Antimicrobial pullulan derivative prepared by grafting with 3-aminopropyltrimethoxysilane: Characterization and ability to form transparent films

Berberine encapsulated phenylboronic acid-conjugated pullulan nanoparticles: Synthesis, characterization and anticancer activity validated in A431 skin cancer cells and 3D spheroids

Polysaccharide-based drug delivery systems are in high demand due to their biocompatibility, non-toxicity, and low-cost. In this study, sialic acid receptor targeted 4-carboxy phenylboronic acid modified pullulan-stearic acid conjugate (4-cPBA-PUL-SA) was synthesized and characterized for the delivery of Berberine (BBR). BBR-loaded 4-cPBA-PUL-SA nanoparticles (BPPNPs) were monodispersed (PDI: 0.238 ± 0.07), with an average hydrodynamic particle size of 191.6 nm and 73.6 % encapsulation efficiency. BPPNPs showed controlled BBR release and excellent colloidal stability, indicating their potential for drug delivery application. The cytotoxicity results indicated that BPPNPs exhibited dose and time-dependent cytotoxicity against human epidermoid carcinoma cells (A431) as well as 3D spheroids. Targeted BPPNPs demonstrated significantly higher anticancer activity compared to BBR and non-targeted BPNPs. The IC50 values for BPPNPs (2.29 μg/ml) were significantly lower than BPNPs (4.13 μg/ml) and BBR (19.61 μg/ml), indicating its potential for skin cancer treatment. Furthermore, CSLM images of A431 cells and 3D spheroids demonstrated that BPPNPs have higher cellular uptake and induced apoptosis compared to free BBR and BPNPs. In conclusion, BPPNPs demonstrate promising potential as an effective drug delivery system for skin cancer therapy.

Exploring the potential of pullulan-based films and coatings for effective food preservation: A comprehensive analysis of properties, activation strategies and applications

Pullulan is naturally occurring polysaccharide exhibited potential applications for food preservation has gained increasing attention over the last half-century. Recent studies focused on efficient preservation and targeted inhibition using active composite ingredients and advanced technologies. This has led to the emergence of pullulan-based biofilm preservation. This review extensively studied the characteristics of pullulan-based films and coatings, including their mechanical strength, water vapor permeability, thermal stability, and potential as a microbial agent. Furthermore, the distinct characteristics of pullulan, production methods, and activation strategies, such as pullulan derivatization, various compounded ingredients (plant extracts, microorganisms, and animal additives), and other technologies (e.g., ultrasound), are thoroughly studied for the functional property enhancement of pullulan-based films and coatings, ensuring optimal preservation conditions for diverse food products. Additionally, we explore hypotheses that further illuminate pullulan's potential as an eco-friendly bioactive material for food packaging applications. In addition, this review evaluates various methods to improve the efficiency of the film-forming mechanism, such as improving the direct coating process, bioactive packaging films, and implementing layer-by-layer coatings. Finally, current analyses put forward suggestions for future advancement in pullulan-based bioactive films, with the aim of expanding their range of potential applications.

Arginine-carboxylated pullulan, a potential antibacterial material for food packaging

Pullulan possesses excellent film-forming properties and oxygen isolation capabilities. However, it exhibits limited antibacterial properties and poor water resistance, thereby hindering its application in the field of food preservation. In this study, we synthesized D-arginine-succinic anhydride-pullulan (Arg-SA-Pul) by carboxylating pullulan and subsequently grafting it with D-arginine. The antimicrobial test demonstrated that Arg-SA-Pul exhibited comparable antibacterial activity against Escherichia coli and Staphylococcus aureus. Using Arg-SA-Pul as the primary material and glycerol as the plasticizer, we fabricated an antibacterial film via the tape casting method. The film's light transmittance, water solubility, and water vapor permeability were evaluated. Compared to the natural pullulan film, the Arg-SA-Pul film exhibited lower vapor permeability. Additionally, we conducted preservation tests on cherries by coating them with the Arg-SA-Pul film. The results demonstrated that the Arg-SA-Pul film exhibited a significant preservation effect on cherries and effectively delayed their ripening and senescence. In the future, the Arg-SA-Pul film could be employed as a bacteriostatic preservation material to extend the shelf life of fruits.

