Amine-functionalized Fe3O4 Research Articles

Efficient adsorption of Congo red (CR) dye onto novel lignin-based magnetic core-shell adsorbent: Synthesis, characterization and experimental studies

BackgroundFurfural residue is a by-product in the furfural production from the biomass, and enriched in cellulose and lignin. Lignin is considered efficient candidates for the preparation of bio-based adsorbents because of a variety of functional groups and reactive sites involved. MethodsIn this study, we prepared the tunable covalent binding of the aldehyde-based furfural residue lignin onto amine-functionalized Fe3O4 magnetic nanoparticles using cyanuric chloride as a chemoselective cross-linker. The novel lignin-based magnetic adsorbent in core-shell structure was reported for the first time to remove Congo red from aqueous solution. Significant FindingsA distinct core-shell structure is formed, according to the SEM, TEM, FTIR, BET, XPS, and VSM techniques. Adsorption studies suggested that endothermic processes occured for CR adsorption onto AFRL@AMNP, and both pseudo-first and pseudo-second order models could provide a good description of the adsorption kinetics. The Langmuir model estimated the qmax of CR by AFRL@AMNP were 218.2 mg/g at 290 K. According to FTIR, XPS, and DFT calculations, electrostatic interactions, hydrogen bonds, and π-π interactions were identified as main mechanisms for CR onto AFRL@AMNP. More importantly, due to the incorporation of Fe3O4 magnetic nanoparticle, AFRL@AMNP can be easier to separate from the aqueous solutions and be reused.

Facile covalent preparation of carbon nanotubes / amine-functionalized Fe3O4 nanocomposites for selective extraction of estradiol in pharmaceutical industry wastewater

As a typical steroid hormone drug, estradiol (E2) is also one of the most frequently detected endocrine disrupting chemicals (EDCs) in the aquatic environment. Herein, in response to the potential risk of E2 in steroid hormone pharmaceutical industry wastewater to human and wildlife, a novel carbon nanotubes / amine-functionalized Fe3O4 (CNTs/MNPs@NH2) nanocomposites with magnetic responsive have been developed for the enrichment and extraction of E2 in pharmaceutical industry wastewater, where amino-functionalized Fe3O4 magnetic nanoparticles (MNPs@NH2) were used as a magnetic source. The resultant CNTs/MNPs@NH2 possessed both the features of CNTs and desired magnetic property, enabling to rapidly recognize and separate E2 from pharmaceutical industry wastewater. Meanwhile, the CNTs/MNPs@NH2 had good binding behavior toward E2 with fast binding kinetics and high adsorption capacity, as well as exhibited satisfactory selectivity to steroidal estrogen compounds. Furthermore, the change of pH value of aqueous phase in adsorption solvent hardly affected the adsorption of E2 by CNTs/MNPs@NH2, and the adsorption capacity of E2 ranged from 19.9 to 17.2 mg g−1 in the pH range of 3.0 to 11.0, which is a latent advantage of the follow-up development method to detect E2 in pharmaceutical industry wastewater. As a result, the CNTs/MNPs@NH2 serving as a solid phase extraction medium were successfully applied to efficiently extract E2 from pharmaceutical industry wastewater. Therefore, the CNTs/MNPs@NH2 nanocomposites could be used as a potential adsorbent for removing steroidal estrogens from water. More importantly, the developed method would provide a promising solution for the monitoring and analysis of EDCs in pharmaceutical industry wastewater.

Design and preparation of core-shell structured magnetic graphene oxide@MIL-101(Fe): Photocatalysis under shell to remove diazinon and atrazine pesticides

