Synthesis of magnetic metal-organic framework (MOF) for efficient removal of organic dyes from water

Technology for the Remediation of Water Pollution: A Review on the Fabrication of Metal Organic Frameworks

The ineffective control of the release of pollutants into water has led to serious water pollution. Compared with conditions in the past, the polluting components in aquatic environments have become increasingly complex. Some emerging substances have led to a new threat to the safety of water. Therefore, developing cost-effective technologies for the remediation of water pollution is urgently needed. Adsorption has been considered the most effective operational unit in water treatment processes and thus adsorption materials have gained wide attention. Among them, metal organic frameworks (denoted as MOFs) have been rapidly developed in recent years due to their unique physicochemical performance. They are characterized by larger porosity and larger specific surface area, easier pore structure designing, and comfortable structural modification. In many fields such as adsorption, separation, storage, and transportation, MOFs show a better performance than conventional adsorption materials such as active carbon. Their performance is often dependent on their structural distribution. To optimize the use of MOFs, their fabrication should be given more attention, without being limited to conventional preparation methods. Alternative preparation methods are given in this review, such as diffusion, solvent thermal, microwave, and ion thermal synthesis. Furthermore, developing functionalized MOFs is an available option to improve the removal efficiencies of a specific contaminant through pre-synthetic modification and post-synthesis modification. Post-synthesis modification has become a recent research hotspot. The coupling of MOFs with other techniques would be another option to ameliorate the remediation of water pollution. On one hand, their intrinsic drawbacks may be reduced. On the other hand, their performance may be enhanced due to their interaction behaviors. Overall, such coupling technologies are able to enhance the performance of an individual material. Because the excellent performance of MOF materials has been widely recognized and their developments have received wide attention, especially in environmental fields, in the present work we provide a review of fabrication of MOFs so as to motivate readers to deepen their understanding of the use of MOFs.

Recent advances in metal-organic frameworks for adsorption of common aromatic pollutants

This review (with 85 refs.) summarizes the recent literature on the adsorption of common aromatic pollutants by using modified metal-organic frameworks (MOFs). Four kinds of aromatic pollutants are discussed, namely benzene homologues, polycyclic aromatic hydrocarbons (PAHs), organic dyes and their intermediates, and pharmaceuticals and personal care products (PPCPs). MOFs are shown to be excellent adsorbents that can be employed to both the elimination of pollutants and to their extraction and quantitation. Adsorption mechanisms and interactions between aromatic pollutants and MOFs are discussed. Finally, the actual challenges of existence and the perspective routes towards future improvements in the field are addressed. Graphical abstract Recent advance on adsorption of common aromatic pollutants including benzene series, polycyclic aromatic hydrocarbons, organic dyes and their intermediates, pharmaceuticals and personal care products by metal-organic frameworks.

Magnetic Zr-MOFs nanocomposites for rapid removal of heavy metal ions and dyes from water

Amino-decorated Zr-based magnetic Metal-Organic Frameworks composites (Zr-MFCs) were prepared by a facile and efficient strategy. The nano-sized Fe₃O₄@SiO₂ core (about 15 nm) was coated with a shell of Zr-MOFs (about 5 nm) by means of in-situ growth. And, Fe₃O₄@SiO₂@UiO-66 and its amino derivatives (Fe₃O₄@SiO₂@UiO-66-NH₂ and Fe₃O₄@SiO₂@UiO-66-Urea) were successfully prepared by using different precursors. The obtained Zr-MFCs were demonstrated to be efficient adsorbents for metal ions/organic dyes removal from aqueous solution, with high adsorption capacity and fast adsorption kinetics. It was found that the amine-decorated MFCs were highly efficient for metal ions/dyes removal compared to raw MFC-O. Among them, MFC-N exhibited the highest capacity for Pb²⁺ (102 mg g^-1) and methylene blue (128 mg g^-1), while MFC-O exhibited the highest capacity for methyl orange (219 mg g^-1). Moreover, anionic and cationic dyes could be selectively separated and removed from the mixed solution just by adjusting the solution pH with Zr-MFCs as the adsorbents. And these Zr-MFCs materials can be easily regenerated by desorbing metal ions/organic dyes from the sorbents with appropriate eluents, and the adsorption capacity can be remained unchanged after 6 recycles. The obtained results demonstrated the great application potential of the prepared MFCs as fascinating adsorbents for water treatment.

