Sodium docusate as a cleaning agent for forward osmosis membranes fouled by landfill leachate wastewater

Pamoic acid and carbenoxolone specifically inhibit CRISPR/Cas9 in bacteria, mammalian cells, and mice in a DNA topology-specific manner

BACKGROUND

Regulation of the target DNA cleavage activity of CRISPR/Cas has naturally evolved in a few bacteria or bacteriophages but is lacking in higher species. Thus, identification of bioactive agents and mechanisms that can suppress the activity of Cas9 is urgently needed to rebalance this new genetic pressure.

RESULTS

Here, we identify four specific inhibitors of Cas9 by screening 4607 compounds that could inhibit the endonuclease activity of Cas9 via three distinct mechanisms: substrate-competitive and protospacer adjacent motif (PAM)-binding site-occupation; substrate-targeting; and sgRNA-targeting mechanisms. These inhibitors inhibit, in a dose-dependent manner, the activity of Streptococcus pyogenes Cas9 (SpyCas9), Staphylococcus aureus Cas9 (SauCas9), and SpyCas9 nickase-based BE4 base editors in in vitro purified enzyme assays, bacteria, mammalian cells, and mice. Importantly, pamoic acid and carbenoxolone show DNA-topology selectivity and preferentially inhibit the cleavage of linear DNA compared with a supercoiled plasmid.

CONCLUSIONS

These pharmacologically selective inhibitors and new mechanisms offer new tools for controlling the DNA-topology selective activity of Cas9.

Fluoroquinolone-Based Organic Salts (GUMBOS) with Antibacterial Potential

Antimicrobial resistance is a silent pandemic considered a public health concern worldwide. Strategic therapies are needed to replace antibacterials that are now ineffective. One approach entails the use of well-known antibacterials along with adjuvants that possess non-antibiotic properties but can extend the lifespan and enhance the effectiveness of the treatment, while also improving the suppression of resistance. In this regard, a group of uniform materials based on organic salts (GUMBOS) presents an alternative to this problem allowing the combination of antibacterials with adjuvants. Fluoroquinolones are a family of antibacterials used to treat respiratory and urinary tract infections with broad-spectrum activity. Ciprofloxacin and moxifloxacin-based GUMBOS were synthesized via anion exchange reactions with lithium and sodium salts. Structural characterization, thermal stability and octanol/water partition ratios were evaluated. The antibacterial profiles of most GUMBOS were comparable to their cationic counterparts when tested against Gram-positive S. aureus and Gram-negative E. coli, except for deoxycholate anion, which demonstrated the least effective antibacterial activity. Additionally, some GUMBOS were less cytotoxic to L929 fibroblast cells and non-hemolytic to red blood cells. Therefore, these agents exhibit promise as an alternative approach to combining drugs for treating infections caused by resistant bacteria.

Novel Approach to Landfill Wastewater Treatment Fouling Mitigation: Air Gap Membrane Distillation with Tin Sulfide-Coated PTFE Membrane

This study addressed the fouling issue in membrane distillation (M.D.) technology, a promising method for water purification and wastewater reclamation. To enhance the anti-fouling properties of the M.D. membrane, a tin sulfide (TS) coating onto polytetrafluoroethylene (PTFE) was proposed and evaluated with air gap membrane distillation (AGMD) using landfill leachate wastewater at high recovery rates (80% and 90%). The presence of TS on the membrane surface was confirmed using various techniques, such as Field Emission Scanning Electron Microscopy (FE-SEM), Fourier Transform Infrared Spectroscopy (FT-IR), Energy Dispersive Spectroscopy (EDS), contact angle measurement, and porosity analysis. The results indicated the TS-PTFE membrane exhibited better anti-fouling properties than the pristine PTFE membrane, and its fouling factors (FFs) were 10.4-13.1% compared to 14.4-16.5% for the PTFE membrane. The fouling was attributed to pore blockage and cake formation of carbonous and nitrogenous compounds. The study also found that physical cleaning with deionized (DI) water effectively restored the water flux, with more than 97% recovered for the TS-PTFE membrane. Additionally, the TS-PTFE membrane showed better water flux and product quality at 55 °C and excellent stability in maintaining the contact angle over time compared to the PTFE membrane.

Synthesis and characterization of porous reduced graphene oxide based geopolymeric membrane with titanium dioxide coating for forward osmosis application

Forward Osmosis (FO) is a promising separation technology with a wide range of applications in water and wastewater treatment. FO membrane is the core of the forward osmosis process. Recently, the organic membrane has been widely used for forward osmosis applications even though inorganic membrane has excellent mechanical properties, decent chemical resistance, high durability, high porosity, and good hydrophilicity. Nevertheless, the utilization of inorganic membrane is hindered by the heat-intensive steps involved in its fabrication and the use of expensive source material. Geopolymerization provides a cost-effective technique for the preparation of inorganic membranes because of its sintering-free steps and utilization of fly ash as source material. Herein, we present a sintering-free, environmentally friendly, and cost-effective synthesis of geopolymeric membrane for application in forward osmosis. Fly ash was mixed with alkaline activator solution and porous reduced graphene oxide (PRGO) to prepare geopolymer slurry. The hydrogen peroxide and egg albumen were used as foaming agent and surfactant, while the membrane surface was coated with titanium dioxide to enhance the hydrophilicity of the membrane surface. The PRGO content improved the mechanical properties of the geopolymeric membrane. The average maximum flux recorded was 21 L/m² h with geopolymer substrate having a pore size of 1.8 μm and hydrophilic coated layer pore size of 0.25 μm. The varying concentrations of PRGO control the substrate's mechanical properties and pore size, as well as provide new insights for future studies. These preliminary results show that low-cost geopolymer material is a promising candidate for FO membrane fabrication.