Aeration-driven piezoelectric activation of peroxymonosulfate achieves effective mitigation of antibiotic resistance dissemination.

The antibiotic resistance dissemination in water has become a globally concerned issue, and the wastewater discharge, especially medical wastewater, is considered as one of the most important sources for antibiotic resistance genes (ARGs). However, the effectiveness of current disinfection techniques in the ARGs reduction still remains controversial. In this study, a novel aeration-driven piezoelectric peroxymonosulfate (PMS) activation system using oxygen-vacancy engineered BaTiO3 (BTO) was developed to effectively eliminate antibiotic resistant bacteria (ARB) and ARGs from water. The ARB can be completely inactivated and ∼3.0 logs of ARGs can be removed by the PMS/BTO/aeration system within 1 h, and the spent BTO nanoparticles can be facilely reused after simple rinsing. The aeration can not only provide the driving force for the piezocatalytic process but also more dissolved oxygen in water that played an important role in the generation of free radicals. The radical quenching experiments and electron spin-resonance (ESR) confirmed that all the free radicals, including singlet oxygen (1O2), hydroxyl radical (OH•), sulfate radical (SO4•-) and superoxide radical (•O2-), contributed to the ARGs reduction and 1O2 radicals were identified as the dominant active species. This work provides a high-efficiency and energy saving approach for the mitigation of ARGs from water as the universal use of aeration in water treatment processes and the good reusability of BTO nanoparticles.

Sub-MIC antibiotics affect microbial ferrihydrite reduction by extracellular membrane vesicles.

Environmental concentrations of antibiotics, usually below MIC, have significant biological effects on bacterial cells. Sub-MIC antibiotics exposure induces bacteria to produce outer membrane vesicles (OMVs). Recently, OMVs is discovered as a novel pathway for dissimilatory iron reducing bacteria (DIRB) to mediate extracellular electron transfer (EET). Whether and how the antibiotic-induced OMVs modulate iron oxides reduction by DIRB have not been studied. This study showed the sub-MIC antibiotics (ampicillin or ciprofloxacin) increased OMVs secretion in Geobacter sulfurreducens, and the antibiotic-induced OMVs contained more redox active cytochromes facilitating iron oxides reduction, especially for the ciprofloxacin-induced OMVs. Deduced from a combination of electron microscopy and proteomic analysis, the influence of ciprofloxacin on SOS response triggered prophage induction and led to the formation of outer-inner membrane vesicles (OIMVs) in, which was a first report in Geobacter species. While ampicillin disrupting cell membrane integrity resulted in more formation of classic OMVs from outer membrane blebbing. The results indicated that the different structure and composition of vesicles were responsible for the antibiotic-dependent regulation on iron oxides reduction. This newly identified regulation on EET-mediated redox reactions by sub-MIC antibiotics expands our knowledge about the impact of antibiotics on microbial processes or "non-target" organisms.

Insight into performance and mechanism of tea polyphenols and ferric ions on reductive decolorization of malachite green cationic dye under moderate conditions.

Dye decolorization is of crucial concern for effectively treating dye wastewater. In this study, rapid and effective decolorization of malachite green cationic dye was achieved by tea polyphenols and ferric ions under moderate conditions. Approximately 96.2% of decolorization efficiency could be obtained within the first 10 min at the initial dye concentration of 50 mg/L. The proposed method can perform excellently in a wide pH range of 5-9 and decolorization kinetics of malachite green under different solution pH were well fitted by the pseudo-second-order model. After the decolorization, only a slight reduction of tea polyphenols was observed, while the strength of peaks assigned to nitrogen-containing groups was significantly weakened, indicating that the N-demethylation reaction might occur during the decolorization process. The nucleophilic attack of deprotonated hydroxyl groups of tea polyphenols was proposed as the decolorization mechanism. The presence of ferric ions at an appropriate dosage could promote the deprotonation process and therefore enhance decolorization efficiency, while excess ferric ions in solution might compete with malachite green dye towards reductive sites on tea polyphenols. The findings from this study provided an economical and environmentally friendly technique for the effective decolorization of dye wastewater.

