Starch-Capped Silver Nanoparticles Impregnated into Propylamine-Substituted PVA Films with Improved Antibacterial and Mechanical Properties for Wound-Bandage Applications

Enhanced antibacterial properties of polyvinyl alcohol/starch/chitosan films with NiO-CuO nanoparticles for food packaging

Packaging is very important to maintain the quality of food and prevent the growth of microbes. Therefore, the use of food packaging with antimicrobial properties protects the food from the growth of microorganisms. In this study, antibacterial nanocomposite films of polyvinyl alcohol/starch/chitosan (PVA/ST/CS) together with nickel oxide-copper oxide nanoparticles (NiO-CuONPs) are prepared for food packaging. NiO-CuONPs were synthesized by the co-precipitation method, and structural characterization of nanoparticles (NPs) was carried out by XRD, FTIR, and SEM techniques. Composites of PVA/ST/CS, containing different percentages of NPs, were prepared by casting and characterized by FTIR and FESEM. The mechanical properties, diffusion barrier, and thermal stability were determined. The nanoparticles have a round structure with an average size of 6.7 ± 1.2 nm. The cross-section of PVA/ST/CS film is dense, uniform, and without cracks. In the mechanical tests, the addition of NPs up to 1% improved the mechanical properties (TS = 31.94 MPa), while 2% of NPs lowered TS to 14.76 MPa. The fibroblast cells toxicity and the films antibacterial activity were also examined. The films displayed stronger antibacterial effects against Gram-positive bacteria (Staphylococcus aureus) compared to Gram-negative bacteria (Escherichia coli). Furthermore, these films have no toxicity to fibroblast cells and the survival rate of these cells in contact with the films is more than 84%. Therefore, this film is recommended for food packaging due to its excellent mechanical and barrier properties, good antibacterial activity, and non-toxicity.

Flexible, foldable and transparent SERS film with high sensitivity and signal homogeneity via silver ion exchange and in-situ reduction

The adhesion between metal plasma and substrate was the key of surface-enhanced Raman scattering (SERS) technology. The preparation of ideal SERS substrate with multiple advantages such as high sensitivity and good signal reproducibility was still the focus of research. A flexible foldable and transparent fluorinated polyimide/silver NPs (FPI@Ag) SERS film was fabricated by the ion exchange and in-situ reduction method in this work. The effects of KOH hydrolysis time, AgNO3 ion exchange time and concentration, the type and concentration of reducing agents on the SERS performance of the FPI@Ag film were systematically discussed. As a result, the hydrolysis time of KOH affected the thickness of the metallic silver layer, the concentration of AgNO3 affected the size and spacing of Ag NPs, and the Raman signal of was remarkably enhanced when borane dimethylamine complex (DMAB) was used as reducing agent. When the detection limit of 4-Aminothiophenol was as low as 1 × 10-11 mol·L-1, the obvious Raman characteristic peak still appeared. The enhancement factor (EF) was up to 9.4 × 107. The linear quantification range was achieved in the range from 10-3-10-11 mol·L-1, R2 = 0.9987. In addition, we also performed multi-cycle bending and torsion test on the FPI@Ag film, and obtained stable Raman signals. The prepared FPI@Ag film can be attached to the surface of uneven samples, which can be used for on-site Raman detection and analysis.

Recent advances of antibacterial starch-based materials

Starch has attracted a lot of attention because it is biodegradable, renewable, nontoxic and low cost. By adding antibacterial substances to starch, starch-based materials have antibacterial properties. The composite with other materials can improve the comprehensive performance of starch-based materials, thus broadening the application field of the material. In this paper, we focus on antibacterial starch-based materials and review their preparation and applications. It was found that antibacterial starch-based materials were most widely used in packaging, followed by medicine, and the research on smart starch-based materials was relatively less. This review may provide some reference value for subsequent studies of starch-based materials.