Switchable adhesive films of pullulan loaded with a deep eutectic solvent-curcumin formulation for the photodynamic treatment of drug-resistant skin infections

Antimicrobial photodynamic therapy (aPDT) is a potent tool to surpass the global rise of antimicrobial resistance; still, the effective topical administration of photosensitizers remains a challenge. Biopolymer-based adhesive films can safely extend the residence time of photosensitizers. However, their wide application is narrowed by their limited water absorption capacity and gel strength. In this study, pullulan-based films with a switchable character (from a solid film to an adhesive hydrogel) were developed. This was accomplished by the incorporation of a betaine-based deep eutectic solvent (DES) containing curcumin (4.4 μg.cm-2) into the pullulan films, which tuned the films' skin moisture absorption ability, and therefore they switch into an adhesive hydrogel capable of delivering the photosensitizer. The obtained transparent films presented higher extensibility (elongation at break up to 338.2%) than the pullulan counterparts (6.08%), when stored at 54% of relative humidity, and the corresponding hydrogels a 4-fold higher adhesiveness than commercial hydrogels. These non-cytotoxic adhesives allowed the inactivation (∼5 log reduction), down to the detection limit of the method, of multiresistant strains of Staphylococcus aureus in ex vivo skin samples. Overall, these materials are promising for aPDT in the treatment of resistant skin infections, while being easily removed from the skin.

The effect of silica-magnetite nanoparticles on the ecotoxicity of the antibiotic ciprofloxacin

The increase in the production and application of engineered nanomaterials, including nanoparticles (NPs), leads to their discharge into the environment, where they can interact with coexisting antibiotics from wastewater, causing a complicated joint effect on organisms that need to be studied. Herein, a typical engineered nanomaterial, silica-magnetite NPs modified with tetraethoxysilane and 3-aminopropyltriethoxysilane (MTA-NPs, 1-2 g/L), and common antibiotic ciprofloxacin (CIP, 0-5 mg/L) were selected as the analytes. Their joint toxicity to a model of ciliates infusoria, Paramecium caudatum was specifically investigated. The impact of CIP, MTA-NPs, and humic acids (HA) was tracked for 24 h, individually and collectively, on the mortality of infusoria. The addition of MTA-NPs and HA at the studied concentrations leads to 40% mortality of organisms. The combined presence of the MTA-NPs at a concentration of 1.5-2 mg/L and HA at a concentration of 20-45 mg/L has a multiplier effect and allows to reduce the mortality rate of ciliates > 30% due to the enhanced removal of CIP. That finding demonstrated a clearly detoxifying role of dissolved organic matter (here, humic substances) in case of complex water pollution where pharmaceuticals and nanomaterials are presented.

Nanofibrous scaffolds based on bacterial cellulose crosslinked with oxidized sucrose

In this work, oxidized sucrose (OS), which is a safe bio-based and non-toxic polyaldehyde, was used as a crosslinker in defibrillated bacterial cellulose (BC) sponges obtained by freeze-drying. For mimicking the proteins' crosslinking, BC was first modified with an aminosilane to partially replace the OH groups on the BC surface with more reactive amino groups. Further, the aminosilane-grafted bacterial cellulose (BCA) was crosslinked with OS in different concentrations and thermally cured. Functionalized bacterial celluloses showed a good thermal stability, comparable to that of unmodified cellulose and much improved mechanical properties. A threefold increase in the compression strength was obtained for the BCA scaffold after crosslinking and curing. This was correlated with the uniform pore structure emphasized by the micro-CT and SEM analyses. The OS-crosslinked BCA scaffolds were not cytotoxic and showed a porosity of around 80 %, which was almost 100 % open porosity. This study shows that the crosslinking of aminated BC scaffolds with OS allows the obtaining of 3D cellulose structures with good mechanical properties and high porosity, suitable for soft tissue engineering. The results recommend this new method as an innovative approach to obtaining biomaterial scaffolds that mimic the natural extracellular matrix.

Downstream processing and structural confirmation of pullulan - A comprehensive review

Pullulan is a microbial polymer, commercially produced from Aureobasidium pullulans. Downstream processing of pullulan involves a multi-stage process which should be efficient, safe and reproducible. In liquid-liquid separations, firstly cell free extract is separated. Cell biomass can be separated after fermentation either by centrifugation or filtration. Due to practically insolubility of pullulan in organic solvents, ethanol and isopropanol are the most commonly used organic solvents for its recovery. Pullulan can also be purified by chromatographic techniques, but these are not cost effective for the purification of pullulan. Efficient aqueous two-phase system can be used for the purification of pullulan. The current review describes the methods and perspectives used for solid-liquid separation, liquid-liquid separations and finishing steps for the recovery of pullulan. Techniques used to determine the structural attributes of pullulan have also been highlighted.

