Surface-modified Magnetic Nanoparticles Research Articles

Advanced green capture of microplastics from different water matrices by surface-modified magnetic nanoparticles

The extensive production and application of plastic in recent decades has resulted in the presence of microplastics (MPs) in different water bodies. Considered as contaminants of emerging concern (CECs), MPs are accessible to a wide range of organisms and can act as vectors for the transport of other persistent organic pollutants. The existing technologies to remove microplastics from wastewaters and prevent their intrusion in nature, still present several limitations, resulting in an urgent need to develop novel, fast, cost-effective and greener alternatives. In this work, the magnetophoretic capture of MPs by their assembly with magnetic nanoparticles through either electrostatic interactions or molecular forces is investigated. For the experimental assessment, magnetic nanoparticles were synthesized by hydrothermal coprecipitation and solvothermal decomposition methods, while polyethylene (PE) microspheres were selected as model microplastic pollutants. As a noteworthy novelty, thermal decomposition and coprecipitation particles were functionalized with amino groups and sodium alginate (SA), respectively, resulting in a modification of their surface properties and enhanced electrostatic or molecular interactions with MPs. After preliminary experiments, a concentration of 1.3 g/L and a contact time of 20 min between magnetic nanoparticles and MPs, were selected as operating conditions to assess the influence of the functional groups on the capture performance. The influence of other variables in the process was also evaluated, including the magnetic nanoparticles synthesis method, the pH of the medium, varied in the range 4–8, and the water constituents that may be present in water bodies. Results demonstrated that the presence of different types of polar groups on the surface of the magnetic nanoparticles make them interact towards MPs through electrostatic attraction or molecular forces, considerably enhancing the capture performance of bare magnetic nanoparticles. This work represents a step forward in the development of new and reliable techniques for the environmentally friendly capture of microplastics from polluted waters.

Field-Swept Magnetic Particle Spectroscopy: A Single-Harmonic Method for Simultaneous Determination of Magnetic Nanoparticle Types and Quantities

Magnetic particle spectroscopy (MPS) allows for highly sensitive and real time characterization of magnetic nanoparticles (MNPs). When combined with surface-modified MNPs that can specifically bind to biomarkers, MPS can serve as a quantitative biosensing platform and have shown enormous potential in point-of-care diagnosis. To improve diagnostic efficiency and accuracy, the simultaneous detection of multiple biomarkers has been studied in MPS, which requires the simultaneous determination of the type and quantity of MNPs. Current methods generally rely on the higher order harmonics (e.g., third to fifth harmonic ratio) of the MNPs’ magnetic responses to the excitation fields, but facing challenges at low concentrations or with small-sized MNPs that are difficult to generate sufficient harmonics. In this paper, we propose a single-harmonic method for simultaneous determination of MNP types and quantities, named field-swept magnetic particle spectroscopy (FS-MPS). An adjustable static magnetic field perpendicular to the alternating magnetic field is introduced and MNPs’ field-dependent response is registered from the static field direction. By comparing simulation results of serval system configurations and the field-swept spectra of different harmonics, we found that the second harmonic component of the MNP signal combines good specificity and robustness with no direct feed-through interference issues. We built the first FS-MPS device and carried out experiments of binary MNP mixtures to verify the effectiveness of the proposed method. Our experimental results showed that the proposed method has up to 90% accuracy for the simultaneous determination of two types of MNPs with a maximum concentration ratio of 9:1. The proposed method can in principle determine more types of MNPs simultaneously, providing an effective tool for the detection of multiple biomolecular markers.

Influence of hydrophilic and hydrophobic functional monomers on the performance of magnetic molecularly imprinted polymers for selective recognition of human insulin