Kinetics, Isotherm, and Thermodynamic Study for Ultrafast Adsorption of Azo Dye by an Efficient Sorbent: Ternary Mg/(Al + Fe) Layered Double Hydroxides

The extremely high adsorption efficiency of malachite green (MG) was examined through a series of batch experiments by using Fe³⁺-doped Mg/Al layered double hydroxides (LDHs). The incorporation of iron into Mg/Al LDH with varying Al + Fe molar ratio of 4 + 1, 3 + 2, 2 + 3, and 1 + 4 increased the adsorption capacity with respect to time. The spectral analysis and N₂ sorption studies showed that there was retention of surface morphology in all of the iron-modified LDH samples. The experimental evidences showed that the adsorbent Mg/(Al + Fe) with a molar ratio of 10:2 + 3 had a significant removal, i.e., 99.94% for MG with the initial concentration of 1000 mg L^-1 at pH ∼ 9 and at room temperature in 5 min. With further increase in iron loading (at ratio 10:1 + 4), there was a decrease in the removal of MG due to the agglomeration of Fe₂O₃ on the surface. The adsorption process was best fitted to the Freundlich isotherm followed by the pseudo-second-order model. The standard thermodynamic parameters (ΔH°, ΔS°, and ΔG°) were obtained over the temperature range of 20-50 °C. It was observed that the adsorption of MG onto Mg/(Al + Fe) LDH was spontaneous, exothermic, and enthalpy driven in the physisorption mode. A worthy desorption efficiency was achieved by using ethanol and water, which was more than 90% in the three cycles. Maintaining almost the same removal efficiency of MG even after three cycles indicated Mg/(Al + Fe) LDH as a promising material for wastewater treatment. This work was anticipated to open up new possibilities in dealing with anionic dye pollutants.

Chitin/clay microspheres with hierarchical architecture for highly efficient removal of organic dyes

Numerous adsorbents have been reported for efficient removal of dye from water, but the high cost raw materials and complicated fabrication process limit their practical applications. Herein, novel nanocomposite microspheres were fabricated from chitin and clay by a simple thermally induced sol-gel transition. Clay nanosheets were uniformly embedded in a nanofiber weaved chitin microsphere matrix, leading to their hierarchical architecture. Benefiting from this unique structure, microspheres could efficiently remove methylene blue (MB) through a spontaneous physic-sorption process which fit well with pseudo-second-order and Langmuir isotherm models. The maximal values of adsorption capability obtained by calculation and experiment were 152.2 and 156.7 mg g^-1, respectively. Chitin/clay microspheres (CCM2) could remove 99.99% MB from its aqueous solution (10 mg g^-1) within 20 min. These findings provide insight into a new strategy for fabrication of dye adsorbents with hierarchical structure from low cost raw materials.

Towards energy efficient separations with metal organic frameworks

The huge energy requirement for industrial separations of chemical mixtures has necessitated the need for the development of energy efficient and alternative separation techniques in order to mitigate the negative environmental impacts associated with greenhouse gas emissions from fossil fuel combustions for energy generation.

Removal of Colored Organic Pollutants from Wastewaters by Magnetite/Carbon Nanocomposites: Single and Binary Systems

This work develops a methodology for selective removal of industrial dyes from wastewaters using adsorption technology based on magnetic adsorbents. The magnetic nanoparticles embedded within a matrix of activated carbon were tested as adsorbents for removal of industrial dyes from aqueous solutions. The effects of four independent variables, solution pH, initial concentration of pollutant, adsorbent dose, contact time, and their interactions on the adsorption capacity of the nanocomposite were investigated in order to optimize the process. The removal efficiency of pollutants depends on solution pH and increases with increasing the carbon content, with initial concentration of the pollutants, the temperature, and the dose of magnetite/carbon nanocomposites. Pseudo-second-order kinetic model was fitted to the kinetic data, and adsorption isotherm analysis and thermodynamics were used to elucidate the adsorption mechanism. The maximum adsorption capacities were 223.82 mg g−1 for Nylosan Blue, 114.68 mg g−1 for Chromazurol S, and 286.91 mg g−1 for Basic Red 2. The regeneration and reuse of the sorbent were evaluated in seven adsorption/desorption cycles. The optimum conditions obtained for individual adsorption were selected as starting conditions for simultaneous adsorption of dyes. In binary systems, in normal conditions, selectivity decreases in the order: Red Basic 2 > Nylosan Blue > Chromazurol S.

A mechanistic approach towards the photocatalytic organic transformations over functionalised metal organic frameworks: a review

This review focuses on the possible mechanisms involved in the organic transformations occurring through photocatalysis over functionalised metal–organic frameworks.

