Antibacterial Films Research Articles

Novel visible-light-driven antibacterial film grafted with 3,3,4,4-benzophenone tetracarboxylic acid (BPTCA) for chilled meats preservation

To improve long-term stability and low-toxicity active packaging systems, three visible-light-driven antibacterial packaging films from chitosan (CS), silk fibroin (SF), polyvinyl alcohol (PVA) and 3,3,4,4-benzophenone tetracarboxylic acid (BPTCA) were fabricated in this study. First, CS/PVA, SF/PVA and CS/SF/PVA films by solution casting method, and enhance their water solubility by glutaraldehyde (GA) cross-linking to obtain CS/PVA-G, SF/PVA-G and CS/SF/PVA-G. Then, BPTCA was covalently immobilized onto CS/PVA-G, SF/PVA-G and CS/SF/PVA-G through the esterification to obtain CS/PVA-B, SF/PVA-B and CS/SF/PVA-B, respectively. The chemical structure, photophysical properties, and antibacterial capacities are characterized. The FTIR revealed that BPTCA is covalently grafted with the polymer matrix via ester bond. Furthermore, grafting of BPTCA enhanced the film's UV-blocking, decreased water contact angle, water vapor permeability, and possessed moderate mechanical properties. Meanwhile, CS/SF/PVA-B has the best reactive oxygen species generation ability and antibacterial activity (against Escherichia coli, Staphylococcus aureus, Salmonella enteritidis), and can recycle four times, overall migration value of BPTCA was within the limits of 10 mg/dm2. We apply CS/SF/PVA-B films combined with palletized packaging to different chilled-meat preservation applications, and measure physicochemical changes and microbial counts. Shelf lives of chilled mutton are extended by 3 d and chicken by 6 d, compared with controls without CS/SF/PVA-B film. A covalent immobilized visible-light-driven antibacterial packaging may improve the long-term quality of chilled meats.

Photo-responsive Cu-tannic acid nanoparticle-mediated antibacterial film for efficient preservation of strawberries

The existing films used for fruit preservation suffer from insufficient preservation abilities. This study introduces Cu-tannic acid (Cu-TA) nanoparticles, synthesized from tannic acid (TA) and Cu2+, to enhance food packaging properties. Integrated into a chitosan-gelatin (CG) matrix, the resultant Cu-TA nanocomposite films exhibit superior antibacterial efficacy and killing rates of Escherichia coli and Staphylococcus aureus more than 99 %, and double the shelf life of strawberries, underscoring the exceptional freshness preservation capabilities of film. Additionally, the tensile strength of the Cu-TA nanocomposite films increased by 1.75 times, the DPPH radical scavenging percentage increased from 29.4 % to 68.4 %, and the water vapor permeability (WVP) decreased by about 60 % compared to the pure CG films. Comprehensive cytotoxicity and migration assessments confirm the safety of film, paving the way for their application in food packaging. The excellent performance of the Cu-TA nanocomposite films positions them as a formidable solution for protecting perishable food items.

Quaternary Ammonium Salt-Based Intrinsic Antibacterial Polyurethanes: Optimizing the Antibacterial Activity via Cationic Main- or Side-Chain Design in Hard Segments.

Thermoplastic polyurethanes (TPUs) are one of the most appealing materials with extensive applications in biomedical fields due to their versatile mechanical properties and excellent biocompatibility. In response to the escalating challenges of bacterial infections, it is desirable to obtain TPUs with intrinsic antibacterial activity, particularly for application in biomedical devices and public places. Herein, a cationic main-/side-chain structure regulation strategy in the TPU hard segment was adopted to introduce and optimize the antibacterial activity. This was achieved by synthesizing two types of quaternary ammonium salts (QAS)-containing chain extenders, i.e., N-methyl-N-alkyl-N,N-bis(2-hydroxyethyl) ammonium bromide (Mn, where n represents the N-alkyl chain length) and N,N-dimethyl-N-alkyl-N-2,3-propylene glycol (Dn), from N-methyldiethanolamine (MDEA) and 3-dimethylamino-1,2-propanediol (DMAD), respectively. Given the structural differences between Mn and Dn, main-chain-type PU-Mn and side-chain-type PU-Dn were subsequently obtained with QAS groups in the hard segment. The N-alkyl chain length, QAS content, and main-/side-chain types were systematically investigated to optimize bactericidal properties. The results revealed that a long N-alkyl chain (from C6 to C14) increased the antibacterial activity of the chain extenders and corresponding TPU films. Besides, side-chain-type PU-Dn films showed higher contact-active antibacterial activity than that exerted by the main-chain-type PU-Mn films. Remarkably, almost 100% of Staphylococcus aureus(S. aureus) could be killed by the PU-D14 film with a low QAS content (1.6 wt %). All the TPUs showed good thermal stability with a degradation temperature of 5% mass loss (Td,5%) above 300 °C. Moreover, the TPU films displayed excellent mechanical properties with the tensile strength at break varying from 20.7 to 47.5 MPa and ultimate elongation above 1000%. All of the intrinsic antibacterial films showed negligible hemolytic activities.