Magnetic molecularly imprinted polymers (MMIPs) were used to detect and bioseparation of insulin. Because of the significant role of electrostatic interactions, the effects of hydrophilic/hydrophobic interactions were investigated in non-covalent molecular imprinting. The imprinting polymer was synthesized using different type and molar ratios of functional monomers containing acrylamide (AAm) as the neutral-hydrophilic monomer alongside methacrylic acid (MAA) and 2-dimethyl aminoethyl methacrylate (DMA) in the two cases: hydrophilic-hydrophobic-neutral (MMIP3) and hydrophobic-neutral (MMIP2), respectively. The MMIPs adsorption results showed high capacity, good selectivity, and high rapidness to insulin adsorption in both cases. The maximum adsorption (Q) and imprinting factor (IF) of MMIP2 and MMIP3 obtained 54 mg.g−1 and 4.4, and 67 mg.g−1 and 3.2, respectively. In addition, dynamic light scattering results revealed that the average particle size of the surface-modified magnetic nanoparticles (Fe3O4@SiO2@MPS), MMIP2, and MMIP3 were equal to 135 ± 8, 360 ± 21, and 275 ± 28 nm, respectively. The thermogravimetric analysis demonstrated that MNIP2 has almost 25% more polymer layer than MNIP3. VSM analysis was also carried out showed the magnetic power of 21.88, 7.74, and 19.93 emu/g for MNPs, MMIP2, and MMIP3, respectively.

Preparation and performance study of a reactive polyurethane hot-melt adhesive/CS-Fe3O4 magnetic nanocomposite film/fabric.

Magnetic nanoparticles are attracting significant attention for their wide application as biomaterials and magnetic storage materials. As an environmentally friendly adhesive, reactive polyurethane hot-melt adhesive (PUR) is a biocompatible polymer with a wide range of applications. In this paper, chitosan (CS)-surface-modified magnetic Fe3O4 nanoparticles were synthesized by the sol–gel method. Surface modification of the Fe3O4 nanoparticles with CS enhanced their mechanical properties in PUR. The nanoparticles were characterized by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analyses, while their surface morphology was elucidated using scanning electron microscopy (SEM) and projection electron microscopy (TEM) techniques. Subsequently, PUR/CS–Fe3O4 magnetic nanocomposite films were prepared using an in situ method, wherein different amounts of CS–surface-modified magnetic Fe3O4 nanoparticles were doped into the PUR and coated on the films. The thermal, UV resistance and mechanical properties of the PUR/CS–Fe3O4 magnetic nanocomposite films were investigated by TGA, UV spectrometer and tensile testing. CS–Fe3O4 nanoparticles were successfully prepared using the sol–gel method and CS to modify the surface of the Fe3O4 nanoparticles. The results show that the mechanical properties and UV resistance of PUR/CS–Fe3O4 magnetic nanocomposites are improved by almost 50%, so the constructed PUR/CS–Fe3O4 magnetic nanocomposites have good UV-resistant properties and mechanical properties. The as-synthesized CS–Fe3O4 magnetic nanocomposites show great potential for application to mechanical and textile development.

Magnetic Biopolymeric Hydrogel Composite Material with Self-healing Attribute

This work presents a polysaccharide-based magnetic self-healing hydrogel fabricated through the incorporation of surface modified magnetic nanoparticles, a silica-surface modified magnetic - Fe3O4@SiO2, (MNP), to a polymer composite synthesized from the oxidation of xanthan gum (XG) and it's crosslinking with chitosan (CS) to generate Schiff base linkages rendering self-healing character. Fourier transform infrared (FT-IR) spectroscopy analyses revealed the successful formation of Schiff base bonding in the CS-OXG and CS-OXG-MNP hydrogels. In incorporating surface-modified magnetic nanoparticles, the resulting CS-OXG-MNP hydrogel with a weight ratio of 1:1:0.2, respectively, exhibited a better self-healing hydrogel in terms of faster self-healing characteristics and stronger mechanical property.

Synthesis and applications of surface-modified magnetic nanoparticles: progress and future prospects

Abstract The growing use of magnetic nanoparticles (MNPs) demands cost-effective methods for their synthesis that allow proper control of particle size and size distribution. The unique properties of MNPs include high specific surface area, ease of functionalization, chemical stability and superparamagnetic behavior, with applications in catalysis, data and energy storage, environmental remediation and biomedicine. This review highlights breakthroughs in the use of MNPs since their initial introduction in biomedicine to the latest challenging applications; special attention is paid to the importance of proper coating and functionalization of the particle surface, which dictates the specific properties for each application. Starting from the first report following LaMer’s theory in 1950, this review discusses and analyzes methods of synthesizing MNPs, with an emphasis on functionality and applications. However, several hurdles, such as the design of reactors with suitable geometries, appropriate control of operating conditions and, in particular, reproducibility and scalability, continue to prevent many applications from reaching the market. The most recent strategy, the use of microfluidics to achieve continuous and controlled synthesis of MNPs, is therefore thoroughly analyzed. This review is the first to survey continuous microfluidic coating or functionalization of particles, including challenging properties and applications.

