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1.
Sci Total Environ ; 953: 176129, 2024 Sep 08.
Artigo em Inglês | MEDLINE | ID: mdl-39255933

RESUMO

Understanding the environmental fate of biodegradable plastics in aquatic systems is crucial, given the alarming amount of plastic waste and microplastic particles transported through aquatic pathways. In particular, there is a need to analyze the biodegradation of commercialized biodegradable plastics upon release from wastewater treatment plants into natural aquatic systems. This study investigates the biodegradation behaviors of poly(butylene adipate terephthalate) (PBAT) and poly(vinyl alcohol) (PVA) in wastewater, freshwater, and seawater. Biodegradation of PBAT and PVA assessed through biochemical oxygen demand (BOD) experiments and microcosm tests revealed that the type of aquatic system governs the biodegradation behaviors of each plastic, with the highest biodegradation rate achieved in wastewater for both PBAT and PVA (25.6 and 32.2 % in 30 d, respectively). Plastic release pathway from wastewater into other aquatic systems simulated by sequential incubation in different microcosms suggested that PBAT exposed to wastewater and freshwater before reaching seawater was more prone to degradation than when directly exposed to seawater. On the other hand, PVA displayed comparable biodegradation rate regardless of whether it was directly exposed to seawater or had passed through other environments beforehand. Metagenome amplicon sequencing of 16S rRNA genes revealed distinct community shifts dependent on the type of plastics in changing environments along the simulated aquatic pathway. Several bacterial species putatively implicated in the biodegradation of PBAT and PVA are discussed. Our findings underscore the significant influence of pollution routes on the biodegradation of PBAT and PVA, highlighting the potential for wastewater treatment to facilitate rapid degradation compared to direct exposure to pristine aquatic environments.

2.
Polymers (Basel) ; 16(17)2024 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-39274027

RESUMO

The utilization of biopolymers incorporated with antimicrobial agents is extremely interesting in the development of environmentally friendly functional materials for food packaging and other applications. In this study, the effect of calcium oxide (CaO) on the morphological, mechanical, thermal, and hydrophilic properties as well as the antimicrobial activity of carboxymethyl chitosan (CMCH) bio-composite films was investigated. The CMCH was synthesized from shrimp chitosan through carboxymethylation, whereas the CaO was synthesized via a co-precipitation method with polyethylene glycol as a stabilizer. The CMCH-CaO bio-composite films were prepared by the addition of synthesized CaO into the synthesized CMCH using a facile solution casting method. As confirmed by XRD and SEM, the synthesized CaO has a cubic shape, with an average crystalline size of 25.84 nm. The synthesized CaO exhibited excellent antimicrobial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) (>99.9% R). The addition of CaO into CMCH improved the mechanical and hydrophobic properties of the CMCH-CaO films. However, it resulted in a slight decrease in thermal stability. Notably, the CMCH-CaO10% films exhibited exceptional antimicrobial activity against E. coli (98.8% R) and S. aureus (91.8% R). As a result, such bio-composite films can be applied as an active packaging material for fruit, vegetable, or meat products.

3.
Polymers (Basel) ; 16(17)2024 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-39274144

RESUMO

Polyvinyl alcohol (PVA) is a popular material used in the packaging industry. However, it is vulnerable to moisture, which can affect its performance and durability. Introducing hydrophobic substances, such as tetraethyl orthosilicate (TEOS) and hexadecyltrimethoxysilane (HDTMS), on the top layer of PVA can help maintain the excellent properties of PVA under high-humidity conditions. The low compatibility of hydrophobic materials with the hydrophilic layers allows them to aggregate more easily. To overcome these issues, we focused on the effects of particle size when increasing the coating suspension's dispersibility. A carbon quantum dot (CQD) suspension is an appropriate novel solvent for hydrophobic TEOS/HDTMS coating suspensions because its particles are small and light and exhibit good dispersibility. The CQD suspension formed a smooth hydrophobic coating on the TEOS/HDTMS materials. Furthermore, the uniformly coated PVA with the CQD suspension exhibited a water contact angle of 110°. The water droplets remained intact without being absorbed, confirming the effectiveness of the surface coating facilitated by CQDs. These results suggested that CQDs improved the dispersibility and enhanced the coating quality of TEOS/HDTMS on PVA. Enhancing the hydrophobicity of PVA is ideal for applications in packaging and other fields.