Green and Facile Synthesis of Pullulan-Stabilized Silver and Gold Nanoparticles for the Inhibition of Quorum Sensing

Pullulan (Pull) decorated with monodisperse Ag and Au nanoparticles (NPs) was synthesized by a simple and green method. Samples were characterized by FTIR, UV–vis, NMR, XRD, TGA, SEM, XPS, DLS, and TEM. SEM images showed highly oriented microforms reported for the first time for Pull, because of the supramolecular self-assembling behavior of Pull chains. Antimicrobial and quorum sensing (QS) inhibition activities were tested against six pathogen bacteria and reporter and biomonitor strain. Pull decorated with NPs, in particular, Ag-modified ones, outperformed pristine Pull. The cell proliferation was tested with an MTT assay. NPs-decorated Pull was studied for the first time as an inhibitory agent against bacterial signal molecules and found to be a good candidate. The promising performance of AgNPs@Pull compared to the commercial antibiotic gentamicin showed that it has great potential as a therapeutic approach to overcome the bacterial resistance that has developed against conventional antibiotics.

Antimicrobial Peptides and Macromolecules for Combating Microbial Infections: From Agents to Interfaces

Bacterial resistance caused by the overuse of antibiotics and the shelter of biofilms has evolved into a global health crisis, which drives researchers to continuously explore antimicrobial molecules and strategies to fight against drug-resistant bacteria and biofilm-associated infections. Cationic antimicrobial peptides (AMPs) are considered to be a category of potential alternative for antibiotics owing to their excellent bactericidal potency and lesser likelihood of inducing drug resistance through their distinctive antimicrobial mechanisms. In this review, the hitherto reported plentiful action modes of AMPs are systematically classified into 15 types and three categories (membrane destructive, nondestructive membrane disturbance, and intracellular targeting mechanisms). Besides natural AMPs, cationic polypeptides, synthetic polymers, and biopolymers enable to achieve tunable antimicrobial properties by optimizing their structures. Subsequently, the applications of these cationic antimicrobial agents at the biointerface as contact-active surface coatings and multifunctional wound dressings are also emphasized here. At last, we provide our perspectives on the development of clinically significant cationic antimicrobials and related challenges in the translation of these materials.

Functionalization of Aminoalkylsilane-Grafted Bacterial Nanocellulose with ZnO-NPs-Doped Pullulan Electrospun Nanofibers for Multifunctional Wound Dressing

High moisture permeability, excellent mechanical properties in a wet state, high water-holding capability, and high exudate absorption make bacterial nanocellulose (BNC) a favorable candidate for biomedical device production, especially wound dressings. The lack of antibacterial activity and healing-promoting ability are the main drawbacks that limit its wide application. Pullulan (Pul) is a nontoxic polymer that can promote wound healing. Zinc oxide nanoparticles (ZnO-NPs) are well-known as a safe antibacterial agent. In this study, aminoalkylsilane was chemically grafted on a BNC membrane (A-g-BNC) and used as a bridge to combine BNC with Pul-ZnO-NPs hybrid electrospun nanofibers. FTIR results confirmed the successful production of A-g-BNC/Pul-ZnO. The obtained dressing demonstrated blood clotting performance better than that of BNC. The dressing showed an ability to release ZnO, and its antibacterial activity was up to 5 log values higher than that of BNC. The cytotoxicity of the dressing toward L929 fibroblast cells clearly showed safety due to the proliferation of fibroblast cells. The animal test in a rat model indicated faster healing and re-epithelialization, small blood vessel formation, and collagen synthesis in the wounds covered by A-g-BNC/Pul-ZnO. The new functional dressing, fabricated with a cost-effective and easy method, not only showed excellent antibacterial activity but could also accelerate wound healing.

