Antibacterial Films Research Articles

Antibacterial and osteogenic thin films on Ti-6Al-4V surface formed by passivation process in copper hydroxide solution

ABSTRACT Implant-associated infections are threatening and devastating complications that lead to bone destruction and loss. As a smooth surface is suitable for inhibiting bacterial adhesion, endowing antibacterial activity to the Ti surface without any structural changes in the surface topography is an effective strategy for preventing infection. The thin film on the Ti-6Al-4 V surface was functionalized to endow antibacterial activity by immersion in a Cu(OH)2 solution. The resulting surface maintains the surface topography with a surface roughness of 0.03 μm even after the immersion in the Cu(OH)2 solution. Moreover, Cu was detected at approximately 10 atom% from the surface and was present up to a depth of 30 nm of thin film. In vitro experiments revealed that the resulting surface exhibited antibacterial activity against methicillin-resistant Staphylococcus aureus and allowed the cellular proliferation, differentiation, and calcification of MC3T3-E1 cells. Furthermore, in vivo experiments determined that the presence of Cu in the thin film on the Ti-6Al-4 V surface led to no inflammatory reactions, including bone resorption. Thus, immersion in a Cu(OH)2 solution incorporates and immobilizes Cu into the thin film on the Ti-6Al-4 V surface without any structural alternations in the surface topography, and the resulting smooth surface exhibits antibacterial activity and osteogenic cell compatibility without cytotoxicity or inflammatory reactions. Our findings provide fundamental insights into the surface design of Ti-based medical devices, to achieve bone reconstruction and infection prevention.

Thermal-Driven Curcumin Release Film with Dual-Mode Synergistic Antibacterial Behavior for Efficient Tangerine Preservation.

Antimicrobial packing showed great potential in extending the shelf life of food. However, developing a new biocomposite film with an intelligent and efficient antimicrobial performance is still desirable. Herein, a Fe-MoOx encapsulated with curcumin (Cur) filled chitosan-based composite film (CCF films) was prepared by solvent casting method. The total color differences of the CCF films were less than 30%, and satisfactory surface color, transparency, hydrophobicity, and thermal stability were also obtained. Besides, the UV-light/water/oxygen barrier capability and mechanical properties were enhanced with the incorporation of Cur@Fe-MoOx. Moreover, CCF films showed photothermal performance and thermal-controlled curcumin release ability, which endowed the CCF0.15 film with excellent antibacterial capability toward E. coli (≥99.95%) and S. aureus (≥99.96%) due to the synergistic antibacterial effect. Fe-MoOx exhibited high cell viability and less than 5% hemolysis even under the concentration of 500 μg mL-1. Based on those unique characteristics, the CCF0.15 film was chosen for tangerine preservation. The CCF0.15 film could prolong the shelf life of tangerine by at least 9 days compared with the unpacking group, and the tangerines could maintain the freshness characteristics over a 24 day storage period. Such thermal-mediated antibacterial film proposed by our work showed promising potential in food packaging.

Key biological processes and essential genes for Proteus mirabilis biofilm development inhibition by protocatechuic acid

Proteus mirabilis is an opportunistic pathogen linked to human urinary tract infections, and is potentially present as a foodborne pathogen within poultry products, including broiler chickens. This report outlines the inhibitory impacts of protocatechuic acid (PCA) on P. mirabilis isolated from a broiler slaughterhouse in China as well as its biofilm. This investigation encompasses assays related to motility and adhesion, bacterial metabolic activity, extracellular polymer (EPS) production, and scavenging capacity. The findings demonstrated that PCA reduced biofilm formation by 61 %. Transcriptomics findings identified that PCA limited the expression of genes like PstS that promote adhesin formation, rbsA and RcsB that alter bacterial chemotaxis, lipopolysaccharide synthesis genes LpxA and EptB, and cell wall synthesis genes MurF and MrdA, and affects the Regulator of Capsule Synthesis (RCS) two-component modulation system. Weighted gene co-expression network analysis (WGCNA) was conducted to identify the core genes. Furthermore, the binding sites of PCA to cytochrome oxidases cydA and cydB, two subunits of ATP synthase atpI and atpH, and ftsZ, which regulate bacterial division, were predicted via molecular docking. Metabolome analysis determined that PCA critically influenced coenzyme A biosynthesis, nucleotide metabolism, alanine, aspartic acid, and glutamate metabolic pathways of P. mirabilis. Therefore, PCA impacts metabolism within bacteria via various pathways, limiting the levels of extracellular polymer and bacterial viability to hinder biofilm formation. Additionally, we prepared an antibacterial plastic film containing protocatechuic acid using PVA as the monomer and CNC as the reinforcing agent. We examined the mechanical and antibacterial properties of this film. When used to wrap chicken, it reduced the total number of colonies, slowed the deterioration of chicken, and maintained the freshness of chicken. In conclusion, the information outlined in this study complements our comprehension of P. mirabilis inhibition by PCA and provides clues for the reduction of foodborne infections associated with P. mirabilis.