K6P2W18O62 encapsulated into magnetic Fe3O4/MIL-101 (Cr) metal–organic framework: a novel magnetically recoverable nanoporous adsorbent for ultrafast treatment of aqueous organic pollutants solutions

In this study, a Wells–Dawson type K₆P₂W₁₈O₆₂ polyoxometalate was encapsulated into the magnetic Fe₃O₄/MIL-101 (Cr) metal–organic framework and applied as a new magnetically recoverable ternary adsorbent to remove organic dyes from aqueous solutions. The as-prepared ternary magnetically recyclable hybrid (denoted as P₂W₁₈O₆₂@Fe₃O₄/MIL-101 (Cr)) was characterized by FT-IR spectroscopy, powder X-ray diffraction (XRD), Raman spectroscopy, EDX, SEM, BET surface area, and magnetic measurements. The results showed the successful encapsulation of K₆P₂W₁₈O₆₂ (∼26.5 wt%) into the magnetic Fe₃O₄/MIL-101 (Cr) framework. The magnetic hybrid had a high specific surface area of 934.89 m² g⁻¹. The adsorption efficiency of this nanohybrid for the removal of methylene blue (MB), rhodamine B (RhB), and methyl orange (MO) from aqueous solutions was evaluated. The magnetic nanohybrid demonstrated the fast and selective adsorption of cationic dyes from mixed dye solutions. The adsorption rate and capacity of P₂W₁₈O₆₂@Fe₃O₄/MIL-101 (Cr) were increased as compared with MIL-101 (Cr), P₂W₁₈O₆₂, and Fe₃O₄/MIL-101 samples due to the increased electrostatic attraction. The effects of parameters such as the adsorbent dosage, temperature, dye concentration, and pH were investigated on the adsorption process. The adsorption kinetics was analyzed by the Freundlich, Langmuir, and Temkin isotherm models and pseudo-second-order and pseudo-first-order kinetics models, with the Langmuir isotherm and pseudo-second-order kinetic model found to be suitable to describe the equilibrium data. Also, the thermodynamic results of the nanohybrid indicated that the adsorption was an endothermic and spontaneous process. After the adsorption reaction, the magnetic nanohybrid could be easily separated and reused without any change in structure. Based on the results of this study, the nanohybrid was an efficient adsorbent for eliminating cationic dyes.

A Wells–Dawson-type K₆P₂W₁₈O₆₂ polyoxometalate was encapsulated into the magnetic Fe₃O₄/MIL-101 (Cr) metal–organic framework and applied as a new magnetically recoverable ternary adsorbent to remove organic dyes from aqueous solutions.

A ligand strategic approach with Cu-MOF for enhanced solar light photocatalysis

A bi-linker approach was employed on Cu-MOF for enhanced solar-light photocatalytic activity

Highly Efficient, Rapid, and Simultaneous Removal of Cationic Dyes from Aqueous Solution Using Monodispersed Mesoporous Silica Nanoparticles as the Adsorbent

In this work, a highly efficient and rapid method for simultaneously removing cationic dyes from aqueous solutions was developed by using monodispersed mesoporous silica nanoparticles (MSNs) as the adsorbents. The MSNs were prepared by a facile one-pot method and characterized by scanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy, and Brunauer-Emmett-Teller. Experimental results demonstrated that the as-prepared MSNs possessed a large specific surface area (about 585 m²/g), uniform particle size (about 30 nm), large pore volume (1.175 cm³/g), and narrow pore size distribution (1.68 nm). The materials showed highly efficient and rapid adsorption properties for cationic dyes including rhodamine B, methylene blue, methyl violet, malachite green, and basic fuchsin. Under the optimized conditions, the maximum adsorption capacities for the above mentioned cationic dyes were in the range of 14.70 mg/g to 34.23 mg/g, which could be achieved within 2 to 6 min. The probable adsorption mechanism of MSNs for adsorption of cationic dyes is proposed. It could be considered that the adsorption is mainly controlled by electrostatic interactions and hydrogen bonding between the cationic dyes and MSNs. As a low-cost, biocompatible, and environmentally friendly material, MSNs have a potential application in wastewater treatment for removing some environmental cationic contaminants.

Reduced Magnetism in Core-Shell Magnetite@MOF Composites

The magnetic susceptibility of synthesized magnetite (Fe₃O₄) microspheres was found to decline after the growth of a metal-organic framework (MOF) shell on the magnetite core. Detailed structural analysis of the core-shell particles using scanning electron microscopy, transmission electron microscopy, atom probe tomography, and⁵⁷Fe-Mössbauer spectroscopy suggests that the distribution of MOF precursors inside the magnetic core resulted in the oxidation of the iron oxide core.