Curcumin-laden hyaluronic acid-co-Pullulan-based biomaterials as a potential platform to synergistically enhance the diabetic wound repair

Injectable hydrogel with multifunctional tunable properties comprising biocompatibility, anti-oxidative, anti-bacterial, and/or anti-infection are highly preferred to efficiently promote diabetic wound repair and its development remains a challenge. In this study, we report hyaluronic acid and Pullulan-based injectable hydrogel loaded with curcumin that could potentiate reepithelization, increase angiogenesis, and collagen deposition at wound microenvironment to endorse healing cascade compared to other treatment groups. The physical interaction and self-assembly of hyaluronic acid-Pullulan-grafted-pluronic F127 injectable hydrogel were confirmed using nuclear magnetic resonance (¹H NMR) and Fourier transformed infrared spectroscopy (FT-IR), and cytocompatibility was confirmed by fibroblast viability assay. The CUR-laden hyaluronic acid-Pullulan-g-F127 injectable hydrogel promptly undergoes a sol-gel transition and has proved to potentiate wound healing in a streptozotocin-induced diabetic rat model by promoting 93% of wound closure compared to other groups having 35%, 38%, and 62%. The comparative in vivo study and histological examination was conducted which demonstrated an expeditious recovery rate by significantly reducing the wound healing days i.e. 35 days in a control group, 33 days in the CUR suspension group, 21 days in unloaded injectable, and 13 days was observed in CUR loaded hydrogel group. Furthermore, we suggest that the injectable hydrogel laden with CUR showed a prompt wound healing potential by increasing the cell proliferation and serves as a drug delivery platform for sustained and targeted delivery of hydrophobic moieties.

Fabrication of hydrophobic and high-strength packaging films based on the esterification modification of galactomannan

There is an increasing interest in substituting current packaging films with biologically-derived films without compromising mechanical properties and hydrophobicity. In this work, the esterified galactomannan (E-GM) films with good hydrophobicity, excellent oxygen barrier performance and high tensile mechanical strength were synthesized using anhydride esterification method prior to film formation. The hydrophobicity, mechanical properties, barrier properties, thermal stability and ultraviolet absorption of the prepared films were determined to fully investigate the features of galactomannan-based films. The results indicated that GM films can be successfully obtained by esterification. Compared to neat GM film, E-GM-1.5 film (acetic anhydride to GM of 1.5:1) achieved the highest degree of esterification (0.05), hydrophobicity (107°) and mechanical strength (92.0 MPa). In addition, the esterified GM films had lower toxicity for macrophages cells. The prepared E-GM films may provide more opportunities for further advancement and applications in the development of food packaging from natural resources.

Pullulan based stimuli responsive and sub cellular targeted nanoplatforms for biomedical application: Synthesis, nanoformulations and toxicological perspective

With growing interest in polymers of natural origin, innumerable polysaccharides have gained attention for their biomedical application. Pullulan, one of the FDA approved nutraceuticals, possesses multiple unique properties which make them highly advantageous for biomedical applications. This present review encompasses the sources, production, properties and applications of pullulan. It highlights various pullulan based stimuli-responsive systems (temperature, pH, ultrasound, magnetic), subcellular targeted systems (mitochondria, Golgi apparatus/endoplasmic reticulum, lysosome, endosome), lipid-vesicular systems (solid-lipid nanoparticles, liposomes), polymeric nanofibres, micelles, inorganic (SPIONs, gold and silver nanoparticles), carbon-based nanoplatforms (carbon nanotubes, fullerenes, nanodiamonds) and quantum dots. This article also gives insight into different biomedical, therapeutic and diagnostic applications of pullulan viz., imaging, tumor targeting, stem cell therapy, gene therapy, vaccine delivery, cosmetic applications, protein delivery, tissue engineering, photodynamic therapy and chaperone-like activities. The review also includes the toxicological profile of pullulan which is helpful for the development of suitable delivery systems for clinical applications.

Preparation, characterization, and 3D printing verification of chitosan/halloysite nanotubes/tea polyphenol nanocomposite films

In this study, chitosan/halloysite nanotubes/tea polyphenol (CS/HNTs/TP) nanocomposite films were prepared by the solution casting method. The scanning electron microscopy (SEM) result showed that the nanocomposite film with a CS/HNTs ratio of 6:4 and a TP content of 10% (C6H4-TP10) had a relatively smooth surface and a dense internal structure. The water vapor barrier property of the nanocomposite film was improved due to the tortuous channels formed by the HNTs. However, the swelling degree and water solubility of the nanocomposite films were decreased. The nanocomposite films have a good antioxidant capacity. Antibacterial experiments showed that the C6H4-TP10 nanocomposite film had certain inhibitory effects on the growth of both E. coli and S. aureus. In addition, we used 3D printer to verify the printability of the optimal formulation of the film-forming solution. Overall, this strategy provides a simple approach to construct promising natural antioxidants and antibacterial food packaging.

