Enhancing antibacterial properties of polypropylene/Cu-loaded montmorillonite nanocomposite filaments through sheath-core morphology

Dual functionalized copper nanoparticles for thermoplastics with improved processing and mechanical properties and superior antibacterial performance

The utilization of metal nanoparticles for antibacterial thermoplastic composites has the potential to enhance the safety of human and animal life by mitigating the spread and transmission of foodborne pathogenic bacteria. The dispersion, antioxidant and antimicrobial activities of metal nanoparticles directly affect the application performance of the composites. This study focused on achieving amine-carboxyl co-modified copper nanoparticles (Cu-AC) with excellent antioxidant properties and monodispersity through in situ grafting of amine and carboxyl groups onto the surface of copper nanoparticles via ligand interaction. Polyacrylic acid's extended carbon chain structure was utilized to improve its dispersion and antioxidant properties, and its antibacterial properties were synergistically enhanced using secondary amines. It was found that Cu-AC possesses high antibacterial properties, with a minimum inhibition concentration of 0.156 mg mL-1. Antibacterial masterbatches and their composites (polypropylene/Cu) manufactured by melt blending of polypropylene and Cu-AC exhibited excellent antibacterial rates of up to 90% and 99% at 300 ppm and 700 ppm Cu-AC, respectively. Additionally, Cu-AC bolstered the thermal degradation, processing and mechanical properties of polypropylene. The successful implementation of this product substantiates the potential applications of polypropylene/Cu composite materials across diverse industries.

A Review on Montmorillonite-Based Nanoantimicrobials: State of the Art

One of the crucial challenges of our time is to effectively use metal and metal oxide nanoparticles (NPs) as an alternative way to combat drug-resistant infections. Metal and metal oxide NPs such as Ag, Ag2O, Cu, Cu2O, CuO, and ZnO have found their way against antimicrobial resistance. However, they also suffer from several limitations ranging from toxicity issues to resistance mechanisms by complex structures of bacterial communities, so-called biofilms. In this regard, scientists are urgently looking for convenient approaches to develop heterostructure synergistic nanocomposites which could overcome toxicity issues, enhance antimicrobial activity, improve thermal and mechanical stability, and increase shelf life. These nanocomposites provide a controlled release of bioactive substances into the surrounding medium, are cost effective, reproducible, and scalable for real life applications such as food additives, nanoantimicrobial coating in food technology, food preservation, optical limiters, the bio medical field, and wastewater treatment application. Naturally abundant and non-toxic Montmorillonite (MMT) is a novel support to accommodate NPs, due to its negative surface charge and control release of NPs and ions. At the time of this review, around 250 articles have been published focusing on the incorporation of Ag-, Cu-, and ZnO-based NPs into MMT support and thus furthering their introduction into polymer matrix composites dominantly used for antimicrobial application. Therefore, it is highly relevant to report a comprehensive review of Ag-, Cu-, and ZnO-modified MMT. This review provides a comprehensive overview of MMT-based nanoantimicrobials, particularly dealing with preparation methods, materials characterization, and mechanisms of action, antimicrobial activity on different bacterial strains, real life applications, and environmental and toxicity issues.

Facile synthesis of Ag nanoparticles-loaded chitosan antibacterial nanocomposite and its application in polypropylene

The development of environmental-friendly antibacterial agents with high efficiency and low cost has become the focus of attention. In this work, the Ag nanoparticles doped into chitosan (Ag NPs-CS) were synthesized by a green and facile method, and the samples were characterized by UV-Vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The antibacterial tests implied that Ag NPs-CS obtained from glucose (G-Ag NPs-CS) exhibited the excellent antimicrobial activities against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) microbes. Besides, the utilization of antibacterial agents in polymeric materials plays an significant role in healthy living. The aim is to impart the antibacterial properties and maintain/improve the mechanical properties. Therefore, the G-Ag NPs-CS with 5 wt% Ag was chosen as the optimal additive to endow polypropylene with antimicrobial activity via a simple melt blending method. The results demonstrated that the suppression of bacteria proliferation was enhanced with increasing the amount of antibacterial agent, and the microorganisms were almost killed when the content reached to 8 wt%. Meanwhile, the considerable improvement in elastic modulus and impact strength along with a slight decrease of elongation at break provided the evidence that Ag NPs-CS/PP nanocomposites were the promising candidate for practical applications.

Evaluation of biological and cytocompatible properties in nano silver-clay based polyethylene nanocomposites

Nano-toxicological evaluation of a biomaterial is of primordial importance for application in therapeutics. This is one of first reports on systematic analysis of in vitro and in vivo cytocompatible properties of an antimicrobial polyethylene/silver-clay hybrid nanocomposite. The polymeric nanocomposite has been prepared using melt compounding route by a twin screw extruder with silver-clay hybrid content varying from 1 to 5 wt%. The morphology of the polyethylene/silver-clay nanocomposites was investigated using a combination of TEM and XRD techniques. The antimicrobial studies suggest strong biocidal action against E. coli, S. aureus and A. niger. In vitro cytocompatibility studies show excellent compatibility with human erythrocytes and dermal fibroblast cell lines, as compared to powder form silver-clay hybrids which demonstrated mild toxicity. Histopathological analysis of skin tissues excised from rats surgically stitched with nanocomposite film show no morphological change following 21 days of exposure. The developed nanocomposites show excellent antimicrobial activity coupled with cytocompatibility and are hence potential candidates for biomedical applications.

Antimicrobial and toxicological behavior of montmorillonite immobilized metal nanoparticles

With increasing demand for novel and potent antimicrobial agents to combat cross-infections and infectious diseases, silver and copper based nanoparticles (NPs) deposited over supports such as montmorillonite (MMT) are playing a crucial role in shaping the current research scenario. Although materials based on Ag NP and Cu NP on MMT have been reported, its toxicological properties on human cell lines have not been accounted for. This paper reports a comparative study on synthesis, antibacterial, antifungal and toxicological behavior of Ag and Cu NPs deposited over MMT nanosheets synthesized by employment of different reduction media. The effect of synthesized NP-MMT hybrids on human erythrocytes and fibroblast cells has been evaluated. The NP formation was facilitated using borohydride and ethyl alcohol (wet chemical route) and photo-reduction and thermal treatment (physical reduction route). The NP-MMT hybrids showed NP formation over supporting silicate layers with particle size ~10-50 nm confirmed by TEM micrographs and loading of ~6-22 wt% of metallic element by EDX analysis. The MMT layers were peeled apart to accommodate NPs inside its galleries, confirmed by increased d-value in powder WAXD. The NP-hybrids showed excellent inhibition zone against bacteria E.coli and S. aureus and fungi A. niger. RBC hemolysis and cytocompatibility assay were performed in vitro to advocate its safety to live human cells. These hybrid materials are potential candidates for new generation advanced antimicrobial materials with less toxicity and highly potent behavior.