Glutathione-Responsive Multifunctional Nanoparticles Based on Mannose-Modified Pillar[5]arene for Targeted Antibiotic Delivery against Intracellular Methicillin-Resistant S. aureus

MRSA can evade the immune system once they are engulfed by phagocytic host cells. This protects them against the bactericidal action of antibiotics and allows the infection to remain latent...

Structure-Based Design of an RNase Chimera for Antimicrobial Therapy

Bacterial resistance to antibiotics urges the development of alternative therapies. Based on the structure-function of antimicrobial members of the RNase A superfamily, we have developed a hybrid enzyme. Within this family, RNase 1 exhibits the highest catalytic activity and the lowest cytotoxicity; in contrast, RNase 3 shows the highest bactericidal action, alas with a reduced catalytic activity. Starting from both parental proteins, we designed a first RNase 3/1-v1 chimera. The construct had a catalytic activity much higher than RNase 3, unfortunately without reaching an equivalent antimicrobial activity. Thus, two new versions were created with improved antimicrobial properties. Both of these versions (RNase 3/1-v2 and -v3) incorporated an antimicrobial loop characteristic of RNase 3, while a flexible RNase 1-specific loop was removed in the latest construct. RNase 3/1-v3 acquired both higher antimicrobial and catalytic activities than previous versions, while retaining the structural determinants for interaction with the RNase inhibitor and displaying non-significant cytotoxicity. Following, we tested the constructs’ ability to eradicate macrophage intracellular infection and observed an enhanced ability in both RNase 3/1-v2 and v3. Interestingly, the inhibition of intracellular infection correlates with the variants’ capacity to induce autophagy. We propose RNase 3/1-v3 chimera as a promising lead for applied therapeutics.

Aqueous mechano-bactericidal action of acicular aragonite crystals

Nanoneedle structures on dragonfly and cicada wing surfaces or black silicon nanoneedles demonstrate antibacterial phenomena, namely mechano-bactericidal action. These air-exposed, mechano-bactericidal surfaces serve to destroy adherent bacteria, but their bactericidal action in the water is no precedent to report. Calcium carbonate easily accumulates on solid surfaces during long-term exposure to hard water. We expect that aragonite nanoneedles, in particular, which grow on TiO2 during the photocatalytic treatment of calcium-rich groundwater, exhibit mechano-bactericidal action against bacteria in water. Here, we showed that acicular aragonite modified on TiO2 ceramics prepared from calcium bicarbonate in mineral water by photocatalysis exhibits mechanical bactericidal activity against E. coli in water. Unmodified, calcite-modified and aragonite-modified TiO2 ceramics were exposed to water containing E. coli (in a petri dish), and their bactericidal action over time was investigated under static and agitated conditions. The surfaces of the materials were observed by scanning electron microscopy, and the live/dead bacterial cells were observed by confocal laser scanning microscopy. As a result, the synergistic bactericidal performance achieved by mechano-bactericidal action and photocatalysis was demonstrated. Aragonite itself has a high biological affinity for the human body different from the other whisker-sharpen nanomaterials, therefore, the mechano-bactericidal action of acicular aragonite in water is expected to inform the development of safe water purification systems for use in developing countries.

On the essence of the therapeutic and protective effect of chemicals in septic infections. Sахl, Donath and Kelen (Wien. Kl. Woch., 1926, no. 20)

Sхl, Donath and Kelen (Wien. Kl. Woch., 1926, No. 20) by experiments on animals were convinced that here it is not about the antiseptic (resp. Bactericidal) action of these substances (for example:, argochrome, trypaflavin, etc.) on microbes, and about their nonspecific effect on the mensenchymal and lymphatic tissue, in the sense of increasing its resistance.

Evaluation of Fruit Extracts Influence on the Susceptibility of Escherichia Coli Rods to the Bactericidal Action of Human Serum

This study determined the influence of the methanol (ME) and water (WE) fruit extracts obtained from eight species of Rosaceae and Grossulariacae family on the susceptibility of Escherichia coli rods to the lytic action of normal human serum (NHS). Bacteria were incubated for 24 h in tryptic soy broth with varying concentrations (1, 5, 10, 20, 30, 40, and 50 mg ml-1) of raspberry, cherry, hawthorn, dog rose, gooseberry, chokeberry, quince, and Japanese quince extracts and then the bactericidal activity of NHS was established. We found that the resistance of E. coli rods to the bactericidal action of serum was altered by prior incubation with all tested extracts and was dependent on plant extract concentration. Among the tested extracts, gooseberry (both ME and WE), raspberry ME and cherry WE were responsible for the most profound changes in serum resistance of E. coli rods. Evaluation of the antimicrobial mechanisms of action of phenolics-rich plant extracts has the potential to impact the development of novel compounds with promising applications in food and biopharmaceutical industry or medical approaches to preventing and treating pathogenic infections.

Aqueous Mechano-Bactericidal Action of Acicular Aragonite Crystals

Nanoneedle structures on dragonfly and cicada wing surfaces or black silicon nanoneedles demonstrate antibacterial phenomena, namely mechano-bactericidal action. These air-exposed, mechano-bactericidal surfaces serve to destroy adherent bacteria, but their bactericidal action in the water is no precedent to report. Calcium carbonate easily accumulates on surfaces during long-term exposure to hard water. We expect that aragonite nanoneedles, in particular, which grow on TiO2 during the photocatalytic treatment of calcium-rich groundwater, exhibit mechano-bactericidal action against bacteria in water. Here, we show that aragonite nanoneedles are grown on TiO2 ceramics from the calcium bicarbonate in mineral water exhibit mechano-bactericidal action against E. coli K-12 in water. Unmodified, calcite-modified as references and aragonite-modified TiO2 ceramics were exposed to water containing E. coli K-12 (in a petri dish), and their bactericidal action over time was investigated under static and agitated conditions. The surfaces of the materials were observed by scanning electron microscopy, and the live/dead bacterial cells were observed by confocal laser scanning microscopy. Further, the synergistic bactericidal performance achieved by mechano-bactericidal action and photocatalysis was demonstrated. Aragonite itself has a high biological affinity for the human body different from the other whisker-sharpen nano-materials, therefore, the mechano-bactericidal action of acicular aragonite in water is expected to inform the development of safe water purification systems for use in developing countries.