PVA/Chitosan Thin Films Containing Silver Nanoparticles and Ibuprofen for the Treatment of Periodontal Disease

Local delivery of drugs or antimicrobial agents is a suitable approach in the management of periodontitis when the infection is localized deep in the pockets and does not adequately respond to mechanical debridement and/or systemic antibiotic treatment. In this context, the objective of this study was to prepare new biocomposite films with antimicrobial, anti-inflammatory, and good mechanical properties to be applied in periodontal pockets. The composite film is eco-friendly synthesized from poly(vinyl alcohol) (PVA) cross-linked with oxidized chitosan (OxCS). Silver nanoparticles (AgNps) were inserted during film synthesis by adding freshly chitosan-capped AgNps colloidal solution to the polymer mixture; the addition of AgNps up to 1.44 wt.% improves the physico-chemical properties of the film. The characterization of the films was performed by FT-IR, atomic mass spectrometry, X-ray spectroscopy, and SEM. The films displayed a high swelling ratio (162%), suitable strength (1.46 MPa), and excellent mucoadhesive properties (0.6 N). Then, ibuprofen (IBF) was incorporated within the best film formulation, and the IBF-loaded PVA/OxCS-Ag films could deliver the drug in a sustained manner up to 72 h. The biocomposite films have good antimicrobial properties against representative pathogens for oral cavities. Moreover, the films are biocompatible, as demonstrated by in vitro tests on HDFa cell lines.

Multifunctional applications of natural polysaccharide starch and cellulose: An update on recent advances

The emergence of clinical complications and therapeutic challenges for treating various diseases necessitate the discovery of novel restorative functional materials. Polymer-based drug delivery systems have been extensively reported in the last two decades. Recently, there has been an increasing interest in the progression of natural biopolymers based controlled therapeutic strategies, especially in drug delivery and tissue engineering applications. However, the solubility and functionalisation due to their complex network structure and intramolecular bonding seem challenging. This review explores the current advancement and prospects of the most promising natural polymers such as cellulose, starch and their derivatives-based drug delivery vehicles like hydrogels, films and composites, in combating major ailments such as bone infections, microbial infections, and cancers. In addition, selective drug targeting using metal-drug (MD) and MD-based polymeric missiles have been exciting but challenging for its application in cancer therapeutics. Owing to high biocompatibility of starch and cellulose, these materials have been extensively evaluated in biomedical and pharmaceutical applications. This review presents a detailed impression of the current trends for the construction of biopolymer-based tissue engineering, drug/gene/protein delivery vehicles.

Comparative Study of Crystallization, Mechanical Properties, and In Vitro Cytotoxicity of Nanocomposites at Low Filler Loadings of Hydroxyapatite for Bone-Tissue Engineering Based on Poly(l-lactic acid)/Cyclo Olefin Copolymer

A poly(l-lactic acid)/nanohydroxyapatite (PLLA/nHA) scaffold works as a bioactive, osteoconductive scaffold for bone-tissue engineering, but its low degradation rate limits embedded HA in PLLA to efficiently interact with body fluids. In this work, nano-hydroxyapatite (nHA) was added in lower filler loadings (1, 5, 10, and 20 wt%) in a poly(l-lactic acid)/cyclo olefin copolymer10 wt% (PLLA/COC10) blend to obtain novel poly(l-lactic acid)/cyclo olefin copolymer/nanohydroxyapatite (PLLA/COC10-nHA) scaffolds for bone-tissue regeneration and repair. Furthermore, the structure-activity relationship of PLLA/COC10-nHA (ternary system) nanocomposites in comparison with PLLA/nHA (binary system) nanocomposites was systematically studied. Nanocomposites were evaluated for structural (morphology, crystallization), thermomechanical properties, antibacterial potential, and cytocompatibility for bone-tissue engineering applications. Scanning electron microscope images revealed that PLLA/COC10-nHA had uniform morphology and dispersion of nanoparticles up to 10% of HA, and the overall nHA dispersion in matrix was better in PLLA/COC10-nHA as compared to PLLA/nHA. Fourier transformation infrared spectroscopy (FTIR), powder X-ray diffraction (XRD), and differential scanning calorimetry (DSC) studies confirmed miscibility and transformation of the α-crystal form of PLLA to the ά-crystal form by the addition of nHA in all nanocomposites. The degree of crystallinity (%) in the case of PLLA/COC10-nHA 10 wt% was 114% higher than pure PLLA/COC10 and 128% higher than pristine PLLA, indicating COC and nHA are acting as nucleating agents in the PLLA/COC10-nHA nanocomposites, causing an increase in the degree of crystallinity (%). Moreover, PLLA/COC10-nHA exhibited 140 to 240% (1-20 wt% HA) enhanced mechanical properties in terms of ductility as compared to PLLA/nHA. Antibacterial activity results showed that 10 wt% HA in PLLA/COC10-nHA showed substantial activity against P. aeruginosa, S. aureus, and L. monocytogenes. In vitro cytocompatibility of PLLA/COC10 and PLLA nanocomposites with nHA osteoprogenitor cells (MC3T3-E1) and bone mesenchymal stem cells (BMSC) was evaluated. Both cell lines showed two- to three-fold enhancement in cell viability and 10- to 30-fold in proliferation upon culture on PLLA/COC10-nHA as compared to PLLA/nHA composites. It was observed that the ternary system PLLA/COC10-nHA had good dispersion and interfacial interaction resulting in improved thermomechanical and enhanced osteoconductive properties as compared to PLLA/nHA.

