Magnetic Silica Nanoparticles Research Articles

Immobilized peptide-N-glycosidase F onto magnetic nanoparticles: A biotechnological tool for protein deglycosylation under native conditions.

The elucidation of glycans biological function is essential to understand their role in biological processes, both normal and pathological. Immobilized glycoenzymes are excellent tools for this purpose as they can selectively release glycans from glycoproteins without altering their backbone. They can be easily removed from the reaction mixture avoiding their interference in subsequent experiments. Here, we describe the immobilization of peptide-N-glycosidase F (PNGase F) onto silica magnetic nanoparticles with immobilization yields of 86% and activity yields of 12%. Immobilized PNGase F showed higher thermal stability than its soluble counterpart, and could be reused for at least seven deglycosylation cycles. It was efficient in the deglycosylation of several glycoproteins (ribonuclease B, bovine fetuin, and ovalbumin) and a protein lysate from the parasite Fasciola hepatica under native conditions, with similar performance to that of the soluble enzyme. Successful deglycosylation was evidenced by a decrease in specific lectin recognition of the glycoproteins (40%-80%). Moreover, deglycosylated F. hepatica lysate allowed us to confirm the role of parasite N-glycans in the inhibition of the lipopolysaccharide-induced maturation of dendritic cells. Immobilized PNGase F probed to be a robust biotechnological tool for deglycosylation of glycoproteins and complex biological samples under native conditions.

Amine and aldehyde functionalized mesoporous silica on magnetic nanoparticles for enhanced lipase immobilization, biodiesel production, and facile separation

In this research, synthesis of fatty acid methyl ester (FAME) from olive oil as model feedstock was carried out in the presence of Rhizopus oryzae lipase (ROL) that was immobilized on the mesoporous silica magnetic nanoparticles (MNPs). MNPs were coated with mesoporous silica (MS) functionalized by amine and aldehyde groups used for immobilization of a lipase, used for biodiesel production, and easy magnetic separation of the immobilized lipase from the biodiesel product. MNPs were synthesized by using the co-precipitation method and coated with MS by sol-gel synthesis using cetyltrimethylammonium bromide (CTAB) as a template for mesoporous formation. ROL was immobilized on these supports via physical adsorption and covalent attachment. Enzyme loading efficiency on mesoporous was doubled compared to that on bare MNPs. Also, the covalent bonding led to an increase in enzyme loading from 67.8 to 82.4%. The physico-chemical properties of MNPs were determined by XRD, EDX, VSM, FESEM, BET, and FTIR and were correlated with their activities for biodiesel synthesis. The evaluations of hydrolytic activity and kinetic parameters revealed that MNPs@MS-AP-GA is a suitable nanomaterial for ROL immobilization. Transesterification of olive oil using ROL-MNPs@MS-AP-GA showed the highest biodiesel production of 84.6% among other nanobiocatalysts.

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.

Highly efficient and green catalyst of {Mo132} nanoballs supported on ionic liquid-functionalized magnetic silica nanoparticles for oxidative desulfurization of dibenzothiophene

A novel core–shell nanostructured catalyst was synthesized by supporting Keplerate nanoball iso-polyoxomolybdate {Mo132} on ionic liquid-functionalized magnetic silica nanoparticles (MSN/IL-{Mo132}), and characterized by several techniques including FT-IR, XRD, TEM, VSM, and EDX analysis. The performance of the catalyst was investigated in deep oxidative desulfurization of a model fuel (MF) containing dibenzothiophene (DBT). The effects of three operational parameters including reaction temperature, O/S molar ratio, and catalyst dosage were evaluated by optimal design of experiments based on response surface methodology (RSM). Moreover, the optimum conditions were obtained at temperature of 62.5 °C, catalyst dosage of 0.0065 g cat/g MF, and O/S molar ratio of 20.5, to achieve a high sulfur removal of 99.97% within 30 min of reaction time. Kinetic study of the process was also performed to better understand the catalytic oxidative desulfurization of DBT. The catalyst was simply separated from the reaction medium by using an external magnetic field and reused four times in the process without significant decrease in its activity. By using GC-MS analysis, DBT sulfone was detected to be the only product in oxidation of DBT over the catalyst. This research describes a new, efficient and magnetically recoverable catalyst which is highly effective in oxidative removal of refractory sulfur-containing compounds such as DBT from fossil fuels.

