Acid Modified Fe3O4 Nanoparticles Research Articles

Magnetic nano-Fe3O4-based oleophilic tracer for stability studies of nano-tracer in oilfields condition

Nano-tracers have demonstrated exceptional performance in the petroleum engineering. However, the challenges of oleophilic nano-tracers persist in the complex separation and detection of these tracers from products, and the stability of nano-tracers in oilfields conditions is not currently explored in detail. In this work, magnetic nanoparticle libraries modified with stearic acid (SA) were harnessed to create a novel oleophilic oilfields tracer (M-Fe3O4 @SA). The quantities of tracer were expanded by doping various metal elements, which have the potential to match the number of fracturing stages. Additionally, the tracers were modified with stearic acid, provides ability to selectively tracing the oil. M-Fe3O4 @SA was examined by X-ray diffraction, Fourier-transform infrared spectroscopy, inductively coupled plasma mass spectrometry, thermogravimetric analysis coupled with differential scanning calorimetry, and vibrating sample magnetometry. The results revealed that the M-Fe3O4 @SA can be approximated as stearic acid-modified Fe3O4 nanoparticles, and its properties are not affected by the doped elements. As an oleophilic tracer, the wettability of the tracer was evaluated according to the static water contact angle. The contact angle reaches its maximum value (151.94°) when modified with 21% stearic acid. The thermal stability evaluation demonstrated that the tracer maintains a high retention rate (93%−73%) at 30 ℃− 90 ℃. The stable radius of the tracer dispersed in dodecane is about 2000 nm, and in ethanol is 1000 nm, which consistent with the theoretical calculation of the extended DLVO theory.

A magnetic “Band-Aid” incorporated with Fe3O4 NPs modified epoxy binder for in-situ repair of organic coating under seawater

To repair the anti-corrosive coatings directly under seawater is an up-and-coming approach, which can effectively prolong the service life of coated steel structures once the coatings suffered from unexpected scratches. Inspired by the design of Band-Aid for the healing of wound, a magnetic “Band-Aid” (MB) combined with oleic acid modified Fe3O4 nanoparticles (OMNPs) was designed to realize the in-situ repair of anti-corrosion coatings under seawater and the experimental results indicated that this coating repair method by MB incorporated with OMNPs modified epoxy binder is satisfying and effective when the addition of OMNPs epoxy binder was more than 1.0 wt%. Furthermore, the penetration of seawater in the vertical direction of the coating can be prevented by MB during the curing process of epoxy binder, the formation of permeation channels parallel to the coating can be blocked with the aid of OMNPs, which mainly based on the magnetic force between the MB and substrate steel, as well as the competitive-wetting and target-driving functions of OMNPs. The current work may provide a feasible approach to repair the organic anti-corrosion coating directly, which coated on the steel structures under seawater.

PH-Responsible Doxorubicin-Loaded Fe3O4@CaCO3 Nanocomposites for Cancer Treatment

A magnetic nanocomposite (MNC) is an integrated nanoplatform that combines a set of functions of two types of materials. A successful combination can give rise to a completely new material with unique physical, chemical, and biological properties. The magnetic core of MNC provides the possibility of magnetic resonance or magnetic particle imaging, magnetic field-influenced targeted delivery, hyperthermia, and other outstanding applications. Recently, MNC gained attention for external magnetic field-guided specific delivery to cancer tissue. Further, drug loading enhancement, construction stability, and biocompatibility improvement may lead to high progress in the area. Herein, the novel method for nanoscale Fe3O4@CaCO3 composites synthesis was proposed. For the procedure, oleic acid-modified Fe3O4 nanoparticles were coated with porous CaCO3 using an ion coprecipitation technique. PEG-2000, Tween 20, and DMEM cell media was successfully used as a stabilization agent and template for Fe3O4@CaCO3 synthesis. Transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and dynamic light scattering (DLS) data were used for the Fe3O4@CaCO3 MNC's characterization. To improve the nanocomposite properties, the concentration of the magnetic core was varied, yielding optimal size, polydispersity, and aggregation ability. The resulting Fe3O4@CaCO3 had a size of 135 nm with narrow size distributions, which is suitable for biomedical applications. The stability experiment in various pH, cell media, and fetal bovine serum was also evaluated. The material showed low cytotoxicity and high biocompatibility. An excellent anticancer drug doxorubicin (DOX) loading of up to 1900 µg/mg (DOX/MNC) was demonstrated. The Fe3O4@CaCO3/DOX displayed high stability at neutral pH and efficient acid-responsive drug release. The series of DOX-loaded Fe3O4@CaCO3 MNCs indicated effective inhibition of Hela and MCF-7 cell lines, and the IC 50 values were calculated. Moreover, 1.5 μg of the DOX-loaded Fe3O4@CaCO3 nanocomposite is sufficient to inhibit 50% of Hela cells, which shows a high prospect for cancer treatment. The stability experiments for DOX-loaded Fe3O4@CaCO3 in human serum albumin solution indicated the drug release due to the formation of a protein corona. The presented experiment showed the "pitfalls" of DOX-loaded nanocomposites and provided step-by-step guidance on efficient, smart, anticancer nanoconstruction fabrication. Thus, the Fe3O4@CaCO3 nanoplatform exhibits good performance in the cancer treatment area.

