High performance self-assembled sulfidized nanoscale zero-valent iron for the immobilization of cadmium in contaminated sediments: Optimization, microbial response, and mechanisms.

Sulfidized nanoscale zero-valent iron (S-nZVI) showed excellent removal capacity for cadmium (Cd) in aqueous phase. However, the remediation effects of S-nZVI on Cd-contaminated sediment and its interactions with microorganisms in relation to Cd fate remain unclear. The complexity of the external environment posed a challenge for Cd remediation. This study synthesized S-nZVI with different S and Fe precursors to investigate the effect of precursors and applied the optimal material to immobilize Cd in sediments. Characterization analysis revealed that the precursor affected the morphology, Fe0 crystallinity, and the degree of oxidation of the material. Incubation experiments demonstrated that the immobilization efficiency of Cd using S-nZVIFe3++S2- (S/Fe = 0.14) reached the peak value of 99.54%. 1% and 5% dosages of S-nZVI significantly reduced Cd concentration in the overlying water, DTPA-extractable Cd content, and exchangeable (EX) Cd speciation (P < 0.05). Cd leaching in sediment and total iron in the overlying water remained at low levels during 90 d of incubation. Notably, each treatment maintained a high Cd immobilization efficiency under different pH, water/sediment ratio, organic acid, and coexisting ion conditions. Sediment physicochemical properties, functional bacteria, and a range of adsorption, complexation and precipitation of CdS effects dominated Cd immobilization.

Activation of persulfate by biochar-supported sulfidized nanoscale zero-valent iron for degradation of ciprofloxacin in aqueous solution: process optimization and degradation pathway.

The pollution of antibiotics, specifically ciprofloxacin (CIP), has emerged as a significant issue in the aquatic environment. Advanced oxidation processes (AOPs) are capable of achieving stable and efficient removal of antibiotics from wastewater. In this work, biochar-supported sulfidized nanoscale zero-valent iron (S-nZVI/BC) was adopted to activate persulfate (PS) for the degradation of CIP. The impacts of different influencing factors such as S/Fe molar ratios, BC/S-nZVI mass ratios, PS concentration, S-nZVI/BC dosage, CIP concentration, initial pH, coexisting anions, and humic acid on CIP degradation efficiency were explored by batch experiments. The results demonstrated that the highest degradation ability of S-nZVI/BC was achieved when the S/Fe molar ratio was 0.07 and the BC/S-nZVI mass ratio was 1:1. Under the experimental conditions with 0.6 g/L S-nZVI/BC, 2 mmol/L PS, and 10 mg/L CIP, the degradation rate reached 97.45% after 90 min. The S-nZVI/BC + PS system showed significant degradation in the pH range from 3 to 9. The coexisting anions affected the CIP degradation efficiency in the following order: CO32- > NO3- > SO42- > Cl-. The radical quenching experiments and electron paramagnetic resonance (EPR) revealed that oxidative species, including SO4•-, HO•, •O2-, and 1O2, all contribute to the degradation of CIP, in which •O2- plays a particularly prominent role. Furthermore, the probable degradation pathway of CIP was explored according to the 12 degradation intermediates identified by LC-MS. This study provides a new idea for the activation method of PS and presents a new approach for the treatment of aqueous antibiotics with highly catalytic active nanomaterials.

Immobilization of cadmium in river sediments by different modified nanoscale zero-valent iron: performance, mechanisms, and Fe dissolution.

Modified nanoscale zero-valent iron (NZVI) exhibited great potential for the remediation of heavy metal contaminated river sediments, but its mechanisms and environmental risks are still unclear. This study systematically discussed the performance and the mechanisms of modified NZVI materials, i.e., sodium alginate-coated NZVI (SNZVI), rhamnolipid-coated NZVI (RNZVI), and graphene oxide-loaded NZVI (GNZVI), for the stabilization of Cd in sediment, with the exploration of their stability to Cd at various pH values and Fe dissolution rate. Compared with the control, the toxicity characteristic leaching procedure (TCLP) leachable Cd decreased by 52.66-96.28%, and the physiologically based extraction test (PBET) extractable Cd decreased by 44.68-70.21% after 56 days of incubation with the immobilization efficiency varying according to GNZVI > RNZVI > SNZVI > NZVI. Besides, the adsorption behavior of Cd on materials was fitted with the Freundlich model and classified as an endothermic, spontaneous, and chemical adsorption process. SEM-EDX, XRD, and FTIR results verified that the stabilization mechanisms of Cd were principally based on the adsorption, complexation of Cd2+ with secondary Fe minerals (including Fe2O3, γ-Fe2O3, and γ-FeOOH) and precipitation (Cd(OH)2). From the risk assessment results, it was observed that the materials were favorable for Cd stabilization at a pH range from 7 to 11, meanwhile, the leaching concentration of Fe in the overlying water was detected below the limit value. These findings pave the way to developing an effective strategy to remediate Cd contaminated river sediments.

