Magnesium oxychloride cement (MOC) is gaining attention as a sustainable alternative to Portland cement. Its mechanical performance and water resistance may be enhanced by reinforcement with two-dimensional nanomaterials, such as graphene (G) and graphene oxide (GO). However, the ecotoxicological impact of these composites, determining their implementation, remains largely unexplored. This study evaluated the effects of G platelets with a surface area of 750 m2/g (G750) and GO, both as isolated particles and embedded within MOC, on a range of prokaryotic (Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa) and eukaryotic (Artemia salina, Sinapis alba, and Desmodesmus subspicatus) model organisms. G750 and GO exhibited species-specific antibacterial activity, notably inhibiting S. aureus growth and biofilm formation, while P. aeruginosa remained largely unaffected. The addition of G750 or GO did not enhance MOC's antibacterial effect, as MOC alone exhibited strong antimicrobial activity. Both G750 and GO were toxic to A. salina at concentrations of ≥0.05 g/L, with GO showing greater toxicity. Phytotoxic effects were observed in S. alba, particularly with the GO and MOC-G750 composites. Algal growth was unaffected by MOC-G750 but inhibited by MOC-GO after extended exposure. G750, GO, and MOC samples showed no genotoxic potential in vitro and in vivo; ROS production occurred without a significant change from the control. Overall, incorporating G750 and GO into MOC improved material properties without substantially increasing ecotoxicity, though species- and material-specific responses underscore the need for thorough environmental impact evaluation.

• Publikační typ
• časopisecké články MeSH

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.

• Klíčová slova
• NanoHy-GPS, antibacterial nanosystems, graphene oxide, one-pot microwave-assisted reaction, polyvinyl alcohol, silver nanoparticles,
• Publikační typ
• časopisecké články MeSH

Biodegradable polymers are promising materials for use in medical applications such as stents. Their properties are comparable to commercially available resistant metal and polymeric stents, which have several major problems, such as stent migration and stent clogging due to microbial biofilm. Consequently, conventional stents have to be removed operatively from the patient's body, which presents a number of complications and can also endanger the patient's life. Biodegradable stents disintegrate into basic substances that decompose in the human body, and no surgery is required. This review focuses on the specific use of stents in the human body, the problems of microbial biofilm, and possibilities of preventing microbial growth by modifying polymers with antimicrobial agents.

• Klíčová slova
• antimicrobial agents, antimicrobial effects, biodegradable polymer, medicine, polylactide, stent,
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Nanodiamonds (NDs) and graphene oxide (GO) are modern carbon-based nanomaterials with promising features for the inhibition of microorganism growth ability. Here we compare the effects of nanodiamond and graphene oxide in both annealed (oxidized) and reduced (hydrogenated) forms in two types of cultivation media-Luria-Bertani (LB) and Mueller-Hinton (MH) broths. The comparison shows that the number of colony forming unit (CFU) of Escherichia coli is significantly lowered (45%) by all the nanomaterials in LB medium for at least 24 h against control. On the contrary, a significant long-term inhibition of E. coli growth (by 45%) in the MH medium is provided only by hydrogenated NDs terminated with C-HX groups. The use of salty agars did not enhance the inhibition effects of nanomaterials used, i.e. disruption of bacterial membrane or differences in ionic concentrations do not play any role in bactericidal effects of nanomaterials used. The specific role of the ND and GO on the enhancement of the oxidative stress of bacteria or possible wrapping bacteria by GO nanosheets, therefore isolating them from both the environment and nutrition was suggested. Analyses by infrared spectroscopy, photoelectron spectroscopy, scanning electron microscopy and dynamic light scattering corroborate these conclusions.

• Klíčová slova
• Escherichia coli, antibacterial activity, graphene oxide, inhibition, nanodiamonds,
• Publikační typ
• časopisecké články MeSH