Preparation and characterization of carvacrol/soybean protein isolate composite film with efficient antimicrobial and antioxidant activities and its application in grape preservation

There is an urgent need for a simple and effective method to enhance the freshness of fruits during transportation. In this study, we developed a composite antibacterial film (CAR film) using carvacrol and soy protein isolate (SPI). The mechanical properties, hydrophobicity, antibacterial activity, and antioxidant capacity of the film were characterized. The results demonstrated that, compared to the soy protein isolate film, the film with 2.5 % carvacrol content exhibited superior mechanical properties (tear strength decreased by approximately 37 %, elongation at break increased by about 108 %), hydrophobicity (water vapor permeability decreased by 38 %), antibacterial activity (inhibition zone diameters against E. coli and S. aureus were 14.21 mm and 11.83 mm, respectively), antioxidant capacity (increased by 5 to 6 times), and biocompatibility (cell survival rate exceeded 90 %). Grape preservation experiments further confirmed that the CAR film effectively prolongs shelf life. Therefore, CAR film is a promising packaging material for fruit preservation.

Preparation and characterization of porous corn starch-based antibacterial sustained-release intelligent film

A novel porous corn starch-based antibacterial sustained-release intelligent film was prepared with the porous corn starch as the substrate, purple corn cob anthocyanin (PCA) as the indicator, and tangerine peel essential oil as the antibacterial agent, and its properties were studied. The results showed that the porous corn starch-based antimicrobial sustained-release indicator film had good mechanical strength, surface hydrophobicity and light transmittance. The tensile strength of the sustained-release indicator film (PLSt-12) prepared by porous corn starch with an enzymatic hydrolysis time of 12 h was 14.35 MPa and the elongation at break was 6.55 %. The water contact angle was 89.10°, and the water vapor transmittance was 6.62 × 10−4 g·mm2·s−1·Pa−1. The PLSt-12 was brown at pH 10 and had a sensitive color response. The PLSt-12 reduced the release rate of anthocyanins by 25.01 %, and the sustained-release mechanism was non-Fick diffusion. It showed a significant color change when the pork quality deteriorated, which can be used to monitor the freshness of the pork. This type of antibacterial sustained-release intelligent film had considerable application potential in indicating food freshness.

Biodegradable antimicrobial films prepared in a continuous way by melt extrusion using plant extracts as effective components

Packaging plays an important role in delaying food spoilage. However, conventional packaging films do not have antimicrobial properties. Films with antimicrobial components are receiving growing research interest. However, many of the reported studies use conventional non-degradable polymers during film preparation, posing a significant threat to the environment and sustainable development. Furthermore, conventional inorganic antibacterial agents are commonly used during film preparation, posing a risk to food safety. In this study, antibacterial compounds were extracted from diverse plants, and then biodegradable antimicrobial films were prepared in a continuous way via the melt extrusion method. Especially, films prepared using Vernicia fordii and Phyllanthus urinaria extracts showed effective antibacterial activities against common foodborne pathogens. This study is the first to prepare antibacterial films in a continuous way using natural plant extracts as the effective components, and may shed new light on future research in preparing green antibacterial films via environment-friendly approaches.