Methodological assessment of the reduction of the content of impurities in nimodipine emulsion via the use of 21 amino acid protection.

PURPOSE: The present study examined the factors affecting the content of impurities of nimodipine (NMP) emulsion and the associated methods of compound protection. METHODS: Destructive testing of NMP emulsion and its active pharmaceutical ingredient (API) were conducted, and ultracentrifugation was used to study the content of impurities in two phases. The impurity of NMP was measured under different potential of hydrogen (pH) conditions, antioxidants and pH-adjusting agents. RESULTS: Following destruction, the degradation of NMP notably occurred in the basic environment. The consumption of the pH-adjusting agent NaOH was proportional to the production of impurities since the inorganic base and/or acid promoted the degradation of NMP. The organic antioxidants, notably amino acids with an appropriate length of intermediate chain and electron-donating side group, exhibited improved antioxidant effects compared with inorganic antioxidants. The minimal amount of impurities was produced following addition of 0.04% lysine and 0.06% leucine in the aqueous phase and adjustment of the pH to a range of 7.5-8.0 in the presence of acetic acid solution. CONCLUSION: NMP was more prone to degradation in an oxidative environment, in an aqueous phase and/or in the presence of inorganic pH-adjusting agents and antioxidants. The appropriate antioxidant and pH-adjusting agent should be selected according to the chemical structure, while destructive testing of the drug is considered to play the optimal protective effect.

[Relation between drug release and the drug status within curcumin-loaded microsphere].

To study the relation between drug release and the drug status within curcumin-loaded microsphere, SPG (shirasu porous glass) membrane emulsification was used to prepare the curcumin-PLGA (polylactic-co-glycolic acid) microspheres with three levels of drug loading respectively, and the in vitro release was studied with high-performance liquid chromatography (HPLC). The morphology of microspheres was observed with scanning electron microscopy (SEM), and the drug status was studied with X-ray diffraction (XRD), differential scanning calorimetry (DSC) and infrared analysis (IR). The drug loading of microspheres was (5.85 ± 0.21)%, (11.71 ± 0.39)%, (15.41 ± 0.40)%, respectively. No chemical connection was found between curcumin and PLGA. According to the results of XRD, curcumin dispersed in PLGA as amorphous form within the microspheres of the lowest drug loading, while (2.12 ± 0.64)% and (5.66 ± 0.07)% curcumin crystals was detected in the other two kinds of microspheres, respectively, indicating that the drug status was different within three kinds of microspheres. In the data analysis, we found that PLGA had a limited capacity of dissolving curcumin. When the drug loading exceeded the limit, the excess curcumin would exist in the form of crystals in microspheres independently. Meanwhile, this factor contributes to the difference in drug release behavior of the three groups of microspheres.

The research about microscopic structure of emulsion membrane in O/W emulsion by NMR and its influence to emulsion stability.

PURPOSE: This paper discussed the influence of microstructure of emulsion membrane on O/W emulsion stability. METHODS: O/W emulsions were emulsified with equal dosage of egg yolk lecithin and increasing dosage of co-emulsifier (oleic acid or HS15). The average particle size and centrifugal stability constant of emulsion, as well as interfacial tension between oil and water phase were determined. The microstructure of emulsion membrane had been studied by (1)H/(13)C NMR, meanwhile the emulsion droplets were visually presented with TEM and IFM. RESULTS: With increasing dosage of co-emulsifier, emulsions showed two stable states, under which the signal intensity of characteristic group (orient to lipophilic core) of egg yolk lecithin disappeared in NMR of emulsions, but that (orient to aqueous phase) of co-emulsifiers only had some reduction at the second stable state. At the two stable states, the emulsion membranes were neater in TEM and emulsion droplets were rounder in IFM. Furthermore, the average particle size of emulsions at the second stable state was bigger than that at the first stable state. CONCLUSIONS: Egg yolk lecithin and co-emulsifier respectively arranged into monolayer and bilayer emulsion membrane at the two stable states. The microstructure of emulsion membrane was related to the stability of emulsion.