Preparation of hydrophobic stearic acid-modified Fe3O4/graphite oxide/melamine sponge for oil-water separation

A fluorine-free strategy was developed for the hydrophobic modification of the melamine (MA) sponge, in which both the stearic acid-modified Fe3O4 nanoparticles (SA-Fe3O4) and the graphite oxide were immobilized on the MA sponge with the use of 3-aminopropyltriethoxysilane by a drop-coating method to prepare the SA-Fe3O4/GO/MA sponge for oil-water separation. The structure of the SA-Fe3O4/GO/MA sponge was investigated by FITR, WAXD, SEM, two-dimensional EDS mapping, TGA, and VSM. The contact angles of the SA-Fe3O4/GO/MA sponge prepared with different amounts of SA-Fe3O4 and GO were in the range of 140.2° − 145.0°, which confirmed the successful hydrophobic surface modification for the MA sponge. The demonstrations exhibited that the SA-Fe3O4/GO/MA sponge could separate the oil from the oil-water mixture by both direct absorption and gravity-driven filtration. Additionally, the SA-Fe3O4/GO/MA sponge possessed not only high absorption capacities for peanut oil, n-hexane, soybean oil, and diesel oil, but also good abilities of being able to recollect magnetically and reuse. The proposed preparation strategy and overall performance of SA-Fe3O4/GO/MA sponge were promising for the oil-water separation in the future.

Supramolecular-interaction-mediated aggregation of anticarcinogens on triformyl cholic acid-functionalized Fe3O4 nanoparticles and their dual-targeting treatment for liver cancer

Herein, triformyl cholic acid-modified Fe3O4 nanoparticles (TCA-MNPs) were first constructed and developed as a novel drug carrier, possessing a high loading capacity, and the synergistic targeted therapy of hepatoma cells in vitro and in vivo.

NIR light-steered magnetic liquid marbles with switchable positive/negative phototaxis

This work has demonstrated a magnetic liquid marble of switchable positive/negative phototaxis and excellent mechanical stability by encapsulating water droplet with oleic acid modified Fe3O4 nanoparticles (Fe3O4@OA NPs). The as-constructed marble can reach a height up to 4.7 mm, indicating an effective surface tension of ∼54 mN m−1. The marble on water surface can be steered by NIR light as well as magnetic field due to the photothermal effect and superparamagnetic feature of the Fe3O4@OA NPs. Its light-steered motion stems from the photothermal effect-induced Marangoni flow with speed controlled by the incident angles and light intensities. More interestingly, the marble can alter the motion direction from toward (positive phototaxis) to away from (negative phototaxis) NIR light source by simply changing the light irradiation position from upper to lower semi-marbles due to the unique light absorbance/transmittance characteristics of the Fe3O4@OA NPs. This is dramatically different from previously reported light-driven active matters that only show single phototaxis. This finding provides an advanced strategy to remotely steer magnetic liquid marbles, which may stimulate the exploitation of their application in chemistry and biology fields at microscale, and enlightens a method for phototactic regulation of active matters.

