Silica-coated Magnetic Nanoparticles Research Articles

Synthesis and characterization of supramolecule grafted on modified magnetic nanoparticles: new hybrid organic–inorganic phase transfer catalyst

In this study, for the first time, calix[4]resorcinarene was grafted on the silica-coated magnetic nanoparticles (MNPs-Si) which efficiently catalyze one-pot epoxide ring opening reaction in excellent yields in a very short reaction time. Various advantages associated with this protocol include simple workup procedure, short reaction times, and high product yields. High catalytic activity and ease of recovery, using an external magnetic field, are additional eco-friendly attributes of this catalytic system.

Synthesis of thermosensitive magnetic nanocarrier for controlled sorafenib delivery

Allyl glycidyl ether/N-isopropylacrylamide-grafted magnetic nanoparticles were prepared using silica-coated magnetic nanoparticles as a substrate for radical copolymerization of allyl glycidyl ether and N-isopropylacrylamide. Chitosan was coupled with the prepared nanoparticles by opening the epoxy ring of the allyl glycidyl ether. The thermosensitive magnetic nanocarrier (TSMNC) obtained can be applied as a potent drug carrier. The TSMNC structure was characterized using Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, differential scanning calorimetry, vibrating sample magnetometer, and elemental analysis. Its morphology and size were investigated using field emission scanning electron microscopy, transmission electron microscopy and dynamic light scattering. The feasibility of employing the TSMNC for adsorption and in vitro controlled release of the chemotherapeutic agent sorafenib was tested. The effect of the adsorption parameters of pH, temperature, and loading time of sorafenib onto TSMNC was evaluated. The adsorption data was fitted to the Langmuir and Freundlich isotherms and the relevant parameters derived. The drug release profile indicated that 88% of the adsorbed drug was released within 35h at 45°C and drug release was Fickian diffusion-controlled. The results confirmed that the TSMNC has a high adsorption capacity at low temperature and good controlled release in a slow rate at a high temperature and could be developed for further application as a drug nanocarrier.

Synthesis of amino-rich silica-coated magnetic nanoparticles for the efficient capture of DNA for PCR

Magnetic separation has great advantages over traditional bio-separation methods and has become popular in the development of methods for the detection of bacterial pathogens, viruses, and transgenic crops. Functionalization of magnetic nanoparticles is a key factor for efficient capture of the target analytes. In this paper, we report the synthesis of amino-rich silica-coated magnetic nanoparticles using a one-pot method. This type of magnetic nanoparticle has a rough surface and a higher density of amino groups than the nanoparticles prepared by a post-modification method. Furthermore, the results of hydrochloric acid treatment indicated that the magnetic nanoparticles were stably coated. The developed amino-rich silica-coated magnetic nanoparticles were used to directly adsorb DNA. After magnetic separation and blocking, the magnetic nanoparticles and DNA complexes were used directly for the polymerase chain reaction (PCR), without onerous and time-consuming purification and elution steps. The results of real-time quantitative PCR showed that the nanoparticles with higher amino group density resulted in improved DNA capture efficiency. The results suggest that amino-rich silica-coated magnetic nanoparticles are of great potential for efficient bio-separation of DNA prior to detection by PCR.

Immobilization of Cellulase on Magnetic Nanocarriers.

The constant increase in the number of sustainable products on the global markets demands new biotechnological processing strategies such as the purification and recovery of biocatalysts. Superparamagnetic iron oxide nanoparticles exhibit excellent recovery properties as carrier materials in enzyme catalysis. We present the simple and fast electrostatic assembly of cellulase (CEL) and low‐priced silica‐coated magnetic nanoparticles, which demonstrates stable enzyme bonding and excellent colloidal stability. The high CEL loading (0.43 g g−1), without leaching of biocatalyst and high recovery yields (75 %), could be sustained over ten magnetic recycling steps. The highlight of this study is the preservation of a high enzymatic activity and, therefore, the outstandingly high lifecycle stability.

Functionalized porous silica&maghemite core-shell nanoparticles for applications in medicine: design, synthesis, and immunotoxicity.