Influence of interaction between surface-modified magnetic nanoparticles with infectious biofilm components in artificial channel digging and biofilm eradication by antibiotics in vitro and in vivo.

Magnetic targeting of antimicrobial-loaded magnetic nanoparticles to micrometer-sized infectious biofilms is challenging. Bacterial biofilms possess water channels that facilitate transport of nutrient and metabolic waste products, but are insufficient to allow deep penetration of antimicrobials and bacterial killing. Artificial channel digging in infectious biofilms involves magnetically propelling nanoparticles through a biofilm to dig additional channels to enhance antimicrobial penetration. This does not require precise targeting. However, it is not known whether interaction of magnetic nanoparticles with biofilm components impacts the efficacy of antibiotics after artificial channel digging. Here, we functionalized magnetic-iron-oxide-nanoparticles (MIONPs) with polydopamine (PDA) to modify their interaction with staphylococcal pathogens and extracellular-polymeric-substances (EPS) and relate the interaction with in vitro biofilm eradication by gentamicin after magnetic channel digging. PDA-modified MIONPs had less negative zeta potentials than unmodified MIONPs due to the presence of amino groups and accordingly more interaction with negatively charged staphylococcal cell surfaces than unmodified MIONPs. Neither unmodified nor PDA-modified MIONPs interacted with EPS. Concurrently, use of non-interacting unmodified MIONPs for artificial channel digging in in vitro grown staphylococcal biofilms enhanced the efficacy of gentamicin more than the use of interacting, PDA-modified MIONPs. In vivo experiments in mice using a sub-cutaneous infection model confirmed that non-interacting, unmodified MIONPs enhanced eradication by gentamicin of Staphylococcus aureus Xen36 biofilms about 10 fold. Combined with the high biocompatibility of magnetic nanoparticles, these results form an important step in understanding the mechanism of artificial channel digging in infectious biofilms for enhancing antibiotic efficacy in hard-to-treat infectious biofilms in patients.

Versatile nanoadsorbents based on magnetic mesostructured silica nanoparticles with tailored surface properties for organic pollutants removal

This paper addresses the development of new magnetic silica-based nanoadsorbents and evaluates their potential application in the removal of contaminants of emerging concern (CECs), polyaromatic hydrocarbons (PAHs) and aliphatic hydrocarbons. For this purpose, magnetic iron oxide nanoparticles were covered with a hybrid shell of silica and 3-(trimethoxysilyl)propyl-octadecyldimethyl-ammonium chloride (TPODAC) as structure directing agent. The as-prepared hybrid material (MMST) was further modified with trimethoxyphenylsilane, obtaining a phenyl-functionalized nanoadsorbent (MMST-Ph). Both materials were thoroughly characterized with diverse physicochemical techniques, and batch sorption tests with single-contaminant and with mixtures of contaminants were performed. MMST-Ph proved to be more efficient for the adsorption of PAHs and aliphatic hydrocarbons. The presence of TPODAC and phenyl moieties anchored on the mesostructured silica frameworks resulted to be a key factor to obtain high PAHs uptakes from aqueous media. In the case of CECs, ibuprofen (IBU), diclofenac (DCF) and carbamazepine (CBZ) were tested. These experiments demonstrated that even though MMST possesses better adsorption capacities of CECs, MMST-Ph achieved high IBU and DCF uptakes. Regeneration and reuse experiments showed that MMST-Ph can be reused in eight cycles without losing the adsorption capacity of anthracene. In the case of MMST, there was a 42% drop in the adsorption capacity of ibuprofen in the second cycle, whereas in the next seven cycles the adsorption capacity remained constant.The promising results obtained in this work strengthen the potential application of surface-modified magnetic silica nanoparticles for the removal of different types of organic pollutants from waters.