Superparamagnetic alginate-based nanocomposite modified by L-arginine: An eco-friendly bifunctional catalysts and an efficient antibacterial agent

In this protocol, the synthesis, antibacterial activity, and catalytic performance of super paramagnetic iron oxide nanoparticles (SPIONs) coated with L-arginine (Arg) grafted alginate (Alg), as an environmental benign heterogeneous catalyst are reported. The SPIONs coated materials were prepared by the co-precipitation method and characterized by Fourier transform infrared spectrometer (FT-IR), scanning electron microscope (SEM (, transmission electron microscopy (TEM), X-ray diffraction (XRD (, vibrating-sample magnetometer (VSM (, thermal gravimetric analysis (TGA), and energy dispersive X-ray spectroscopy (EDS). Moreover, the synthesized Fe3O4@Alg@CPTMS@Arg was employed for the preparation of 2,4,5-triarylimidazoles derivatives via a one-pot three-component reaction between ammonium acetate, aldehyde derivatives, and benzil under reflux in ethanol. Fe3O4@Alg@CPTMS@Arg exhibited highly effective catalytic activity. Apart from the catalytic activity, a study on the antibacterial activity of the prepared amino acid modified Fe3O4 nanoparticles, Fe3O4@Alg@CPTMS@Arg, was carried out on bacterial strain and compared with the antibacterial activity of the bare alginate. The results shown high antibacterial activity for the prepared nanocomposites against both Gram-positive Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli) compared to alginate. It is assumed that the antibacterial synergism is the combined effect of alginate and L-arginine.

Preparation and Evaluation of pH Sensitive Novel Anticancer Drug Carrier Based on Magnetic Chitosan Quartets.

Chitosan-coated magnetic nanoparticles are an appropriate drug delivery method which can improve the therapeutic properties of chemotherapy agents and also can be useful as MRI contrast agent for early cancer diagnosis. This research discovers the optimization of the possible therapeutic effects of Chitosan- citric acid- Fe3O4- CUR quartets. Chitosan as a natural polymer can use to encapsulate citric acid modified Fe3O4 nanoparticles. The successful preparation of CUR-loaded nano-carriers was confirmed by X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM) and transmission electron microscopy (TEM) techniques. Moreover, the hemolysis test was used for the study of hemobiocompatibility. The loading capacity and encapsulation efficiency of CUR molecules were 11±0.09% and 49.5±0.41%, respectively. The anticancer effect of the void of CUR and CUR-loaded nano-carriers were compared by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay on the treated MCF-7 cell lines. It can be concluded that the use of these nanoparticles are a better and more efficient approach for the controlled and slow release of CUR in the cancer treatment.

Surfactant‐enhanced spectrofluorimetric detection after magnetic nanoparticles‐based micro‐solid‐phase extraction coupled with dispersive liquid–liquid micro‐extraction for determination of ciprofloxacin in human plasma

A sensitive and fast micro-solid-phase extraction (μ-SPE) coupled with dispersive liquid–liquid micro-extraction (DLLME) was reported before micelle enhanced spectrofluorimetric detection for determination of ciprofloxacin antibiotic in human plasma samples. The DLLME was performed using methanol as disperser and 1-octanol as extracting solvent. Oleic acid-modified Fe3O4 nanoparticles (as hydrophobic adsorbents) were applied in μ-SPE step to extract the analyte from DLLME procedure. The method uses the advantageous of high surface area and strong superparamagnetism of these nanoparticles to many avoid labourhood column/cartridge-passing processes of traditional SPE. The major parameters affecting signal enhancement and analyte recovery were evaluated and optimised. Under the optimal conditions, the calibration curve (with calibration equation of I f = 2.5826 C + 10.273) was linear in the range 0.5–600 μg L−1 (R 2 = 0.997) with low limit of detection of 0.21 µg L−1 and limit of quantification of 0.63 µg L−1. The intra-day and inter-day precisions (as relative standard deviation) were in the range of 1.01–1.67% and high recoveries in the range of 93.5–102.4% were obtained. The results demonstrated that the proposed method is easy, low cost, and accurate. In addition, it confirms that choosing extraction solvent was not restricted to the high-density solvents which can extent the versatility of DLLME.

Porous multifunctional fluoropolymer composite foams prepared via humic acid modified Fe3O4 nanoparticles stabilized Pickering high internal phase emulsion using cationic fluorosurfactant as co-stabilizer