4.
Foods ; 13(9)2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38731754

RESUMO

Despite the excellent oxygen barrier and biodegradability of polyvinyl alcohol (PVA), its poor physical properties owing to its inherent hydrophilicity limit its application. In this paper, we report a novel surface modification technique for PVA films, involving the control of the predrying conditions (i.e., amount of residual solvent) of the coated PVA film and adjusting the electrospinning process of hydrophobic polycaprolactone (PCL) nanofibers onto the PVA films. The residual solvent of the coated PVA film was varied by changing the predrying time. A shorter predrying time increased the residual solvent content significantly (p < 0.05) and the flexibility of the coated PVA film. Moreover, scanning electron microscopy depicted the improved physical binding of hydrophobic PCL nanofibers to the hydrophilic PVA surface with increased penetration depth to the PVA film with shorter drying times. The PVA/PCL composite films with different predrying times and electrospun PCL nanofibers exhibited an apparent increase in the contact angle from 8.3° to 95.1°. The tensile strength of the pure PVA film increased significantly (p < 0.05) from 7.5 MPa to 77.4 MPa and its oxygen permeability decreased from 5.5 to 1.9 cc/m2·day. Therefore, our newly developed technique is cost-effective for modifying the surface and physical properties of hydrophilic polymers, broadening their industrial applications.

5.
Int J Biol Macromol ; 271(Pt 2): 132495, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38763256

RESUMO

Incorporating starch, which is a potential biodegradable substitute for petroleum-based polymers, into conventional polymers is challenging owing to limitations in processability and weak-performing resulting materials. Herein, corn starch/polyvinyl alcohol (PVA) blend films (starch: PVA ratio of 50:50) were prepared via the solvent casting method using glycerol as a plasticizer and with varying concentrations of maleic acid as the crosslinking agent. Fourier transform infrared spectroscopy revealed the molecular interactions of the maleic acid crosslinker with the polymeric network of starch and PVA through an ester linkage. The properties of the films were strongly dependent on the maleic acid concentration. An increasing maleic acid concentration imparted hydrophobicity to the film; therefore, water swelling was significantly reduced, and water resistance was enhanced. The film containing 20 wt% maleic acid exhibited excellent barrier properties, with the lowest oxygen and water vapor transmission rates of 0.5 ± 0.2 cc/m2⋅day and 232.3 ± 5.4 g/m2⋅day, respectively. Moreover, the mechanical properties of the film improved with increasing crosslinking. This study demonstrates that the addition of maleic acid leads to an improvement in the overall performance of starch/PVA blend films. Therefore, maleic acid-crosslinked films can be used as barrier materials in food packaging applications.


Assuntos
Embalagem de Alimentos , Maleatos , Álcool de Polivinil , Amido , Álcool de Polivinil/química , Amido/química , Maleatos/química , Embalagem de Alimentos/métodos , Reagentes de Ligações Cruzadas/química , Interações Hidrofóbicas e Hidrofílicas , Água/química , Espectroscopia de Infravermelho com Transformada de Fourier , Permeabilidade , Plastificantes/química , Vapor
6.
Food Chem ; 445: 138772, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-38394908

RESUMO

The fabrication of coated papers using hydrophilic and biodegradable polymers is important for developing sustainable packaging materials with high barrier and superior mechanical properties. However, water, which is used as the solvent in the paper coating process using hydrophilic polymers, deforms the shape of the paper and deteriorates performance. Therefore, we propose a new coating process that treats Kraft paper (KP) with epichlorohydrin (ECH) as a binder before the coating process. Crosslinked polyvinyl alcohol is coated on the ECH-treated KP using a solution casting method. ECH maintains the shape of the paper and improves coating uniformity; significantly enhances interfacial interactions, which increases barrier properties and sealing strength; and extends the shelf life of biscuits by reducing oxygen and moisture permeability. An ecotoxicity test using Lolium multiflorum demonstrates an insignificant phytotoxicity level for the as-prepared coated papers. Thus, ECH-treated KP is a potential candidate for high-barrier food packaging.