Magnetic phosphorylated chitosan composite as a novel adsorbent for highly effective and selective capture of lead from aqueous solution

Separating and recovering lead from heavy metal contaminated wastewater is crucial for the environment remediation and reutilization of lead resources. Herein, a novel adsorbent, the phosphorylated chitosan-coated magnetic silica nanoparticles (Fe3O4@SiO2@CS-P), was successfully fabricated and applied to highly selective adsorption of lead. Competitive experiments were conducted in a multi-ion solution (7 metal ions coexist) at pH 6.0, Fe3O4@SiO2@CS-P exhibited an excellent selectively for capturing lead with the distribution coefficient (0.75 L g−1) more ten times than other metal, while Fe3O4@SiO2@CS demonstrated a highly selective adsorption of silver. These implied that phosphorylation of adsorbent not only improves the sorption performance of lead, but also changes the selective adsorption of metal types. Acidity experiments can draw conclusions that Fe3O4@SiO2@CS-P exhibited better acid resistance (with barely any iron leaching) than silica-uncoated adsorbent (Fe3O4@CS-P) at pH 1.0. Furthermore, the FTIR and XPS spectra after adsorption suggested that the high adsorption performance and selective capture lead were predominantly controlled by the coordination of the phosphate groups on the surface of the adsorbent. This work shows a broad prospect of developing a series of novel, acid-resistant, good reusable and rapidly separable magnetic materials that can be used to efficiently and selectively capture lead from aqueous solutions.

Implant-based direction of magnetic nanoporous silica nanoparticles – influence of macrophage depletion and infection

Implant associated infections are still key problem in surgery. In the present study, the combination of a magnetic implant with administered magnetic nanoporous silica nanoparticles as potential drug carriers was examined in mice in dependence of local infection and macrophages as influencing factors. Four groups of mice (with and without implant infection and with and without macrophage depletion) received a magnet on the left and a titanium control on the right hind leg. Then, fluorescent nanoparticles were administered and particle accumulations at implant surfaces and in inner organs as well as local tissue reactions were analyzed. Magnetic nanoparticles could be found at the surfaces of magnetic implants in different amounts depending on the treatment groups and only rarely at titanium surfaces. Different interactions of magnetic implants, particles, infection and surrounding tissues occurred. The general principle of targeted accumulation of magnetic nanoparticles could be proven.

Co-immobilization of two-component hydroxylase monooxygenase by functionalized magnetic nanoparticles for preserving high catalytic activity and enhancing enzyme stabilty

Cascade reactions catalyzed by two or more enzymes have been widely used in industrial production and exhibited many advantages over the single-enzyme catalytic system. In this study, two components of hydroxylase monooxygenase (HpaBC) were first co-immobilized by Ni2+-nitrilotriacetic acid (Ni-NTA) functionalized magnetic silica nanoparticles (Ni-NTA/H2N-SiO2@Fe3O4) for enhancing the stability and activity of biocatalysts with multi-components. These two components, HpaB and HpaC, were modified with histidine-tag and employed to construct a bi-enzyme catalytic system. After co-immobilization, the activity of the bi-enzyme system was 2.6 times of free enzymes. Meanwhile, the co-immobilized system was more stable against high temperature and alkaline condition, and maintained 76.6% of the initial activity for storage 12 days. Moreover, the co-immobilized HpaBC remained more than 60% catalytic activity after 7 cycles. These results showed that co-immobilized multi-component enzymes based on functionalized magnetic nanoparticles without purification would play a great potential role in the field of industrial biocatalysis.

Preparation of bovine serum albumin restricted access octadecyl/phenyl-mixed-functionalized magnetic silica nanoparticles for magnetic solid phase extraction of antidepressants in aquatic products followed by UHPLC-MS/MS

Pharmaceuticals are widespread in aquatic ecosystem, which may pose a potential threat to fish and human. In the study, a robust and reliable magnetic solid-phase extraction (MSPE) based on bovine serum albumin (BSA) restricted access octadecyl/phenyl-mixed-functionalized magnetic silica nanoparticles (BSA-C18/Ph-Fe3O4@SiO2 NPs) as sorbent was developed for the extraction of venlafaxine, paroxetine, fluoxetine, norfluoxetine, sertraline and diphenhydramine from the muscle extracts of aquatic products followed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) detection. The homemade sorbent showed appropriate compatibility in aqueous solution and good performance in reducing matrix interference of snakehead muscle tissue extracts with absolute matrix effect ranging in 95.4%–105.5%. The protocol was validated in analyte-free snakehead muscle with favorable recoveries ranging in 91.6%–103.6% and relative standard deviations (RSDs) less than 9.5%. Limits of detection (LODs) of the drugs were lower than 0.018 μg kg−1. Short-term drug-exposure experiments at low and high doses were conducted on snakeheads, and the measured contents of analytes were in the range 0.029–9.58 μg kg−1 with appropriate recoveries (90.0%–114.0%). The approach was extensively applied for the analysis of twelve species of market-sale aquatic products (total 37 samples), and up to 1.868 and 0.521 μg kg−1 of diphenhydramine and venlafaxine were measured, respectively. The approach shows remarkable potential in biological complex samples.