Antimicrobial Activity of Isoniazid in Conjugation with Surface-Modified Magnetic Nanoparticles against Mycobacterium tuberculosis and Nonmycobacterial Microorganisms

Isoniazid, the choice antitubercular agent, has only been employed against Mycobacterium tuberculosis. This study evaluated if the enzyme-mimetic activities of magnetic nanoparticles could accelerate the activation process of isoniazid against mycobacterial and, more importantly, non-mycobacterial microorganisms. First, magnetic nanoparticles were synthesized and coated by lipoamino acid; then, isoniazid was conjugated to synthesized nanoparticles. Antibacterial activities of nanoconjugated isoniazid were evaluated against Mycobacterium tuberculosis and four Gram-positive and Gram-negative nonmycobacterial strains through a microdilution broth process. Results showed that the required amount of isoniazid against Mycobacterium tuberculosis would decrease to 44.8% and 16.7% in conjugation with naked and surface-modified magnetic nanoparticles, respectively. Also, 32 μg/mL and 38 μg/mL of isoniazid in conjugation with naked and surface-modified nanoparticles, respectively, could prevent the growth of Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. Hence, the vicinity of magnetic nanoparticles with isoniazid could declare promising aspects of isoniazid antibacterial capabilities.

Preparation and surface engineering of CM-β-CD functionalized Fe3O4@TiO2 nanoparticles for photocatalytic degradation of polychlorinated biphenyls (PCBs) from transformer oil

The aim of the present research is to investigate the efficiency of surface-modified magnetic nanoparticles for photocatalytic degradation of PCBs from transformer oil. Therefore, CMCD-Fe3O4@TiO2 was successfully produced via grafting of carboxymethyl-β-cyclodextrin (CM-β-CD) onto the core-shell titania magnetic nanoparticles surface. The photocatalytic efficiency of CMCD-Fe3O4@TiO2 for degradation of PCBs was systematically evaluated using an experimental design and the process parameters were optimized by response surface methodology (RSM). The central composite design (CCD) with four experimental parameters was used successfully in the modeling and optimization of photocatalytic efficiency in removing PCBs from transformer oil. ANOVA analysis confirmed a high R-squared value of 0.9769 describing the goodness of fit of the proposed model for the significance estimation of the individual and the interaction effects of variables. The optimal degradation yields of PCBs was achieved 83 % at a temperature of 25 °C, time of 16 min, the dosage of the catalyst of 8.35 mg and oil: ethanol ratio of 1:5. These findings encourage the practical use of CM-β-CD-Fe3O4@TiO2 as a promising and alternative photocatalyst on an industrial scale for the cleaning of organic pollutants such as PCBs due to its environmental friendliness, the benefit of magnetic separation and good reusability after five times.

Comprehensive study on the effects of total monomers' content and polymerization temperature control on the formation of the polymer-layer in preparation of insulin-imprinted magnetic nanoparticles

The potential of surface-modified magnetic nanoparticles was used as the support for molecular imprinting to separate insulin. The effects of the total monomers’ content (at seven levels) and overall temperature (ambient, controlled at 23 and 28 °C) during the formation of the surface polymer layer in aqueous media were for the first time explored via general factorial experimental design. Methacrylic acid (MAA) and acrylamide (AAm) were chosen as the functional monomers, and methylenebisacrylamide (MBAAm) was applied as the cross-linker. Six responses were simultaneously optimized using the desirability function. The software results demonstrated the importance of choosing proper amounts of constituents and controlling the temperature. The optimum conditions were determined to be for the magnetic molecularly imprinted polymers synthesized at 23 °C and with the molar ratio of 1:40:200:10 for Insulin:MAA:AAm:MBAAm with an imprinting factor of 2.5. TGA and VSM analyses confirmed the thin (about 7% of total weight) and uniform core-shell structure of polymers with high saturation magnetization (20.1 emu g−1). The outcomes of adsorption kinetics and rebinding isotherm revealed that the imprinted cavities located on or close to its surface, and are practical for the separation of low and high abundance of insulin. This system could be reused for at least five times cyclically.

Enhanced performance of Candida rugosa lipase immobilized onto alkyl chain modified-magnetic nanocomposites

Lipase-immobilized nanomaterials with high activity and stable reusability would have a great impact in different fields. However, developing such materials has proven to be challenging. Herein, polymer (pAcDED)-coated magnetic nanoparticles (MNPs) displaying long alkyl chains, either octyl (C8) or hexadecyl (C16), have been prepared and used for immobilization of Candida rugosa lipase. The aim of the study was to develop magnetic supports able to bind enzyme via interfacial activation thus to stabilized the lipase open conformation. Among the developed nanosupports, the one endowed with the longest alkyl chains (MNPs-pAcDED-C16) provided the best efficiencies of the immobilized enzyme (70% vs. tributyrin and 130% vs. ethyl butyrate). Such results suggest both enzyme adsorption in open conformation and a change of enzyme specificity during immobilization. The MNPs-pAcDED-C16 system also showed better resistance to temperature inactivation in the 25–70 °C temperature range compared to free lipase and good reusability (4 consecutive cycles). The overall performances together with the convenience in the recovery offered by magnetic separation indicate our surface-modified MNPs as efficient and environmentally compatible materials for lipase immobilization.