Antibacterial Hydrophilic ZnO Microstructure Film with Underwater Oleophobic and Self-Cleaning Antifouling Properties.

Super-hydrophilic and oleophobic functional materials can prevent pollution or adsorption by repelling oil, and have good circulation. However, traditional strategies for preparing these functional materials either use expensive fabrication machines or contain possibly toxic organic polymers, which may prohibit the practical application. The research of multifunctional ZnO microstructures or nanoarrays thin films with super-hydrophilic, antifouling, and antibacterial properties has not been reported yet. Moreover, the exploration of underwater oleophobic and self-cleaning antifouling properties in ZnO micro/nanostructures is still in its infancy. Here, we prepared ZnO microstructured films on fluorine-doped tin oxide substrates (F-ZMF) for the development of advanced self-cleaning type super-hydrophilic and oleophobic materials. With the increase of the accelerators, the average size of the F-ZMF microstructures decreased. The F-ZMF shows excellent self-cleaning performance and hydrophilic (water contact angle ≤ 10°) and oleophobic characteristics in the underwater antifouling experiment. Under a dark condition, F-ZMF-4 showed good antibacterial effects against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) with inhibition rates of 99.1% and 99.9%, respectively. This study broadens the application scope of ZnO-based material and provides a novel prospect for the development of self-cleaning super-hydrophilic and oleophobic materials.

Antioxidant, antibacterial and biodegradable hydrogel films from carboxymethyl tragacanth gum and clove extract: Potential for wound dressings application

Bioactive films based on sodium carboxymethyl tragacanth gum (CMT) and polyvinyl alcohol (PVA) enriched with clove extract (CE) for potential wound healing applications were fabricated by the solution casting method. The fabricated films were characterized by FTIR, XRD, EDX, SEM, and TGA analyses. The XRD pattern of CMT/PVA/CE5 % showed an amorphous structure with broad peaks, suggesting that the presence of CE led to a reduction in crystallinity and an increase in amorphousness in the polymer film. The fabricated films showed a high water absorption capacity and swelled up to 80 % over 24 h for the CMT/PVA/CE5 % formulation crosslinked with 15 % citric acid. Excellent biodegradability with 88 % was observed in soil over 40 days for CMT/PVA/CE5 %. The presence of CE in CMT/PVA improved the antioxidant activity by up to 92 % within 30 min. Strong antibacterial effects of CMT/PVA/CE5 % film were observed against Salmonella enterica and Staphylococcus aureus, with inhibition zone diameters of 20 mm and 18 mm, respectively. Across concentrations from 25 to 600 μg/mL, CMT/PVA/CE5 % films displayed over 80 % cell viability on cultured human dermal fibroblasts after 48 h. The results indicated that CMT/PVA/CE5 % bioactive film can be employed as effective, non-toxic wound dressings with infection prevention and healing promotion capabilities.