Preparation of magnetic MIL-101 (Cr) for efficient removal of ciprofloxacin

Metal organic frameworks are widely used as adsorbent materials in recent years. In this study, the most prepared metal organic framework MIL-101 was prepared by hydrothermal method and featured magnetic property using co-precipitation method Fe₃O₄. Then, the prepared composite (MIL-101/Fe₃O₄) was first characterized using XRD, FTIR, SEM-EDS, and surface area analysis, then was used for the adsorptive removal of the most used antibiotic, ciprofloxacin (CIP). The effect of different adsorption variables which may affect the removal of CIP by MIL-101/Fe₃O₄ was investigated, as well as their adsorbent quantity, initial CIP concentration, pH, temperature, and contact time. The non-linear Langmuir and Freundlich isotherm were applied to experimental data. It was observed that rising solution temperature decreases adsorption efficiency, as the maximum adsorption uptake value was 63.28 mg g^-1 at 298 K and 22.93 mg g^-1 at 313 K, indicating the exothermic nature of the adsorption. The adsorption was studied kinetically and found to follow the pseudo-second-order kinetic model. The desorption of CIP from the MIL-101/Fe₃O₄ was investigated using three different eluents, and the results showed that phosphate-buffered solution was the most effective desorption eluent. Graphical abstract Schematic diagram of the preparation steps of MIL-101/Fe3O4.

Removal of Congo red dye from aqueous solution with nickel-based metal-organic framework/graphene oxide composites prepared by ultrasonic wave-assisted ball milling

Metal-organic frameworks (MOFs) were successfully synthesized by ultrasonic wave-assisted ball milling. In the absence of organic solvent, the coupling effect of ultrasonic wave and mechanical force played an significant role in the synthesis of MOFs. Adsorption of Congo red (CR) was studied in view of adsorption kinetic, isotherm and thermodynamics. The adsorbent was carried out using X-ray diffraction (XRD), thermogravimetric analysis (TGA), N₂ adsorption-desorption isotherms, Raman spectroscopy and scanning electron microscope (SEM) methods. It was found that pseudo-second-order kinetic model and Freundlich adsorption isotherm matched well for the adsorption of CR onto nickel-based metal-organic framework/graphene oxide composites (Ni-MOF/GO). The results of the adsorption thermodynamics indicated that the adsorption process was a spontaneous and endothermic process. The adsorption capacity of graphene oxide/metal-organic frameworks (GO/MOFs) for CR reached 2489mg/g, much higher than previous reports. It was demonstrated that an increase in the number of active metal sites can dramatically improve the adsorption capacity of dye. A suitable dry temperature is beneficial for the improvement of adsorption capacity for dye. In this paper, the adsorption results indicated that ultrasonic wave-assisted ball milling has a good prospect for synthesis of MOFs with excellent adsorption performance.

One Dimensional Coordination Polymer of Zn(II) for Developing Multifunctional Nanoparticles

A variety of nanoparticles (NPs) including Ag, Au, Pd, Cr and mixed Cu/Fe have been synthesized in a non-activated (without solvent removal) one dimensional coordination polymer (CP) of Zn(II) via two different mechanisms, acid formation and redox activity of the framework. Main driving force to grow these NPs within the cavities of CP is the presence of free oxygens of one of the monodentate carboxylate groups of BDC ligand. These free oxygens act as anchoring sites for the metal ions of the metal precursors. Chemical and physical characteristics of the NPs within the framework have been evaluated by the high resolution transmission electron microscopic (HRTEM) images. Excluding Ag(0) and Pd(0) other NPs are present as combinations of their elemental as well as oxide forms (Au/Au₂O₃, Cr/Cr₂O₃/CrO₂ and Cu/Cu₂O, Fe/FeO). Synthesized Ag NPs within the framework show remarkable antibacterial efficacy at extremely low concentrations. Ag, Au and Cu/Fe NPs show ferromagnetic properties within the framework at room temperature. This polymer has potential to sequester highly toxic Cr(VI) to non toxic Cr(0), Cr(III) and Cr(IV) species.