Expanding the Horizon of Multicomponent Oxidative Coupling Reaction via the Design of a Unique, 3D Copper Isophthalate MOF-Based Catalyst Decorated with Mixed Spinel CoFe2O4 Nanoparticles.

This work discloses the first ever magnetically retrievable copper isophthalate-based metal-organic framework (MOF) decorated with surface-modified cobalt ferrite (CoFe2O4) nanoparticles that have been utilized as catalytic reactors for obtaining a relatively large number of biologically active benzimidazole scaffolds. A facile one-pot solvothermal approach was employed for obtaining spherical and monodisperse CoFe2O4 nanoparticles, which were subsequently modified using suitable protecting and functionalizing agents. Finally, these functionalized magnetic nanoparticles were anchored onto the three-dimensional copper isophthalate MOF via a covalent immobilization methodology. The exploitation of advanced microscopic tools such as transmission electron microscopy and scanning electron microscopy provided valuable insights into the morphology of the immobilized MOF. These results indicated that the surface-modified magnetic nanoparticles had grown onto the surface of copper-5-nitroisophthalic acid MOF. A greener C–H functionalization strategy that involves the multicomponent oxidative cross-coupling between two different set of amines (sp2-hybridized nitrogen-containing anilines and sp3-hybridized nitrogen-containing alkyl/aryl amine derivatives) and sodium azide has been incorporated to provide access to a broad spectrum of the value-added target benzimidazole moieties. It is interesting to note that this magnetic MOF-catalyzed protocol not only replaces toxic solvents with water, which is a green solvent, but also enhances the economic competitiveness since the magnetic catalyst can be readily recovered and recycled for eight consecutive runs.

Preparation and characterization of surface-modified Fe3O4 magnetic nanoparticles for extraction of flutamide in biological samples using HPLC

Flutamide (FLU) loaded onto functionalized magnetite iron oxide nanoparticles were prepared and characterized with scanning electron microscopy, elemental analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy, and energy dispersive spectroscopy techniques. In addition, the effects of parameters of pH, temperature, contact time, and concentration on the adsorption capacity of nanoparticles were evaluated and optimized. The adsorption data were fitted to the Langmuir isotherm and the relevant parameters were inferred. Findings of the study suggested that N-vinylcaprolactam-allylimidazole copolymer coated MNPs are promising carrier for FLU delivery. The solid phase extraction technique was investigated for biological samples. Urine extraction recovery obtained about 91%.

D,l-lysine functionalized Fe3O4 nanoparticles for detection of cancer cells

Amino-modified magnetic nanoparticles were prepared by direct chemisorption of biocompatible d,l-lysine (DLL) on electrostatically stabilized magnetic nanoparticles with the aim to bind specific antibodies (Ab) able to detect cancer cells. The magnetic nanoparticles prepared by coprecipitation were stabilized in an acidic medium. A full optimization study of amino modification performed by UV/Vis spectroscopy and Dynamic Light Scattering measurement (DLS) confirmed an optimal DLL/Fe3O4 weight ratio of 2. The sample was subjected to complex characterizations using different techniques such as UV/Vis, FTIR and X-ray photoelectron spectroscopies (XPS) together with transmission electron microscopy and size/zeta potential measurements. While FTIR spectroscopy, UV/Vis spectroscopy and XPS confirmed the successful amino modification of Fe3O4 nanoparticles, a characterization using a vibrating sample magnetometer (VSM) indicated superparamagnetic behavior in all the prepared samples, suggesting that the coating process did not significantly affect the size and structure of the Fe3O4 nanoparticles. Magnetic nanoparticles with the optimal DLL content were conjugated with the M75 monoclonal antibody specific to carbonic anhydrase IX (CA IX), which is considered one of the best markers of tumor hypoxia and a prognostic indicator of cancer progression. The results demonstrate that all tested cell lines survived and even proliferated in the presence of amino-modified magnetic nanoparticles. Even the tubulin cytoskeletal structure was not disrupted after the exposure of cells to surface-modified magnetic nanoparticles. In contrast, internalization of the antibody-conjugated magnetic nanoparticles led to abrogation of the formation of long and extended microtubules. Finally, the finding supports the view that the M75 antibody conjugated to nanoparticles mediates their specific uptake and intracellular accumulation and that the antibody conjugated magnetic nanoparticles can be potentially used for the selective growth inhibition of CA IX-expressing cells.

