Determination of the Cytotoxicity and Antibiofilm Potential Effect of Equisetum arvense Silver Nanoparticles

Investigation of virulence factor genes and biofilm formation of antibiotic resistant clinical E.coli isolates

PURPOSE

The aim of this study is to investigate the antibiotic sensitivity, presence of virulence genes and biofilm formation capacity of 90 clinical E. coli isolates.

METHODS

The presence of virulence genes in E.coli isolates were investigated by PCR. Ninety clinical isolates of E.coli were subjected to biofilm quantitative analysis using the semi-quantitative crystal violet staining method.

RESULTS

it was observed that the isolates were resistant to quinolone, cephalosporin, aminoglycoside, carbapenem and penicillin group antibiotics. The presence of virulence factor genes were observed in a total of 86/90 E. coli. The highest rate of fim (92.2 %) virulence factor gene was detected in the strains. Afa, pap, cnf, sfa, hly were detected in 30 %, 13 %, 13 %, 3.3 %, 2.2 % respectively. Also, 13 different virulence factor gene patterns were determined in 90 E. coli isolates. Of the 90 E. coli isolates whose biofilm-forming capacities were evaluated, 42 were found to have biofilm-forming capacity. Of these 26 (28.8 %) the weak, 12 (13.3 %) moderate and 4 (4.4 %) strong biofilm-forming. Also, statistical analysis was performed to investigate the relationship between virulence factor genes and biofilm formation, and none of the 7 genes analyzed showed a significant relationship with biofilm formation.

CONCLUSION

since pathogenic E. coli is an important public health problem, investigating antibiotic resistance, virulence factor genes and biofilm formation in bacterial pathogens is important for better treatment options.

Green Synthesis of Ag and Cu Nanoparticles Using E. telmateia Ehrh Extract: Coating, Characterization, and Bioactivity on PEEK Polymer Substrates

PEEK-based implant materials have gained increasing attention as an alternative to titanium due to their biocompatibility and bone-like elasticity. However, PEEK's surface quality and wear resistance are lower than those of metals. This study aimed to enhance the bioactivity and surface quality of PEEK by coating it with silver and copper nanoparticles synthesized via a green method using Equisetum telmateia Ehrh. extract. PEEK samples (Ø 25 mm, 3 mm thick) were coated with single and double layers using spray (airbrush-spray) and drop-coating methods. Comprehensive analyses including SEM, EDX, FT-IR, UV-Vis, surface roughness, release studies, antioxidant and cytotoxicity activity, and antibacterial tests were conducted on the coated samples. The results demonstrated that AgNPs and CuNPs coatings significantly improved the surface quality of PEEK. SEM analysis revealed particle sizes ranging from 48 to 160 nm for AgNPs and 50-135 nm for CuNPs, with superior dispersion obtained using the airbrush-spray method. Surface roughness measurements showed a reduction of 17-33% for AgNPs-coated samples and 7-15% for CuNPs-coated samples compared to uncoated PEEK, with airbrush-spray coatings providing smoother surfaces. Antioxidant activity tests indicated that AgNPs provided 35% higher antioxidant activity compared to CuNPs. Additionally, antibacterial tests revealed that AgNPs exhibited a higher zone of inhibition (up to 14 mm for S. aureus and 18 mm for E. coli) compared to CuNPs, which exhibited zones of 8 mm and 10 mm, respectively. This study concludes that green-synthesized AgNPs, in particular, enhance the bioactivity and surface properties of PEEK, making it a promising material for biomedical applications such as infection-resistant implants.

Biogenic Ag2O nanoparticles with "Hoja Santa" (Piper auritum) extract: characterization and biological capabilities

The 'sacred leaf' or "Hoja Santa" (Piper auritum Kunth) has a great value for Mexican culture and has gained popularity worldwide for its excellent properties from culinary to remedies. To contribute to its heritage, in this project we proposed the green synthesis of silver oxide nanoparticles (Ag2O NPs) using an extract of "Hoja Santa" (Piper auritum) as a reducing and stabilizing agent. The synthesized Ag2O NPs were characterized by UV-Visible spectroscopy (plasmon located at 405 nm), X-ray diffraction (XRD) (particle size diameter of 10 nm), scanning electron microscopy (SEM) (particle size diameter of 13.62 ± 4.61 nm), and Fourier-transform infrared spectroscopy (FTIR) (functional groups from "Hoja Santa" attached to nanoparticles). Antioxidant capacity was evaluated using DPPH, ABTS and FRAP methods. Furthermore, the antimicrobial activity of NPs against a panel of clinically relevant bacterial strains, including both Gram-positive (Staphylococcus aureus) and Gram-negative bacteria (Salmonella Enteritidis and Escherichia coli O157:H7), was over 90% at concentrations of 200 µg/mL. Additionally, we assessed the antibiofilm activity of the NPs against Pseudomonas aeruginosa (reaching 98% of biofilm destruction at 800 µg/mL), as biofilm formation plays a crucial role in bacterial resistance and chronic infections. Moreover, we investigated the impact of Ag2O NPs on immune cell viability, respiratory burst, and phagocytic activity to understand their effects on the immune system.