Precipitation of Iron Oxide in Hydrogel with Superparamagnetic and Stimuli-Responsive Properties

In this work, we present a template-based preparation of iron oxide-containing hydrogels (ferrogels) with ionic sensitive and superparamagnetic properties. The influence of the cross-linked template polyacrylamide and the concentration of the iron salts and sodium hydroxide on the precipitation of the iron oxide particles is investigated with respect to the stability of the ferrogels. Scanning electron microscope images show cubic particles, which can be semiquantitatively classified in three groups of particle size with respect to the dilution level. Magnetic hysteresis curves reveal a sigmoidal shape without remanence and coercivity for all samples. The higher cross-linked ferrogels, in comparison with the lower cross-linked ferrogels, possess a steady-state degree of swelling in ultrapure water and a stimuli-sensitive deswelling over a wide range of varying ionic strengths. Thus, they are suitable candidates for applications in sensing and microfluidics.

Surface Modification of PES Hollow Fiber Membranes using Iron Oxide Particles for Water Treatment Does Particle Size Really Matter?

Factors such as particle type and its loading have been previously studied in tailoring the efficiency of particles-modified polymeric membranes for water treatment. However, the role of particle sizes in membrane modification is often overlooked.

In Situ Functionalization of Iron Oxide Particles with Alginate: A Promising Biosorbent for Retention of Metal Ions

In this study, alginate extracted from marine algae biomass was used for the functionalization of iron oxide particles obtained in situ. This procedure ensured a complete recovery of the alginate from the aqueous solution obtained after extraction and allowed the preparation of a new biosorbent. The obtained iron oxide microparticles functionalized with alginate (Alg-Fe3O4-MPs) were analyzed (FTIR spectrometry, energy dispersive X-ray spectroscopy and scanning electron microscopy), and their biosorptive performance was tested for the removal of Cu(II), Co(II) and Zn(II) ions. The optimal conditions were established as pH = 5.4, adsorbent dosage of 2 g/L, contact time of minimum 60 min and room temperature (23 ± 1 °C). The retention of metal ions was quantitative (99% for Cu(II), 89% for Co(II) and 95% for Zn(II)) when the concentration of metal ions was less than 0.80 mmol M(II)/L. The Langmuir model was found to be the best fitted model for the equilibrium data, while biosorption kinetics followed the pseudo-second order model. Biosorption processes were spontaneous (ΔG0 < 0), endothermic (ΔH0 > 0), and accompanied by an increase in entropy (ΔS0 > 0). The high maximum biosorption capacity of Alg-Fe3O4-MPs and its good regeneration highlight the potential of this biosorbent for applications in decontamination processes.

Folic Acid Decorated β-Cyclodextrin-Based Poly(ε-Caprolactone)/Dextran Star Polymer with Disulfide Bond-Linker as Theranostic Nanoparticle for Tumor-Targeted MRI and Chemotherapy

&beta;-cyclodextrin-based star polymers have attracted much interest because of their unique structures and potential biomedical and biological applications. Herein, we synthesized well-defined folic acid (FA)-conjugated and disulfide bond-linked star polymer ((FA-Dex-SS)-&beta;CD-(PCL)14) acted as theranostic nanoparticles for tumor-targeted magnetic resonance imaging (MRI) and chemotherapy. Theranostic nanoparticles were obtained by loading doxorubicin (DOX) and superparamagnetic iron oxide particles (SPIO) were loaded into the star polymer nanoparticles to obtain ((FA-Dex-SS)-&beta;CD-(PCL)14@DOX/SPIO) theranostic nanoparticles. In vitro drug release studies showed that approximately 100% of the DOX was released from disulfide bond-linked theranostic nanoparticles within 24 h under a reducing environment in the presence of 10.0 mM GSH. DOX and SPIO could be delivered into HepG2 cells efficiently, owing to folate receptor-mediated endocytosis process of the nanoparticles and GSH triggered disulfide-bonds cleaving.Moreover, (FA-Dex-SS)-&beta;CD-(PCL)14@DOX/SPIO showed strong MRI contrast enhancement properties. In conclusion, folate-decorated reduction-sensitive star polymeric nanoparticles are a potential theranostic nanoparticle candidate for tumor-targeted MRI and chemotherapy.