Assuntos
Epicloroidrina , Água , Embalagem de Alimentos , Polímeros , Solventes
7.
Sci Total Environ ; 882: 163446, 2023 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-37075991

RESUMO

The extensive use of petroleum-based non-biodegradable plastics for various applications has led to global concerns regarding the severe environmental issues associated with them. However, biodegradable plastics are emerging as green alternatives to petroleum-based non-biodegradable plastics. Biodegradable plastics, which include bio-based and petroleum-based biodegradable polymers, exhibit advantageous properties such as renewability, biocompatibility, and non-toxicity. Furthermore, certain biodegradable plastics are compatible with existing recycling streams intended for conventional plastics and are biodegradable in controlled and/or predicted environments. Recycling biodegradable plastics before their end-of-life (EOL) degradation further enhances their sustainability and reduces their carbon footprint. Since the production of biodegradable plastic is increasing and these materials will coexist with conventional plastics for many years to come, it is essential to identify the optimal recycling options for each of the most prevalent biodegradable plastics. The substitution of virgin biodegradable plastics by their recyclates leads to higher savings in the primary energy demand and reduces global warming impact. This review covers the current state of the mechanical, chemical, and bio-recycling of post-industrial and post-consumer waste of biodegradable plastics and their related composites. The effects of recycling on the chemical structure and thermomechanical properties of biodegradable plastics are also reported. Additionally, the improvement of biodegradable plastics by blending them with other polymers and nanoparticles is comprehensively discussed. Finally, the status of bioplastic usage, life cycle assessment, EOL management, bioplastic market, and the challenges associated with the recyclability of biodegradable plastics are addressed. This review gives comprehensive insights into the recycling processes that may be employed for the recycling of biodegradable plastics.


Assuntos
Plásticos Biodegradáveis , Plásticos/química , Polímeros/metabolismo , Biopolímeros , Reciclagem , Indústrias
8.
Crit Rev Food Sci Nutr ; 63(23): 6464-6483, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-35099331

RESUMO

Packaging materials for microwave application should be generally designed based on products properties and processing conditions such as microwavability, susceptibility, processing condition, barrier properties, mechanical properties, storage condition, sustainability, convenience, and so on. Ready-to-eat products are packed in materials that can sustain thermal processing in an industrial oven and warming process in a household oven. In this context, high barrier polymers are versatile microwave packaging materials due to the microwave transparency (unlike metalized film) and high barrier. Additionally, microwave packaging materials used for ready-to-cook are intended to facilitate the microwave heating of the products in a domestic oven. The introduction of a functional feather to microwave packaging tends to improve the microwaving efficiency such as susceptor and shielding in the household oven or self-venting microwave packaging to safely release the internal steam. Furthermore, microwave-assisted thermal processing intends to control microbial contamination, requiring materials with adequate stability during processing and storage. The features of these materials are addressed in this review along with details on the basic requirements and advanced technologies for microwave packaging, microwave processing of prepackaged food, and migration testing. The prospects of microwave packaging materials in the near future are also discussed.


Assuntos
Temperatura Alta , Micro-Ondas , Culinária , Polímeros , Vapor , Embalagem de Alimentos
9.
Compr Rev Food Sci Food Saf ; 21(3): 2615-2638, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-35279943

RESUMO

The fourth industrial revolution (I4.0) intends to digitalize the product life cycle using smart technologies interconnected with web-based platforms. I4.0 elements can be employed to enable packaging 4.0 with improved productivity and efficiency. However, the applicability of I4.0 in packaging science has not been fully investigated due to the understanding gap regarding the I4.0 elements in packaging science. In addition, the evolution of market and customers' demands results in complexity, which requires a business model with a high level of precision. As packaging stays with goods from manufacturing to the consumer stage, the digitalization of the product life cycle using packaging can be realized. Herein, the implications of I4.0 on packaging science are discussed to identify the potential benefits of packaging 4.0 in various sectors, for example, manufacturing, materials, supply chain, retail, and postconsumer. In this study, packaging 4.0 is defined based on a framework comprised of packaging manufacturing, packaging and products, packaging and consumer, and packaging and sustainability (ecologically, economically, and socially). In addition, a decentralized model is introduced to realize a self-controlling concept using decentralized decision-making centers. In this context, packaging 4.0 can be enabled using the combination of horizontal integration of enterprises, vertical integration of enterprises, and end-to-end engineering. Smart devices, for example, sensors, indicators, actuators, and wearable smart devices, interconnected to the internet of things and the cloud is an efficient way to realize a decentralized paradigm. The implementation of an intelligent platform in the packaging 4.0 context enables decentralized data collection in the supply chain, in-store, and postpurchasing stages, which in turn realizes consistent life-cycle monitoring.