NEW ZINC-BONE APATITE FILMS SHOW ANTI-TUMOUR EFFICACY AGAINST BONE METASTASES IN VITRO

Decreasing the chance of local relapse or infection after surgical excision of bone metastases is a main goals in orthopedic oncology. Indeed, bone metastases have high incidence rate (up to 75%) and important cross-relations with infection and bone regeneration. Even in patients with advanced cancer, bone gaps resulting from tumor excision must be filled with bone substitutes. Functionalization of these substitutes with antitumor and antibacterial compounds could constitute a promising approach to overcome infection and tumor at one same time. Here, for the first time, we propose the use of nanostructured zinc-bone apatite coatings having antitumor and antimicrobial efficacy. The coatings are obtained by Ionized Jet Deposition from composite targets of zinc and bovine-derived bone apatite. Antibacterial and antibiofilm efficacy of the coatings is demonstrated in vitro against S. Aureus and E. Coli. Anti-tumor efficacy is investigated against MDA- MB-231 cells and biocompatibility is assessed on L929 and MSCs.A microfluidic based approach is used to select the optimal concentration of zinc to be used to obtain antitumor efficacy and avoid cytotoxicity, exploiting a custom gradient generator microfluidic device, specifically designed for the experiments. Then, coatings capable of releasing the desired amount of active compounds are manufactured. Films morphology, composition and ion-release are studies by FEG- SEM/EDS, XRD and ICP. Efficacy and biocompatibility of the coatings are verified by investigating MDA, MSCs and L929 viability and morphology by Alamar Blue, Live/Dead Assay and FEG-SEM at different timepoints. Statistical analysis is performed by SPSS/PC + Statistics TM 25.0 software, one-way ANOVA and post-hoc Sheffe? test. Data are reported as Mean ± standard Deviation at a significance level of p <0.05.Results and Discussion. Coatings have a nanostructured surface morphology and a composition mimicking the target. They permit sustained zinc release for over 14 days in medium. Thanks to these characteristics, they show high antibacterial ability (inhibition of bacteria viability and adhesion to substrate) against both the gram + and gram – strain.The gradient generator microfluidic device permits a fine selection of the concentration of zinc to be used, with many potential perspectives for the design of biomaterials. For the first time, we show that zinc and zinc-based coatings have a selective efficacy against MDA cells. Upon mixing with bone apatite, the efficacy is maintained and cytotoxicity is avoided. For the first time, new antibacterial metal-based films are proposed for addressing bone metastases and infection at one same time. At the same time, a new approach is proposed for the design of the coatings, based on a microfluidic approach. We demonstrated the efficacy of Zn against the MDA-MB-231 cells, characterized for their ability to form bone metastases in vivo, and the possibility to use nanostructured metallic coatings against bone tumors. At the same time, we show that the gradient-generator approach is promising for the design of antitumor biomaterials. Efficacy of Zn films must be verified in vivo, but the dual-efficacy coatings appear promising for orthopedic applications.

Design and preparation of novel antioxidant and antibacterial films containing procyanidins and phycocyanin for food packaging.

The purpose of this study was to design a novel antioxidant and antibacterial film for food packaging using food-grade raw materials. The films were designed and fabricated based on carboxymethyl chitosan and pectin incorporated with procyanidins (PCs) and phycocyanin (Phy) by the tape casting method. The effects of different proportions of PCs and Phy on the properties and functions of the prepared films were studied. The results showed that the thickness of films could range from 55 to 70 μm, with dense network structure and uniform distribution of elements. Compared with C-Film group, the film loaded with PCs and Phy had lower water solubility and swelling rate, and higher tensile strength and elongation at break. FITR and XRD spectra revealed the molecular interaction mechanism among carboxymethyl chitosan, pectin, PCs and Phy, which could effectively endow the films with ultraviolet barrier properties. Moreover, the addition of PCs and Phy could effectively improve the antioxidant capacity and antibacterial effect of films, for example, the free radical scavenging abilities of most films were above 80% when the concentration of PCs was 40 μg mL-1. In view of these functional properties, the prepared film containing PCs and Phy have been successfully used in food packaging, which was proved by the preservation experiment of grapes. This study can provide theoretical and technical guidance for the preparation of biodegradable antibacterial films, and their application in the food packaging field.

Lactide oligomers modified with linear polyethyleneimine for antibacterial coatings

Antibacterial polylactide film composed of commercial PLA and block copolymer of lactide and linear polyethyleneimine (L-PEI) has been prepared. To observe complete inhibition of bacterial growth only 1.1 wt% of linear L-PEI is required.