Fluoropolymers are very important owing to their excellent application performances, especially in extreme conditions. On the other hand, the preparation of porous fluoropolymers is a difficult task due to unavailability of suitable surfactants as well as tedious synthesis steps. Here we prepared multifunctional porous fluoropolymer composite foams with a simple process of “high internal phase emulsion (HIPE)” by using humic acid modified iron oxide nanoparticles (HA-Fe3O4 NPs) and cationic fluorosurfactant (CFS) (PDMAEMA-b-PHFBA) as co-stabilizer. The inclusion of HA-Fe3O4 NPs in the system made fluoro-HIPE more stable than the emulsion prepared using only CFS or other conventional stabilizers. Morphology of the prepared polyHIPE was easily controlled by altering the concentration of HA-Fe3O4 and/or CFS in the original formulation. Adjustment of the porous structure with open/close cells was performed and the average diameter of the pores tuned between 4.9 and 23 μm. With the increase in specific surface area by using nanoparticles (NPs) and CFS as co-surfactants, Pickering HIPE monoliths adsorbed double amount of oil compared to foams based solely on HIPE template. Multiple functional groups were bound onto Fe3O4 NPs through HA modification that made the fluoro-monolith capable of adsorbing dye, i.e. methylene blue, from water. A simple centrifugation enabled regeneration of the oil soaked foams and adsorption capacity was not decreased after 10 adsorption/regeneration cycles.

Magnetic Solid-Phase Extraction Combined with Dispersive Liquid-Liquid Microextraction Followed by HPLC for Determination of Four Aromatic Amines Released from Azo Dyes in Paper Samples

A novel extraction technique combining dispersive liquid-liquid microextraction (DLLME) with magnetic solid-phase extraction (MSPE) is presented for pre-concentration of four primary aromatic amines (PAAs) released from azo dyes in paper samples prior to high performance liquid chromatography (HPLC). n-Octanol was used as the extractant and hydrophobic oleic acid modified Fe3O4 nanoparticles (Fe3O4@OA NPs) as an efficient adsorbent was applied to retrieve the PAAs-containing n-octanol in the DLLME step. Because of the rapid mass transfer associated with the DLLME and MSPE steps, fast extraction could be achieved. The main parameters affecting the efficiency of MSPE-DLLME procedure of PAAs were investigated and optimized. Under optimum conditions, the recoveries ranged from 79.6 to 88.5% and the limits of detection (LODs) were in the range of 0.21-1.16 ng mL-1 (S / N = 3). The intra-day precision (relative standard deviation (RSD)) was below 7.8% and inter-day RSD was less than 11%.

Magnetic Solid-Phase Extraction in Combination with Ultra High-Performance Liquid Chromatography-Tandem Mass Spectrometry Analysis: Quantification of Risperidone and 9-Hydroxyrisperidone in Biological Samples

Oleic acid modified Fe3O4 nanoparticles were proposed for magnetic solid-phase extraction coupled with ultra high-performance liquid chromatography-tandem mass spectrometry to determine risperidone (RISP) and 9-hydroxyrisperidone (9OHR) in biological samples. The effects of various experimental parameters including adsorbent amount, pH, adsorption time, eluent type and concentration were systematically investigated. Under optimal conditions, the calibration curve was linear within the concentration range of 0.2-200 ng mL-1 with the correlation coefficient (r) of 0.9962 and the lower limit of quantification was 0.06 ng mL-1 for RISP; the calibration curve was linear within the concentration range of 0.2-200 ng mL-1 with the correlation coefficient of 0.9956 and the lower limit of quantification was 0.04 ng mL-1 for 9OHR. The extraction recoveries were over 90.0% with relative standard deviation less than 5.0%. All these results suggested that magnetic extraction method can be used for enrichment and quantification of RISP and 9OHR in biological samples.

Fabrication of redox and pH dual-responsive magnetic graphene oxide microcapsules via sonochemical method

In this study, the biocompatible redox and pH dual-responsive magnetic graphene oxide microcapsules (MGOMCs) were prepared by a simple sonochemical method. The disulfide bonds cross-linked the wall of MGOMCs were formed from the hydrosulfuryl on the surface of thiolated graphene oxide, which was synthesized by functionalizing graphene oxide with cysteine, showed an excellent redox-responsive property to control drugs release. Moreover, oleic acid modified Fe3O4 nanoparticles were encapsulated into the microcapsules successfully with the hydrophobic drugs dispersed in the hydroxy silicone oil. The MGOMCs possess distinguished magnetic property and pH-responsive ability. Besides, the microcapsules could be engulfed by Hela cells successfully due to the appropriate size and flexible shell. The MGOMCs could be a good carrier for hydrophobic drugs, especially the anticancer drugs.

Preparation of magnetic and pH-responsive chitosan microcapsules via sonochemical method

Magnetic and pH-responsive chitosan microcapsules (MPRCMCs) were prepared by a simple sonochemical method. Superparamagnetic oleic acid modified Fe3O4 nanoparticles (OA-Fe3O4 NPs) and hydrophobic drugs could be directly loaded into MPRCMCs during sonication. The obtained microcapsules had a well-defined spherical morphology with the average size of 2 μm. The microcapsules showed an excellent magnetic property. In addition, the pH-responsive controlled release of coumarin 6 (C6) from MPRCMCs indicated that the developed microcapsules could be a promising candidate for drugs carriers.