A magnetically separable support with core-shell morphology comprising amine-functionalized Fe3O4 wrapped with graphene oxide (AFG) was successfully prepared and used to support MIL-101(Fe). The ternary AFG@MIL-101(Fe) composite was investigated as a photo-Fenton catalyst for the degradation of recalcitrant diazinon (DIZ) and atrazine (ATZ) pesticides. After 105 min visible light irradiation, the AFG@30MIL-101(Fe) photocatalyst achieved 100 ± 1% and 81 ± 1% photocatalytic degradation efficiency for DIZ and ATZ pollutants, respectively. The recorded data indicated superior photocatalytic ability of the nanocomposite as compared to AF@30MIL-101(Fe) and MIL-101(Fe) photocatalysts for the removal of both pollutants. Total Organic Carbon (TOC) analysis revealed 84 ± 0.5% and 62 ± 0.5% mineralization for DIZ and ATZ, respectively. The obtained results of characterization and also photocatalytic behavior suggest enhanced conversion between Fe2+/Fe3+ as well as fast electron transfer through interlayers of graphene oxide in this unique core-shell structure. After assaying the adsorption performance of photocatalyst, it was found that ATZ adsorption was more pronounced than DIZ. Furthermore, radical quenching tests revealed OH radicals were the main oxidizing players in this process even though the contribution of other species cannot be ruled out. It is noteworthy that magnetic stability was well preserved after 4 consecutive photocatalytic cycles, suggesting that this work can be a guideline to prepare efficient and stable magnetic Fenton systems.

Localization of Coated Iron Oxide (Fe3O4) Nanoparticles on Tomato Seeds and Their Effects on Growth.

Food demand due to the growing global population has been stretching the agriculture sector to the limit. This demands the cultivation of plants in shrinking land areas which makes the search for highly effective systems for plant nutrition and pest control important. In this context, the application of nanoparticles (NPs) in agriculture can have a transformative effect on food production techniques as it can enable the delivery of bioactive agents (including growth factors, pesticides, and fungicides) directly to plants. Herein, we report the application of unfunctionalized as well as amine-functionalized and polycaprolactone-coated Fe3O4 NPs to seed treatment in tomato (Solanum lycopersicum). The study reveals that the treatment has no side effects on plant germination and development. Furthermore, the translocation of NPs in seeds and seedlings posttreatment depends on the surface functionalization of the NPs. X-ray fluorescence spectroscopy analysis of seedlings suggested that around 66% of unfunctionalized Fe3O4 NPs were translocated in the cotyledons, while only 50% of functionalized NPs (both amine and polycaprolactone) were translocated. Our results demonstrate that all particles were taken up by the seeds, thus suggesting that the functionalized NPs can act as a versatile platform for delivering of active compounds, such as fungicides and growth factor agents.

Enhanced CO2 absorption and desorption efficiency using DETA functionalized nanomagnetite/water nano-fluid

The main objective of this research is based on the enhancement in CO2 solubility in water using amine-functionalized Fe3O4 nano-particle at low pressure. The performance of prepared nano-fluid is investigated in CO2 absorption/desorption process in an isothermal batch reactor in the temperature range of 293.15–308.15 K, nano-particle loading ranged from 0 to 0.5 wt.%, and pressure range 120–240 kPa. The prepared nano-fluids are evaluated in terms of CO2 absorption capacity, molar fraction of CO2 in liquid phase and regeneration efficiency of conventional heating method and proposed sonication procedure. The absorption capacity was evaluated to be 0.051, 0.075, 0.082 and 0.087 mol CO2/Kg nano-fluid for the weight percentages of 0, 0.1, 0.3 and 0.5, respectively at 308.15 K and 200 kPa. Thus, increasing the concentration of functionalized nano-particles significantly improves the absorption capacity. The superior improvement of about 77 % was attained using the prepared nano-fluid at 293.15 K. Additionally, the proposed sonicated based regeneration procedure could significantly reduce the demand of regeneration energy (about 23.2 %). Based on the experimental data, the higher CO2 solubility, lower reduction in cyclic absorption/desorption capacity and higher energy efficiency of whole process are achievable using the functionalized nano-fluid and regeneration with the proposed sonication-based procedure.

A novel facile synthesis of the amine-functionalized magnetic core coated carboxylated nanochitosan shells as an amphoteric nanobiosupport

We developed a novel synthesis method for a multifunctional nanocomposite with amine-functionalized Fe3O4 core coated with carboxylated nanochitosan shells (NH2-Fe3O4@NCS-COOH) via carbodiimide activation. The chemical structures of chitosan and carboxylated nanochitosan (NCS-COOH) were verified by 1H NMR which confirmed the incorporation of citric acid by the formation of the new signal of the CH2 H-atoms. TEM image displayed the synthesized NH2-Fe3O4@NCS-COOH nanoparticles were in a spherical shape with an average size of 100 nm. The results of XRD revealed that NH2-Fe3O4@NCS-COOH have a good crystalline nature with the face center cubic structure and with the average crystallite size of 17 nm. The characterization using VSM showed that the magnetic nanoparticle had superparamagnetic behavior and the saturation magnetization was up to 30 emu/g. The BET specific surface area of NH2-Fe3O4@NCS-COOH was 45.18 m2/g. The synthesized nanostructure was found to be stable in different ranges of pH due to covalent bonds between nanochitosan and Fe3O4.