Assuntos
Embalagem de Alimentos , Embalagem de Alimentos/métodos
10.
Polymers (Basel) ; 15(1)2022 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-36616481

RESUMO

Owing to its biodegradability, non-toxicity, and biocompatibility, chitosan (Cs) is a ubiquitous biopolymer. However, applications of Cs are limited owing to the existence of strong inter- and intra-molecular hydrogen bonds within its network. To address this issue, we regenerated medium-molecular-weight Cs to enhance the physico-chemical and functional properties using a cationic approach. Accordingly, alkaline modification was employed to introduce an additional positive charge to the amine functional groups of Cs and moderately disintegrate the inter- and intra-hydrogen bonds. The chemical structure of Cs and regenerated chitosan (RCs) was confirmed through Fourier transform infrared and 1H-NMR spectroscopy. RCs showed higher zeta potential value compared to Cs. Additionally, using X-ray diffraction, RCs exhibited low crystallinity, which can be attributed to the repulsive force caused by the positive surface charge and the destruction of hydrogen bonds. The RCs exhibited stronger antioxidant activity than Cs. Furthermore, the minimum inhibition concentrations (MICs) of RCs against Escherichia coli and Staphylococcus aureus were reduced by almost four times compared with those of Cs. The superior functional properties of RCs can be attributed to the formation of a polycationic structure after alkaline modification. Thus, RCs can be introduced as potent agents for various biomedical purposes.

11.
Food Chem ; 351: 129362, 2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-33647698

RESUMO

A ligand film with citric acid (CA) on the surface as a biochelator was prepared via photografting. Polypropylene film was photochemically brushed by immobilizing glycidyl methacrylate onto the film surface (PP-g-GMA) in the presence of benzophenone. The ligand film (PP-g-GMA-g-CA) was developed via a ring-opening reaction between PP-g-GMA and CA. The chemical structure was examined using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Microstructure and grafting morphology were observed using scanning electron microscopy and atomic force microscopy, and brushed-like configuration and porous surface morphology were described. A large amount of carboxylic acid (215 ± 11 nm) was detected on the surface of PP-g-GMA-g-CA and afforded chelation of Fe3+ (215 ± 11 nm). This ligand film exhibited chelating activity in vitamin C and virgin olive oil (p < 0.05), which extended the shelf-life of these foods. Moreover, overall migration analysis demonstrated that it can be considered as a non-migratory antioxidant.


Assuntos
Antioxidantes/química , Quelantes/química , Processos Fotoquímicos , Polipropilenos/química , Ácido Ascórbico/química , Compostos de Epóxi/química , Metacrilatos/química
12.
Polymers (Basel) ; 13(5)2021 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-33673483

RESUMO

To improve the dimensional thermal stability of polyethylene terephthalate (PET), a poly(ethylene glycol 1,4-cyclohexane dimethylene (CHDM) isosorbide (ISB) terephthalate) (PEICT) known as ECOZEN®T110 (EZT) was introduced into PET using a melt blending technique. The miscibility, morphology, and thermal properties of the PET/EZT samples were investigated. The introduction of amorphous EZT into semi-crystalline PET increased the glass transition temperature (Tg) but decreased the crystallinity, which could be related to the transesterification reaction. By adding EZT contents up to 20%, the PET/EZT samples showed a single Tg, which indicated the miscibility between PET and EZT. However, two Tg values were observed in the PET/EZT samples with higher EZT contents (30-70%), indicating partial miscibility. This may have been due to the slightly different rheological and thermodynamic parameters that were affected by a higher ratio of bulky (rigid ISB and ductile CHDM) groups in EZT. However, the heat distortion temperature of the PET/EZT samples remarkably increased, which indicated that the dimensional stability was truly enhanced. Although the crystallinity of the PET/EZT samples decreased with increasing EZT content, the tensile strength and Young's modulus decreased slightly. Based on these results, the as-prepared PET/EZT samples with high dimensional stability can be used as a high-temperature polymeric material in various applications.

