Synthesis and antimicrobial effects of highly dispersed, cellulose-stabilized silver/cellulose nanocomposites

Harvesting the Power of Green Synthesis: Gold Nanoparticles Tailored for Prostate Cancer Therapy

Biosynthetic gold nanoparticles (bAuNPs) present a promising avenue for enhancing bio-compatibility and offering an economically and environmentally responsible alternative to traditional production methods, achieved through a reduction in the use of hazardous chemicals. While the potential of bAuNPs as anticancer agents has been explored, there is a limited body of research focusing on the crucial physicochemical conditions influencing bAuNP production. In this study, we aim to identify the optimal growth phase of Pseudomonas aeruginosa cultures that maximizes the redox potential and coordinates the formation of bAuNPs with increased efficiency. The investigation employs 2,6-dichlorophenolindophenol (DCIP) as a redox indicator. Simultaneously, we explore the impact of temperature, pH, and incubation duration on the biosynthesis of bAuNPs, with a specific emphasis on their potential application as antitumor agents. Characterization of the resulting bAuNPs is conducted using ATR-FT-IR, TEM, and UV-Vis spectroscopy. To gain insights into the anticancer potential of bAuNPs, an experimental model is employed, utilizing both non-neoplastic (HPEpiC) and neoplastic (PC3) epithelial cell lines. Notably, P. aeruginosa cultures at 9 h/OD600 = 1, combined with biosynthesis at pH 9.0 for 24 h at 58 °C, produce bAuNPs that exhibit smaller, more spherical, and less aggregated characteristics. Crucially, these nanoparticles demonstrate negligible effects on HPEpiC cells while significantly impacting PC3 cells, resulting in reduced viability, migration, and lower IL-6 levels. This research lays the groundwork for the development of more specialized, economical, and ecologically friendly treatment modalities.

Synthesis of bacterial cellulose nanofibers/Ag nanoparticles: Structure, characterization and antibacterial activity

The aim of this study was to compare the characterization of bacterial cellulose nanofibers/Ag nanoparticles (BCNs/Ag nanoparticles) obtained by three different pretreatment methods of BCNs (no pretreatment, sodium hydroxide activation pretreatment and TEMPO-mediated oxidation pretreatment), which were recoded as N-BCNs/Ag nanoparticles, A-BCNs/Ag nanoparticles and O-BCNs/Ag nanoparticles, respectively. The results of scanning electron microscopy and transmission electron microscopy showed the prepared Ag nanoparticles by three different pretreatment methods were spherical and dispersed on the surface of BCNs, while the Ag nanoparticles in O-BCNs/Ag nanoparticles displayed the smallest diameter with a value of 20.25 nm and showed the most uniform dispersion on the surface of BCNs. The ICP-MS result showed O-BCNs/Ag nanoparticles had the highest content of Ag nanoparticles with a value of 2.98 wt%, followed by A-BCNs/Ag nanoparticles (1.53 wt%) and N-BCNs/Ag nanoparticles (0.84 wt%). The cytotoxicity assessment showed that the prepared BCNs/Ag nanoparticles were relatively safe. Furthermore, the O-BCNs/Ag nanoparticles had the best antioxidant and antibacterial activities as compared with the other two types of BCNs/Ag nanoparticles, where O-BCNs/Ag nanoparticles destroyed the structure of bacterial cell membranes to lead the leakage of intracellular components. This study showed that O-BCNs/Ag nanoparticles as antibacterial agents have great potential in food packaging.

Interdisciplinary Undergraduate Laboratory for an Integrated Chemistry/Biology Program: Synthesis of Silver Nanoparticles (AgNPs)-Cellulose Composite Materials with Antimicrobial Activity

This laboratory exercise integrates chemistry and biology concepts to give third/fourth-year undergraduate students an opportunity to apply knowledge from different subject areas to address a real-world biomedical issue such as pathogen inhibition using composite materials. It involves the preparation of a bacteria-derived cellulosic biopolymer through microbial cultivation, impregnation of the bacterial cellulose (BC) with silver nanoparticles (AgNPs), followed by the analysis of the materials and the antimicrobial properties of the biomaterial-AgNPs composites. The methods are relatively simple and use inexpensive chemicals. A Tollens type approach is adopted to produce silver nanoparticles-bacterial cellulose (AgNPs-BC) composites by the reduction of [Ag(NH₃)₂]⁺ complex embedded in the cellulose matrix. The samples were dried by two different methods: freeze-drying or vacuum-drying. The dried AgNPs-BC films were evaluated for antimicrobial properties against a test organism, in this example, Pseudomonas aeruginosa, a Gram-negative biosafety containment level 2 (BSL 2) bacterium, using an agar diffusion test. For additional flexibility and customization, options for dividing the chemistry/biology content of this laboratory into smaller units with an emphasis on characterization techniques of nanomaterials for chemistry majors are also discussed.

