2D TiO2 nanosheets decorated via sphere-like BiVO4: a promising non-toxic material for liquid phase photocatalysis and bacterial eradication

An in-depth investigation was conducted on a promising composite material (BiVO4/TiO2), focusing on its potential toxicity, photoinduced catalytic properties, as well as its antibiofilm and antimicrobial functionalities. The preparation process involved the synthesis of 2D-TiO2 using the lyophilization method, which was subsequently functionalized with sphere-like BiVO4. Finally, we developed BiVO4/TiO2 S-scheme heterojunctions which can greatly promote the separation of electron-hole pairs to achieve high photocatalytic performance. The evaluation of concentration- and time-dependent viability inhibition was performed on human lung carcinoma epithelial A549 cells. This assessment included the estimation of glutathione levels and mitochondrial dehydrogenase activity. Significantly, the BiVO4/TiO2 composite demonstrated minimal toxicity towards A549 cells. Impressively, the BiVO4/TiO2 composite exhibited notable photocatalytic performance in the degradation of rhodamine B (k =0.135 min-1) and phenol (k = 0.016 min-1). In terms of photoinduced antimicrobial performance, the composite effectively inactivated both gram-negative E. coli and gram-positive E. faecalis bacteria upon 60-min of UV-A light exposure, resulting in a significant log6(log10CFU/mL) reduction in bacterial count. These promising results can be attributed to the unique 2D morphology of TiO2 modified by sphere-like BiVO4, leading to an increased generation of (intracellular)hydroxyl radicals, which plays a crucial role in treatments of both organic pollutants and bacteria.

Biocidal activity of multifunctional cuprite-doped anion exchanger - Influence of bacteria type and medium composition

The study presents unconventional, bifunctional, heterogeneous antimicrobial agents - Cu2O-loaded anion exchangers. The synergetic effect of a cuprous oxide deposit and polymeric support with trimethyl ammonium groups was studied against the reference strains of Enterococcus faecalis ATCC 29212 and Pseudomonas aeruginosa ATCC 27853. Biological testing (minimum bactericidal concentration, MBC), time- and dose-dependent bactericidal effect (under different conditions - medium composition and static/dynamic culture) demonstrated promising antimicrobial activity and confirmed its multimode character. The standard values of MBC, for all studied hybrid polymers and bacteria, were similar (64-128 mg/mL). However, depending on the medium conditions, due to the copper release into the bulk solution, bacteria were actively killed even at much lower doses of the hybrid polymer (25 mg/mL) and low Cu(II) concentrations in solution (0.01 mg/L). Simultaneously, confocal microscopic studies confirmed the effective inhibition of bacterial adhesion and biofilm formation on their surface. The studies conducted under different conditions showed also the influence of the structure and physical properties of studied materials on the biocidal efficacy and an antimicrobial action mechanism was proposed that could be significantly affected by electrostatic interactions and copper release to the solution. Although the antibacterial activity was also dependent on various strategies of bacterial cell resistance to heavy metals present in the aqueous medium, the studied hybrid polymers are versatile and efficient biocidal agents against bacteria of both types, Gram-positive and Gram-negative. Therefore, they can be a convenient alternative for point-of-use water disinfection systems providing water quality in medical devices such as dental units, spa equipment, and aesthetic devices used in the cosmetic sector.

Mechanism of Action and Efficiency of Ag3PO4-Based Photocatalysts for the Control of Hazardous Gram-Positive Pathogens

Silver phosphate and its composites have been attracting extensive interest as photocatalysts potentially effective against pathogenic microorganisms. The purpose of the present study was to investigate the mechanism of bactericidal action on cells of opportunistic pathogens. The Ag3PO4/P25 (AGP/P25) and Ag3PO4/HA (HA/AGP) powders were prepared via a co-precipitation method. Thereafter, their antimicrobial properties against Enterococcus faecalis, Staphylococcus epidermidis, and Staphylococcus aureus (clinical and reference strains) were analyzed in the dark and after exposure to visible light (VIS). The mechanism leading to cell death was investigated by the leakage of metabolites and potassium ions, oxidative stress, and ROS production. Morphological changes of the bacterial cells were visualized by transmission electron microscopy (TEM) and scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy (SEM EDS) analysis. It has been shown that Ag3PO4-based composites are highly effective agents that can eradicate 100% of bacterial populations during the 60 min photocatalytic inactivation. Their action is mainly due to the production of hydroxyl radicals and photogenerated holes which lead to oxidative stress in cells. The strong affinity to the bacterial cell wall, as well as the well-known biocidal properties of silver itself, increase undoubtedly the antimicrobial potential of the Ag3PO4-based composites.