Adsorptive removal of Rhodamine B from aqueous solution by nanoporous polydivinylbenzene

Nanoporous polydivinylbenzene (PDVB) material has been successfully prepared via the copolymerization of divinylbenzene monomers. The nanoporous PDVB was characterized through N₂ adsorption/desorption isotherms, Fourier transform infrared spectroscopy, scanning electron microscopy, and thermogravimetric analysis. The nanoporous PDVB as an adsorbent was applied for the removal of Rhodamine B (RhB). The adsorption behavior of PDVB for the removal of RhB showed that the isotherm data followed the Langmuir isotherm model and the kinetic adsorption obeyed the pseudo-second-order model. Thermodynamic parameters illustrated that the adsorption process was spontaneous and exothermic. Interestingly, the spent nanoporous PDVB has excellent regenerative performance through treating it with ethanol. These results revealed that PDVB might be an excellent adsorbent for the removal of RhB from wastewater.

Microwave-assisted synthesis of a viologen-based covalent organic polymer with redox-tunable polarity for dye adsorption

We report the efficient synthesis, by microwave-assisted Menshutkin reaction, of a viologen-based covalent organic polymer, and the application of its different redox state in dye removal.

Fe3O4@ZIF-8: a magnetic nanocomposite for highly efficient UO22+ adsorption and selective UO22+/Ln3+ separation

Fe₃O₄@ZIF-8 nanoparticles with outstanding UO₂²⁺ adsorption capacity and selectivity for lanthanide ions could be simply separated by magnet from a solution containing lanthanide ions.

Renewable metal–organic-frameworks-coated 3D printing film for removal of malachite green

A renewable metal–organic-frameworks (MOFs)-polylactic acid (PLA) film was designed and prepared in order to remove malachite green (MG) in waste water.

Synthesis and characterization of metal–organic frameworks fabricated by microwave-assisted ball milling for adsorptive removal of Congo red from aqueous solutions

In this study, four metal–organic frameworks (MOFs) were prepared using a simple, low-cost, and high-efficiency technique utilizing simple carboxylic acids and metal salts by microwave-assisted ball milling.

A Combined Experimental and Theoretical Study on the Extraction of Uranium by Amino-Derived Metal-Organic Frameworks through Post-Synthetic Strategy

A novel carboxyl-functionalized metal-organic framework for highly efficient uranium sorption was prepared through a generic postsynthetic strategy, and this MOF's saturation sorption capacity is found to be as high as 314 mg·g^-1. The preliminary application illustrated that the grafted free-standing carboxyl groups have notably enhanced the sorption of uranyl ions on MIL-101. In addition, we have performed molecular dynamics simulation combined with density functional theory calculations to investigate the molecular insights of uranyl ions binding on MOFs. The high selectivity and easy separation of the as-prepared material have shown tremendous potential for practical applications in the nuclear industry or radioactive water treatment, and the functionalized MOF can be extended readily upon the versatility of click chemistry. This work provides a facile and purposeful approach for developing MOFs toward a highly efficient and selective extraction of uranium(VI) in aqueous solution, and it further facilitates the structure-based design of nanomaterials for radionuclide-containing-medium pretreatment.

Cu/Cu2O/CuO loaded on the carbon layer derived from novel precursors with amazing catalytic performance

A simple, novel method for synthesis of Cu/Cu2O/CuO on surfaces of carbon (Cu/Cu2O/CuO@C) as a non-noble-metal catalyst for reduction of organic compounds is presented. Compared with noble metals, Cu/Cu2O/CuO@C particles are more efficient and less expensive. Characterization of the Cu/Cu2O/CuO@C composites by high-resolution transmission electron microscope (HRTEM), x-ray diffraction (XRD), infrared spectroscopy and Raman analysis, revealed that it was composed of graphitized carbon with numerous nanoparticles (100nm in diameter) of Cu/CuO/Cu2O that were uniformly distributed on internal and external surfaces of the carbon support. Gallic acid (GA) has been used as both organic ligand and carbon precursor with metal organic frameworks (MOFs) as the sacrificial template and metal oxide precursor in this green synthesis. The material combined the advantages of MOFs and Cu-containing materials, the porous structure provided a large contact area and channels for the pollutions, which results in more rapid catalytic degradation of pollutants and leads to greater efficiency of catalysis. The material gave excellent catalytic performance for organic dyes and phenols. In this study, Cu/Cu2O/CuO@C was used as catalytic to reduce 4-NP, which has been usually adopted as a model reaction to check the catalytic ability. Catalytic experiment results show that 4-NP was degraded approximately 3min by use of 0.04mg of catalyst and the conversion of pollutants can reach more than 99%. The catalyst exhibited little change in efficacy after being utilized five times. Rates of degradation of dyes, such as Methylene blue (MB) and Rhodamine B (RhB) and phenolic compounds such as O-Nitrophenol (O-NP) and 2-Nitroaniline (2-NA) were all similar.