13.
Microb Pathog ; 149: 104290, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32492458

RESUMO

Solvothermal synthesis was used to investigate the formation of zinc oxide (ZnO) nanoparticles (NPs). A series of ZnO NPs was synthesized with different relative ratios of didodecyldimethylammonium bromide (DDAB) and zinc nitrate (ZN). The variation in the molarity influenced the crystallinity, size, and morphology of the obtained ZnO NPs. X-ray diffraction, Fourier-transform infrared spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, and zeta potential analysis were used to study the characteristic features of the ZnO NPs. The ZnO surface charge, size, and morphological structure were highly reliant on the concentrations of DDAB and ZN. With increasing relative ratio of DDAB to ZN, the particle size of ZnO NPs decreased and the surface charge increased to higher positive value. The ZnO NPs synthesized with cationic liquid DDAB presented enhanced performance in preventing the growth of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) strains. The antibacterial activity of ZnO NPs have direct contact with the microbial cell wall resulting in destruction of bacterial cell integrity, release of antimicrobial Zn2+ ions, and induce cell death. This is due to the positively charged smaller ZnO NPs, prepared with DDAB cationic surfactant, effectively acting as an antimicrobial agent against food-borne pathogenic bacteria.


Assuntos
Nanopartículas Metálicas , Nanopartículas , Óxido de Zinco , Antibacterianos/farmacologia , Bactérias , Escherichia coli , Testes de Sensibilidade Microbiana , Espectroscopia de Infravermelho com Transformada de Fourier , Staphylococcus aureus , Difração de Raios X , Óxido de Zinco/farmacologia
14.
Mater Sci Eng C Mater Biol Appl ; 111: 110781, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32279809

RESUMO

A series of nylon (NY)/linear low-density polyethylene (LLDPE) containing calcined corals (NY/LL-CORALS) composite films were prepared using the cast extrusion method. We investigated the effect of different contents of incorporated calcined corals on the physical properties and antimicrobial activity of the composite films as well as their feasibility for milk storage applications. The results indicated that the main compound in calcined corals was calcium oxide (CaO). As the calcined corals content increased, the crystallinity of the composite films slightly decreased, but no significant changes in their thermal stability and permeability were observed. The NY/LL-CORALS composite films exhibited excellent antimicrobial performance against Escherichia coli and Staphylococcus aureus. Notably, the NY/LL-CORALS packaging significantly extended the lag time of bacteria and delayed the bacterial growth cycle in milk during storage. Thus, the NY/LL-CORALS composite films could be a potential food packaging material that could prolong the shelf life of fresh food.


Assuntos
Antozoários/química , Anti-Infecciosos/química , Embalagem de Alimentos/métodos , Leite/microbiologia , Animais , Anti-Infecciosos/farmacologia , Compostos de Cálcio/química , Escherichia coli/efeitos dos fármacos , Interações Hidrofóbicas e Hidrofílicas , Nylons/química , Óxidos/química , Polietileno/química , Staphylococcus aureus/efeitos dos fármacos , Temperatura
15.
Mater Sci Eng C Mater Biol Appl ; 107: 110193, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31761189

RESUMO

In this study, natural waste of marine corals was calcined to prepare an antimicrobial agent. Energy-dispersive X-ray fluorescence spectroscopy showed that the major element and compound of calcined corals were Ca and CaO, respectively, while X-ray photoelectron spectroscopy revealed the occurrence of more than one oxygen species (O1s) on the surface of calcined corals, which was ascribed to the presence of MgO. Scanning electron microscopy imaging showed that calcined corals had a rough surface and an irregular shape, and the particle size distribution indicated that the average particle size of the calcined corals was 7.3 µm. The calcined corals exhibited large zones of inhibition against gram-positive (Staphylococcus aureus) and gram-negative (Escherichia coli) bacteria as well as a fungus (Penicillium sp.), in the antimicrobial tests using well diffusion method. Notably, as a membrane-active and species-specific agent, pronounced antimicrobial activity for calcined corals was observed against S. aureus. Our newly developed bioactive calcined corals could be the potential antimicrobial agents in medical, biological, and food packaging applications.


