Crucial cytotoxic and antimicrobial activity changes driven by amount of doped silver in biocompatible carbon nitride nanosheets.

The use of Ag-modified nanomaterials continues to attract attention in biological contamination control, their potential cytotoxicity is often overlooked. Herein, biocompatible carbon nitride is modified with 1 and 5 wt.% Ag and effects of different nanomaterial dose and Ag content on antimicrobial activity and cytotoxicity is studied. Pure Ag nanoparticles and AgNO3 is tested for comparison, together with ten bacterial strains including pan-resistant Pseudomonas aeruginosa. Cytotoxicity is then investigated in three adherent and two suspension human cell lines, and results confirm that cancer adherent cell lines are the most immune lines and human cervical adenocarcinoma cells (HeLa) are more resilient than human lung adenocarcinoma cells (A549). The HeLa remains over 90 % viable even after 24 -h treatment with the highest concentration of 5%Ag/g-C3N4 (300 mg L-1) while A549 sustained viability only up to 100 mg L-1. Higher concentrations then induce cytotoxicity and A549 cell viability decreases. Our results show the importance of complementary testing of cytotoxicity by LIVE/DEAD assay using flow cytometry with more different human cell lines, which might be less immune to tested nanomaterials than HeLa and A549. Combined controls of new antibacterial agent activity tests then provide increased knowledge of their biocompatibility.

Lipophosphonoxins II: Design, Synthesis, and Properties of Novel Broad Spectrum Antibacterial Agents.

The increase in the number of bacterial strains resistant to known antibiotics is alarming. In this study we report the synthesis of novel compounds termed Lipophosphonoxins II (LPPO II). We show that LPPO II display excellent activities against Gram-positive and -negative bacteria, including pathogens and multiresistant strains. We describe their mechanism of action-plasmatic membrane pore-forming activity selective for bacteria. Importantly, LPPO II neither damage nor cross the eukaryotic plasmatic membrane at their bactericidal concentrations. Further, we demonstrate LPPO II have low propensity for resistance development, likely due to their rapid membrane-targeting mode of action. Finally, we reveal that LPPO II are not toxic to either eukaryotic cells or model animals when administered orally or topically. Collectively, these results suggest that LPPO II are highly promising compounds for development into pharmaceuticals.

Enhanced formation of silver nanoparticles in Ag+-NOM-iron(II, III) systems and antibacterial activity studies.

This work reports the role of iron redox pair (Fe(3+)/Fe(2+)) in the formation of naturally occurring silver nanoparticles (AgNPs) in the aquatic environment. The results showed that Fe(3+) or Fe(2+) ions in the mixtures of Ag(+) and natural organic matter enhanced the formation of AgNPs. The formation of AgNPs depended on pH and types of organic matter. Increase in pH enhanced the formation of AgNPs, and humic acids as ligands showed higher formation of AgNPs compared to fulvic acids. The observed results were described by considering the potentials of redox pairs of silver and iron species and the possible species involved in reducing silver ions to AgNPs. Dynamic light scattering and transmission electron microscopy measurements of AgNPs revealed mostly bimodal size distribution with decrease in size of AgNPs due to iron species in the reaction mixture. Minimum inhibitory concentration of AgNPs needed to inhibit the growth of various bacterial species suggested the role of surfaces of tested Gram-positive and Gram-negative bacteria. Stability study of AgNPs, formed in Ag(+)-humic acid/fulvic acids-Fe(3+) mixtures over a period of several months showed high stability of the particles with significant increase in surface plasmon resonance peak. The environmental implications of the results in terms of fate, transport, and ecotoxicity of organic-coated AgNPs are briefly presented.

The in vitro antimicrobial activity of silicone oils used in ophthalmic surgery.

BACKGROUND: The aim of the study was in vitro assessment and comparison of the antimicrobial activity of three types of silicone oils used in ophthalmic surgery. METHODS: The silicone oils (Arciolane 1300 centistokes, Arciolane 5500 centistokes and Oxane Hd, heavy silicone oil) were inoculated with microbes common in endophthalmitis and their growth was observed continuously. Control tests of microbial growth were performed on silicone oil-free media, i.e. saline and standard enrichment media. In both tested oils and control media, the microbes were cultured aerobically for 21 days, bacteria at 37 °C and yeasts and fungi at 30 °C. Prior to and during incubation at given intervals (days 0, 2, 4, 7, 9, 11, 14, 16, 18 and 21), 10 µl samples were taken from all test tubes. These were diluted in saline in a series of test tubes, with the minimum concentration reaching 10(-8). From each dilution, 25 µl were inoculated onto agar media. After 24 h of aerobic incubation at 37 °C (bacteria) and 48 h at 30 °C (yeasts and fungi), the grown colonies were counted and the numbers of colony-forming units in 1 ml (CFU/ml) were determined. RESULTS: In vitro, the highest antimicrobial effect was observed for the Oxane Hd silicone oil. CONCLUSIONS: If endophthalmitis is treated by pars plana vitrectomy, the application of Oxane Hd silicone oil into the vitreous cavity at the end of surgery may contribute to the elimination of microorganisms from the intraocular space but clinical trials are needed to assess its safety.

Usefulness of McRAPD for typing and importance of biofilm production in a case of nosocomial ventriculoperitoneal shunt infection caused by Candida lusitaniae.

A case report of ventriculoperitoneal shunt infection caused by Candida lusitaniae in a 6-year-old patient with cerebral astrocytoma and obstructive hydrocephalus is presented briefly with emphasis on the course of antifungal treatment. Seven isolates recovered subsequently from the cerebrospinal fluid were studied retrospectively. To confirm identity, isolates were typed using pulsed-field gel electrophoresis and melting curve of random amplified polymorphic DNA (McRAPD). Further, the ability to form biofilm and its susceptibility to systemic antifungals were evaluated. Using McRAPD, identity of C. lusitaniae isolates showing slight microevolutionary changes in karyotypes was undoubtedly confirmed; successful application of numerical interpretation of McRAPD for typing is demonstrated here for the first time. The strain was also recognized as a strong biofilm producer. Moreover, minimum biofilm inhibitory concentrations were very high, in contrast to low antifungal minimum inhibitory concentrations of isolates. It can be concluded that McRAPD seems to be a simple and reliable method not only for identification but also for typing of yeasts. A ventriculoperitoneal shunt colonized by C. lusitaniae was revealed as the source of this nosocomial infection, and the ability of the strain to form biofilm on its surface likely caused treatment failure.

Biosafety, antioxidant status, and metabolites in urine after consumption of dried cranberry juice in healthy women: a pilot double-blind placebo-controlled trial.

This study assessed the effect of an 8 week consumption of dried cranberry juice (DCJ) on 65 healthy young women. Basic biochemical and hematological parameters, antioxidant status, presence of metabolites in urine, and urine ex vivo antiadherence activity were determined throughout the trial. A 400 mg amount of DCJ/day had no influence on any parameter tested. A 1200 mg amount of DCJ/day resulted in a statistically significant decrease in serum levels of advanced oxidation protein products. This specific protective effect against oxidative damage of proteins is described here for the first time. Urine samples had an inhibitory effect on the adhesion of uropathogenic Escherichia coli strains, but no increase in urine acidity was noted. Hippuric acid, isomers of salicyluric and dihydroxybenzoic acids, and quercetin glucuronide were identified as the main metabolites. In conclusion, cranberry fruits are effective not only in the prevention of urinary tract infection but also for the prevention of oxidative stress.