Metal affinity immobilization of cellulase on Fe3O4 nanoparticles with copper as ligand for biocatalytic applications

The immobilization of cellulase on amine-functionalized Fe3O4 magnetic nanoparticles (MNPs), via metal affinity immobilization, as a nano-biocatalyst was investigated. Copper was chosen as ligand and loaded onto MNPs in a buffering environment without adding any intermediates. Immobilization conditions were optimized by a 23 full factorial design method. Under optimized working conditions (Cu/MNPs = 1, E/MNPs = 0.11, pH = 6), the relative enzyme activity and the amount of enzyme immobilization were 91% and 164 (mg enzyme/g MNPs), respectively. The immobilized cellulase (tested by carboxymethyl cellulose hydrolysis at 1% concentration) was found to be more stable than the free enzyme. Also, the immobilized enzyme still retained 73% of its initial activity after five cycles of usage. Furthermore, the free and immobilized cellulases retained 70 and 84% of their initial activity after eight days storage at 4 °C, respectively. Immobilization of enzymes, using this method, could be a good and economic option for various industries.

Simultaneous detection of fumonisin B1 and ochratoxin A using dual-color, time-resolved luminescent nanoparticles (NaYF4: Ce, Tb and NH2-Eu/DPA@SiO2) as labels

A rapid and highly sensitive time-resolved fluorescence (TRF)-based aptasensor for simultaneous recognition of mycotoxins ochratoxin A (OTA) and fumonisin B1 (FB1) was developed using multi-color, Ln3+-doped time-resolved fluorescence nanoparticles (TRF-NPs) (NaYF4: Ce, Tb and NH2-Eu/DPA@SiO2 NPs) coupled with complementary strand DNA (cDNA) as luminescence probe and aptamers-conjugated amine-functionalized Fe3O4 magnetic nanoparticles (MNPs) act as a capture probe. Under the optimized conditions, the time-resolved fluorescence intensities at 544 and 618nm corresponded with Tb3+ and Eu3+, respectively, were used to measure FB1 (Y = 19,177.1 + (- 12,054.4)x, R2 = 0.9917) and OTA (Y = 4138.8 + (- 11,182.6)x, R2 = 0.9924), respectively. The limits of detection (LODs) for FB1 and OTA were 0.019pgmL-1 and 0.015pgmL-1, respectively, which were much lower than previously described methods for simultaneous recognition of mycotoxins OTA and FB1 while detection range varied from 0.0001-0.5ngmL-1. This aptasensor was effectively applied to quantity FB1 and OTA in maize samples and results were compared with ELISA method. This is the first reported time-resolved fluorescence (TRF)-based aptasensor to detect two agriculturally important toxins in the maize. The developed aptasensor has potential to be used for detection of toxins in food safety fields. Graphical abstract.

Magnetic bio-metal–organic framework nanocomposites decorated with folic acid conjugated chitosan as a promising biocompatible targeted theranostic system for cancer treatment