Efficient removal of anionic dyes from aqueous media using newly in situ synthesized triazine-based nitrogen-rich network-modified magnetic nanoparticles

In this research, a triazine-based polymeric network surface-modified magnetic nanoparticles (TPN/MNPs) were synthesized for the adsorption of anionic compounds. To obtain TPN/MNPs, melamine–terephthaldehyde polymeric network was synthesized in the presence of magnetic nanoparticles. After characterization by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and transmission electron microscopy (TEM), the adsorption behaviors of methyl orange (MO) as model anionic dye on TPN/MNPs were investigated. Obtained results showed MO removal efficiency has not been influenced by pH (5–9) and high salt concentration (up to 10% w/v) of the solution. The adsorption isotherm was described by Langmuir model. The results indicated that TPN/MNPs adsorbed MO effectively with a large capacity of 80.6 mg g−1. The adsorption reached the equilibrium within 10 min and the kinetics followed pseudo-second-order model. The magnetic separation after adsorption was easily achieved, and TPN/MNPs could be quantitatively regenerated by washing with 1.0 mL of the mixture of methanol/0.1 mol L−1 HCl (50:50, v/v%) solution. The results confirmed that TPN/MNPs have the potential superiority in removal of MO from aqueous solution.

Biological evaluation of surface-modified magnetic nanoparticles as a platform for colon cancer cell theranostics

Magnetic nanoparticles offer multiple possibilities for biomedical applications. Besides their physico-chemical properties, nanoparticle-cellular interactions are determinant for biological safety. In this work, magnetic nanoparticles were synthesized by one-shot precipitation or two-step reaction and coated with biocompatible polymers, such as poly(l-lysine) and poly(N,N-dimethylacrylamide-co-acrylic acid), and carbohydrates, like l-ascorbic acid, d-galactose, d-mannose, and sucrose. The resulting magnetic nanoparticles were characterized by dynamic light scattering, FT-Raman spectroscopy, transmission electron microscopy, SQUID magnetometry, and Mössbauer spectroscopy. Ability of the nanoparticles to be used in theranostic applications was also evaluated, showing that coating with biocompatible polymers increased the heating efficiency. Nanoparticles synthesized by one-shot precipitation were 50% larger (∼13nm) than those obtained by a two-step reaction (∼8nm). Magnetic nanoparticles at concentrations up to 500μgmL−1 were non-cytotoxic to L929 fibroblasts. Particles synthesized by one-shot precipitation had little effect on viability, cell cycle and apoptosis of the three human colon cancer cell lines used: Caco-2, HT-29, and SW-480. At the same concentration (500μgmL−1), magnetic particles prepared by a two-step reaction reduced colon cancer cell viability by 20%, affecting cell cycle and inducing cell apoptosis. Uptake of surface-coated magnetic nanoparticles by colon cancer cells was dependent on particle synthesis, surface coating and incubation time.

Development and Characterization of Magnetite/Poly(butylcyanoacrylate) Nanoparticles for Magnetic Targeted Delivery of Cancer Drugs.