Visible Light-Activated Dye-sensitized TiO2 Antibacterial Film: A Novel Strategy for Enhancing Food Safety and Quality

Visible Light-Activated Dye-sensitized TiO2 Antibacterial Film: A Novel Strategy for Enhancing Food Safety and Quality

Prediction of the postharvest quality of Boletus wild mushrooms stored with mesoporous silica nanoparticles antibacterial film using Long Short-Term Memory model combined with the Northern Goshawk Optimization (NGO-LSTM)

This study aimed to address the challenge of extending the shelf life of Boletus wild mushrooms, which are prone to environmental and microbial contamination. An antibacterial film composed of polylactic acid (PLA) and mesoporous silica nanoparticles loaded with citral (CMP film) was developed for this purpose. Fifteen quality indices were assessed, and the data were integrated using AHP and TOPSIS to evaluate the film's efficacy. The CMP film effectively maintained the quality of mushroom over time. Additionally, a Nonlinear Global Optimization-Long Short-Term Memory (NGO-LSTM) model was employed to predict storage quality, using seven highly correlated quality indicators. The model achieved a high predictive accuracy, with the R2 exceeding 0.999. This study presents a novel packaging solution and a predictive model that together enhance the storage and quality control of Boletus wild mushrooms.

Preparation of chitosan/polyvinyl alcohol antibacterial indicator composite film loaded with AgNPs and purple sweet potato anthocyanins and its application in strawberry preservation

This study incorporated purple sweet potato anthocyanin (PSPA) and silver-nanoparticles (AgNPs) into the chitosan/polyvinyl alcohol film matrix (PVA/CS) to successfully prepare a composite film, which effectively inhibited bacterial growth and indicated product freshness. The addition of AgNPs and PSPA led to a dense structure of the film, which effectively enhanced its physical properties, barrier properties and functional properties. The incorporation of PSPA made the composite film highly pH-sensitive, which exhibited distinct color changes in varying pH solutions. The PVA/CS-AgNPs-PSPA10 composite film with PSPA and AgNPs resulted the shelf life of strawberries to 13 days at 4 °C, which effectively reduced strawberry breathing during storage. Additionally, such composite film changed color from purple to yellow-purple, indicating the deterioration of strawberries. It also showed an antibacterial indication through its excellent antibacterial property and freshness indication performance, which demonstrated its significance in developing antibacterial indicator composite packaging materials for fruits and vegetables preservation.

Preparation of antibacterial composite film based on arginine-modified chitosan and its application in the preservation of ready-to-eat sea cucumber

An edible composite film was developed and applied for ready-to-eat sea cucumber storage to improve the product quality. The PAC film base is first prepared by mixing 0.5 % glycerin (GL) with 4 % polyvinyl alcohol (PVA) and 1 % arginine-modified chitosan (Arg-CTS) in the same volume. After the addition of nano-ZnO (ZnO) and thymol (Thy) to the PAC film base, the mechanical properties and functions were tested. Compared to the PAC film, the PAC-ZnO-ThyH composite film showed a 1.34-fold increase in the DPPH scavenging rate and a 2.19-fold increase in the ABTS scavenging rate. Contrary to the PAC film, the inhibition zone diameter of Escherichia coli and Staphylococcus aureus significantly increased by 2.35 and 4.08 folds in the PAC-Zno-ThyH film, respectively. After applying the PAC-ZnO-ThyH film to store ready-to-eat sea cucumber for 10 days, there was a significant reduction in weight loss, total volatile basic nitrogen (TVB-N), and lipid oxidation levels to 1.47 and 1.26 folds to the Ctrl group. After preservation, the hardness and chewiness of ready-to-eat sea cucumber were maintained at 1079.62 ± 138.86 N and 913.73 ± 175.79 N, respectively. The novel PAC-ZnO-ThyH composite film can be used as an active food packaging for promising seafood applications.

Fabrication of chitosan-encapsulated microcapsules containing wood wax oil for antibacterial self-healing wood coatings