Characterization and immobilization of trypsin on tannic acid modified Fe3O4 nanoparticles

Fe3O4 nanoparticles (NPs) were synthesized by co-precipitating Fe2+ and Fe3+ in an ammonia solution. Fe3O4 NPs functionalized with tannic acid were prepared. After functionalization process, trypsin enzyme was immobilized on these Fe3O4 NPs. The influence of pH, temperature, thermal stability, storage time stability and reusability on non-covalent immobilization was studied. The properties of Fe3O4 and its modified forms were examined by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), UV–vis spectrometer (UV) and X-ray diffraction (XRD), magnetization and zeta potential measurements. The immobilized enzyme was slightly more stable than the free enzyme at 45°C. According to the results, the activity of immobilized trypsin was preserved 55% at 45°C after 2h and 90% after 120 days storage. In addition, the activity of the immobilized trypsin was preserved 40% of its initial activity after eight times of successive reuse.

Folate-bovine serum albumin functionalized polymeric micelles loaded with superparamagnetic iron oxide nanoparticles for tumor targeting and magnetic resonance imaging

Polymeric micelles functionalized with folate conjugated bovine serum albumin (FA-BSA) and loaded with superparamagnetic iron oxide nanoparticles (SPIONs) are investigated as a specific contrast agent for tumor targeting and magnetic resonance imaging (MRI) in vitro and in vivo. The SPIONs-loaded polymeric micelles are produced by self-assembly of amphiphilic poly(HFMA-co-MOTAC)-g-PEGMA copolymers and oleic acid modified Fe3O4 nanoparticles and functionalized with FA-BSA by electrostatic interaction. The FA-BSA modified magnetic micelles have a hydrodynamic diameter of 196.1nm, saturation magnetization of 5.5emu/g, and transverse relaxivity of 167.0mM−1S−1. In vitro MR imaging, Prussian blue staining, and intracellular iron determination studies demonstrate that the folate-functionalized magnetic micelles have larger cellular uptake against the folate-receptor positive hepatoma cells Bel-7402 than the unmodified magnetic micelles. In vivo MR imaging conducted on nude mice bearing the Bel-7402 xenografts after bolus intravenous administration reveals excellent tumor targeting and MR imaging capabilities, especially at 24h post-injection. These findings suggest the potential of FA-BSA modified magnetic micelles as targeting MRI probe in tumor detection.

Application of dispersive liquid–liquid microextraction coupled with vortex-assisted hydrophobic magnetic nanoparticles based solid-phase extraction for determination of aflatoxin M1 in milk samples by sensitive micelle enhanced spectrofluorimetry

An efficient, simple and fast low-density solvent based dispersive liquid–liquid microextraction (LDS-DLLME) followed by vortex-assisted dispersive solid phase extraction (VA-D-SPE) has been developed as a new approach for extraction and preconcentration of aflatoxin M1 in milk samples prior to its micelle enhanced spectrofluorimetic determination. In this LDS-DLLME coupled VA-D-SPE method, milk samples were first treated with methanol/water (80:20, v/v) after removing the fat layer. This solvent was directly used as the dispersing solvent in DLLME along with using 1-heptanol (as a low-density solvent with respect to water) as the extracting solvent. In VA-D-SPE approach, hydrophobic oleic acid modified Fe3O4 nanoparticles were used to retrieve the analyte from the DLLME step. It is considerably that the target of VA-D-SPE was 1-heptanol rather than the aflatoxin M1 directly. The main parameters affecting the efficiency of LDS-DLLME and VA-D-SPE procedures and signal enhancement of aflatoxin M1 were investigated and optimized. Under the optimum conditions, the method was linear in the range from 0.02 to 200µgL−1 with the correlation coefficient (R2) of 0.9989 and detection limit of 13ngL−1. The intra-day precision was 2.9 and 4.3% and the inter-day precision was 2.1 and 3.3% for concentration of 2 and 50µgL−1 respectively. The developed method was applied for extraction and preconcentration of AFM1 in three commercially available milk samples and the results were compared with the official AOAC method.