Effect of heat treatment on thermal resistance, transparency and antimicrobial activity of sonicated ginger cellulose film

Transparent film with high thermal resistance and antimicrobial properties has many applications in the food packaging industry particularly packaging for reheatable food. This work investigates the effects of heat treatment on the thermal resistance, stability of transparency and antimicrobial activity of transparent cellulose film. The film from ginger nanocellulose fibers was prepared with chemicals and ultrasonication. The dried film was heated at 150 °C for 30, 60, 90, or 120 min. The unheated and sonicated film had the lowest crystallinity index and the lowest thermal properties. After heating, the film became brownish-yellow resulting from thermal oxidation. The reheated film had higher thermal resistance than unheated film. Heating led to further relaxation of cellulose network evidenced by shifting of the XRD peak positions toward lower values. The antimicrobial activity decreased due to heating. Average opacity value increases after short heating durations. It was relatively stable for further heating.

Bacterial cellulose sponges obtained with green cross-linkers for tissue engineering

Three-dimensional (3D) porous structures with controlled pore size and interconnected pores, good mechanical properties and biocompatibility are of great interest for tissue engineering. In this work we propose a new strategy to obtain highly porous 3D structures with improved properties using bacterial cellulose (BC) and eco-friendly additives and processes. Glucose, vanillin and citric acid were used as non-toxic and cheap cross-linkers and γ-aminopropyltriethoxysilane was used to partially replace the surface OH groups of cellulose with amino groups. The efficiency of grafting and cross-linking reactions was confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The morphological investigation of BC sponges revealed a multi-hierarchical organization after functionalization and cross-linking. Micro-computed tomography analysis showed 80-90% open porosity in modified BC sponges. The thermal and mechanical properties of the sponges were influenced by the cross-linker type and concentration. The strength-to-weight ratio of BC sponges cross-linked with glucose and citric acid was 150% and 120% higher compared to that of unmodified BC sponge. In vitro assays revealed that the modified BC sponges are non-cytotoxic and do not trigger an inflammatory response in macrophages. This study provides a simple and green method to obtain highly porous cellulose sponges with hierarchical design, biocompatibility and good mechanical properties.

Prospect of Polysaccharide-Based Materials as Advanced Food Packaging

The use of polysaccharide-based materials presents an eco-friendly technological solution, by reducing dependence on fossil resources while reducing a product's carbon footprint, when compared to conventional plastic packaging materials. This review discusses the potential of polysaccharides as a raw material to produce multifunctional materials for food packaging applications. The covered areas include the recent innovations and properties of the polysaccharide-based materials. Emphasis is given to hemicelluloses, marine polysaccharides, and bacterial exopolysaccharides and their potential application in the latest trends of food packaging materials, including edible coatings, intelligent films, and thermo-insulated aerogel packaging.

Polymeric Nanocomposites and Nanocoatings for Food Packaging: A Review

Special properties of the polymeric nanomaterials (nanoscale size, large surface area to mass ratio and high reactivity individualize them in food packaging materials. They can be processed in precisely engineered materials with multifunctional and bioactive activity. This review offers a general view on polymeric nanocomposites and nanocoatings including classification, preparation methods, properties and short methodology of characterization, applications, selected types of them used in food packaging field and their antimicrobial, antioxidant, biological, biocatalyst and so forth, functions.

New approach for immobilization of 3-aminopropyltrimethoxysilane and TiO2 nanoparticles into cellulose for BJ1 skin cells proliferation

In the present study, tosylcellulose (TC) was used as a key intermediate for the selective coupling with 3-aminopropyltrimethoxysilane (APTMS) affording amino-propylsilane-grafted tosylcellulose (TC-Si). Solid state ¹³C NMR and FT-IR analyses confirmed the coupling and self-condensation of APTMS along TC. The changes in the surface morphology of the functionalized cellulose were identified by SEM imaging. The thermal stability of TC-Si was significantly improved as compared to MCC and TC. A new organic/inorganic hybrid cellulosic material was fabricated by embedding TiO₂ nanoparticles into TC-Si network. The new cellulose polymers were investigated for their ability to promote the proliferation of human skin fibroblast (BJ1). The cell cytotoxicity assay showed that both TC and TC-Si possessed moderate toxicity to BJ1 cells by 17% and 23.8%, respectively at 20 μM. Meanwhile, TC-Si/TiO₂ hybrid enhanced the proliferation of BJ1 by 42%. Additionally TC-Si/TiO₂ hybrid demonstrated promising antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans.