Wood multifunctional smart coating is a new functional coating that combines smart material technology with traditional wood. In this study, wood wax oil based on thistle oil and flaxseed oil was used as the core material, and chitosan was used as the wall material to prepare self-repairing antibacterial microcapsules. The optimal preparation conditions were found to be an oil-water ratio (OWR) of 2:1, a core-to-wall ratio of 3:1, using OP-10 as the emulsifier at a concentration of 10.0 %, and a crosslinker concentration of 0.18 g/mL. The encapsulation efficiency of microcapsules was 73.7 % by spray drying, and the thermal stability was improved. The chitosan microcapsules exhibit the characteristics of water sensitivity and acid selective response, with rapid release at pH 7.0. Blending microcapsules at concentrations of 2.0 %, 5.0 %, and 8.0 % with UV topcoat and applying them to walnut plywood resulted in a multifunctional wood coating. Artificially simulated daily scratch damage was effectively repaired within 7 d. Furthermore, the 10.0 % microcapsules demonstrated antibacterial properties against Escherichia coli (E. coli) and Escherichia coli (E. coli), with an antibacterial E. coli and S. aureus rate of up to 75.82 % and 42.96 %. The IC50 of the wood coatings against E. coli was 5.667, while against S. aureus it was 15.45. The minimum inhibitory concentration (MIC) of the microcapsules against both E. coli and S. aureus was 10.0 %. The coating film containing 2.0 % microcapsules demonstrated superior overall performance. This research established a foundation for the development of self-healing antibacterial coatings for wood and addressed the gap in dual-functional self-healing antibacterial paint films for wood.

Fabrication of N-halamine/MWPPy-ZnO hybrids based cellulose nanofibril composite films with improved UV-protective, antibacterial, and biofilm control functions

The design and fabrication of synergistic hybrid antibacterial materials is a promising approach for achieving effective sterilization while compensating for the deficiency of a single component. Despite being highly effective biocidal components, the poor UV light stability of some N-halamines limits their applications. This study was conducted to address this issue by the rational integration of cyclic N-halamine precursor (PGHAPA) with microwaved zinc oxide (MWPPy-ZnO) nanoparticles via covalent bonds and the preparation of cellulose nanofibrils based antibacterial composite films after chlorination (CNF/MWPPy-ZnO-PGHAPA-Cl). The proposed films offered tight lamellar structure, considerable thermal stability and better mechanical properties. The results from the FT-IR and XPS experiments provided the evidence of chemical reactions among the PGHAPA, MWPPy-ZnO, and CNF film. Notably, the CNF/MWPPy-ZnO-PGHAPA-Cl films showed improved UV stability with a chlorine content of up to 0.16 % after 24 h of irradiation, which was much greater than that of the CNF/PGHAPA-Cl films. Furthermore, the CNF/MWPPy-ZnO-PGHAPA-Cl films displayed rapid bactericidal activity, inactivating all the contacted Staphylococcus aureus and Escherichia coli O157:H7 strains within 5 min, along with prominent biofilm disruption, indicating great potential for daily food packaging applications.

ScCO2-processed thermoplastic starch/chitosan oligosaccharide blown films and their oxygen barrier or antibacterial applications

Abstract Antibacterial and oxygen barrier films were inventively prepared by blending very small loadings (<2 wt%) of chitosan oligosaccharide (COS) or chitosan (CS) in thermoplastic starch (TPS) and/or processing with supercritical carbon dioxide (scCO2). Oxygen transmission rates (OTR) and free-volume-hole (FVH) characteristics of scCO2-processed TPS/COS and TPS/CS blown films diminish to a minimum, as their COS or CS approach a specific compatibility limit content. The minimum OTR and FVH characteristics of scCO2-processed TPS/COS films are somewhat smaller than those of corresponding TPS/COS films without scCO2-assistance, and decrease further with decreasing COS molecular weights. The minimum OTR values of scCO2-processed TPS/COS blown films with COS’s molecular weight of 200 and 500 are only 4.1 and 4.5 cm3/m2 × day × atm, respectively, and their antibacterial rates of Staphylococcus aureus are ≥97 %, which make them as promising antibacterial and oxygen barrier films having OTR ≦ 5 cm3/m2 × day × atm. Among other things, longitudinal or transversal tensile strengths acquired for the properly scCO2-processed TPS/COS or TPS/CS films are ∼30 to ∼50 % higher than those of the TPS films. Dynamic mechanical relaxation results of these scCO2-processed reveal that chitosan oligosaccharide or chitosan are compatible with TPS, as COS or CS contents are ≤ the compatibility limit value.