Оценка антибактериальных свойств монослойных покрытий Cu-Nb и Cu-Ta на биомедицинском сплаве Ti-6Al-4V

The aim of this study: Evaluation of the antibacterial properties of two-component metal coatings based on Cu-Ta and Cu-Nb applied to samples from the biomedical Ti-6Al-4V alloy by magnetron sputtering. Methods. Two-component metal coatings based on Cu-Ta and Cu-Nb were obtained by magnetron sputtering with joint spraying of targets made of pure metals Cu, Nb, Ta. The antibacterial and antimicrobial properties of the coatings were evaluated in vitro using the disk diffusion method, also known as the radial diffusion method in agar. Results. It was found that coatings with a thickness of 10 microns demonstrated varying degrees of antimicrobial efficacy during three days of testing: the maximum inhibition zone of the Ta-Cu coating reached 24.0 mm for S. Aureus and 17.0 mm for C. Albicans. For Nb-Cu coating, the maximum inhibition zone reached 25.0 mm for S. Aureus and 15.5 mm for C. Albicans. Conclusions. The optimal parameters of direct current magnetron sputtering of Ta-Cu Nb-Cu antibacterial thin films on Ti-6Al-4V alloy substrates have been selected. The antimicrobial effect of Ta-Cu and Nb-Cu coatings is more effective against bacteria than against fungi, and with the same thickness, Ta-Cu coatings are better suited to protect the endoprosthesis from microbial infections than Nb-Cu coatings. Ta-Cu and Nb-Cu coatings are promising for the production of endoprosthesis implants with increased surface resistance to both bacteria and fungi. The results obtained are promising for the development of technologies for obtaining coatings for medical implants with increased bactericidal and biocompatible surface properties.

Study of biodegradability of chitosan-based antibacterial films

In one of our previous works, we obtained films based on chitosan, glycerol, and iron (III) cations. These films possess antibacterial properties, thus they can find applications in the food industry and medicine. In this study, we evaluated the biodegradability of previously described films by keeping them in soil for 4 weeks. For the control experiment, we utilized soil that underwent thermal treatment several times during the experiment. 4 out of 5 samples demonstrated mass loss slightly different from the mass loss in the control experiment (the difference in mass loss compared to the control for these samples did not exceed 3%). This might indicate that their mass loss was solely related to the dissolution process. The last sample, containing chitosan, iron chloride, glycerol, and a chitosanderived cation, exhibited a 40% decrease in mass, which is 26% more compared to the control experiment.

Fabrication, characterization, and application of pea protein-based edible film enhanced by oregano essential oil (OEO) micro- or nano-emulsion

Pea protein isolate (PPI)-based active films were prepared by incorporating 0.5 %, 1.0 %, or 2.0 % of oregano essential oil (OEO), either in the form of micro-emulsion (MOEO) or nano-emulsion (NOEO). The particle size and polydispersity index of OEO droplets were 2755.00 nm and 0.63 for MOEO, and 256.30 nm and 0.20 for NOEO. The surface and cross-sectional SEM results revealed the presence of holes and internal pores within the film upon the addition of OEO. The molecular interaction between PPI and OEO was confirmed by FTIR. The addition of OEO significantly increased film thickness, decreased water contact angle, and imparted a more yellow color. At a low concentration (0.5 %), the addition of OEO significantly improved the water vapor barrier and mechanical properties of the film. However, at higher concentrations, these film properties were significantly weakened. Additionally, the film antimicrobial properties were assessed after OEO addition. In vitro inhibition zone results indicated that a 2.0 % addition of OEO significantly suppressed the growth of three Salmonella strains [Salmonella Typhimurium (ATCC14028), Salmonella Infantis 94-1, and Salmonella Enteritidis PT-30]. Application of pea protein-based film with 2.0 % OEO on chicken breast demonstrated significant reduction in microbial count. Our results further showed that reducing the particle size of OEO from micrometer-scale to nanometer-scale in the PPI film matrix did not significantly alter film properties or antimicrobial activities. The study demonstrated that the antibacterial film based on pea protein and OEO is an innovative food packing material for prohibiting bacteria growth on poultry products.