Composites of Crosslinked Aggregates of Eversa® Transform and Magnetic Nanoparticles. Performance in the Ethanolysis of Soybean Oil

Eversa® Transform 2.0 has been launched to be used in free form, but its immobilization may improve its performance. This work aimed to optimize the immobilization of Eversa® Transform 2.0 by the crosslinked enzyme aggregates (CLEAs) technique, using almost all the available tools to improve its performance. Several variables in the CLEA preparation were optimized to improve the recovered activity, such as precipitant nature and crosslinker concentration. Moreover, some feeders were co-precipitated to improve the crosslinking step, such as bovine serum albumin, soy protein, or polyethyleneimine. Starch (later enzymatically degraded) was utilized as a porogenic agent to decrease the substrate diffusion limitations. Silica magnetic nanoparticles were also utilized to simplify the CLEA handling, but it was found that a large percentage of the Eversa activity could be immobilized on these nanoparticles before aggregation. The best CLEA protocol gave a 98.9% immobilization yield and 30.1% recovered activity, exhibited a porous structure, and an excellent performance in the transesterification of soybean oil with ethanol: 89.8 wt% of fatty acid ethyl esters (FAEEs) yield after 12 h of reaction, while the free enzyme required a 48 h reaction to give the same yield. A caustic polishing step of the product yielded a biodiesel containing 98.9 wt% of FAEEs and a free fatty acids content lower than 0.25%, thus the final product met the international standards for biodiesel. The immobilized biocatalyst could be reused for at least five 12 h-batches maintaining 89.6% of the first-batch yield, showing the efficient catalyst recovery by applying an external magnetic field.

Aldehyde oxidase assay by capillary electrophoresis: From off-line, online up to immobilized enzyme reactor.

Capillary electrophoresis is a modern separation technique characterized by many benefits, which qualify it also for enzyme assays and the study of enzyme kinetics during drug development. Homogeneous or heterogeneous approaches can be followed for the enzymatic incubation. In this study, an immobilization procedure of aldehyde oxidase on magnetic particles was developed considering their integration with capillary electrophoresis. A number of magnetic nano/microparticle types were tested for this purpose, showing that aldehyde oxidase was most active when immobilized on bare silica magnetic nanoparticles. Primarily, the reusability of the enzyme immobilized on bare silica nanoparticles was tested. Three consecutive incubations with substrate could be performed, but the activity considerably dropped after the first incubation. One reason could be an enzyme detachment from the nanoparticles, but no release was detected neither at 4°C nor at 37°C during 5 h. The drop in enzymatic activity observed in consecutive incubations, could also be due to inactivation of the enzyme over time at given temperature. For the immobilized enzyme stored at 4°C, the activity decreased to 83% after 5 h, in contrast with a steep decrease at 37°C to 37%.

Polycyclic aromatic hydrocarbon functionalized organosilocanes based chemosensors: Synthesis, magnetic nanoparticles and biological application

This present work highlights the construction of new chemosensors based on polycyclic aromatic hydrocarbon (PAH) appended organosilocane which have been structurally characterized by various spectroscopic techniques such as IR, NMR, and mass spectrometry. The prepared chemosensors were found to be proficient for the detection of Sn2+ and Cr3+ ions with UV–Visible spectroscopy and Cu2+ ion with fluorescence technique. The limit of detection for Sn2+, Cr3+ and Cu2+ ions turns out to be 5.74 ppb, 5.14 ppb and 0.55 ppm, respectively, as calculated by Benesi-Hildebrand plot and Stern Volmer graph. Moreover, biological applications like total antioxidant activity and cytotoxic studies of the prepared organosilocanes have been evaluated. Total antioxidant activity was of IC50 0.06 ± 0.01 mM and 0.2 ± 0.01 mM, for compounds 3a and 3b, respectively. Interestingly, compound 3a has a noteworthy cytotoxic activity against SAF-1 cell line with EC50 of 4.07 ± 0.32 μM. Further immobilisation of compound 3a onto the surface of magnetic silica (Fe3O4@SiO2) nanoparticles enhanced the properties of chemosensitivity for Sn2+ ion and the limit of detection lowered to 0.1 ppb. The resultant nanoparticles have been characterized by physicochemical techniques such as FT-IR, XRD, EDX, FESEM and TGA.

Immobilization of Laccase on Magnetic Chelator Nanoparticles for Apple Juice Clarification in Magnetically Stabilized Fluidized Bed.

