Application of Argon Plasma Technology for the Synthesis of Anti-Infective Copper Nanoparticles.

The synthesis of copper nanoparticles (CuNPs) was accomplished by using a rapid, green, and versatile argon plasma reduction method that involves solvent extraction. With this method, a plasma-solid state interaction forms and CuNPs can be synthesized from copper(II) sulfate using a low-pressure, low-temperature argon plasma. Characterization studies of the CuNPs revealed that when a metal precursor is treated under optimal experimental conditions of 80 W of argon plasma for 300 s, brown CuNPs are synthesized. However, when those same brown CuNPs are placed in Milli-Q water for a period of 10 days, oxidation occurs and green CuNPs are formed. Confirmation of the chemical identity of the CuNPs was performed by using X-ray photoelectron spectroscopy. The results reveal that the brown CuNPs are predominantly Cu0 or what we refer to as CuNPs, while the green CuNPs are a mixture of Cu0 and Cu(OH)2 NPs. Upon further characterization of both brown and green CuNPs with scanning electron microscopy (SEM), the results depict brown CuNPs with a rod-like shape and approximate dimensions of 40 nm × 160 nm, while the green CuNPs were smaller in size, with dimensions of 40-80 nm, and more of a round shape. When testing the antibacterial activity of both brown and green CuNPs, our findings demonstrate the effectiveness of both CuNPs against Escherichia coli and Staphylococcus aureus bacteria at a concentration of 17 µg/mL. The inactivation of S. aureus and E. coli 7-day-old biofilms required CuNP concentrations of 99 µg/mL. SEM images of treated 7-day-old S. aureus and E. coli biofilms depict cell membranes that are completely damaged, suggesting a physical killing mechanism. In addition, when the same concentration of CuNPs used to inactivate biofilms were tested with human fibroblasts, both brown and green CuNPs were found to be biocompatible.

The nutritional supplement taurine activates p53-dependent and independent tumor suppressor mechanisms in various cellular models of ovarian cancer.

Loss of treatment-induced ovarian carcinoma (OC) growth suppression poses a major clinical challenge because it leads to disease recurrence. Therefore, there is a compelling need for well- -tolerated approaches that can support tumor growth-suppression after therapy is stopped. We have profiled ascites as OC tumor microenvironments to search for potential non-toxic soluble components that would activate tumor suppressor pathways in OC cells. Our investigations revealed that low levels of taurine, a non-proteogenic sulfonic amino acid, were present within OC ascites. Taurine supplementation, beyond levels found in ascites, induced growth suppression without causing cytotoxicity in various OC cells, including chemotherapy-resistant cell clones and patient-derived organoids representing primary or chemotherapy recovered disease. Inhibition of proliferation by taurine was linked to increased mutant or wild-type p53 proteins binding to DNA, induction of p21, and independently of p53, TIGAR expression. Taurine-induced activation of p21 and TIGAR was associated with suppression of cell-cycle progression, glycolysis, and mitochondrial respiration. Expression of p21 or TIGAR in OC cells mimicked taurine-induced growth suppression. Our studies support the potential therapeutic value of taurine supplementation in OC.

Extracellular Matrix Modulates Outgrowth Dynamics in Ovarian Cancer.

Ovarian carcinoma (OC) forms outgrowths that extend from the outer surface of an afflicted organ into the peritoneum. OC outgrowth formation is poorly understood due to the limited availability of cell culture models examining the behavior of cells that form outgrowths. Prompted by immunochemical evaluation of extracellular matrix (ECM) components in human tissues, laminin and collagen-rich ECM-reconstituted cell culture models amenable to studies of cell clusters that can form outgrowths are developed. It is demonstrated that ECM promotes outgrowth formation in fallopian tube non-ciliated epithelial cells (FNE) expressing mutant p53 and various OC cell lines. Outgrowths are initiated by cells that underwent outward translocation and retained the ability to intercalate into mesothelial cell monolayers. Electron microscopy, optical coherence tomography, and small amplitude oscillatory shear experiments reveal that increased ECM levels led to increased fibrous network thickness and high shear elasticity of the microenvironment. These physical characteristics are associated with outgrowth suppression. The low ECM microenvironment mimicks the viscoelasticity of malignant peritoneal fluid (ascites) and supports cell proliferation, cell translocation, and outgrowth formation. These results highlight the importance of the ECM microenvironment in modulating OC growth and can provide additional insights into the mode of dissemination of primary and recurrent ovarian tumors.

Plasma-initiated graft polymerization of carbon nanoparticles as nano-based drug delivery systems.