Development of carboxymethyl cellulose–chitosan based antibacterial films incorporating a Persicaria minor Huds. essential oil nanoemulsion

As plastic waste has continued to increase over the years, there is an appeal for environmental-friendly packaging containing bioactive components such as essential oil for food packaging.

AgNPs-loaded chitosan/sodium alginate hydrogel film by in-situ green reduction with tannins for enhancing antibacterial activity

Bacterial infections pose a significant challenge to global public health, and the development of innovative antibacterial materials is becoming increasingly urgent. Currently, hydrogels are widely studied for the treatment of bacterial infection. However, it is still a great challenge to load antibacterial nanoparticles into the hydrogel matrix by using green synthesis method. Tannic acid (TA) is an eco-friendly reducing agent for the synthesis of metal nanoparticles, and it also has antibacterial activity. In this paper, an antibacterial chitosan/sodium alginate (HCS/SA) hydrogel film embedded with AgNPs was fabricated through in-situ green reduction with TA to utilize the synergistic antibacterial effect of TA and silver nanoparticles (AgNPs). The chemical composition and morphology of the antibacterial hydrogel were characterized by using FTIR, XRD, SEM, and EDS. The results demonstrated that TA solution under alkaline conditions could convert AgNO3 to AgNPs, and AgNPs were embedded uniformly on the surface of the HCS/SA hydrogel film. In addition, the pH of the TA solution significantly influenced the swelling behavior of the antibacterial hydrogel films. When the pH of the TA solution increased from 7 to 10, the swelling ratio of the antibacterial hydrogel film increased from 388.89% to 648.69%. In addition, the hemolysis rates of our prepared hydrogel films were below 5%, meeting the safety requirements. In vitro antibacterial experiments revealed that the fabricated hydrogel films showed excellent antibacterial effects against E. coli, S. aureus, and P. aeruginosa with inhibition zones up to 25.8 ± 0.24 mm, 32.2 ± 0.62 mm, and 22.6 ± 0.49 mm, respectively. Therefore, the antibacterial hydrogel films developed in this study hold potential for treating bacteria-infected wounds.

Cost-effective synthesis of copper sulfide nanoparticles and flexible films for photocatalytic and antibiotic applications

Herein, we investigate the effects of temperature and thiourea addition rate on the synthesis of copper sulfide nanoparticles (CuS NPs) via a chemical co-precipitation method, exploring their impact on the size and morphology of CuS NPs. Our systematic approach resulted in the successful synthesis of CuS NPs with significantly smaller nanoflower sizes than previously reported in the literature, providing insights into the nucleation and growth mechanisms under various synthesis conditions. Furthermore, the photocatalytic activity of the synthesized CuS NPs with three types of distinctive morphologies, namely, nanoflowers with 50 nm diameter (F-50), nanoflowers with 200 nm diameter, and nanogravels with 50 nm diameter, is comparatively analyzed. Notably, the F-50 exhibits a superior photocatalytic performance compared to the other samples, demonstrating the considerable influence of the NP size and morphology on their functional properties. Furthermore, the antibacterial property of the small CuS nanoflowers is examined using an antibacterial film fabricated by coating the NPs on a polyethylene terephthalate substrate, which is widely used as a protective or packaging film in various industries because of its transparency and flexibility. The antibacterial film can be used to kill both gram-positive and -negative bacteria effectively. This research contributes significantly to the understanding and optimization of CuS NP synthesis and application, emphasizing the potential of small-sized nanoflower CuS NPs in photocatalysis and antibacterial applications.