Poly(ethylene glycol)-Modified PAMAM-Fe3O4-Doxorubicin Triads with the Potential for Improved Therapeutic Efficacy: Generation-Dependent Increased Drug Loading and Retention at Neutral pH and Increased Release at Acidic pH

Polyamidoamine (PAMAM) dendrimer-coated magnetic nanoparticles are a promising drug-delivery system that can enhance the therapeutic effects of chemotherapy drugs, such as doxorubicin (DOX), with minimized side effects. This work explores the optimization of the potential therapeutic efficiency of PAMAM-Fe3O4-DOX triads. Different generations (G3, G5, and G6) of PAMAMs were synthesized and modified with poly(ethylene glycol) (PEG) and then used to encapsulate glutamic acid-modified Fe3O4 nanoparticles. The Fe3O4-dendrimer carriers (Fe3O4-DGx where x = the generation 3, 5, or 6 of dendrimers) were electrostatically conjugated with drug DOX. The loading and releasing efficiencies of DOX increased with the PAMAM generation from 3 to 6. The loading efficiencies of DOX molecules were 87, 93, and 96% for generations 3, 5, and 6, respectively. At pH 5, the DOX release efficiencies within 24 h were approximately 60, 68, and 80% for generations 3, 5, and 6, respectively. At pH 7.4, the DOX releasing efficiency was as low as ∼ 15%. Compared to the negative control, the PAMAM-Fe3O4-DOX triads showed only mild toxicity against human cervical adenocarcinoma cell line HeLa at pH 7.4, which indicated that DOX can be fairly benignly carried and sparingly released until PAMAM-Fe3O4-DOX is taken up into the cell.

Self-assembled magnetic luminescent hybrid micelles containing rare earth Eu for dual-modality MR and optical imaging

In this study, we report new water-soluble multifunctional nanomaterials based on amphiphilic poly(HFMA-co-Eu(AA)3Phen)-g-PEG copolymers and oleic acid modified Fe3O4 nanoparticles. The nanoparticles can self-assemble to form magnetic and luminescent hybrid micelles and show a spherical morphology, paramagnetic properties with a maximum saturation magnetization of 7.05 emu g-1, and a high transverse relaxivity of 340 mM-1 s-1. According to in vivo magnetic resonance imaging (MRI) experiments, excellent contrast of the liver and spleen was achieved after injection of the hybrid micelles. Fluorescence spectra show characteristic emission peaks from the rare earth Eu at 616 nm and vivid red fluorescence can be observed by 2-photon confocal laser scanning microscopy (CLSM). In vivo optical imaging demonstrates the unique fluorescent characteristics of the magnetic and luminescent hybrid micelles in the liver and spleen and the excellent multifunctional properties suggest the possibility of clinical use as nanocarriers in magnetic resonance imaging and optical imaging.

Efficient bacterial capture with amino acid modified magnetic nanoparticles

Traditional chemical disinfectants are becoming increasingly defective due to the generation of carcinogenic disinfection byproducts and the emergence of antibiotic-resistant bacterial strains. Functionalized magnetic nanoparticles yet have shown great application potentials in water treatment processes especially for bacterial removal. In this study, three types of amino acids (arginine, lysine, and poly-l-lysine) functionalized Fe3O4 nanoparticles (Fe3O4@Arg, Fe3O4@Lys, and Fe3O4@PLL) were prepared through a facile and inexpensive two-step process. The amino acid modified Fe3O4 nanoparticles (Fe3O4@AA) showed rapid and efficient capture and removal properties for both Gram-positive Bacillus subtilis (B. subtilis) and Gram-negative Escherichia coli 15597 (E. coli). For both strains, more than 97% of bacteria (initial concentration of 1.5 × 107 CFU mL−1) could be captured by all three types of magnetic nanoparticles within 20 min. With E. coli as a model strain, Fe3O4@AA could remove more than 94% of cells from solutions over a broad pH range (from 4 to 10). Solution ionic strength did not affect cell capture efficiency. The co-presence of sulfate and nitrate in solutions did not affect the capture efficiency, whereas, the presence of phosphate and silicate slightly decreased the removal rate. However, around 90% and 80% of cells could be captured by Fe3O4@AA even at 10 mM of silicate and phosphate, respectively. Bacterial capture efficiencies were over 90% and 82% even in the present of 10 mg L−1 of humic acid and alginate, respectively. Moreover, Fe3O4@AA nanoparticles exhibited good reusability, and greater than 90% of E. coli cells could be captured even in the fifth regeneration cycle. The results showed Fe3O4@AA fabricated in this study have great application potential for bacteria removal from water.