Cellulose-Silver Composites Materials: Preparation and Applications

Cellulose has received great attention owing to its distinctive structural features, exciting physico-chemical properties, and varied applications. The combination of cellulose and silver nanoparticles currently allows to fabricate different promising functional nanocomposites with unique properties. The current work offers a wide and accurate overview of the preparation methods of cellulose-silver nanocomposite materials, also providing a punctual discussion of their potential applications in different fields (i.e., wound dressing, high-performance textiles, electronics, catalysis, sensing, antimicrobial filtering, and packaging). In particular, different preparation methods of cellulose/silver nanocomposites based on in situ thermal reduction, blending and dip-coating, or additive manufacturing techniques were thoroughly described. Hence, the correlations among the structure and physico-chemical properties in cellulose/silver nanocomposites were investigated in order to better control the final properties of the nanocomposites and analyze the key points and limitations of the current manufacturing approaches.

Anticoagulation and antibacterial properties of heparinized nanosilver with different morphologies

Synthesis and characterization of nanoparticles with different morphologies coupled to minimal chemical interventions for sustainable applications is one of the contemporary topics in the field of nanotechnology. In the current study, heparinized silver nanoparticles were synthesized using a chemical reduction method. Different concentrations of heparin were used to investigate its role in the stability and morphological properties of silver nanoparticles. Interestingly, it has been observed that the concentration of the stabilizing agent heparin plays a pivotal role in dictating the size and shape of the nanosilver. As visualized under a transmission electron microscope, nanosilver with different morphological states such as triangles, truncated triangles, hexagon, and spheres has been experimentally trapped. Such modular property of heparin coated nanosilver has also exhibited substantial differences in their anticoagulation and antimicrobial activities.

Maize Stalk Material for On-Site Treatment of Highly Polluted Leachate and Mine Wastewater

New research applications involving the use of cellulosic material derived from maize stalk for on-site treatment of leachate were evaluated for specific removal of Cu(II) and Fe(III) from real, highly polluted tailing pond and mine wastewater samples. Two major issues generated by anthropic mining activities were also tackled: wastewater metal content decrease to improve water quality and subsequently metal specific recovery, increasing the economic efficiency of metal production by using a green technology for residual management. Rapid saturation of the maize stalk mass determined in batch studies and the mine pilot experiment led to diminished metal concentrations in the second pilot experiment, where Cu(II) and Pb(II) from synthetic solutions were monitored in order to test biomaterial performances. In addition, in the second pilot experiment, maize stalk removed Pb(II) in the first 36 h, below the determination limit of the analytical method. The biomaterial bed in the column was saturated after 252 h of inflow solution. FTIR-ATR, TG and SEM techniques probed the interaction between maize stalk polar groups C=O, -OH, C-O and tailing water metallic ions by large FTIR band displacements, intensity decrease and shape changes, modification of thermal stability and by changes in the appearance of adsorbent microstructure images owing mainly to ion exchange mechanism.

Antimicrobial activity and inhibition of biofilm formation in vitro and on human dentine by silver nanoparticles/carboxymethyl-cellulose composites

OBJECTIVE

To evaluate the antimicrobial activity of a silver nanoparticles/carboxymethyl-cellulose (AgNPs/CMC) composite on in vitro and dentine disc heterogeneous biofilms.

DESIGN

AgNPs/CMC composite effect on normal human gingival fibroblast cells (HGF) viability was determined by the MTT reduction assay. In addition, we evaluated the antimicrobial effect of AgNPs/CMC composite on Candida albicans, Enterococcus faecalis, and Fusobacterium nucleatum growth in vitro and heterogeneous biofilms, as well as dentine disc biofilms.

RESULTS

Quasi-spherical AgNPs/CMC composites, with a mean 22.3 nm particle-size were synthesized. They were not toxic to HGF cells at concentrations tested that were antimicrobial, however they caused significant cytotoxicity (89 %, p <  0.05) at concentrations > 15 μg/mL. In vitro, they inhibited up to 67 %, 66 %, and 96 % C. albicans, E. faecalis, and F. nucleatum growth at concentrations ranging from 1.2 μg/mL to 9.6 μg/mL, as compared with untreated control. We also demonstrated significant (p <  0.05) 58 % biofilm reduction by 4.8 μg/mL AgNPs/CMC composite on human dentine discs.

CONCLUSION

AgNPs/CMC composite showed anti biofilm activity on monocultures, heterogenous cultures, and dentine discs, resulting a potentially effective alternative to prevent and eliminate infections after endodontic treatment.

Advances in Using Nanotechnology Structuring Approaches for Improving Food Packaging

Recent advances in food packaging materials largely rely on nanotechnology structuring. Owing to several unique properties of nanostructures that are lacking in their bulk forms, the incorporation of nanostructures into packaging materials has greatly improved the performance and enriched the functionalities of these materials. This review focuses on the functions and applications of widely studied nanostructures for developing novel food packaging materials. Nanostructures that offer antimicrobial activity, enhance mechanical and barrier properties, and monitor food product freshness are discussed and compared. Furthermore, the safety and potential toxicity of nanostructures in food products are evaluated by summarizing the migration activity of nanostructures to different food systems and discussing the metabolism of nanostructures at the cellular level and in animal models.