Nanoreactor Based on Macroporous Single Crystals of Metal-Organic Framework

A sacrificial template strategy is developed for the synthesis of yolk-shell Au@ZIF-8 nanoreactor. The Au@ZIF-8 nanoreactor possesses single-crystalline metal-organic framework (MOF) shell with intrinsic monodisperse micropores and introduced macropores. In each of the macropores, one Au NP is encapsulated to form a nanoreactor unit. The quantity of the reactor units in the MOF shell can be readily regulated. Such structure features of the Au@ZIF-8 nanoreactor facilitate the size selectivity of reactants, the accessibility of Au nanoparticles to reactants, and the mass transfer of reactants and products. As a result, the Au@ZIF-8 nanoreactor delivers excellent size selectivity, enhanced conversion, and good cycling stability when used to catalyze the aerobic oxidation of alcohols with different molecular size.

Emerging adsorptive removal of azo dye by metal-organic frameworks

Adsorptive removal of toxic compounds using advanced porous materials is one of the most attractive approaches. In recent years, the metal-organic frameworks (MOFs), a subset of advanced porous nano-structured materials, due to their unique characteristics are showing great promise for better adsorption/separation of various water contaminants. Given the importance of azo dye removal, as an important class of pollutants, this paper aims to review and summarize the recently published research on the effectiveness of various MOFs adsorbents under different physico-chemical process parameters in dyes adsorption. The effect of pH, the adsorption mechanism and the applicability of various adsorption kinetic and thermodynamic models are briefly discussed. Most of the results observed showed that the adsorption kinetic and isotherm of azo dyes onto the MOFs mostly followed the pseudo-second order and Langmuir models respectively. Also, the optimum pH value for the removal of majority of azo dyes by MOFs was observed to be in the range of ∼5-7.

Magnetic Nanoparticles Interaction with Humic Acid: In the Presence of Surfactants

Adsorbed humic acid (HA) on surfaces of nanoparticles (NPs) will affect their transport, transfer, and fate in the aquatic environment, especially in the presence of surfactants, and thereby potentially alter exposures and bioavailable fractions of NPs and surfactants. This study investigated adsorption of HA on Fe3O4 NPs in the presence or absence of surfactant. Surfactant established a bridge connecting HA and Fe3O4 NPs, and significantly changed adsorption behavior of HA on NPs. Adsorption of HA in the absence of surfactant was 120.3 mg/g, but 350.0 mg/g and 146.5 mg/g in the present of CTAB (hexadecyl trimethylammonium bromide) and SDS (sodium dodecyl sulfate), respectively. Surfactants can form different stages (hemimicelles, mixed hemimicelles and admicelles) on Fe3O4 NPs by electrostatic and hydrophobic interactions, adsorption of HA was different for each of those stages. Adsorption of HA on surface of Fe3O4 NPs/CTAB was codetermined by hydrophobic, electrostatic interactions and ligand exchange. The presence of CTAB or SDS changed mechanisms for adsorption and effects of functional groups. Results of Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) indicated that carbohydrate carbon was important in adsorption of HA on Fe3O4 NPs in the presence of surfactants.

Novel multifunctional pH-sensitive nanoparticles loaded into microbubbles as drug delivery vehicles for enhanced tumor targeting

This study fabricated novel multifunctional pH-sensitive nanoparticles loaded into microbubbles (PNP-MB) with the combined advantages of two excellent drug delivery vehicles, namely, pH-sensitive nanoparticles and microbubbles. As an antitumor drug, resveratrol (RES) was loaded into acetylated β-cyclodextrin nanoparticles (RES-PNP). The drug-loaded nanoparticles were then encapsulated into the internal space of the microbubbles. The characterization and morphology of this vehicle were investigated through dynamic light scattering and confocal laser scanning microscopy, respectively. In vitro drug release was performed to investigate the pH sensitivity of RES-PNP. The antitumor property of RES-loaded PNP-MB (RES-PNP-MB) was also analyzed in vivo to evaluate the antitumor effect of RES-PNP-MB. Results suggested that PNP exhibited pH sensitivity, and was successfully encapsulated into the microbubbles. RES-PNP-MB exhibit effective tumor growth suppressing in vivo. Therefore, such drug delivery vehicle should be of great attention in tumor therapy.