Quaternary Ammonium Salt-Based Cross-Linked Micelles to Combat Biofilm.

Due to self-produced extracellular polymeric substances (EPS), biofilms are hard to eradicate by common antimicrobials. Herein, a new quaternary ammonium salt based cross-linked micelle (QAS@CM) was created to combat biofilms. The QAS@CM adsorbed first onto the biofilm surface through multicharged interaction, then penetrated the EPS in the form of nanoparticles and diffused throughout the films. By responding to the biofilm acid/lipase microenvironment, these nanoparticles would further break into quaternary ammonium oligomers and act as the polyvalent inhibitors to effectively destroy the established biofilm and kill the corresponding bacteria within it.

Covalent capture of supramolecular species in an aqueous solution of water-miscible small organic molecules.

Since an early report in the 1970s, the mesoscale inhomogeneities formed in an aqueous solution of water-miscible small organic molecules have been debated for over forty years with a variety of explanations. Although it was recently established that these inhomogeneities are supramolecular species caused by trace impurities, the structure of the supramolecular species and the mechanism behind their formation are not yet clear. By means of covalent capture, we herein disclose that the formation mechanism of the supramolecular species consists of a two-step self-assembly process: the small molecules first assemble into primary micelles with a trace amount of impurity, and the formed dynamic ultra-small micelles aggregate further through hydrogen bonding to achieve a buildup of thermodynamic mesoscale inhomogeneities. Based on this finding, supramolecular species have been used as elements for pH-responsive size-changeable drug carriers, which respond to the acidic tumour extracellular milieu and decompose into small particles for deep tumour penetration and effective distribution.

One-Pot Synthesis of Cellulose-Based Carbon Aerogel Loaded with TiO2 and g-C3N4 and Its Photocatalytic Degradation of Rhodamine B.

A cellulose-based carbon aerogel (CTN) loaded with titanium dioxide (TiO2) and graphitic carbon nitride (g-C3N4) was prepared using sol-gel, freeze-drying, and high-temperature carbonization methods. The formation of the sol-gel was carried out through a one-pot method using refining papermaking pulp, tetrabutyl titanate, and urea as raw materials and hectorite as a cross-linking and reinforcing agent. Due to the cross-linking ability of hectorite, the carbonized aerogel maintained a porous structure and had a large specific surface area with low density (0.0209 g/cm3). The analysis of XRD, XPS, and Raman spectra revealed that the titanium dioxide (TiO2) and graphitic carbon nitride (g-C3N4) were uniformly distributed in the CTN, while TEM and SEM observations demonstrated the uniformly distributed three-dimensional porous structure of CTN. The photocatalytic activity of the CTN was determined according to its ability to degrade rhodamine B. The removal rate reached 89% under visible light after 120 min. In addition, the CTN was still stable after five reuse cycles. The proposed catalyst exhibits excellent photocatalytic performance under visible light conditions.

Biochar loaded with cobalt ferrate activated persulfate to degrade naphthalene.

Considering the simple preparation of biochar and the excellent activation performance of cobalt ferrate material, a biochar supported cobalt ferrate composite was synthesized by a solvothermal method. The material was used to activate persulfate (PS) to degrade naphthalene (NAP) in water. The structure and morphology characterization showed that the composite (CoFe2O4-BC) was successfully prepared. Under the conditions of 0.25 g L-1 CoFe2O4-BC and 1 mM PS, 90.6% NAP (the initial concentration was 0.1 mM) was degraded after 30 minutes. The degradation kinetics of NAP followed the pseudo-first-order kinetic model with a rate constant of 0.0645 min-1. With the increase of the dosage of activator and PS, the removal rate of NAP could be increased to 99.5%. The coexistence of anions and humic acids inhibited the removal of NAP. The acid environment promoted the removal of NAP while the alkaline environment inhibited it. After four cycles of CoFe2O4-BC material, the removal rate of NAP decreased from 90.6% to 79.4%. The removal of TOC was about 45% after each cycle. After the first cycle, the concentration of leached cobalt ion and leached iron ion was about 310 µg L-1 and 30 µg L-1 respectively. The free radical quenching experiments showed that SO4 -˙ and OH˙ were the main causes of NAP removal, and the possible degradation path of NAP was elucidated by DFT calculation.

Antibacterial coordination polymer hydrogels composed of silver(i)-PEGylated bisimidazolylbenzyl alcohol.

Herein, antibacterial coordination polymer hydrogels were conveniently fabricated in water via coordination between silver nitrate and PEGylated bisimidazolylbenzyl alcohol (1a-c). These coordination polymer hydrogels exhibit much better antibacterial activity than silver nitrate against both Gram-negative and Gram-positive pathogens including multidrug-resistant pathogens. The coordination polymer Ag/1c with a long PEG chain (PEG1000) was demonstrated to be the most effective antibacterial material, and its minimum inhibition concentrations (MICs) could be as low as 15.2 times for common Staphylococcus aureus and 4.8 times for methicillin-resistant Staphylococcus aureus over that of silver nitrate. With improved antibacterial performance, easy preparation method, improved stability, sustained releasability, outstanding ductility and low cytotoxicity, the as-prepared coordination polymer hydrogels should find various potential applications such as in clinical burn and wound dressings, biofilms, bioadhesives, and coatings of biomedical materials.