Statistically Optimized Production of Saccharides Stabilized Silver Nanoparticles Using Liquid-Plasma Reduction Approach for Antibacterial Treatment of Water

Various conventional approaches have been reported for the synthesis of nanomaterials without optimizing the role of synthesis parameters. The unoptimized studies not only raise the process cost but also complicate the physicochemical characteristics of the nanostructures. The liquid–plasma reduction with optimized synthesis parameters is an environmentally friendly and low-cost technique for the synthesis of a range of nanomaterials. This work is focused on the statistically optimized production of silver nanoparticles (AgNPs) by using a liquid–plasma reduction process sustained with an argon plasma jet. A simplex centroid design (SCD) was made in Minitab statistical package to optimize the combined effect of stabilizers on the structural growth and UV absorbance of AgNPs. Different combinations of glucose, fructose, sucrose and lactose stabilizers were tested at five different levels (−2, −1, 0, 1, 2) in SCD. The effect of individual and mixed stabilizers on AgNPs growth parameters was assumed significant when p-value in SCD is less than 0.05. A surface plasmon resonance band was fixed at 302 nm after SCD optimization of UV results. A bond stretching at 1633 cm⁻¹ in FTIR spectra was assigned to C=O, which slightly shifts towards a larger wavelength in the presence of saccharides in the solution. The presence of FCC structured AgNPs with an average size of 15 nm was confirmed from XRD and EDX spectra under optimized conditions. The antibacterial activity of these nanoparticles was checked against Staphylococcus aureus and Escherichia coli strains by adopting the shake flask method. The antibacterial study revealed the slightly better performance of AgNPs against Staph. aureus strain than Escherichia coli.

Anticancer and Antimicrobial Activity Evaluation of Cowpea-Porous-Starch-Formulated Silver Nanoparticles

Health issues involving inadequate treatment of diseases such as cancer and microbial infections continue to be the subject of much ongoing recent research. Biosynthesized silver nanoparticles (AgNPs) were characterized using Transmission Electron Microscopy (TEM), Zeta Sizer, Ultraviolet (UV), and Fourier Transform Infrared (FTIR) spectroscopy. Their antimicrobial activity was evaluated on selected Gram-positive and Gram-negative bacterial strains, using the disc diffusion and broth dilution assays. Cell viability profiles were evaluated using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) and apoptosis studies on selected human noncancer and cancer cells. The biosynthesized AgNPs were evaluated to be spherical clusters, with sizes between 40 and 70 nm. The absorption peak at 423 nm and the presence of polyphenols confirmed the synthesis and stabilization of these tested AgNPs. The AgNPs showed a good stability of −23.9 ± 1.02 mV. Good antimicrobial activity (6.0–18.0 mm) was seen on all tested bacteria at a minimum inhibitory concentration (MIC) ranging from 5 to 16 μg/ml, with the highest activity seen against Gram-negative Escherichia coli (18 ± 0.5 mm), and the lowest activity was seen against Gram-positive Listeria monocytogenes (6.0 ± 0.4 mm) after treatment with the AgNPs. These NPs showed a concentration-dependent and cell-specific cytotoxicity with low IC50 values (41.7, 56.3, and 63.8 μg/ml). The NPs were well tolerated by tested cells as indicated by a more than 50% cell viability at the high dose tested and low apoptotic indices (<0.2). These findings indicated that these biosynthesized AgNPs showed great potential as effective antibacterial agents and anticancer drug delivery modalities.