Development of a Chitosan‐Based Food Packaging Film with the Incorporation of Pectin and Silver Nanoparticles for Improved Antibacterial and Physical Properties

AbstractThis research incorporated grapefruit peel‐derived Pectin and Silver nanoparticles (AgNPs) into the Chitosan‐based bio‐packaging film to improve its antibacterial efficacy and physical properties such as moisture content, swelling degree, and biodegradability in soil. Systematic investigations revealed that preservative films made from Chitosan 1.75 wt %, Pectin 0.55 wt %, and AgNP 31 ppm have shown a 17.5‐fold reduction in swelling degree in water compared to Chitosan films. At the same time, the anti‐gram‐positive and anti‐gram‐negative bacteria capacity, the ability to retain moisture, and biodegradability in soil, have been enhanced. Low swelling degrees provided better barrier performance, extending the shelf life of packaged products by preventing the ingress of oxygen, and water vapor; on the other hand, higher moisture content improved the flexibility and handling characteristics of packaging films, making them easier to manipulate during packaging processes. These findings herald a sustainable option for eco‐friendly food packaging, a critical step toward minimizing plastic waste and strengthening food preservation procedures using Chitosan‐based antibacterial films enhanced with natural additives.

Antibacterial composite films of oxidized alginate-chitosan-ZnO anchored Cu nanoparticles for the degradation of organic pollutants

The growing population and urbanization have adversely affected the environment including water. The waste water from industries has affected not only human but also animals. The availability of clean water is one of the foremost needs for living organism. This makes very urgent to find reliable solutions for cleaning waste water. These days catalysis is one the best solutions to remove and degrade organic pollutants. In this work, porous composite polymer films have been designed through facile method which were employed to stabilize zero-valent metal nanoparticles (NPs). The sustainable, environmentally friendly polymer matrix with attached metal NPs was applied for the effective catalytic degradation of both phenolic compounds and organic dyes. The different composite films consist of ZnO NPs embedded in an Oxidized Alginate-Chitosan (OAlg-CS) biomatrix named as OAlg-CS/ZnO with various percentages of ZnO as a support for metallic Cu NPs. The ZnO NPs have been incorporated into OAlg-CS polymer with 10, 15, and 20 wt% and are designated as OAlg-CS/ZnO-10, OAlg-CS/ZnO-15, OAlg-CS/ZnO-20. Various analytical techniques were utilized to investigate the shape, morphology, elemental composition, functional groups and stability of the composite films. All these polymer nanocomposite films were then evaluated for removal of model organic pollutants comprising p-nitrophenol (4-NP), methylene blue (MB), and methyl orange (MO). The Kapp value for 4-NP was 2.19 × 10−1 min−1, 4.68 × 10−1 min−1 for MO and 8.99× 10−1 min−1 for MB. The experimental results demonstrated that OAlg-CS/ZnO-20 films show the highest catalytic activity as compared to OAlg-CS/ZnO, OAlg-CS/ZnO-10, and OAlg-CS/ZnO-15. The order of rate constants for nitrophenol and dyes using OAlg-CS/ZnO-20 was found to be MB ˃ MO ˃ 4-NP, showing the selectivity of these composite films. The prepared composite films were also investigated for their antibacterial activity against Gram-positive and Gram-negative bacteria and all the films exhibited good anti-bacterial activity, with OAlg-CS/ZnO-20 showed the highest anti-bacterial activity.

A grafting approach for nisin-chitosan bio-based antibacterial films: preparation and characterization

Nisin is a bacteriocin produced by Gram-positive lactic acid bacterium,Lactococcus lactisand currently recognized in the Generally Recognızed as Safe (GRAS) category due to its non-toxicity. Herein, nisin has been grafted to chitosan structure to obtain natural bio-active films with enhanced antibacterial activity. Grafting was performed using ethyl ester lysine diisocyanate and dimer fatty acid-based diisocyanate (DDI); two different close to fully bio-based diisocyanates and Disuccinimidyl suberate; a homo-bifunctional molecule acting as a crosslinker between amino groups. The grafting process allowed the chemical immobilization of nisin to chitosan structure. Physicochemical characterization studies showed the successful grafting of nisin. The antibacterial activity againstStaphylococcus aureuswas evident for all nisin modified chitosan films and best pronounced when DDI was used as a crosslinker with a maximum zone of inhibition of ∼13 mm. All nisin grafted chitosan films were cytocompatible and the cell viability of L929 fibroblasts were >80% pointing out the non-toxic structure. Considering the results of the presented study, bio-based diisocyanates and homo-bifunctional crosslinkers are effective molecules in synthesis of nisin grafted chitosan structures and the new chitosan based antibacterial biopolymers obtained after nisin modification come forward as promising non-toxic and bioactive candidates to be applied in medical devices, implants, and various food coating products.