Effects of Fe(OH)3 and MnO2 Flocs on Iron/Manganese Removal and Fouling in Aerated Submerged Membrane Systems

Many treatment methods are used to remove iron and manganese from water. Aeration and membrane filtration are two of these methods. In this study, Fe2+ and Mn2+ removal by aeration with different catalysts and instead of simple membrane filtration applied in other studies, the aerated-submerged membrane systems were evaluated separately. When Fe(OH)3 was applied in the aeration step and complete oxidation of Fe2+ was obtained after 27 min, while complete Mn2+ oxidation was obtained in 76 min. However, when MnO2 was applied in the aeration step, complete oxidation of Fe2+ and Mn2+ was relatively slow (36 and 110 min, respectively). According to the results obtained from the aerated membrane system, Fe2+ and Mn2+ removal were extended by Fe(OH)3 via adsorption/surface oxidation. It is clearly shown from the flux, resistance results, scanning electron microscope (SEM) and Fourier transform infrared (FT/IR) spectroscopy observation that manganese oxides were deposited mainly in membrane pores forming membrane fouling by small flocs, while iron oxide particles were deposited on the membrane surface. Although the flux performance of PT PES membrane was higher than HF PP membrane, fouling resistance of HF PP membrane was higher than PT PES.

Solar-Driven Desalination Using Nanoparticles

Due to the high light absorption and the possibility of localizing boiling to the interior of the receiver, nanoparticles are promising for solar-driven desalination. The paper presents an experimental study of the nanoparticle-based photothermal boiling of water with sea salt. The experiments were carried out using a laboratory-scale system with a transparent photothermal receiver of light and a closed condensate cycle. In this study, we tested three types of nanoparticles: multiwall carbon nanotubes with two main sizes of 49 nm and 72 nm, 110 nm iron oxide particles Fe3O4, and a commercial paste based on carbon nanotubes. The concentration of nanoparticles was varied up to 10% wt. We found that the nanoparticles enhance the steam generation by 23%, relative to a conventional desalinator with a black-body receiver. The best result was obtained for the 5% wt. concentration of carbon nanotubes.

Magnetic Mesoporous Silica Nanoparticles Incorporated with miR-451 Suppress Development of Cervical Cancer and Enhance Radio Sensitization in Cervical Cancer

Cervical cancer (CC) is one of the most common gynecological malignancies with high mortality, threatening female’s health and reducing their life quality. This study evaluated the synergistic effect of magnetic mesoporous silica nanoparticles (MMSNs), miR-451 on radio sensitivity and cell apoptosis in CC. Magnetic mesoporous silica (Fe3O4/SiO2) nanoparticles were prepared and loaded with miR-451. Then the CC cells were treated with Fe3O4/SiO2 nanoparticles, miR-451-loaded Fe3O4/SiO2 nanoparticles (control group) and untreated (blank group). Cell proliferation was determined by MTT assay, while apoptosis and Hoechst were assessed by flow cytometry. As colony formation assay was conducted to evaluate cell sensitivity to radiotherapy, Western blot analysis detected the expression of apoptosis- and radiosensitization-related genes. Iron oxide particles were present inside and outside the SiO2 channel with characteristic peaks for Fe and skeleton of silica. The miR-451-loaded Fe3O4/SiO2 nanoparticles had an obvious absorption peak with drug loading rate and encapsulation rate reaching 6% and 91%. The release content of drugs increased with decreased pH. Of note, combined treatment with miR-451 and Fe3O4/SiO2 nanoparticles significantly decreased cancer cell proliferation and increased apoptosis (34.36±2.31%), compared to control group and blank group. Furthermore, the levels of D0 (1.67), Dq (0.94), N (1.56), and SF2 (0.43) declined in the presence of miR-451-Fe3O4/SiO2 nanoparticles, accompanied with elevation of ATM and γ-H2AX expression. Meanwhile, the treated CC cells had decreased expressions of DNA damage repair related genes ATM and γ-H2AX. MMSNs carrying miR-451 decreased cell proliferation activity and increased apoptosis and sensitized the CC cells to radiotherapy, to improve tissue repairing. These findings may provide a novel insight into pathogenesis of CC.