Testing Antimicrobial Properties of Selected Short Amyloids

Amyloids and antimicrobial peptides (AMPs) have many similarities, e.g., both kill microorganisms by destroying their membranes, form aggregates, and modulate the innate immune system. Given these similarities and the fact that the antimicrobial properties of short amyloids have not yet been investigated, we chose a group of potentially antimicrobial short amyloids to verify their impact on bacterial and eukaryotic cells. We used AmpGram, a best-performing AMP classification model, and selected ten amyloids with the highest AMP probability for our experimental research. Our results indicate that four tested amyloids: VQIVCK, VCIVYK, KCWCFT, and GGYLLG, formed aggregates under the conditions routinely used to evaluate peptide antimicrobial properties, but none of the tested amyloids exhibited antimicrobial or cytotoxic properties. Accordingly, they should be included in the negative datasets to train the next-generation AMP prediction models, based on experimentally confirmed AMP and non-AMP sequences. In the article, we also emphasize the importance of reporting non-AMPs, given that only a handful of such sequences have been officially confirmed.

Antimicrobial O-Alkyl Derivatives of Naringenin and Their Oximes Against Multidrug-Resistant Bacteria

New antimicrobial agents are needed to address infections caused by multidrug-resistant bacteria. Here, we are reporting novel O-alkyl derivatives of naringenin and their oximes, including novel compounds with a naringenin core and O-hexyl chains, showing activity against clinical strains of clarithromycin-resistant Helicobacter pylori, vancomycin-resistant Enterococcus faecalis, methicillin-resistant Staphylococcus aureus, and beta-lactam-resistant Acinetobacter baumannii and Klebsiella pneumoniae. The minimum inhibitory concentrations (MICs), which provide a quantitative measure of antimicrobial activity, were in the low microgram range for the selected compounds. Checkerboard assays for the most active compounds in combination with antibiotics revealed interactions that varied from synergistic to neutral.

An efficient Nb-modified BiVO4 film for photo-induced bacterial inactivation and photocatalytic removal of organic pollutants

For the first time, Methicillin-resistant Staphylococcus aureus (MRSA) was inactivated using a Nb-modified BiVO₄ photocatalyst.

Photo-catalytic inactivation of an Enterococcus biofilm: the anti-microbial effect of sulphated and europium-doped titanium dioxide nanopowders

The control and prevention of biofilm-related infections is an important public healthcare issue. Given the increasing antibiotic resistance among bacteria and fungi that cause serious infections in humans, promotion of new strategies combating microorganisms has been essential. One attractive approach to inactivate microorganisms is the use of semiconductor photo-catalysis, which has become the subject of extensive research. In this study, the bactericidal properties of four photo-catalysts, TiO₂, TiO₂-S, TiO₂-Eu and TiO₂-Eu-S, were investigated against established 24, 48, 72 and 96 h biofilms of Enterococcus The exposure of biofilms to the catalysts induced the production of superoxide radical anions. The best photo-catalytic inactivation was achieved with the TiO₂-Eu-S and TiO₂-S nanopowders and 24 h biofilms. Transmission electron microscopy images showed significant changes in the structure of the biofilm cells following photo-inactivation. The results suggest that doping with europium and modifying the surface with sulphate groups enhanced the bactericidal activity of the TiO₂ nanoparticles against enterococcal biofilms.

Enterococcus in wound infections: virulence and antimicrobial resistance

Enterococci, a complex group of facultative pathogens have become increasingly isolated in various hospital settings. They are considerable frequently cultured from traumatic and surgical wounds. We investigated 57 strains of the species E. faecalis, E. faecium and E. casseliflavus isolated from infected wounds. Their ability to produce virulence factors and their sensitivity to antibiotics were evaluated using phenotypic and genotyping methods. In the phenotype studies, significant portion of the isolates produced biofilm (66.7%) and gelatinase (36.8%). Nearly 30% of the strains expressed hemolytic properties. Only a few produced DNAse (15.8%) and lipase (7.0%). The genes esp, gelE, cylA, cylB, cylM and agg were detected in most of the isolates (38.6-87.7%). All the isolated enterococci were susceptible to vancomycin and were characterized by their low resistance to antibiotics, except aminoglycosides (HLR).

Virulence of Enterococcus isolates collected in Lower Silesia (Poland)

148 enterococcal strains: E.faecalis (108), E.faecium (35), E.gallinarum (3), E.casseliflavus (1) and E.durans (1) from various clinical specimens were investigated for their ability to adhere to Caco-2 and HEp-2 cell lines, and also for the presence of the esp gene, biofilm formation, production of haemolysins, DNAse and lipase. Several types of enterococcal adhesion to both cell lines were noted. An aggregative adherence was the most frequent among E.faecalis and E.faecium isolates. Other species presented various adhesive types. The occurrence of virulence factors in the whole group of strains was as follows: esp gene in 53.4%, biofilm in 45.3%, haemolysins in 15.5%, DNAse in 12.2% and lipase in 33.1% of enterococcal isolates. It appears that the adherence of the enterococci studied was not significantly associated with the presence of virulence factors.

