No abstract

Increased resistance of bacteria to disinfection and antimicrobial treatment poses a serious public health threat worldwide. This has prompted the search for agents that can inhibit both bacterial growth and withstand harsh conditions (e.g., high organic loads). In the current study, N-halamine-derivatized cross-linked polymethacrylamide nanoparticles (NPs) were synthesized by copolymerization of the monomer methacrylamide (MAA) and the cross-linker monomer N,N-methylenebis(acrylamide) (MBAA) and were subsequently loaded with oxidative chlorine using sodium hypochlorite (NaOCl). The chlorinated NPs demonstrated remarkable stability and durability to organic reagents and to repetitive bacterial loading cycles as compared with the common disinfectant NaOCl (bleach), which was extremely labile under these conditions. The antibacterial mechanism of the cross-linked P(MAA-MBAA)-Cl NPs was found to involve generation of reactive oxygen species (ROS) only upon exposure to organic media. Importantly, ROS were not generated upon suspension in water, revealing that the mode of action is target-specific. Further, a unique and specific interaction of the chlorinated NPs with Staphylococcus aureus was discovered, whereby these microorganisms were all specifically targeted and marked for destruction. This bacterial encircling was achieved without using a targeting module (e.g., an antibody or a ligand) and represents a highly beneficial, natural property of the P(MAA-MBAA)-Cl nanostructures. Our findings provide insights into the mechanism of action of P(MAA-MBAA)-Cl NPs and demonstrate the superior efficacy of the NPs over bleach (i.e., stability, specificity, and targeting). This work underscores the potential of developing sustainable P(MAA-MBAA)-Cl NP-based devices for inhibiting bacterial colonization and growth.

In this study, we describe the synthesis and characterization of superparamagnetic core-shell iron oxide (IO)/N-halamine antibacterial nanoparticles (NPs). For this purpose, superparamagnetic IO core NPs were coated with cross-linked polymethacrylamide (PMAA) by surfactant-free dispersion copolymerization of methacrylamide and N,N-methylenebis(acrylamide) in an aqueous continuous phase. The effect of the polymerization process on the chemical composition, size, shape, crystallinity, and magnetic properties of the IO/PMAA NPs was elucidated. Conversion of the core-shell IO/PMAA NPs into their N-halamine form, IO/PMAA-Cl, was accomplished using a chlorination reaction with sodium hypochlorite. The influence of chlorination on the shape, crystallinity, and magnetic properties of the IO/PMAA NPs was studied. The IO/PMAA-Cl NPs demonstrated excellent antibacterial activity against Gram-negative and Gram-positive bacteria. Finally, the chlorination recharging capabilities of the NPs and their potential for use in the purification of water containing bacteria were demonstrated with magnetic columns packed with the IO/PMAA-Cl NPs.

Most illicit drug casework samples at the Israel Police National Drug Laboratory are found to be mixtures of substances. Some are a mixture of an illicit drug with fillers, and others may contain more than one illicit drug. This study was triggered by a routine gas chromatography‐mass spectrometry (GC‐MS) analysis of an unusual casework sample. The sample chromatogram showed a mixture of two illicit drugs, 4‐acetoxy‐DMT and psilocin. Considering the two substances’ similar skeletal structure, the authors wondered whether the sample was indeed a mixture of the two substances, or whether perhaps 4‐acetoxy‐DMT was hydrolyzed to psilocin during the analysis. This study hypothesized that indeed the base used in the pre‐injection sample preparation hydrolyzed the ester group on the 4‐acetoxy‐DMT yielding a hydroxide group. This was tested using several concentrations of ammonium hydroxide and two additional bases – pyridine (a weak base) and sodium hydroxide (a strong base). Results showed that media with a higher pH (induced by the stronger base) yielded a higher psilocin to 4‐acetoxy‐DMT ratio which is compatible with degradation of 4‐acetoxy‐DMT. This study also explored the possibility that psilocin was a byproduct of thermal decomposition of 4‐acetoxy‐DMT and found it thermally stable in the temperature of the GC injection port (200°C). The 4‐acetoxy‐DMT case demonstrates how pre‐injection laboratory procedures can inadvertently modify casework samples. Caution is clearly advisable in selecting reagents and processes in general, and specifically in the case of GC‐MS pre‐injection procedures conducted to analyze substances like the ones in the present study.

The increased demand for water highlights the need to utilize reclaimed water of various types. In agriculture, for example, which is considered the largest consumer of freshwater, irrigation with treated wastewater can replace much of the need for freshwater. Wastewater is generally used for irrigation through drippers, releasing small amounts of water to the crops. The contaminants found in treated wastewater increase the accumulation of fouling on the drippers, ultimately culminating in blocking of water exit. Thus, there is a crucial need to develop novel approaches to limit biofilm formation on the dripper. Here, we describe the synthesis of N-halamine-derivatized cross-linked polymethacrylamide nanoparticles (NPs) by copolymerization of the monomer methacrylamide and the cross-linker monomer N,N-methylenebisacrylamide and their subsequent embedding in the polyethylene that is used to fabricate the drippers. The newly designed drip system was activated by chlorinating the incorporated NPs and then was fully characterized. The nanofunctionalized drippers were tested in the field, showing excellent antifouling activity for at least 5 months compared to the control. In addition, the inherent recharging capacity of the antifouling NPs constitutes yet another valuable advantage of the currently reported technology.