AimTo determine cytotoxicity and effect of silica-coated magnetic nanoparticles (MNPs) on immune response, in particular lymphocyte proliferative activity, phagocytic activity, and leukocyte respiratory burst and in vitro production of interleukin-6 (IL-6) and 8 (IL-8), interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), and granulocyte macrophage colony stimulating factor (GM-CSF).MethodsMaghemite was prepared by coprecipitation of iron salts with ammonia, oxidation with NaOCl and modified by tetramethyl orthosilicate and aminosilanes. Particles were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier-transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). Cytotoxicity and lymphocyte proliferative activity were assessed using [3H]-thymidine incorporation into DNA of proliferating human peripheral blood cells. Phagocytic activity and leukocyte respiratory burst were measured by flow cytometry; cytokine levels in cell supernatants were determined by ELISA.Resultsγ-Fe2O3&SiO2-NH2 MNPs were 13 nm in size. According to TEM, they were localized in the cell cytoplasm and extracellular space. Neither cytotoxic effect nor significant differences in T-lymphocyte and T-dependent B-cell proliferative response were found at particle concentrations 0.12-75 μg/cm2 after 24, 48, and 72 h incubation. Significantly increased production of IL-6 and 8, and GM-CSF cytokines was observed in the cells treated with 3, 15, and 75 µg of particles/cm2 for 48 h and stimulated with pokeweed mitogen (PHA). No significant changes in TNF-α and IFN-γ production were observed. MNPs did not affect phagocytic activity of monocytes and granulocytes when added to cells for 24 and 48 h. Phagocytic respiratory burst was significantly enhanced in the cultures exposed to 75 µg MNPs/cm2 for 48 h.ConclusionsThe cytotoxicity and in vitro immunotoxicity were found to be minimal in the newly developed porous core-shell γ-Fe2O3&SiO2-NH2 magnetic nanoparticles.

Synthesis of pyridinecarboxaldimine grafted to magnetic nanoparticles (Fe3O4@SiO2) and its application in the aerobic oxidation of primary alcohols catalyzed by CuBr2/TEMPO

A pyridinecarboxaldimine grafted to silica-coated magnetic nanoparticles was prepared. The structure and magnetic properties of the functionalized magnetic silica nanoparticles were identified by TEM, FT-IR, XRD, elemental analysis, and vibrating sample magnetometer (VSM). The supported pyridinecarboxaldimine as chelating ligand in combination with CuBr2 and 2,2,6,6-tetramethyl-1-piperadoxyl (TEMPO) exhibited efficient catalytic performance in the aerobic oxidation of primary alcohols to aldehydes. The functionalized magnetic silica nanoparticles could be easily recovered using an external magnetic field and reused for at least 6 times with low reduction in its performance in the aerobic oxidation of benzyl alcohol.

Ultra-high performance liquid chromatography combined with mass spectrometry for determination of aflatoxins using dummy molecularly imprinted polymers deposited on silica-coated magnetic nanoparticles

This article describes a method for determination of four aflatoxins by a combination of ultra-high performance liquid chromatography and mass spectrometry (UHPLC-MS/MS). Magnetic dummy molecularly imprinted polymers (md-MIPs) are used for fairly selective preconcentration. The preparation of the md-MIP involves (a) coating of magnetic nanoparticles (with a typical diameter of 200 nm) with a shell of silica, (b) modifying the surface with methacryloxy groups, and (c) creating a MIP on the surface by graft imprinting in aqueous solutions using 5,7-dimethoxycoumarin as the dummy template, and methacrylic acid and 4-vinylpyridine as the functional monomers. After elution of the template, the md-MIPs can be used for fairly selective extraction of the aflatoxins B1, B2, G1 and G2. Following magnetic separation of the particles, the aflatoxins were eluted and quantified by UHPLC-MS/MS. The limit of detection is 0.05 μg·kg−1 for aflatoxins B2 and G2, and 0.1 μg·kg−1 for aflatoxins B1 and G1. False-positive samples were identified by UHPLC-MS/MS in the positive ionization mode with multiple reaction monitoring.

Development of magnetic graphene oxide adsorbent for the removal and preconcentration of As(III) and As(V) species from environmental water samples.