Assuntos
Antozoários/química , Anti-Infecciosos/química , Compostos de Cálcio/química , Óxidos/química , Animais , Antozoários/metabolismo , Anti-Infecciosos/farmacologia , Cálcio/química , Testes de Sensibilidade a Antimicrobianos por Disco-Difusão , Escherichia coli/efeitos dos fármacos , Tamanho da Partícula , Penicillium/efeitos dos fármacos , Pós/química , Staphylococcus aureus/efeitos dos fármacos
16.
Curr Pharm Des ; 25(34): 3645-3663, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31656147

RESUMO

Water pollution due to waste effluents of the textile industry is seriously causing various health problems in humans. Water pollution with pathogenic bacteria, especially Escherichia coli (E. coli) and other microbes is due to the mixing of fecal material with drinking water, industrial and domestic sewage, pasture and agricultural runoff. Among the chemical pollutants, organic dyes due to toxic nature, are one of the major contaminants of industrial wastewater. Adequate sanitation services and drinking quality water would eliminate 200 million cases of diarrhea, which results in 2.1 million less deaths caused by diarrheal disease due to E. coli each year. Nanotechnology is an excellent platform as compared to conventional treatment methods of water treatment and remediation from microorganisms and organic dyes. In the current study, toxicity and carcinogenicity of the organic dyes have been studied as well as the remediation/inactivation of dyes and microorganism has been discussed. Remediation by biological, physical and chemical methods has been reviewed critically. A physical process like adsorption is cost-effective, but can't degrade dyes. Biological methods were considered to be ecofriendly and cost-effective. Microbiological degradation of dyes is cost-effective, eco-friendly and alternative to the chemical reduction. Besides, certain enzymes especially horseradish peroxidase are used as versatile catalysts in a number of industrial processes. Moreover, this document has been prepared by gathering recent research works related to the dyes and microbial pollution elimination from water sources by using heterogeneous photocatalysts, metal nanoparticles catalysts, metal oxides and enzymes.


Assuntos
Biodegradação Ambiental , Corantes/toxicidade , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/toxicidade , Carcinógenos/toxicidade , Escherichia coli , Humanos , Nanotecnologia , Indústria Têxtil
17.
Polymers (Basel) ; 11(9)2019 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-31480385

RESUMO

A series of PLA/ZnO bionanocomposite films were prepared by introducing positively surface charged zinc oxide nanoparticles (ZnO NPs) into biodegradable poly(lactic acid) (PLA) by the solvent casting method, and their physical properties and antibacterial activities were evaluated. The physical properties and antibacterial efficiencies of the bionanocomposite films were strongly dependent on the ZnO NPs content. The bionanocomposite films with over 3% ZnO NPs exhibited a rough surface, poor dispersion, hard agglomerates, and voids, leading to a reduction in the crystallinity and morphological defects. With the increasing ZnO NPs content, the thermal stability and barrier properties of the PLA/ZnO bionanocomposite films were decreased while their hydrophobicity increased. The bionanocomposite films showed appreciable antimicrobial activity against Staphylococcus aureus and Escherichia coli. Especially, the films with over 3% of ZnO NPs exhibited a complete growth inhibition of E. coli. The strong interactions between the positively charged surface ZnO NPs and negatively charged surface of the bacterial membrane led to the production of reactive oxygen species (ROS) and eventually bacterial cell death. Consequently, these PLA/ZnO bionanocomposite films can potentially be used as a food packaging material with excellent UV protective and antibacterial properties.

18.
Mater Sci Eng C Mater Biol Appl ; 105: 110016, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31546351

RESUMO

Allyl isothiocyanate (AITC) is a highly volatile organic compound that is a potential antibacterial agent against food spoilage bacteria. Naturally formed halloysite nanotubes (HNTs) have a length of 1 µm and diameter ranging from 10 to 50 nm. The biocompatibility of HNT allows safe release of drugs to bacterial cells at a relatively low concentration compared to other systems. We encapsulated AITC inside HNTs that were then coated with sodium polyacrylate (PA). The HNT-AITC-PA nanocomposites (NCs) were characterized by Fourier-transform infrared spectroscopy, thermal gravimetric, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses. In vitro antibacterial activity was evaluated against gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria capable of food spoilage. HNT-AITC-PA NCs effectively inhibited the growth of both bacteria. The activity was pronounced against E. coli at 100 µg/mL, with concentrations of 25 µg/mL and 200 µg/mL reducing the viable cell population by 41% and 96%, respectively. Thus, HNT-AITC-PA NCs are a novel and promising material against food spoilage bacteria for use in active antibacterial food packaging.