Plasma-initiated free radical polymerization was used to engineer carbon nanoparticles (CNPs) with tailored chemical and physical properties. Following surface modification, CNPs were loaded with a highly effective anti-infection agent called metal-free Russian propolis ethanol extract (MFRPEE), thus, creating nano-based drug delivery systems (NBDDSs). The loading of MFRPEE onto grafted CNPs occurred naturally through both electrostatic interactions and hydrogen bonding. When constructed under optimal experimental conditions, the NBDDSs were stable under physiologic conditions, and demonstrated enhanced anti-biofilm activity when compared with free MFRPEE. Mechanistic studies revealed that the enhanced anti-infectious activity of the NBDDSs was attributed to the modified surface chemistry of grafted CNPs. More specifically, the overall positive surface charge on grafted CNPs, which stems from quaternary ammonium polymer brushes covalently bound to the CNPs, provides NBDDSs with the ability to specifically target negatively charged components of biofilms. When studying the release profile of MFRPEE from the modified CNPs, acidic components produced by a biofilm triggered the release of MFRPEE bound to the NBDDS. Once in its free form, the anti-infectious properties of MFRPEE became activated and damaged the extracellular polymeric matrix (EPM) of the biofilm. Once the architecture of the biofilm became compromised, the EPM was no longer capable of protecting the bacteria encapsulated within the biofilm from the anti-infectious agent. Consequently, exposure of bacteria to MFRPEE led to bacterial cell death and biofilm inactivation. The results obtained from this study begin to examine the potential application of NBDDSs for the treatment of healthcare-associated infections (HCAIs).

Rapid Synthesis of Metal Nanoparticles Using Low-Temperature, Low-Pressure Argon Plasma Chemistry and Self-Assembly.

The synthesis of metal nanoparticles has become a priority for the advancement of nanotechnology. In attempts to create these nanoparticles, several different methods: chemistry, physics, and biology, have all been used. In this study, we report the reduction of cations using argon plasma chemistry to produce nanoparticles of gold (AuNPs), silver (AgNPs), and copper (CuNPs). Although other groups have used plasma-reduction methods to synthesize metal nanoparticles from their cation counterparts, these approaches often require plasma|liquid state interactions, high temperature, specific combinations of gases, and extended treatment times (>10 minutes), for which only specific cations (noble or non-noble) may be reduced. As a result, we have developed a non-thermal, low-pressure argon-plasma|solid state approach for the reduction of both noble and non-noble cations. More specifically, when 50-µL droplets of 2-mM solutions of gold(III) chloride, silver nitrate, or copper(II) sulfate are exposed to vacuum, they undergo an evaporation process. As the pressure in the chamber decreases to 220 mtorr, the droplets become completely evaporated, leaving behind a metal precursor. Nucleation and growth studies reveal that when the metal precursors of gold(III) chloride, silver nitrate, and copper(II) sulfate are treated with 80 watts of argon plasma for 5, 60, and 150 seconds, respectively, nanoparticles could be synthesized with efficiency rates of upwards of 98%. The size of nanoparticles synthesized in this work was studied using Scanning Electron Microscopy, and the scattering properties of the nanoparticles was studied using UV/Vis spectroscopy. Transmission Electron Microscopy with corresponding elemental analysis was also very useful in confirming the identity of the synthesized nanoparticles. The results from this study reveal that we have synthesized metal nanoparticles with distinct chemical and physical properties. Scanning Electron Microscopy depicts AgNPs with a round-shape and diameters from 40 - 80 nm, while AuNPs were hexagonal, with sizes from 40 - 80 nm, and CuNPs were rod-shaped, with dimensions 40 by 160 nm. Our findings demonstrate that the argon plasma approach used in this study is a rapid, green, and versatile reduction method for the synthesis of both noble and non-noble metal nanoparticles.

Are Russian propolis ethanol extracts the future for the prevention of medical and biomedical implant contaminations?

BACKGROUND: Most studies reveal that the mechanism of action of propolis against bacteria is functional rather than structural and is attributed to a synergism between the compounds in the extracts. HYPOTHESIS/PURPOSE: Propolis is said to inhibit bacterial adherence, division, inhibition of water-insoluble glucan formation, and protein synthesis. However, it has been shown that the mechanism of action of Russian propolis ethanol extracts is structural rather than functional and may be attributed to the metals found in propolis. If the metals found in propolis are removed, cell lysis still occurs and these modified extracts may be used in the prevention of medical and biomedical implant contaminations. STUDY DESIGN: The antibacterial activity of metal-free Russian propolis ethanol extracts (MFRPEE) on two biofilm forming bacteria: penicillin-resistant Staphylococcus aureus and Escherichia coli was evaluated using MTT and a Live/Dead staining technique. Toxicity studies were conducted on mouse osteoblast (MC-3T3) cells using the same viability assays. METHODS: In the MTT assay, biofilms were incubated with MTT at 37°C for 30min. After washing, the purple formazan formed inside the bacterial cells was dissolved by SDS and then measured using a microplate reader by setting the detecting and reference wavelengths at 570nm and 630nm, respectively. Live and dead distributions of cells were studied by confocal laser scanning microscopy. RESULTS: Complete biofilm inactivation was observed when biofilms were treated for 40h with 2µg/ml of MFRPEE. Results indicate that the metals present in propolis possess antibacterial activity, but do not have an essential role in the antibacterial mechanism of action. Additionally, the same concentration of metals found in propolis samples, were toxic to tissue cells. Comparable to samples with metals, metal free samples caused damage to the cell membrane structures of both bacterial species, resulting in cell lysis. CONCLUSION: Results suggest that the structural mechanism of action of Russian propolis ethanol extracts stem predominate from the organic compounds. Further studies revealed drastically reduced toxicity to mammalian cells when metals were removed from Russian propolis ethanol extracts, suggesting a potential for medical and biomedical applications.