Chemical Composition and Cytotoxic Evaluation of the Essential Oil of Phyllogonium viride (Phyllogoniaceae, Bryophyta).

The present study aimed to determine the chemical composition and biological activity of the essential oil obtained from Phyllogonium viride Brid. (Phyllogoniaceae, Bryophyta), whose samples were collected in southern Brazil. For the first time, the cytotoxic activity of the essential oil of P. viride in breast and colorectal tumor cells (MCF-7 and HCT-116) was evaluated, as well as the cytotoxic potential of this oil in non-tumoral cells of human immortalized keratinocytes (HaCaT) via MTT assay. The compounds majorly found in P. viride essential oil were ß-bazzanene (20.30 %), ß-caryophyllene (17.06 %), ß-chamigrene (14.02), and germacrene B (11.72 %). Treatment with P. viride essential oil in the different tested cell lines did not induce any toxicity in most of the tested concentrations. These data contribute to generating new scientific information about this understudied plant species. Furthermore, the chemical characterization of the compounds present in the essential oil of P. viride can lead to greater elucidation of its biotechnological potential.

Light, Copper, Action: Visible-Light Illumination Enhances Bactericidal Activity of Copper Particles.

Bacteria are an old concern to human health, as they are responsible for nosocomial infections, and the number of antibiotic-resistant microorganisms keeps growing. Copper is known for its intrinsic biocidal properties, and therefore, it is a promising material to combat infections when added to surfaces. However, its biocidal properties in the presence of light illumination have not been fully explored, especially regarding the use of microsized particles since nanoparticles have taken over all fields of research and subjugated microparticles despite them being abundant and less expensive. Thus, the present work studied the bactericidal properties of metallic copper particles, in microscale (CuMPs) and nanoscale (CuNPs), in the absence of light and under white LED light illumination. The minimum bactericidal concentration (MBC) of CuMPs against Staphylococcus aureus that achieved a 6-log reduction was 5.0 and 2.5 mg mL-1 for assays conducted in the absence of light and under light illumination, respectively. Similar behavior was observed against Escherichia coli. The bactericidal activity under illumination provided a percentage increase in log reduction values of 65.2% for S. aureus and 166.7% for E. coli when compared to the assays under dark. This assay reproduced the testing CuNPs, which showed superior bactericidal activity since the concentration of 2.5 mg mL-1 promoted a 6-log reduction of both bacteria even under dark. Its superior bactericidal activity, which overcame the effect of illumination, was expected once the nanoscale facilitated the interaction of copper within the surface of bacteria. The results from MBC were supported by fluorescence microscopy and atomic absorption spectroscopy. Therefore, CuMPs and CuNPs proved to have size- and dose-dependent biocidal activity. However, we have shown that CuMPs photoactivity is competitive compared to that of CuNPs, allowing their application as a self-cleaning material for disinfection processes assisted by conventional light sources without additives to contain the spread of pathogens.

Antimicrobial PAA/PAH Electrospun Fiber Containing Green Synthesized Zinc Oxide Nanoparticles for Wound Healing.

Wound infections are the main complication when treating skin wounds. This work reports a novel antimicrobial material using green synthesized zinc oxide nanoparticles (ZnONPs) incorporated in polymeric fibers for wound healing purposes. ZnONPs are a promising antimicrobial nanomaterial with high activity against a range of microorganisms, including drug-resistant bacteria. The electrospun fibers were obtained using polyacrylic acid (PAA) and polyallylamine hydrochloride (PAH) and were loaded with ZnONPs green synthesized from Ilex paraguariensis leaves with a spherical shape and ~18 nm diameter size. The fibers were produced using the electrospinning technique and SEM images showed a uniform morphology with a diameter of ~230 nm. EDS analysis proved a consistent dispersion of Zn in the fiber mat, however, particle agglomerates with varying sizes were observed. FTIR spectra confirmed the interaction of PAA carboxylic groups with the amine of PAH molecules. Although ZnONPs presented higher antimicrobial activity against S. aureus than E. coli, resazurin viability assay revealed that the PAA/PAH/ZnONPs composite successfully inhibited both bacteria strains growth. Photomicrographs support these results where bacteria clusters were observed only in the control samples. The PAA/PAH/ZnONPs composite developed presents antimicrobial activity and mimics the extracellular matrix morphology of skin tissue, showing potential for wound healing treatments.

Comparative Study of Physicochemical Properties and Biocompatibility (L929 and MG63 Cells) of TiN Coatings Obtained by Plasma Nitriding and Thin Film Deposition.

Ti6Al4V is one of the most lightweight, mechanically resistant, and appropriate for biologically induced corrosion alloys. However, surface properties often must be tuned for fitting into biomedical applications, and therefore, surface modification is of paramount importance to carry on its use. This work compares the interaction between two different cell lines (L929 fibroblasts and osteoblast-like MG63) and medical grade Ti6Al4V after surface modification by plasma nitriding or thin film deposition. We studied the adhesion of these two cell lines, exploring which trends are consistent for cell behavior, correlating with osseointegration and in vivo conditions. Modified surfaces were analyzed through several physicochemical characterization techniques. Plasma nitriding led to a more pronounced increase in surface roughness, a thicker aluminum-free layer, made up of diverse titanium nitride phases, whereas thin film deposition resulted in a single-phase pure titanium nitride layer that leveled the ridged topography. The selective adhesion of osteoblast-like cells over fibroblasts was observed in nitrided samples but not in thin film deposited films, indicating that the competitive cellular behavior is more pronounced in plasma nitrided surfaces. The obtained coatings presented an appropriate performance for its use in biomedical-aimed applications, including the possibility of a higher success rate in osseointegration of implants.