In this work, a multifunctional magnetic Bio-Metal-Organic Framework (Fe3O4@Bio-MOF) coated with folic acid-chitosan conjugate (FC) was successfully prepared for tumor-targeted delivery of curcumin (CUR) and 5-fluorouracil (5-FU) simultaneously. Bio-MOF nanocomposite based on CUR as organic linker and zinc as metal ion was prepared by hydrothermal method in the presence of amine-functionalized Fe3O4 magnetic nanoparticles (Fe3O4@NH2 MNPs). 5-FU was loaded in the magnetic Bio-MOF and the obtained nanocarrier was then coated with FC network. The prepared nanocomposite (NC) was fully characterized by high resolution-transmission electron microscope (HR-TEM), field emission scanning electron microscopy (FE-SEM), Dynamic light scattering (DLS), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), nuclear magnetic resonance (NMR), and UV–vis analyses. In vitro release study showed controlled release of CUR and 5-FU in acidic pH confirming high selectivity and performance of the carrier in cancerous microenvironments. The selective uptake of 5-FU-loaded Fe3O4@Bio-MOF-FC by folate receptor-positive MDA-MB-231 cells was investigated and verified. The ultimate nanocarrier exhibited no significant toxicity, while drug loaded nanocarrier showed selective and higher toxicity against the cancerous cells than normal cells. SDS PAGE was also utilized to determine the protein pattern attached on the surface of the nanocarriers. In vitro and in vivo MRI studies showed negative signal enhancement in tumor confirming the ability of the nanocarrier to be applied as diagnostic agent. Owing to the selective anticancer release and cellular uptake, acceptable blood compatibility as well as suitable T2 MRI contrast performance, the target nanocarrier could be considered as favorable theranostic in breast cancer.

Facile Electrochemical Sensor for Nanomolar Rutin Detection Based on Magnetite Nanoparticles and Reduced Graphene Oxide Decorated Electrode.

A new electrochemical sensor for nanomolar rutin detection based on amine-functionalized Fe3O4 nanoparticles and electrochemically reduced graphene oxide nanocomposite modified glassy carbon electrode (NH2-Fe3O4 NPs-ErGO/GCE) was fabricated through a simple method, and the X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), vibrating sample magnetometer (VSM) and electrochemical technique were used to characterize the modified electrode. The electrochemical behavior of rutin on the Fe3O4 NPs-ErGO/GCE was studied in detail. The electrochemical response of rutin at this modified electrode was remarkably higher than that of the bare GCE or other modified GCE (GO/GCE, Fe3O4 NPs-GO/GCE, and ErGO/GCE). Under the optimum determination conditions, Fe3O4 NPs-ErGO/GCE provided rutin with a broader detection range of 6.0 nM–0.1 µM; 0.1–8.0 µM and 8.0–80 µM, a minimum detectable concentration of 4.0 nM was obtained after 210 s accumulation. This novel method was applied in determination of rutin in pharmaceutical tablets and urine samples with satisfactory results.

Efficient adsorption of diclofenac sodium from aqueous solutions using magnetic amine-functionalized chitosan

In this study, we prepared a magnetic composite based on amine-functionalized chitosan (aminochitosan; AmCS) and Fe3O4 to remove diclofenac sodium (DS) from water. The fabricated AmCS@Fe3O4 composite was characterized using Fourier-transform infrared spectroscopy, transmission electron microscopy, scanning electron microscopy, vibrating sample magnetometry, X-ray diffraction, and thermogravimetric analysis. Furthermore, we investigated the influence of pH, initial DS concentration, and adsorbent dosage on the adsorption of DS. Through thermodynamic analysis, we found that the data corresponded with the Langmuir adsorption isotherm model. The maximum adsorption capacity reached 469.48 mg g−1, and the adsorption process followed the pseudo-second-order kinetic model. Finally, the AmCS@Fe3O4 composite retained good adsorption characteristics after four consecutive cycles, with removal efficiency exceeding 70%. Therefore, the developed adsorbent could be used for efficient adsorptive removal of trace drugs and personal care products from water bodies.

An acid-resistant magnetic Nb-substituted crystalline silicotitanate for selective separation of strontium and/or cesium ions from aqueous solution

In this work, magnetic Nb-substituted crystalline silicotitanate (mag-Nb-CST), which can be used for separation of Sr2+ and Cs+ from aqueous solution, is successfully synthesized by embedding amine-functionalized Fe3O4 into the Nb-substituted crystalline silicotitanate (Nb-CST), being characterized by various techniques such as XRD, SEM, EDS, XPS, and VSM. The studies on the adsorption behaviors show that the adsorption process reaches equilibrium within about 8 h, and the maximum adsorption capacity on mag-Nb-CST is 14.38 mg g−1 at pH 11.00 for Sr2+, and 11.18 mg g−1 at pH 4.00 for Cs+, respectively. Besides the excellent selectivity towards Sr2+ and Cs+ over various lanthanides and actinides, the pH dependence on the adsorption capacity suggests a possibility to separate Sr2+ and Cs+ from each other by simply adjusting pH. Mag-Nb-CST is able to remove most of the Sr2+ and Cs+ at ppb level. Even in real seawater, it is able to remove 94.19% of Cs+. Moreover, mag-Nb-CST shows good acid-resistance and radiation stability. The crystal structure and morphology remained almost the same after γ-irradiation with an adsorbed dose up to 435.8 kGy. Most importantly, only less than 0.1% of Fe is leached out from mag-Nb-CST at pH > 2, indicating that the embedded Fe3O4 nanoparticles are protected from corrosion by the coated Nb-CST, which is in favor of elimination of Sr2+ and Cs+ in acidic solutions. Thus, mag-Nb-CST is a promising adsorbent in the treatment of acidic radioactive liquid wastes, and the purification of contaminated seawater.