A great attention is presently paid to the design of drug delivery vehicles based on surface-modified magnetic nanoparticles. They can, in principle, be directed to a desired target area for releasing their drug payload, a process triggered by pH, temperature, radiation, or even magnetic field. To this, the possibility of forming part of diagnostic tools by enhanced magnetic resonance imaging or that of further treatment by magnetic hyperthermia can be added. Bare particles are rapidly eliminated from the bloodstream by the phagocyte mononuclear system, leading to short biological half-life. It is hence required to coat them in order to increase their biocompatibility and facilitate the drug incorporation. In this work, magnetite nanoparticles were coated with poly(butylcyanoacrylate) (PBCA) manufactured and characterized with regard to their physical properties and their suitability as a platform for magnetically controlled drug delivery. The average diameter of magnetite and core-shell nanoparticles was 97 ± 19 and 140 ± 20 nm, respectively. Infrared analysis, electrophoretic mobility, surface thermodynamics analysis, and X-ray diffraction all confirmed that the magnetic particles were sufficiently covered by the polymer in the composite nanoparticles. In addition, assays using normal (CCD-18 and MCF-10A) and tumoral (T-84 and MCF-7) cell lines derived from colon and breast tissue, respectively, demonstrated that nanocomposites have low or negligible cytotoxicity. It is concluded that PBCA-coated magnetite core-shell nanoparticles represent a remarkable promise as a platform for magnetically controlled drug delivery.

Efficient Removal of Enhanced-Oil-Recovery Polymer From Produced Water With Magnetic Nanoparticles and Regeneration/Reuse of Spent Particles

Summary Polymer flooding is a proven technology to improve sweep efficiency, while being one of the most economical enhanced-oil-recovery (EOR) processes. Partially hydrolyzed polyacrylamide (HPAM) has been widely used for polymer flooding. As the HPAM usage for EOR increases, the challenge of produced-water management is also raised because residual HPAM in produced water could increase oil content and unwanted viscosity in discharging or reinjecting the water. As the environmental standards and regulations get more stringent, it is difficult for the conventional methods to meet the requirement for discharge. Use of magnetic nanoparticles (MNPs) to remove contaminants from produced water is a promising way to treat produced water in an environmentally friendly way with minimal use of chemicals. The main attraction for MNPs is their quick response to move in a desired direction with application of an external magnetic field. Another attraction of MNPs is versatile and efficient surface modification through suitable polymer coating, depending on the characteristics of target contaminants. In this study, we investigate the feasibility of polymer removal with surface-modified MNPs and regeneration of spent MNPs for multiple reuse. MNPs, in-house synthesized with prescribed surface coating, were superparamagnetic with an average individual particle size of ≈10 nm. The removal efficiency of HPAM from water with the MNPs depended on the type and concentration of brines, concentration of amine-functionalized MNPs, surface coating of MNPs, molecular weight of polymer, and how many times the MNPs were regenerated and reused. Virtually 100% removal of HPAM from water was feasible, depending on the reaction conditions. The regeneration of spent MNPs, with pH adjustment to recover the reactive sites, maintained more than 90% removal efficiency for three-time repetitive usages. The electrostatic attraction between negatively charged HPAM polymer and positively charged MNPs controls the attachment of MNPs to HPAM molecular chains; the subsequent aggregation of the now neutralized MNP-attached HPAM plays a critical role for accelerated and efficient magnetic separation.

Studies of magnetic alginate-based electrospun matrices crosslinked with different methods for potential hyperthermia treatment

The magnetic electrospun mats were lately established as an innovative biomaterial for hyperthermic cancer treatment. Unlike those surface-modified magnetic nanoparticles that may not firmly adhere onto the tumor for long-term duration, the magnetic mats with nanofibrous structure can promote cell adhesion and kill the tumor directly within an alternating magnetic field. However, most magnetic electrospun mats were fabricated using non-biodegradable polymers and organic solvents, causing the problems of removal after therapy and the suspected biotoxicity associated with residual solvent. Alginate (SA) was utilized in this investigation as the main material for electrospinning because of being biodegradable and water-soluble. The alginate-based electrospun mats were then treated by an ionic or a covalent crosslinking method, and then followed by chelation with Fe2+/Fe3+ for chemical coprecipitation of Fe3O4 magnetic nanoparticles. Significant less cytotoxicity was noted on both liquid extracts from the ionic-crosslinked (Fe3O4-SA/PEO) and covalent-crosslinked (Fe3O4-SA/PVA) magnetic electrospun mats as well as the surface of Fe3O4-SA/PVA. In vitro hyperthermia assay indicated that the covalent-crosslinked magnetic alginate-based mats reduced tumor cell viability greater than Fe3O4 nanoparticles. Such magnetic electrospun mats are of potential for hyperthermia treatment by endoscopic/surgical delivery as well as serving as a supplementary debridement treatment after surgical tumor removal.