New-generation adsorbent, Fe3O4@SiO2/GO, was developed by modification of graphene oxide (GO) with silica-coated (SiO2) magnetic nanoparticles (Fe3O4). The synthesized adsorbent was characterized using Fourier transform infrared spectroscopy, X-ray diffractometry, energy-dispersive X-ray spectroscopy, and field emission scanning electron microscopy. The developed adsorbent was used for the removal and simultaneous preconcentration of As(III) and As(V) from environmental waters prior to ICP-MS analysis. Fe3O4@SiO2/GO provided high adsorption capacities, i.e., 7.51 and 11.46mgg(-1) for As(III) and As(V), respectively, at pH 4.0. Adsorption isotherm, kinetic, and thermodynamic were investigated for As(III) and As(V) adsorption. Preconcentration of As(III) and As(V) were studied using magnetic solid-phase extraction (MSPE) method at pH 9.0 as the adsorbent showed selective adsorption for As(III) only in pH range 7-10. MSPE using Fe3O4@SiO2/GO was developed with good linearities (0.05-2.0ngmL(-1)) and high coefficient of determination (R (2) = 0.9992 and 0.9985) for As(III) and As(V), respectively. The limits of detection (LODs) (3× SD/m, n = 3) obtained were 7.9pgmL(-1) for As(III) and 28.0pgmL(-1) for As(V). The LOD obtained is 357-1265× lower than the WHO maximum permissible limit of 10.0ngmL(-1). The developed MSPE method showed good relative recoveries (72.55-109.71%) and good RSDs (0.1-4.3%, n = 3) for spring water, lake, river, and tap water samples. The new-generation adsorbent can be used for the removal and simultaneous preconcentration of As(III) and As(V) from water samples successfully. The adsorbent removal for As(III) is better than As(V).

The synthesis of silica-coated magnetic nanoparticles and using as adsorbent

In this work, the silica-coated magnetic field-sensitive iron nanoparticles (Si-γFe2O3) were successfully prepared by sol–gel method and used as the adsorbent in the adsorption of methylene blue. The adsorption capacity was evaluated. Batch adsorption experiments were performed as a function of contact time, initial dye concentration (5–20 mg/L), solution pH (4.0–9.6) and temperature (298–328 K). The structure and the morphology of this material were characterized by the Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The adsorption kinetic studies were achieved using pseudo-first order, and pseudo-second order kinetic models. The adsorption kinetic of methylene blue on Si-γFe2O3 is consistent with the pseudo-second order kinetic model. Thermodynamic parameters such as Gibbs free energy (ΔG°), enthalpy (ΔH°) and entropy (ΔS°) changes were evaluated and the results indicated that adsorption process was endothermic and spontaneous. The equilibrium isotherms for the adsorption of methylene blue on the adsorbent were described by the Freundlich and Langmuir isotherm models.

Synthesis of mesoporous silica-coated magnetic nanoparticles modified with 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole and its application as Cu(II) adsorbent from aqueous samples

This study presents an alternative, rapid, and environment-friendly synthesis procedure of a magnetic core–shell mesoporous SBA-15 silica composite, its functionalization with 4-amino-3-hydrazino-5-mercapto-1,2,4-triazole (Purpald), and its application in dispersive solid-phase microextraction (DSPME) for Cu(II) from water. The materials were characterized through magnetization measurements, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infrared (FTIR), nuclear magnetic resonance (NMR) of 29Si and 13C, elemental analysis, and surface area measurements. FTIR and NMR analyses indicated the presence of the ligand on the functionalized material and that it was coupled through a CS bond. TEM images clearly show that the magnetite core particles were effectively coated with a silica shell. The material presented a surface area of 287.99m2g−1 and an average pore diameter of approximately 15.1nm. The material had its point of zero charge (PZC) determined (6.17) and its adsorption capacity was evaluated as a function of time, pH, and metal concentration. Dynamic adsorption equilibrium was reached in 120min, and it had a good correlation with the pseudo-second-order kinetic model (r2=0.9997). The maximum experimental adsorption capacity (0.0786mmolg−1) and the value calculated by the linearized Langmuir model (0.0799mmolg−1) are very approximate, indicating the formation of a monolayer over the material. Furthermore, the material proved to be very stable, because their adsorption capacity remained greater than 95% even after 10 cycles of adsorption/desorption. A high enrichment factor of 98.1-fold was observed, indicating that this material is suitable for the preconcentration of trace Cu(II) ions before analysis through flame atomic absorption spectrometry (FAAS).

