Assessing morphological effect on antimicrobial activity using needleless electrospinning

This study utilized polyethylene glycol (PEG) as a compatibilizer, and prepared nanocrystalline cellulose (NCC) reinforced polylactic acid (PLA) nanocomposite films by blown film extrusion. The physical properties, including the mechanical performance, barrier characteristics, processing flow properties, and thermal properties, were evaluated, and the microstructure was estimated. The consequences showed that the NCC could significantly enhance the physical properties of the PLA nanocomposite film. When the NCC concentration was 3%, the tensile strength of the composite film was 45.02 MPa, and the melting index was 1.03 g/min, which were 17.85% and 6.40% greater than those of the PLA/PEG composite film, respectively. The oxygen transmission rate (OTR) of the composite film with NCC was 5.438 × 10−4 cm3/(m2·d·Pa), which was 96.70% lower compared to the composite film without NCC. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analysis showed that adding NCC and PEG could increase the stability of the PLA/PEG/NCC composite film, but NCC had little impact on the thermal properties of the PLA/PEG/NCC composite film. Scanning electron microscopy (SEM) analysis showed that the PLA, PEG and NCC had better compatibility and dispersion.

640 Mussel-inspired Polydopamine-assisted Bromelain Immobilization onto Electrospun Fibrous Membrane for Potential Application as Wound Dressing

Nanocrystalline cellulose (NCC) was used to improve the anti-yellowing property of polyurethane (PU). The NCC was modified with 3-glycidoxypropyltrimethoxysilane (GPTMS) to enhance its compatibility with PU, and the surface-modified NCC was characterized by contact angle (CA), X-ray powder diffraction (XRD), and thermogravimetric analysis (TG). NCC/PU composite was examined by scanning electron microscopy (SEM), Fourier transform infrared spectrophotometer (FT-IR), and X-ray photoelectron spectroscopy (XPS). Anti-yellowing property of the NCC/PU composite was determined using the Chinese National Standard GB/T 23999-2009. The results showed that the CA between modified NCC and PU was decreased by 26.6% (with 8% GPTMS). The crystal structure of NCC was inconspicuously affected by the surface modification, while the thermal stability of modified NCC was enhanced by 5.5%. The surface-modified NCC particles were homogeneously dispersed in the PU (as shown in the SEM micrographs). FT-IR and O1s XPS survey spectra of NCC/PU composites indicated the oxidation of hydroxyl groups and the production of carbonyl groups, while the photochemical degradation of PU resulting from UV radiation was prevented by the addition of NCC. The anti-yellowing property of the NCC/PU composite with 1.5% surface-modified NCC was increased by 57.7% and the contribution was decreased when the content of modified NCC was 2.0%.

Preparation and characterization of poly (lactic acid)-chitosan blend fibrous electrospun membrane loaded with bioactive glass nanoparticles for guided bone/tissue regeneration

A bio-plastic composite film based on nanocrystalline cellulose-zinc oxide reinforced poly (lactic acid) with enhanced UV-shielding effect and antibacterial activity for food packaging applications

A propolis enriched polyurethane-hyaluronic acid nanofibrous wound dressing with remarkable antibacterial and wound healing activities

Fabrication of eugenol loaded gelatin nanofibers by electrospinning technique as active packaging material