Assuntos
Acrilatos/química , Antibacterianos/farmacologia , Argila/química , Conservação de Alimentos , Isotiocianatos/farmacologia , Difusão Dinâmica da Luz , Escherichia coli/efeitos dos fármacos , Escherichia coli/ultraestrutura , Testes de Sensibilidade Microbiana , Nanocompostos/química , Nanotubos/química , Tamanho da Partícula , Espectroscopia de Infravermelho com Transformada de Fourier
19.
Mater Sci Eng C Mater Biol Appl ; 98: 717-725, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30813076

RESUMO

Mg-doped zinc oxide (Zn1-xMgxO, where x = 0.000, 0.001, 0.003, 0.005, and 0.010 M) nanoparticles (MgZnO NPs) were synthesized via a co-precipitation method and subjected to various analyses for application as functional additives in food packaging. The MgZnO NPs were successfully formed at approximately 360 °C and showed an increase in the optical band gap with respect to the increase in the concentration of Mg doping. The X-ray diffraction and scanning electron microscopy analyses of MgZnO NPs confirmed the formation of hexagonal wurtzite structure and rod-like morphology. X-ray photoelectron spectra revealed that the Mg (1s) peaks centered at 1303.35 and 1303.38 eV were ascribed to the presence of Mg2+ replacing Zn2+. Transmission electron microscopy images showed rod shapes with the length of 208-650nm and width of 84-142 nm. Various concentrations of synthesized MgZnO NPs were investigated against a gram-negative (Escherichia coli - DH5α) bacterial strain under light and dark conditions. Among the studied samples, 0.010 M MgZnO NPs of concentration 3 mg/mL showed the best antibacterial activity under the light condition. MgZnO NPs revealed uneven ridges on the outer surface, which promote the diffusion ability of Zn2+ and increased production of reactive oxygen species, and consequently lead to bacterial lysis. Furthermore, this study demonstrates excellent feasibility for the application of MgZnO NPs as fillers with good antibacterial activity, especially in antimicrobial food packaging applications.


Assuntos
Antibacterianos/química , Luz , Magnésio/química , Nanopartículas Metálicas/química , Óxido de Zinco/química , Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Nanotubos/química , Espécies Reativas de Oxigênio/metabolismo
20.
Int J Biol Macromol ; 112: 530-536, 2018 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29391228

RESUMO

In the present work, we report the synthesis of chitosan:starch­silver nanoparticle (Cht:St-AgNPs) coated papers for antimicrobial packaging applications. The starch-assisted synthesized St-AgNPs are spherical in shape with an average particle size of 7 nm. Chitosan was mixed into the synthesized St-AgNPs solution with different ratios of 9:1, 8:2, 7:3, and 5:5 by weight. Further, the influence of different ratios of Cht:St-AgNPs on the various paper properties such as mechanical properties, water and oil resistance, and antimicrobial activities was investigated. It was observed that the properties of the coated papers were strongly dependent on the composition of Cht:St-AgNPs. The Cht:St-AgNPs-coated paper prepared with the ratio of 9:1 showed excellent mechanical properties and good resistance properties against water and oil. The Cht:St-AgNPs coated papers showed a remarkable enhancement in mechanical strength, oil and water resistance, and antibacterial and antifungal activity, which can make them a potential candidate for functional antimicrobial packaging applications.


Assuntos
Anti-Infecciosos/farmacologia , Quitosana/química , Nanopartículas Metálicas/química , Papel , Prata/farmacologia , Adsorção , Bactérias/efeitos dos fármacos , Fungos/efeitos dos fármacos , Nanopartículas Metálicas/ultraestrutura , Testes de Sensibilidade Microbiana , Espectrofotometria Ultravioleta , Água
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