Electrostatically Immobilized Hemoglobin on Silica-Coated Magnetic Nanoparticles for Simultaneous Determination of Dopamine, Uric Acid, and Folic Acid

This work describes the development of a novel biosensor for simultaneous determination of dopamine, uric acid, and folic acid by carbon paste electrode modified by hemoglobin which is electrostatically immobilized on silica-coated magnetic nanoparticles and multi-walled carbon nanotubes. Peroxidase properties of hemoglobin nominate this protein as an abundant and inexpensive alternative for costly peroxidase enzymes in dopamine biosensor fabrication. Silica-coated nanoparticles of Fe3O4 as a suitable support for hemoglobin immobilization can enhance the loading and stability of hemoglobin. Magnetic nanoparticles were synthesized via a simple co-precipitation method and then were coated with silica to immobilize hemoglobin electrostatically on them. All synthesis and modification steps were characterized by different techniques and then the conditions of hemoglobin immobilization on magnetic nanoparticles were optimized. Multi-walled carbon nanotubes were used as an additional modifier of carbon paste electrode because of their high electroactive surface area and interesting electrocatalytic properties. The modified carbon paste electrode provided a sensitive and stable biosensor for simultaneous determination of dopamine, uric acid, and folic acid whose performance is much better than those of many previously reported sensors. The detection limits were calculated to be about 12 nM, 14 nM and 18 nM and the linear range for determination of DA, UA and FA are 1–30.6 μM, 1–286 μM and 1–369 μM, for dopamine, uric acid, and folic acid, respectively. Finally, the applicability of the proposed biosensor was verified by dopamine evaluation in serum samples.

High efficient chromogenic catalysis of tetramethylbenzidine with horseradish peroxidase immobilized magnetic nanoparticles

The improving method of enzyme activity can be a great way to enhance the economics of biocatalytic processes. This work reported the highly efficient bio-nanocatalyst (HRP@Si-MNPs) with horseradish peroxidase (HRP) immobilization on the silica-coated magnetic nanoparticles (Si-MNPs). These bio-nanocatalysts were prepared by the reversible immobilization of silica-coated magnetic nanoparticles and HRP protein via electrostatic interactions. The binding capacity of HRP onto Si-MNPs could reach 5±1.5μg per 1mg of Si-MNPs. Subsequently, the chromogenic decomposition of tetramethylbenzidine (TMB) was evaluated by HRP@Si-MNPs and free HRP. As a result, HRP@Si-MNPs appeared darker-blue color than that of free HRP at same substrate concentration. In addition, the apparent kinetic constant value (Vmax) of immobilized HRP was 260μmolmin−1mgprotein−1, which was 88-folds higher than the free HRP. Therefore this approach opens new opportunities to lower manufacturing costs in large-scale industries of environment and biotechnology.

Ionic liquid-modified silica-coated magnetic nanoparticles: promising adsorbents for ultra-fast extraction of paraquat from aqueous solution.

In the present study, ionic liquid-modified silica-coated magnetic nanoparticles (Fe3O4@SiO2@IL) were synthesized and applied as adsorbents for extraction and determination of paraquat (PQ) followed by high-performance liquid chromatography. For assurance of the extraction efficiency, the obtained results were compared with those obtained by bared magnetic nanoparticles (MNPs). Experimental design and response surface methodology were used for optimization of different parameters which affect extraction efficiency of paraquat using both adsorbents. Under the optimized conditions, extraction recoveries in the range of 20-25 and 35-40 % with satisfactory repeatability values (RSDs%, n = 4) less than 5.0 % were obtained for bared MNPs and Fe3O4@SiO2@IL, respectively. The limits of detection were 0.1 and 0.25 μg/L using Fe3O4@SiO2@IL and bared MNPs, respectively. The linearity was obtained in the range of 0.25 to 25 μg/L and 0.5 to 25 μg/L for Fe3O4@SiO2@IL and bared MNPs, respectively, with the coefficients of determination better than 0.9950. Finally, Fe3O4@SiO2@IL was chosen as superior adsorbent due to more dispersion ability, higher extraction recovery, lower detection limit, as well as better linearity and repeatability. Calculated errors (%) were in the range of 3 to 10 % depicting acceptable accuracy for the analysis of PQ by the proposed method. Finally, the method was successfully applied for extraction and determination of PQ in some water and countryside soil samples.