Synergistic effects of EDTA and lysozyme on the properties of hydroxypropyl starch nano antibacterial films

Hydroxypropyl starch (HPS) nano antibacterial films incorporating Ethylene Diamine Tetraacetic Acid (EDTA) and lysozyme (LY) were fabricated via solvent casting method. The synergistic effects of EDTA and LY on the microstructure, component interactions, color, optical, mechanical, barrier and antibacterial properties of HPS nano antibacterial films were evaluated. The results indicated that EDTA and LY were well dispersed in the matrix of the HPS nano antibacterial films, the film-forming substrates have good compatibility, resulting in a dense multi-layer structure of the HPS nano antibacterial films. The addition of EDTA and LY increased the color parameters (L*, a*, b* and △E*) of the HPS nano antibacterial films. The synergistic effects of EDTA and LY significantly decreased the light transmission of the HPS nano antibacterial films. The presence of EDTA and LY increased the tensile strength (TS) and the elongation at break (EAB) of the HPS nano antibacterial films. The TS and EAB of E2.5L1 reached the highest values of 6.329 MPa and 50.24 %, respectively. The incorporation of EDTA and LY had positive effects on the improvement of water vapor permeability (WVP) and oxygen permeability (OP). The WVP and OP of E2.5L1 reached the highest values of 0.9350 × 10−12 g cm/cm2•s•Pa and 0.297 × 10 −2 g m/m2 •d, respectively. In addition, EDTA and LY had significant synergistic effects on the antibacterial activity against S. aureus (Gram-positive bacteria) and E. coli (Gram-negative bacteria). E2.5L1 exhibited the highest antibacterial activity and the inhibition zone diameters of S. aureus and E. coli were 3.69 mm and 4.28 mm, respectively. The HPS nano antibacterial films incorporating EDTA and LY are potential functional packaging materials.

Mechanism of a novel antibacterial polymeric film with freshness‐retentive and hygiene‐keeping functions

AbstractThe growing concerns surrounding food loss and waste, coupled with the amplified need for effective antimicrobial technologies due to the COVID‐19 pandemic have highlighted the significance of antimicrobial solutions. This study introduces novel polymer‐based antibacterial films to address such challenges by combining antibacterial properties with durability. Using stearyldiethanolamine (C18DEA) as the active ingredient, the polyethylene‐based (PE) film is designed to prevent bacterial growth on its surface. The present study investigated the antibacterial mechanism, durability, and effectiveness of the films against representative gram‐positive and gram‐negative bacterial strains. The films developed in this study demonstrated notable durability against high water temperatures and harsh light exposure for preserving its antibacterial function on the tested bacteria from both representative groups. Scanning electron microscopy (SEM) analysis of bacteria in contact with film surface revealed damages to cellular structure leading to cell lysis even at the lower tested concentration of 800 ppm C18DEA in the film. Our proposed bactericidal mechanism suggests the alkyl chain of C18DEA disrupts bacterial cell membranes, leading to irreversible damage and cell death. Overall, the films hold significant promise for diverse applications, including extended shelf life for perishable foods and enhanced hygiene management, driven by their durability and potent antimicrobial effects.Highlights Mechanism of action of a PE film with C18DEA as active ingredient was studied. Broad‐spectrum bactericidal effect on gram‐positive and gram‐negative bacteria. Films demonstrated resistance to high water temperatures and light exposure. Study highlights the films' application in hygiene, safety, and food preservation.

Antibacterial films based on polylactide and polybutylene adipate terephthalate loaded with zinc oxide or silver nanoparticles: Characterization and application in fresh noodles packaging

adipate terephthalate (PBAT) as matrix and zinc oxide nanoparticles (ZnONPs) and silver nanoparticles (AgNPs) as antibacterial agents, a series of antibacterial PLA/PBAT films were prepared by melt blending. The weight ratio of PLA, PBAT and nanoparticles in composite films was 70:900:10 (lower loading) or 70:900:20 (higher loading). The results showed that comparing with the PLA/PBAT films, the hydrophilicity, oxygen barrier properties, mechanical performance and antibacterial activities of PLA/PBAT/nanoparticles films were significantly improved (P＜0.05), and influenced by the content and type of nanoparticles. After the addition of nanoparticles, the maximum change of films performance was from 71.3° to 35.8°for water contact angle, from 7.4 × 10−14 cm3 cm.cm−2. s−1. Pa−1 to 5.5 × 10−14 cm3 cm.cm−2. s−1. Pa−1 for oxygen transmission permeability, from 26.4 MPa to 31.4 MPa for tensile strength, and from 0% to 57.8% (Escherichia coli) or 58.6% (Staphylococcus aureus) for antibacterial ratio. The films with higher loading content of nanoparticles showed a better antibacterial activity. For the same nanoparticles content, the antibacterial activity of PLA/PBAT/AgNPs was better than PLA/PBAT/ZnONPs. The overall migration in food simulants involving acetic acid (3%) ethanol (10% and 95%) was below 10 mg/dm2 for most films, however, the overall migration for the films with higher content of AgNPs exceeded the limit value. The fresh noodles packaged by PLA/PBAT/AgNPs films showed the significant lowest total viable count with 4.6 lg (CFU/g) and the best appearance color characterized by L* (lightness), a*(red-green) and b*(yellow-blue) at storage time of 7 d in contrast with PLA/PBAT and PLA/PBAT/ZnONPs films, indicating the potential application of prepared films in active packaging to prolong the shelf life of food.