In this study, nanocomposite hydrogels composed of sodium carboxymethylated starch (CMS)-containing CuO nanoparticles (CMS@CuO) were synthesized and used as experimental wound healing materials. The hydrogels were fabricated by a solution-casting technique using citric acid as a crosslinking agent. They were characterized by Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA) to evaluate their physicochemical properties. In addition, swelling, antibacterial activities, antioxidant activities, cytotoxicity, and in vivo wound healing were investigated to evaluate the wound healing potential of the CMS@CuO nanocomposite hydrogels. Growth inhibition of the Gram-positive and Gram-negative pathogens, antioxidant activity, and swelling were observed in the CMS@CuO nanocomposite hydrogels containing 2 wt.% and 4 wt.% CuO nanoparticles. The hydrogel containing 2 wt.% CuO nanoparticles displayed low toxicity to human fibroblasts and exhibited good biocompatibility. Wounds created in rats and treated with the CMS@2%CuO nanocomposite hydrogel healed within 13 days, whereas wounds were still present when treated for the same time-period with CMS only. The impact of antibacterial and antioxidant activities on accelerating wound healing could be ascribed to the antibacterial and antioxidant activities of the nanocomposite hydrogel. Incorporation of CuO nanoparticles in the hydrogel improved its antibacterial properties, antioxidant activity, and degree of swelling. The present nanocomposite hydrogel has the potential to be used clinically as a novel wound healing material.

Nanocrystalline cellulose (NCCs) was synthesized from pruning waste of Zizyphus spina christi using H2SO4 (64 %, wt/wt) under suitable hydrolysis conditions. The crystal growth of the NCCs from nano- into identical micrometric-scaled needles confirmed their ability to self-assembly. The aspect ratio of the NCCs was estimated using optical microscopy for needles, and by scanning electron microscopy (SEM) for powder, while their crystallinity index (CI), crystallite size (CS) and lattice spacing (LS) were estimated by X-ray diffraction (XRD). Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were also performed. The XRD-diffractogram of the NCCs was similar to that known for cellulose I. The CI of the NCCs was much higher (86.75%) than that for cellulose I. The CS of the NCCs was 2.78 nm that is smaller than that for cellulose I. The distance between the strata within the NCCs (LS) was found to be 0.214 nm. The TGA indicated a gradual increase in the mass loss upon heating the NCCs from 25°C up to 500°C in a flowing N2-atmosphere. The DTA showed presence of an endothermic peak (due to H2O-evaporation) and one exothermic peak (due to depolymerization and decomposition of the NCCs. Based on the results, the Zizyphus wood is suitable precursor for the NCCs production.

Antibacterial and angiogenic potential of iron oxide nanoparticles-stabilized acrylate-based scaffolds for bone tissue engineering applications

The medical sector is one of the biggest consumers of single-use materials, and while the insurance of sterile media is non-negotiable, the environmental aspect is a chronic problem. Nanocellulose (NC) is one of the safest and most promising materials that can be used in medical applications due to its valuable properties like biocompatibility and biodegradability, along with its good mechanical properties and high water uptake capacity. However, NC has no bactericidal activity, which is a critical need for the effective prevention of infections in chronic diabetic wound dressing applications. Therefore, in this work, a natural product, propolis extract (PE), was used as an antibacterial agent, in different amounts, together with NC to obtain sponge-like structures (NC/PE). The scanning electron microscope (SEM) images showed well-impregnated cellulose fibers and a more compact structure with the addition of PE. According to the thermogravimetric analysis (TGA), the samples containing PE underwent thermal degradation before the unmodified NC due to the presence of volatile compounds in the extract. However, the peak degradation temperature in the first derivative thermogravimetric curves was higher for all the sponges containing PE when compared to the unmodified NC. The antibacterial efficacy of the samples was tested against Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, as well as on two clinically resistant isolates. The samples completely inhibited the development of Staphylococcus aureus, and Pseudomonas aeruginosa was partially inhibited, while Escherichia coli was resistant to the PE action. Considering the physical and biological properties along with the environmental and economic benefits, the development of an NC/PE wound dressing seems promising.