Heating ability and biocompatibility study of silica-coated magnetic nanoparticles as heating mediators for magnetic hyperthermia and magnetically triggered drug delivery systems

The aim of this study is to prepare core–shell La0.73Sr0.27MnO3–silica nanoparticles and evaluating their heat generation ability under the safe alternating magnetic field (f = 100 kHz and H = 10–20 kA m−1) for potential applications in magnetic fluid hyperthermia and magnetically triggered drug delivery systems. The magnetic cores of La0.73Sr0.27MnO3 with an average particle size of 54 nm were synthesized by the citrate–gel method. Then, the Stober method was applied to encapsulate nanoparticles with 5-nm-thick silica shell. The core–shell structure of nanoparticles was confirmed by X-ray diffraction, fourier transform infrared spectroscopy and transmission electron microscopy analyses. Cytotoxicity of bare and silica-coated nanoparticles was evaluated by methyl thiazol tetrazolium bromide assay with MCF-7 cell line. The results revealed that the both samples have negligible toxicity below 500 μg ml−1 and silica coating can improve the biocompatibility of nanoparticle. In addition, calorimetric measurements were used to determine the heating efficiency of the core–shell nanostructures in aqueous medium. The results showed that the heat generated of the prepared sample could be safely controlled in the range of 40–60∘C which is suitable for biomedical applications.

Simultaneous extraction of DNA and RNA from Escherichia coli BL 21 based on silica-coated magnetic nanoparticles

The extraction of nucleic acid is recognized as one of the most essential steps in molecular biology for initiating other downstream applications such as sequencing, amplification, hybridization, and cloning. Many commercial kits and methods are currently available that allow the extraction of only one type of nucleic acids-DNA or RNA. However, in parallel clinical detection of several diseases, a method for simultaneous extraction of both DNA and RNA from the same source is needed in such cases. In this study, a method for simultaneous extraction of DNA and RNA from bacteria based on magnetic nanoparticles (MNPs) was described. Lysis buffers were prepared to help the nucleic acid released and adsorbed to MNPs. Then, two washing buffers were used to remove the contamination of proteins and carbohydrates. The nucleic acids were finally eluted by Deoxyribonuclease (DNase) and Ribonucleases (RNase) free water. Different factors which might affect the purification of the nucleic acid were investigated, and the quantity and quality parameters of the nucleic acid were also recorded. The DNA and RNA extracted from bacteria were then respectively subjected to polymerase chain reaction (PCR) and reverse transcription PCR (RT-PCR) to further confirm its quality. The results indicated that our method can be successfully used to simultaneously extract DNA and RNA from bacteria.

Delivery of tissue plasminogen activator and streptokinase magnetic nanoparticles to target vascular diseases

Thrombolytic therapy for acute myocardial infarction standardly makes use of the medications streptokinase (SK) and tissue plasminogen activator (tPA). In this study, the potential of silica-coated magnetic nanoparticles (SiO2-MNPs) as nanocarriers clinical thrombolytic therapy was investigated. SiO2-MNPs for use in targeted therapeutic delivery of tPA and SK were prepared using a combined technique incorporating controlled precipitation and hydrothermal methods. Response surface methodology (RSM) was employed to evaluate the efficiency of the SiO2-MNPs. The production of SK secreted from Streptococcus equi was enhanced using random mutagenesis. The tPA and SK A were encapsulated by means of a silanizing agent with a surface rich in 3-aminopropyltrimethoxysilane layered around the SiO2-MNPs. Blood clot lysis assays and fibrin-containing agarose plates were used to carry out in vitro thrombolysis testing. The optimum conditions for producing MNPs were found to be at pH=13 and at a temperature of 75°C for 45min. Culture conditions of 2.75% NaCl concentration at initial pH=7.5 for 90s under UV resulted in maximum SK activity. The tPA/SK-conjugated SiO2-MNPs (SiO2-MNP-tPA-SK) increased operating stability in whole blood and storage stability in a buffer by 92%. More effective thrombolysis using magnetic targeting was indicated by a 38% reduction in blood clot lysis time achieved with SiO2-MNP-tPA-SK compared to administering the SiO2-MNPs without guidance. The silica-coated magnetic nanocarriers developed in this study show potential for improved clinical thrombolytic therapy.