Engineering eco-friendly and biodegradable biomass-based multifunctional antibacterial packaging films for sustainable food preservation

The study presents a new class of eco-friendly and biodegradable biomass-based multifunctional antibacterial packaging films (G-OCSI) based on oxidized corn starch-based nonionic biopolymer (OCSI) and gelatin (Gel), and investigates the effects of different OCSI contents on the properties of G-OCSI. The results demonstrated that G-OCSI 0.25 had good water vapor barrier properties, antioxidant activity (DPPH RSA: 85.84 %), UV resistance (UV blocking > 99.9 %), water resistance (WCA: 122.30°), and tensile properties. Based on the disk diffusion experiment, G-OCSI exhibited significant bactericidal and antibacterial effects against S. aureus and E. coli. Moreover, G-OCSI had good biodegradability in natural environments, and could obviously accelerate the crops growth. Finally, a banana preservation experiment confirmed that G-OCSI could significantly extend the shelf life of bananas at room temperature at least 3 days. The biodegradable packaging films not only realizes the sustainable utilization of biomass resources but also has the potential to replace traditional petroleum-based plastics.

Preparation of photosensitive antibacterial nanocomposite film and its preservation effect on pork loin

Enhancing antimicrobial activity of food packaging is highly desirable and challenging. In this study, biodegradable and effective antibacterial nanocomposite films were prepared by incorporating self-assembled nanoparticles of the natural photosensitizer berberine and 3,4,5-methoxy cinnamic acid into the gelatin-based film matrixes. The self-assembled berberine-3,4,5-methoxycinnamic acid nanoparticles (BT NPs) exhibit aggregation-induced emission activity when exposed to visible light, resulting in enhanced antibacterial activity. With the addition of BT NPs, the nanocomposite films showed improved UV shielding ability, hydrophobicity, and water vapor transmission rate. More importantly, the nanocomposite films utilized sunlight to produce reactive oxygen species (ROS) and thus inactivated all the inoculated Staphylococcus aureus within merely 15 min. Additionally, even under dark, NPs exhibited adequate antimicrobial activity. Finally, the antimicrobial effect of packaging tests on pork tenderloin samples was confirmed, as the total bacterial count of the samples remained below 6 log CFU/g on the 10 d. Therefore, this study offers new perspectives on the development of natural and potent antimicrobial food packaging.

Development of biodegradable films reinforced with silver functionalized cow milk carbon dots for active food packaging applications

Synthetic food packaging films exhibit poor biodegradability and their use has resulted in significant environmental issues. The objective of this work was to develop organic, biopolymer-based antibacterial packaging films as an alternative to synthetic packaging films. In this study, agar was chosen as a biopolymer matrix, carbon dots (CDs) derived from cow milk served as an antibacterial source and Ag nanoparticles were added to enhance the antibacterial activity. The prepared films were characterized by SEM, TEM, UTM, XRD, TGA-DTA, FT-IR, and water contact angle measurements. The prepared films showed good antibacterial activity against E.coli and S. aureus and a tensile strength value of about 41.85 MPa. In addition to these, the prepared films showed good biodegradable properties of about 86 % degradation in 60 days and good UV barrier properties. Finally, the films were tested for real-time application on sliced tomatoes, which also showed good results even after 4 days at room temperature.