Characterization of biopolymers based antibacterial films enriched with thyme essential oil and their application for milk cake preservation

Characterization of biopolymers based antibacterial films enriched with thyme essential oil and their application for milk cake preservation

Antibacterial and antioxidant phlorizin-loaded nanofiber film effectively promotes the healing of burn wounds.

Burns usually result in damage and loss of skin forming irregular wound wounds. The lack of skin tissue protection makes the wound site highly vulnerable to bacterial infections, hindering the healing process. However, commonly used wound dressings do not readily provide complete coverage of irregular wounds compared to regular wounds. Therefore, there is an urgent need to prepare a wound dressing with high antimicrobial efficacy for the administration of drugs to irregular wounds. In this study, a chitosan (CS)/polyvinylpyrrolidone (PVP) composite nanofiber membrane (CS/PVP/Phlorizin) loaded with root bark glycosides (Phlorizin) was developed using an electrostatic spinning technique. The incorporation of phlorizin, a natural antioxidant, into the fiber membranes notably boosted their antimicrobial and antioxidant capabilities, along with demonstrating excellent hydrophilic characteristics. In vitro cellular experiments showed that CS/PVP/Phlorizin increased Hacat cell viability with the presence of better cytocompatibility. In scald wound healing experiments, Phlorizin-loaded nanofibrous membranes significantly promoted re-epithelialization and angiogenesis at the wound site, and reduced the inflammatory response at the wound site. Therefore, the above results indicate that this nanofiber membrane is expected to be an ideal dressing for burn wounds.

Aloe vera-synthesized Ag nanoparticles loaded on PVA/chitosan as biodegradable and antibacterial film for food storage

We have developed a novel, eco-friendly, and active food packaging film by incorporating green-synthesized silver nanoparticles (AgNPs) into polyvinyl alcohol (PVA) and chitosan matrices. The AgNPs were in situ and green synthesized in high-yield by using Aloe vera extract as a reducing agent and chitosan as a stabilizing agent at high temperature. The obtained AgNPs exhibit quasi-spherical shapes and tunable size in the range 20 ∼ 30 nm by controlling the content of AgNO3 precursor in the growth solution. The in situ synthesis enables the homogeneous distribution of AgNPs throughout the films and eliminates the need for purification. The effect of the loaded amounts of Aloe vera-synthesized AgNPs on the film characteristics was investigated. The results show that the obtained AgNPs-loaded films exhibit excellent mechanical properties (tensile strength of 36.7 MPa and elongation at break of 213.9%) and superior bacterial killing and inhibition effects against E. coli. Moreover, the incorporation of green-synthesized AgNPs into the polymeric films also results in a significant improvement in the contact angles formed between the film surface and glycerol droplets, enhanced thermal stability, and a reduction in water swelling and water solubility. All these results highlight the great potential of these biodegradable and antibacterial membranes as an alternative to petroleum-based plastics in food packaging and preservation.

Ferulic acid-arabinoxylan conjugates: Synthesis, characterization and applications in antibacterial film formation

A novel antibacterial film based on arabinoxylan (AX) was prepared by introducing ferulic acid (FA) to AX through a laccase-catalyzed procedure. The ferulic acid-arabinoxylan conjugates (FA-AX conjugates) have been characterized. Results showed that FA was successfully grafted onto the AX chains by covalent linkages, likely through nucleophilic addition between O-Ph in the phenolic hydroxyl group of FA, or through Michael addition via O-quinone intermediates. FA-AX conjugates showed improved crystallinity, thermal stability, and rheological properties, as well as a distinct surface morphology, compared with those of native AX. Moreover, FA-AX conjugates exhibited enhanced antibacterial ability against Staphylococcus aureus, Escherichia coli, Shewanella sp., and Pseudomonas sp. Mechanistic studies revealed that the enhanced antibacterial ability was due to the penetration of bacterial membrane by the phenolic molecule and the steric effect of FA-AX conjugates. The study demonstrates that the laccase-induced grafting method was effective in producing FA-AX conjugates; we have demonstrated its antibacterial ability and great potential in prolonging the shelf life of fresh seafood products.