Virulence factors and in vitro adherence of Enterococcus strains to urinary catheters

The ability to adhere in vitro to urinary catheters and the presence of enterococcal virulence factors was determined in 30 Enterococcus urinary isolates (12 E. faecalis, 12 E. faecium, 3 E. casseliflavus, 3 E. gallinarum). Silicone, siliconized latex and polyvinyl chloride (PVC) were examined by sonication quantitative culture technique and scanning electron microscope. As compared to E. faecalis and E. faecium, E. casseliflavus and E. gallinarum displayed lower adhesion to all synthetic materials. All the tests performed showed higher adherence of all tested strains to siliconized latex and silicone than to PVC. Biofilmforming ability was observed in 5 E. faecalis but in none of the remaining strains. The gene coding enterococcal surface protein (Esp) was detected in 7 E. faecalis and 6 E. faecium strains. Gelatinase was found in 1 E. faecalis, 2 E. faecium and hemolysins were found in 6 E. faecalis and 1 E. faecium strains. All E. casseliflavus and E. gallinarum strainswere negative for these traits. Hydrophobic type of cell surface (measured by its affinity for n-hexadecane) was shown in a few isolates. Bacterial adherence was not significantly associated with the above pathogenic factors.

[The metal concentration in water and ground deposit in the area of Upper Silesia]

The metal concentration in water and ground deposits of 6 collapse water reservoirs in the area of Upper Silesia was tested. The examined reservoirs are situated in the so-called cross-town tract near Swietochłowice and Ruda Slaska. It was concluded that the metal concentration in water samples was low. In accordance with the present regulations, this allows to classify the water in these reservoirs to the 1st class purity water. The metal content in the ground deposits is high. Iron (Fe) concentration in the deposits ranged from 28288.9 mg/kg to 39162.9 mg/kg; the concentration of manganese (Mn) ranged from 2557.95 mg/kg to 3398.52 mg/kg and that of zinc (Zn) was 1288.78 mg/kg average through the year. The highest zinc concentration reached 2834.74 mg/kg. Cadmium (Cd) occurred in the deposits in the content of 10.4 mg/kg. The average year concentration of lead (Pb) in the deposits was 252.4 mg/kg. Copper (Cu) was found in the deposits in the amount of 45.0 mg/kg. The highest concentration of this metal in the ground deposits was 103.14 mg/kg. Magnesium (Mg) was on average present in the deposits in the concentration of 1913 mg/kg and its highest concentration reached 6777.89 mg/kg.

[Extensivity of infection of Fasciola hepatica L. in cattle in Lublin's voivodship in the years 1993-2001]

Extensivity of infection of Fasciola hepatica L. among cattle in Lublin's voivodship from 1993-2001. Aim of the work was to determine extensitivity of appearance of hepatica among catlle put to slaughter in slaughtershouses in Lublin's voivodship from 1993 to 2001. Substance for the work was braught from the annual reports of official examination of slaughtered animals, reached from both main Inspectorate (department) of Veterinary in the Ministry of Agriculture and from Regional Institute of Veterinar's Hygiene in Lublin. Results of researches are as follow: extensivity of infection of Fasciola hepatica among cattle in Lublin and voivodship between 1993 - 1999 oscillates about 5%. In 2000 extensivity of invasion reached 10,9%.

[Extensivity of appearance of echinococcosis among swine in Lublin's voivodship in period 1993-2000]

Aim of the work was presentation of appearance of hydatid among swine in Lublin' s voivodship between 1993-2000. Substance for researches was brought from annual reports inserted into journals of official examination leaded by Veterinary's Inspenction of Sanitation in slaughterhouses. It was proved that average 10,1% of swine on territory of Lublin's voivodship in period 1993-2000 was infected. Frequency of infection among examined animals were the highest in last year of researches 200 and reached 13,4%.

Studies of antibacterial activity of binuclear rhodium (II) complexes with heterocyclic nitrogen ligands

Binuclear rhodium (II) complexes, [Rh2(OOCPh)2(phen)2(H2O)2] (OOCPh)2 (1), [Rh2(OOCPh)2(bpy)2(H2O)2] (OOCPh)2 (2), [Rh2(OOCBu(n))2 (bpy)2(H2O)2] (OOCBu(n)2 (3), and [Rh2(OOCPr(n)2 (phen)2(H2O)2] (OOCPr(n)2 (4) (Phen = 1,10-phenanthroline and bpy = 2,2'-bipyridine), have been synthesized and characterized using NMR, IR and electronic spectra. Activity of these compounds against Gram-positive bacteria decreases in the order: 1?2?3 > 4. Complex 1 is active against many Staphylococcus strains resistant to commonly used antibiotics. The complexes 1-4 are much less active agents against Gram-negative bacteria.

Synthesis and cytotoxic evaluation of some Mannich bases of alicyclic ketones

A number of Mannich bases of alicyclic ketones containing one and two basic centres were prepared in order to evaluate the theory of sequential cytotoxicity and develop structure-activity relationships in these series of compounds. The compounds were evaluated in vitro against murine P388 D1 lymphocytic leukemia cells. The data generated supported the theory of sequential cytotoxicity and in general, compounds containing alicyclic rings of five and six carbon atoms possessed greater activity than the corresponding dodecyl analogues. Those Mannich bases containing dialkylamino groups were associated with greater cytotoxicity than related compounds possessing a basic heterocycle. Calculations of the atomic charges of the enone groups from selected compounds afforded some rationalization for the cytotoxic screening results.