Towards single crystalline, highly monodisperse and catalytically active gold nanoparticles capped with probiotic Lactobacillus plantarum derived lipase

Owing to the eco-friendly nature of biomolecules, there lies a huge interest in exploring them as capping agents for nanoparticles to achieve stability and biocompatibility. Lipase extracted from the probiotic Lactobacillus plantarum is utilized for the first time to study its efficacy in capping gold nanoparticles (GNPs) in the room temperature synthesis using HAuCl4. The synthesized lipase-capped GNPs are characterized using UV–visible spectroscopy, FT-IR, HR-TEM, DLS and zeta potential measurements. Importantly, selected area electron diffraction (SAED) studies with HR-TEM have revealed the effect of lipase capping in tuning the polycrystallinity of the GNPs. The lipase-capped GNPs are explored for their catalytic efficiency towards an environmentally and industrially important conversion of 4-nitrophenol to 4-aminophenol. Exploiting the amine functional groups in the protein, the recoverability and reusability of the GNPs have been demonstrated through immobilization over amine-functionalized Fe3O4 nanoparticles.

Magnetic Porous Polymers Prepared via High Internal Phase Emulsions for Efficient Removal of Pb2+ and Cd2+

Magnetic porous polymers (MPPs) were successfully fabricated by a facile strategy of the high internal phase emulsions (HIPEs) technique. The microstructure, chemical composition, and magnetic properties of the MPPs were characterized. Impregnated with poly(styrene-divinylbenzene), stabilized by the amine-functionalized Fe3O4 nanoparticles (Fe3O4–NH2), the as-prepared MPPs with rich pore hierarchy were employed to removal Pb2+ and Cd2+ from aqueous solution. The MPPs display outstanding removal capacities toward Pb2+ (257 mg/g) and Cd2+ (129 mg/g) within 15 min, and the encapsulated Fe3O4–NH2 nanoparticles endow the MPPs with the ability of magnetic separation (30.15 emu/g). Additionally, the results indicate that the adsorptions of Pb2+ and Cd2+ are strongly dependent on pH and ionic strength, demonstrating that the interactions of Pb2+ and Cd2+ were mainly dominated by outer-sphere surface complexation and electrostatic attraction. The adsorption process is revealed by thermodynamic parameters to be spo...

Simple, Hackable, Size-Selective, Amine-Functionalized Fe-Oxide Nanoparticles for Biomedical Applications.

A facile one-pot method for synthesizing amine-functionalized nonspherical Fe3O4 nanoparticles in gram-scale quantities is presented using just a single source of iron (iron(II) chloride) and an amine (triethylamine). The amine not only transforms iron salt to Fe3O4, but also directs the morphology of the nanoparticles along with the temperature of the reaction and functionalizes them, making the synthesis very economical. By modifying the surface further, these nanoparticles promise to offer useful biomedical applications. For example, after biocide coating, the particles are found to be 100% effective in deactivating methicillin-resistant Staphylococcus aureus (MRSA) bacteria in 2 h. Cellular-uptake studies using biocompatible EDTA-Na3 (N-(trimethoxysilyl-propyl)ethylenediaminetriacetate, trisodium salt)-coated nanoparticles in human glioblastoma U-251 cells show that the majority of the particles are internalized by the cells in the presence of a small dc-magnetic field, making these particles a potential candidate as drug carriers for magnetic field-targeted delivery and hyperthermia.