Recent advances in sulfidized nanoscale zero-valent iron materials for environmental remediation and challenges.

Over the past decade, sulfidized nanoscale zero-valent iron (S-nZVI) has been developed as a promising tool for the remediation of contaminated soil, sediment, and water. Although most studies have focused on applying S-nZVI for clean-up purposes, there is still a lack of systematic summary and discussion from its synthesis, application, to toxicity assessment. This review firstly summarized and compared the properties of S-nZVI synthesized from one-step and two-step synthesis methods, and the modification protocols for obtaining better stability and reactivity. In the context of environmental remediation, this review outlined an update on the latest development of S-nZVI for removal of heavy metals, organic pollutants, antibiotic resistance genes (ARGs), and antibiotic resistant bacteria (ARB) and also discussed the underlying removal mechanisms. Environmental factors affecting the remediation performance of S-nZVI (e.g., humic acid, coexisting ions, S/Fe molar ratio, pH, and oxygen condition) were highlighted. Besides, the application potential of S-nZVI in advanced oxidation processes (AOP), especially in activating persulfate, was also evaluated. The toxicity impacts of S-nZVI on the environmental microorganism were described. Finally, the future challenges and remaining restrains to be resolved for better applicability of S-nZVI are also proposed. This review could provide guidance for the environmental remediation with S-nZVI-based technology from theoretical basis and practical perspectives.

Informatics on Drug Repurposing for Breast Cancer.

Moving a new drug from bench to bedside is a long and arduous process. The tactic of drug repurposing, which solves "new" diseases with "old" existing drugs, is more efficient and economical than conventional ab-initio way for drug development. Information technology has dramatically changed the paradigm of biomedical research in the new century, and drug repurposing studies have been significantly accelerated by implementing informatics techniques related to genomics, systems biology and biophysics during the past few years. A series of remarkable achievements in this field comes with the practical applications of in silico approaches including transcriptomic signature matching, gene-connection-based scanning, and simulated structure docking in repositioning drug therapies against breast cancer. In this review, we systematically curated these impressive accomplishments with summarization of the main findings on potentially repurposable drugs, and provide our insights into the current issues as well as future directions of the field. With the prospective improvement in reliability, the computer-assisted repurposing strategy will play a more critical role in drug research and development.

An Isoxazoloquinone Derivative Inhibits Tumor Growth by Targeting STAT3 and Triggering Its Ubiquitin-Dependent Degradation.

BACKGROUND: Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype, with shorter five-year survival than other breast cancer subtypes, and lacks targeted and hormonal treatment strategies. The signal transducer and activator of transcription 3 (STAT3) signaling is up-regulated in various tumors, including TNBC, and plays a vital role in regulating the expression of multiple proliferation- and apoptosis-related genes. RESULTS: By combining the unique structures of the natural compounds STA-21 and Aulosirazole with antitumor activities, we synthesized a class of novel isoxazoloquinone derivatives and showed that one of these compounds, ZSW, binds to the SH2 domain of STAT3, leading to decreased STAT3 expression and activation in TNBC cells. Furthermore, ZSW promotes STAT3 ubiquitination, inhibits the proliferation of TNBC cells in vitro, and attenuates tumor growth with manageable toxicities in vivo. ZSW also decreases the mammosphere formation of breast cancer stem cells (BCSCs) by inhibiting STAT3. CONCLUSIONS: We conclude that the novel isoxazoloquinone ZSW may be developed as a cancer therapeutic because it targets STAT3, thereby inhibiting the stemness of cancer cells.

Synthesis and biological evaluation of novel isothiazoloquinoline quinone analogues.

Natural quinones and their analogues have attracted growing attention because of their novel anticancer activities. A series of novel isothiazoloquinoline quinone analogues were synthesized and evaluated for antitumor activities against four different kind of cancer cells. Among them, isothiazoloquinolinoquinones inhibited cancer cells proliferation effectively with IC50 values in the nanomolar range, and isothiazoloquinolinoquinone 13a induced the cell apoptosis. Further exploration of possible mechanism of action indicates that 13a not only activates ROS production through NQO1-directed redox cycling but also inhibits the phosphorylation of STAT3. These findings indicate that 13a has potential use for the development of new skeleton drug candidate as an efficient substrate of NQO1 and STAT3 inhibitor.