Development of a Teat Bio-sealant and Evaluation of its Technological and Functional Properties

A teat bio-sealant was developed using Weissella cibaria, and the bio-sealant's technological and functional properties were assessed. The development included four experimental phases that were analyzed using independent experimental designs. Initially, sterilized or pasteurized Aloe vera gels were used, and the effect of heat treatment was investigated. In the second phase, the effects of time, storage temperature, and addition of cryopreservatives on the viability of the probiotic were observed. The third phase consisted of evaluating the synergistic effects of the cryopreservatives. The fourth phase involved selecting a material that would provide viscosity to the teat sealant. Technological and functional properties were measured in terms of viability of W. cibaria, and antimicrobial activity against Staphylococcus aureus and Streptococcus agalactiae was also analyzed. A mixture of milk powder and glycerol preserved this antimicrobial activity. Pullulan provided greater viscosity and maintained the technological and functional properties of the bio-sealant for 29 days. This teat bio-sealant can be used as an alternative for the prevention of bovine mastitis.

Review of Bionanocomposite Coating Films and Their Applications

The properties of a composite material depend on its constituent materials such as natural biopolymers or synthetic biodegradable polymers and inorganic or organic nanomaterials or nano-scale minerals. The significance of bio-based and synthetic polymers and their drawbacks on coating film application is currently being discussed in research papers and articles. Properties and applications vary for each novel synthetic bio-based material, and a number of such materials have been fabricated in recent years. This review provides an in-depth discussion on the properties and applications of biopolymer-based nanocomposite coating films. Recent works and articles are cited in this paper. These citations are ubiquitous in the development of novel bionanocomposites and their applications.

Combating Antimicrobial Resistance in Foodborne Microorganisms

This review addresses an important public health hazard affecting food safety. Antimicrobial agents are used in foods to reduce or eliminate microorganisms that cause disease. Many traditional organic compounds, novel synthetic organic agents, natural products, peptides, and proteins have been extensively studied for their effectiveness as antimicrobial agents against foodborne Campylobacter spp., Escherichia coli, Listeria spp. and Salmonella. However, antimicrobial resistance can develop in microorganisms, enhancing their ability to withstand the inhibiting or killing action of antimicrobial agents. Knowledge gaps still exist with regard to the actual chemical and microbiological mechanisms that must be identified to facilitate the search for new antimicrobial agents. Technical implementation of antimicrobial active packing films and coatings against target microorganisms must also be improved for extended product shelf life. Recent advances in antimicrobial susceptibility testing can provide researchers with new momentum to pursue their quest for a resistance panacea.

Active Packaging Coatings

Active food packaging involves the packaging of foods with materials that provide an enhanced functionality, such as antimicrobial, antioxidant or biocatalytic functions. This can be achieved through the incorporation of active compounds into the matrix of the commonly used packaging materials, or by the application of coatings with the corresponding functionality through surface modification. The latter option offers the advantage of preserving the packaging materials’ bulk properties nearly intact. Herein, different coating technologies like embedding for controlled release, immobilization, layer-by-layer deposition, and photografting are explained and their potential application for active food packaging is explored and discussed.

Exceptional oxygen barrier performance of pullulan nanocomposites with ultra-low loading of graphene oxide

Polymer nanocomposites are increasingly important in food packaging sectors. Biopolymer pullulan is promising in manufacturing packaging films or coatings due to its excellent optical clarity, mechanical strength, and high water-solubility as compared to other biopolymers. This work aims to enhance its oxygen barrier properties and overcome its intrinsic brittleness by utilizing two-dimensional planar graphene oxide (GO) nanoplatelets. It has been found that the addition of only 0.2 wt% of GO enhanced the tensile strength, Young's modulus, and elongation at break of pullulan films by about 40, 44 and 52%, respectively. The light transmittance at 550 nm of the pullulan/GO films was 92.3% and haze values were within 3.0% threshold, which meets the general requirement for food packaging materials. In particular, the oxygen permeability coefficient of pullulan was reduced from 6337 to 2614 mL μm m(-2) (24 h(-1)) atm(-1) with as low as 0.05 wt% of GO loading and further to 1357 mL μm m(-2) (24 h(-1)) atm(-1) when GO concentration reached 0.3 wt%. The simultaneous improvement of the mechanical and oxygen barrier properties of pullulan was ascribed to the homogeneous distribution and prevalent unidirectional alignment of GO nanosheets, as determined from the characterization and theoretical modelling results. The exceptional oxygen barrier properties of pullulan/GO nanocomposites with enhanced mechanical flexibility and good optical clarity will add new values to high performance food packaging materials.