Study on Structure, Thermal Behavior and Viscoelastic Properties of Nanodiamond-Reinforced Poly (vinyl alcohol) Nanocomposites

In this work, advanced polymer nanocomposites comprising of polyvinyl alcohol (PVA) and nanodiamonds (NDs) were developed using a single-step solution-casting method. The properties of the prepared PVA/NDs nanocomposites were investigated using Raman spectroscopy, small- and wide-angle X-ray scattering (SAXS/WAXS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). It was revealed that the tensile strength improved dramatically with increasing ND content in the PVA matrix, suggesting a strong interaction between the NDs and the PVA. SEM, TEM, and SAXS showed that NDs were present in the form of agglomerates with an average size of ~60 nm with primary particles of diameter ~5 nm. These results showed that NDs could act as a good nanofiller for PVA in terms of improving its stability and mechanical properties.

Aramid nanofibers reinforced polyvinyl alcohol/tannic acid hydrogel with improved mechanical and antibacterial properties for potential application as wound dressing

The poor mechanical properties and the lack of antibacterial ability of hydrogels limit their applications as wound dressing. In this work, a novel and high strength polyvinyl alcohol (PVA)/tannic acid (TA) hydrogel with aramid nanofibers (ANFs) as the reinforcement was successfully fabricated. The surface composition and microstructure of the hydrogel were characterized by fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The mechanical properties, water content and swelling behaviors, as well as the antibacterial abilities and biocompatibility of the prepared hydrogel were systematically analyzed as well. The results indicated that the prepared hydrogel showed excellent mechanical properties. The tensile strength and elongation of the prepared hydrogel can respectively reach 2.06 MPa and 950% owing to the formation of the multiple H bonds among PVA, ANFs and TA. What's more, PVA/ANFs/TA (PAT) hydrogel possessed shape memory and broad-spectrum antibacterial properties against S. aureus, E. coli and P. aeruginosa (100% antibacterial rate) at the concentration of 12 mg/mL. PAT hydrogels also had low cytotoxicity, affirming its potential application as wound dressing.

Polymer-Based Graphene Derivatives and Microwave-Assisted Silver Nanoparticles Decoration as a Potential Antibacterial Agent

Nanocomposites obtained by the decoration of graphene-based materials with silver nanoparticles (AgNPs) have received increasing attention owing to their antimicrobial activity. However, the complex synthetic methods for their preparation have limited practical applications. This study aims to synthesize novel NanoHybrid Systems based on graphene, polymer, and AgNPs (namely, NanoHy-GPS) through an easy microwave irradiation approach free of reductants and surfactants. The polymer plays a crucial role, as it assures the coating layer/substrate compatibility making the platform easily adaptable for a specific substrate. AgNPs' loading (from 5% to 87%) can be tuned by the amount of Silver salt used during the microwave-assisted reaction, obtaining spherical AgNPs with average sizes of 5-12 nm homogeneously distributed on a polymer-graphene nanosystem. Interestingly, microwave irradiation partially restored the graphene sp2 network without damage of ester bonds. The structure, morphology, and chemical composition of NanoHy-GPS and its subunits were characterized by means of UV-vis spectroscopy, thermal analysis, differential light scattering (DLS), Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive X-ray analysis (EDX), Atomic Force Microscopy (AFM), and High-Resolution Transmission Electron Microscopy (HRTEM) techniques. A preliminary qualitative empirical assay against the typical bacterial load on common hand-contacted surfaces has been performed to assess the antibacterial properties of NanoHy-GPS, evidencing a significative reduction of bacterial colonies spreading.

Silver-Polystyrene (Ag/PS) Nanocomposites Doped with Polyvinyl Alcohol (PVA)-Fabrication and Bactericidal Activity

In the present work, we report the studies on perfectly homogeneous nanocomposites composed of polystyrene-grafted silver nanoparticles (Ag@PS) as a bioactive fulfilment and a mixture of polystyrene (PS) and polyvinyl alcohol (PVA) as a matrix. The procedure developed by our group of the nanocomposites’ preparation consists of three steps: synthesis of narrow-dispersive AgNPs (5.96 ± 1.02 nm); grafting of narrowly dispersed polystyrene onto the surface of AgNPs; thermoforming with a mixture of PS/PVA. Kirby-Bauer (K-B) and Dynamic Shake Flask (DSF) assays revealed high antibacterial activity against a series of Gram(−) and Gram(+) bacteria strains of the fabricated nanocomposites at low silver content (0.5%). We showed that the doping of Ag/PS composites with PVA increases the antibacterial activity of composites. The hydrophilic component in the nanocomposites enables easier water migration inside the polymer matrix, which makes releasing silver nanoparticles and silver ions to the environment facile.