Protein surface labeling reactivity of N-hydroxysuccinimide esters conjugated to Fe3O4@SiO2 magnetic nanoparticles

The N-hydroxysuccinimide (NHS) ester moiety is one of the most widely used amine reactive groups for covalent conjugation of proteins/peptides to other functional targets. In this study, a cleave-analyze approach was developed to quantify NHS ester groups conjugated to silica-coated iron oxide magnetic nanoparticles (Fe3O4@SiO2 MNPs). The fluorophore dansylcadaverine was attached to Fe3O4@SiO2 magnetic nanoparticles (MNPs) via reaction with NHS ester groups, and then released from the MNPs by cleavage of the disulfide bond in the linker between the fluorophore and the MNPs moiety. The fluorophore released from Fe3O4@SiO2 MNPs was fluorometrically measured, and the amount of fluorophore should be equivalent to the quantity of the NHS ester groups on the surface of Fe3O4@SiO2 MNPs that participated in the fluorophore conjugation reaction. Another sensitive and semiquantitative fluorescence microscopic test was also developed to confirm the presence of NHS ester groups on the surface of Fe3O4@SiO2 MNPs. Surface-conjugated NHS ester group measurements were primarily performed on Fe3O4@SiO2 MNPs of 100–150 nm in diameter and also on 20-nm nanoparticles of the same type but prepared by a different method. The efficiency of labeling native proteins by NHS ester-coated Fe3O4@SiO2 MNPs was explored in terms of maximizing the number of MNPs conjugated per BSA molecule or maximizing the number of BSA molecules conjugated per each nanoparticle. Maintaining the amount of fresh NHS ester moieties in the labeling reaction system was essential especially when maximizing the number of MNPs conjugated per protein molecule. The methodology demonstrated in this study can serve as a guide in labeling the exposed portions of proteins by bulky multivalent labeling reagents.

Silica-coated magnetic NiFe2O4 nanoparticles-supported H3PW12O40; synthesis, preparation, and application as an efficient, magnetic, green catalyst for one-pot synthesis of tetrahydrobenzo[b]pyran and pyrano[2,3-c]pyrazole derivatives

A powerful, magnetic, supported, acid catalyst, NiFe2O4@SiO2–H3PW12O40, was prepared by chemical support of Keggin (H3PW12O40) heteropolyacid (HPA) on silica-coated NiFe2O4 magnetic nanoparticles. XRD, TEM, SEM, VSM, and FTIR confirmed that the keggin HPA is well dispersed on the surface of silica-coated NiFe2O4 magnetic nanoparticles. The magnetically recoverable catalyst could be easily recycled at least six times without significant loss of catalytic activity. After full characterization, its catalytic activity was investigated in the synthesis of tetrahydrobenzo[b]pyran and pyrano[2,3-c]pyrazole derivatives. (1) Novel silica-coated magnetic NiFe2O4 nanoparticles-supported H3PW12O40 was fabricated and characterized. (2) Recyclability of the catalyst. (3) Avoiding use of corrosive acid catalysts. (4) Green chemistry.

Fabrication and characterization of polyethyleneimine immobilized on chloropropyl- and silica-coated magnetic nanoparticles for Pb2+ removal from aqueous solution

A new surface polymeric functionalized magnetic adsorbent was synthesized through the grafting polyethyleneimine onto chloropropyl- and silica-coated magnetic nanoparticles and characterized by transmission electron microscopy, X-ray diffraction, IR, elemental analysis, and thermo gravimetric analysis. The relationship between grafting reaction conditions, such as solvent, reaction time, reaction temperature, and the polyethyleneimine amount added, and grafting percentage was investigated systematically. Under the optimized conditions, the magnetic adsorbent was fabricated and used for the removal of Pb2+ from the solutions for the first time. Batch experiments were carried out to examine the influence of different sorption parameters, for example, solution pH, initial concentration of Pb2+, contact time, and adsorbent dosage. The equilibrium sorption data fitted Langmuir adsorption isotherm well and the adsorbent–adsorbate kinetics followed pseudo-second-order model with a maximum adsorption capacity of 131 mg g−1, which revealed that the prepared polymeric magnetic adsorbent was attractive and effective material with high uptake capacity.

Preparation of Fe3O4 encapsulated-silica sulfonic acid nanoparticles and study of their in vitro antimicrobial activity

A simple and efficient method for the functionalization of silica-coated Fe3O4 magnetic nanoparticles (Fe3O4@SiO2) using chlorosulfonic acid is described. The prepared compounds were screened for antibacterial activity against Escherichia coli (E. coli ATCC 25922) and Staphylococcus aureus (S. aureus ATCC 25923) under UV-light and dark conditions. It was found that the Fe3O4@SiO2–SO3H was significantly indicated the higher photocatalytic inactivation than both Fe3O4 and Fe3O4@SiO2 against E. coli in compared with S. aureus. Furthermore, the inactivation efficiency against both organisms under light conditions has been higher than this efficiency under dark conditions.