging. In addition, antifungal properties of nanoparticles led to less fungal growth on cakes packed in GNE films. The cakes packed in GNE films own more organoleptic and texture acceptability than the ones packed in other films. Generally, according to the results GNE films are acceptable for packaging of sponge cakes which contain no preservative because this packaging can prevent fungal growth for a longer time and even more can maintain the cake chemical and organoleptic quality.

Reinforced ZnONPs/ rosemary essential oil-incorporated zein electrospun nanofibers by κ-carrageenan

In this study, the reinforced ZnONPs/ rosemary essential oil-incorporated zein nanofibers with κ-carrageenan (Z/KC/ZnONPs/RE) were fabricated using the electrospinning technique for application in food packaging. The SEM images of Z/KC/ZnONPs/RE nanofiber displayed bead-free homogeneous morphology that its average fiber diameter was 672 ± 240 nm. The formation of new hydrogen bonds by addition of κ-carrageenan and active agents was approved by FT-IR and DSC structural conformations. The Z/KC/ZnONPs/RE nanofiber exhibited satisfactory thermal and mechanical properties, as well as high surface hydrophobicity. In addition, the Z/KC/ZnONPs/RE sample showed inhibition activity against S. aureus (18.5 ± 1.9 mm) and E. coli (14.7 ± 1.5 mm) bacteria. The DPPH scavenging activity of Z/KC/ZnONPs/RE nanofiber was 54.5 ± 3.6 %. Additionally, the fabricated nanofibers showed no cell cytotoxicity, indicating their good biocompatibility. Thus, we believe that the fabricated Z/KC/ZnONPs/RE electrospun nanofiber is a potential candidate for using as an active layer in food packaging system.

Poisonous Caterpillar-Inspired Chitosan Nanofiber Enabling Dual Photothermal and Photodynamic Tumor Ablation

As caterpillars detect the presence of predators and secrete poison, herein, we show an innovative and highly effective cancer therapeutic system using biocompatible chitosan nanofiber (CNf) installed with a pH-responsive motif that senses tumor extracellular pH, pH_e, prior to delivering dual-modal light-activatable materials for tumor reduction. The filamentous nanostructure of CNf is dynamic during cell interaction and durable in blood circulation. Due to its amine group, CNf uptakes a large amount of photothermal gold nanoparticles (AuNPs, >25 wt %) and photodynamic chlorin e6 (Ce6, >5 wt %). As the innovative CNf approaches tumors, cationic CNf effectively discharges AuNPs connected to the pH-responsive motif via electrostatic repulsion and selectively binds to tumor cells that are generally anionic, via the electrostatic attraction accompanied by CNf. We demonstrated via these actions that the endocytosed Ce6 (on CNf) and AuNPs (free from CNf) significantly elicited tumor cell death under light irradiation. As a result, the synergistic interplay of thermogenesis and photodynamic action was observed to switch on at the pH_e, resulting in a striking reduction in tumor formation and growth rate upon light exposure.