In order to improve the optical and mechanical performances of waterborne polyurethane (WPU), nanocrystalline cellulose (NCC)/WPU composites were synthesized in this study. NCC (prepared by acid hydrolysis of cotton fiber) was modified by (3-aminopropyl)triethoxysilane (APTES) to enhance its compatibility with WPU, and the surface-modified NCC was characterized by grafting ratio, crystallinity and contact angle (CA). NCC/WPU composites were examined by scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and thermogravimetric analysis (TG). The anti-yellowing property, specular gloss, pencil hardness, and abrasion resistance of NCC/WPU composites were investigated by the methods of Chinese National Standards GB/T 23999-2009, GB/T 9754-2007, GB/T 6739-2006 and GB/T 1768-2006, respectively. The results showed that the grafting ratio of NCC modified by 6% APTES was 36.01% and the crystallinity of modified NCC was decreased with the enhancement of APTES. CA of the modified NCC was decreased by 28.8% and the nanoparticles were homogeneously dispersed in the WPU matrix. The XRD patterns of the NCC/WPU composites were relatively steady, while the thermal stability of the composites was enhanced by 6.7% with 1.0 wt% modified NCC. Modified NCC affected the specular gloss of NCC/WPU composites more obviously than the anti-yellowing property. The pencil hardness of NCC/WPU composites was increased from 2H to 4H by addition of NCC and the abrasion resistance of the composites was enhanced significantly. In general, NCC/WPU composites showed significant improvements in the optical and mechanical performances.

Additive manufacturing (AM) of eco‐friendly biocomposites has been growing recently to obtain green fillers capable of reducing bioplastic costs without compromising the material processability and performance. This paper aims to study the effect of using different Agave America fiber volume ratios on the morphological, chemical, and thermal properties, contact angle, and hardness of poly(lactic) acid (PLA) filament for 3D printing. Sustainable biofilaments of PLA filled with 10 and 5 wt% of Agave Americana fiber were prepared in a thermokinetic mixer and extruded in a machine, and then used to print testing samples using fused deposition modeling (FDM) 3D printer. Biofilaments were characterized using scanning electron microscopy (SEM), thermogravimetry (TGA), differential scanning calorimetry (DSC), and Fourier‐transform infrared spectroscopy (FTIR) techniques. The addition of fiber did not significantly influence the biofilament's diameter and density compared to pure PLA. On the other hand, it influenced printed biofilaments' thermal stability and morphological characteristics. The biocomposites developed have shown enhancement in their shore hardness. Thus, the use of Agave Americana fiber reinforced in a PLA matrix did not compromise its thermal properties, nor its processability and printability, which could open the possibility of future research with a biocomposite with higher fiber content and an environmentally friendly alternative over traditional filler materials.

Owing to the spread of resistance between pathogenic bacteria, searching for novel compounds with antibacterial activity is essential. Here, we investigated the potential antibacterial activity of Greek clover or Trigonella foenum-graecum herb extract on Salmonella typhimurium clinical isolates. The chemical profile of the herb was initially determined using LC-ESI-MS/MS, which explored 36 different compounds. Interestingly, the fenugreek extract possessed antibacterial action in vitro with minimum inhibitory concentrations of 64 to 512 µg/mL. The potential mechanism of action was studied by elucidating the effect of the fenugreek extract on the membrane properties of S. typhimurium bacteria, including the inner and outer membrane permeability and membrane integrity. Remarkably, the fenugreek extract had detrimental effects on the membrane properties in 40-60% of the isolates. Moreover, the in vivo antibacterial action was studied using a gastrointestinal infection model with S. typhimurium bacteria. Interestingly, the fenugreek extract (200 mg/kg) improved the infection outcomes in the tested mice. This was represented by the noteworthy decrease (p < 0.05) in the bacterial count in the small intestine and caecum tissues. The survival rate of the fenugreek-extract-treated mice significantly increased compared to the S. typhimurium-infected group. Additionally, there was an improvement in the histological and immunohistochemical features of tumor necrosis factor-alpha. In addition, using an ELISA and qRT-PCR, there was an improvement in the proinflammatory and oxidative stress markers in the fenugreek-extract-treated group. Consequently, fenugreek extract should be investigated further on other food pathogens.

Characterization and evaluation of antibacterial and wound healing activity of naringenin-loaded polyethylene glycol/polycaprolactone electrospun nanofibers