Synthesis of amine-functionalized Fe3O4@C nanoparticles for laccase immobilization

Amine-functionalized Fe3O4@C nanoparticles with an average diameter of 266nm have been successfully synthesized by a solvothermal reduction method. The structure, morphology and properties of the Fe3O4@C nanoparticles were investigated through different analytical tools. Due to the magnetic nature and the presence of amine-functionalized groups, the as-prepared Fe3O4@C nanoparticles were employed as magnetic carriers for laccase immobilization. The results indicated that the loading of laccase onto the amine-functionalized Fe3O4@C nanoparticles was approximately 195mg/g. In comparison with free laccase, the pH, operational and storage stabilities of the immobilized laccase were significantly improved. After 10 consecutive operations, the immobilized laccase retained above 60% residual activity. The removal rates of o-phenylenediamine (OPD) by immobilized laccase were 88%, which were much higher than that of free laccase (50%). It hoped that the amine-functionalized Fe3O4@C nanoparticles may find an application in biotechnology and catalysis.

Single step synthesis of amine-functionalized mesoporous magnetite nanoparticles and their application for copper ions removal from aqueous solution

Amine-functionalized mesoporous superparamagnetic Fe3O4 nanoparticles with an average size of 70nm have been synthesized using a single step solvothermal method by the introduction of triethylenetetramine (TETA), a chelating agent recommended for the removal of excess copper in patients with Wilson’s disease. The synthesized nanoparticles were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, nitrogen adsorption/desorption isotherm, vibrating sample magnetometer (VSM), and Fourier transform infrared spectroscopy (FTIR). It is confirmed that the magnetic nanoparticles have been functionalized with TETA during the synthetic process, and the concentration of TETA is crucial for the formation of monodisperse mesoporous nanoparticles. The obtained single-crystal magnetic nanoparticles have a high magnetization, which enhances their response to external magnetic field and therefore should greatly facilitate the manipulation of the particles in practical uses. Reaction parameters affecting the formation of mesoporous structure were explored, and a possible formation mechanism involving templated aggregation and recrystallization processes was proposed. The capacity of the synthesized amine-functionalized Fe3O4 nanoparticles toward Cu(II) removal from aqueous solution was investigated. The adsorption rate of Cu(II) on amine-functionalized Fe3O4 nanoparticles followed a pseudo-second order kinetic model. The results of this study demonstrated that the amine-functionalized mesoporous superparamagnetic Fe3O4 nanoparticles could be used as an efficient adsorbent in water treatment and would also find potential application for Cu(II) removal in vivo.

Injectable, magnetoresponsive hydrogels for in situ physical actuation of osteochondral tissue regeneration

Event Abstract Back to Event Injectable, magnetoresponsive hydrogels for in situ physical actuation of osteochondral tissue regeneration Adedokun Adedoyin1 and Adam K. Ekenseair1 1 Northeastern University, Chemical Engineering, United States Introduction: Every year 3.1 million surgeries are performed to treat bone and cartilage damage caused by Osteoarthritis (OA), however, many of these procedures fail to restore full functionality and structure[1]. In particular, articular cartilage has proven challenging to heal due to its avascular and heterogeneous structure. Recent efforts have sought to move away from implantable scaffolds and develop novel, minimally invasive therapies capable of forming in situ and promoting close contact with existing tissue to enhance tissue repair. In particular, thermogelling macromers (TGM) that have a lower critical solution temperature (LCST) close to body temperature, such as poly(N-isopropylacrylamide) (PNiPAAm), are promising candidates capable of delivering viable encapsulated cells[2]. The next grand challenge in the development of injectable scaffolds is to create responsive materials that can be externally directed in a spatiotemporal manner to guide the regeneration of a heterogeneous tissue defect. This paper reports on the development of injectable, dual-gelling bionanocomposite hydrogels composed of PNiPAAm-based TGMs, degradable polyamidoamine (PAMAM) crosslinkers, and functional iron oxide (Fe3O4) nanoparticles capable of responding to an external magnetic field in order to stimulate cell activity and control the regenerative process in situ. Materials and Methods: PNiPAAm was copolymerized with glycidyl methacrylate (GMA) and PAMAM crosslinkers were created from piperazine and methylene bisacrylamide following previous synthesis procedures[3]. 50 nm and 500 nm amine-functionalized Fe3O4 particles were purchased from Ocean Nanotech, LLC. Injectable solutions were mixed and injected into a Teflon mold at 37ºC to form magnetic hydrogels. Polymer molecular weight was determined by GPC; LCST by differential scanning calorimetry (DSC); and Young’s Modulus by rheology. The magnetic properties of the hydrogel were determined by SQUID and tangential force measurements. The viability, activity and differentiation of mesenchymal stem cells were evaluated in vitro under varied magnetically-actuated stimulation regimes. Results and Discussion: The incorporation of nanoparticles into the injectable hydrogel system did not alter the LCST or thermogelation process. SQUID analysis demonstrated that the nanocomposite hydrogels exhibit paramagnetic behavior under strong magnetic fields, and tangential force measurements were made to evaluate the efficacy of utilizing an externally-controlled magnetic field to mechanically stimulate encapsulated cells (Fig, 1 & 2). Finally, the in situ delivery of viable cell populations encapsulated in the bionanocomposite hydrogel was demonstrated (Fig. 2 inset), and the effects of magnetic stimulation were elucidated. Conclusions: An injectable, bionanocomposite hydrogel scaffold responsive to an external magnetic field was developed and demonstrated potential for guided regeneration of osteochondral tissue defects. Robert Egan at Northeastern University; Dr. Abigail Koppes at Northeastern University; Dr. Sridhar at Northeastern University; Northeastern University's Tier 1 Grant Program; Chemical Engineering Department Northeastern University

Dispersive liquid-liquid microextraction based on amine-functionalized Fe3 O4 nanoparticles for the determination of phenolic acids in vegetable oils by high-performance liquid chromatography with UV detection

A novel dispersive liquid-liquid microextraction method based on amine-functionalized Fe3O4 magnetic nanoparticles was developed for the determination of six phenolic acids in vegetable oils by high-performance liquid chromatography. Amine-functionalized Fe3O4 was synthesized by a one-pot solvothermal reaction between Fe3O4 and 1,6-hexanediamine and characterized by transmission electron microscopy and Fourier transform infrared spectrophotometry. A trace amount of phosphate buffer solution (extractant) was adsorbed on bare Fe3O4-NH2 nanoparticles by hydrophilic interaction to form the "magnetic extractant". Rapid extraction could be achieved while the "magnetic extractant" on amine-functionalized Fe3O4 nanoparticles was dispersed in the sample solution by vortexing. After extraction, the "magnetic extractant" was collected by application of an external magnet. Some important parameters, such as pH and volume of extraction and desorption solvents, the extraction and desorption time needed were carefully investigated and optimized to achieve the best extraction efficiency. Under the optimal conditions, satisfactory extraction recoveries were obtained for the six phenolic acids in the range of 84.2-106.3%. Relative standard deviations for intra- and inter-day precisions were less than 6.3 and 10.0%, respectively. Finally, the established method was successfully applied for the determination of six phenolic acids in eight kinds of vegetable oils.

Rapid determination of trans-resveratrol in vegetable oils using magnetic hydrophilic multi-walled carbon nanotubes as adsorbents followed by liquid chromatography–tandem mass spectrometry

In the present work, a rapid and simple procedure was developed and validated for the analysis of trans-resveratrol in vegetable oils based on magnetic hydrophilic multi-walled carbon nanotubes (h-MWCNT-MNPs) combined with liquid chromatography–tandem mass spectrometry (LC–MS/MS). h-MWCNT-MNPs were simply obtained by wrapping amine-functionalized Fe3O4 magnetic nanoparticles into previously oxidized hydrophilic multi-walled carbon nanotubes. The major parameters affecting extraction efficiency were investigated, including the type and volume of desorption solvents, extraction and desorption time, washing solution, and sorbent amount. The limit of detection (LOD) and the limit of quantification (LOQ) were calculated as 0.6 and 2.0μg/kg, respectively. The recoveries of trans-resveratrol in oil samples were in the range of 90.0–110.0% with RSDs of less than 17.5%. The results showed that only peanut oil contained trans-resveratrol, ranging from 8±1 to 103±12μg/kg. The proposed method is reliable and robust, having an excellent potential for the analysis of trans-resveratrol in edible oils.