The juice clarification, one of the key steps in juice processing, suffers from haze formation that results from residual phenolic compounds. In this study, laccase was immobilized on metal-chelated magnetic silica nanoparticles and used for continuous juice clarification in a magnetically stabilized fluidized bed (MSFB) assisted by alternating magnetic field. Furthermore, a new combination of laccase catalysis and microfiltration was developed for the juice clarification. Immobilized laccase provided high relative activity within broader ranges of pH and temperature compared to the free enzyme. Magnetic immobilized laccase exhibited the best reaction rate of 12.1 μmol g–1 min–1 for catechol oxidation under the alternating magnetic field of 400 Hz, 60 Gs. No activity loss occurred in immobilized laccase after 20 h continuous operation of juice treatment in MSFB under an alternating magnetic field. Combined with microfiltration after treatment with immobilized laccase, the color of apple juice was decreased by 33.7%, and the light transmittance was enhanced by 20.2%. Furthermore, only 16.3% of phenolic compounds and 15.1% of antioxidant activity was reduced for apple juice after the clarification. By this combination strategy, the apple juice possessed good freeze–thaw and thermal stability.

Optimization using the response surface methodology for adsorption of polychlorinated biphenyls (PCBs) from transformer oil by magnetic CMCD-Fe3O4@SiO2 nanoparticles

The main objective of this work was to synthesis a novel magnetic nanoparticles functionalized with β-cyclodextrin and use it to refine transformer oil contaminated with high concentration of PCBs. Carboxymethyl-β-cyclodextrin modified Fe3O4@SiO2 magnetic nanoparticles (CMCD-Fe3O4@SiO2) were fabricated by grafting onto the core-shell silica magnetic nanoparticles surface using carbodiimide. The successful synthesis of nanocomposites was characterized by FTIR, XRD, VSM, SEM, TEM, VSM, TGA and EDX analysis. Hereinafter, the application of response surface methodology (RSM) based on the central composite design (CCD) was employed for optimization of the interactive effects of the three main variables on the removal efficiency of PCBs. A quadratic model was applied as a final model to measure the adequacy and the significance of the individual and interactive effects of variables via analysis of variance. The design matrix under the optimum conditions exhibited that the maximum PCBs removal of 82% was attained to be at adsorbent dosage, contact time and temperature of 10 mg/mL, 30 min, and 50 °C, respectively. The obtained results revealed that the adsorbent dosage is known as the key operating parameter (P < 0.0001) affecting PCB removal efficiency. Thermodynamic parameters (ΔH0 > 0, ΔG0 > 0, ΔS0 > 0) were confirmed that the adsorption process was nonspontaneous and endothermic and assess physical phenomena occurring on the surface of adsorbent. The experimental results were proposed that the as-synthesized β-cyclodextrin -modified magnetic nanoparticles could be an ideal candidate for purification of PCB compounds from contaminated transformer oil owing to its simple process and rapid separation and good reusability after five times.

Efficient pre-concentration of As(III) in food samples using guanidine-modified magnetic mesoporous silica

An efficient magnetic mesoporous structure was designed and prepared for the facile pre-concentration of As(III) ions. To prepare the sorbent, core–shell magnetic silica nanoparticles were covered by MCM-41 like structure and then the surface was modified by guanidine via an amine linker (GA-MSMP). The prepared adsorbent was investigated as an effective and sensitive material for the adsorption of arsenic ions from the aqueous solution by applying a normal batch method. The imperative variables of the adsorption were studied to increase efficiency. The dynamic and static processes were tested that matched a pseudo-second-order of kinetic model and the Langmuir isotherm model, respectively. The sorbent reusability was investigated and it was confirmed that the designed product could be applied at best for six cycles successively without any significant efficiency losing. The synthesized product was tested to determine and pre-concentrate trace amounts of arsenic ions in rice and natural waters as a real sample. A desorption process applying 5 mL of hydrochloric acid (0.5 mol L−1) as an eluent, exhibited about 98% recovery of the As(III) ions adsorbed on the GA-MSMP sorbent. The maximum adsorption capacity of the GA-MSMP was calculated to be 312 mg g−1 for adsorption of As(III) under the optimal conditions.

Magnetic solid-phase extraction based on fluconazole-functionalized Fe3O4@SiO2 nanoparticles for the spectrophotometric determination of cationic dyes in environmental water samples

In the present study, a novel method based on fluconazole-functionalized magnetic silica nanoparticles as the adsorbent is introduced for the extraction of malachite green and crystal violet. The synthesized nanoparticles were characterized using SEM, EDX, XRD, FT-IR, and BET methods. The adsorbent were added to the sample solution containing 100.0 ng mL−1 of each dye (pH 5.0); then, the mixture was agitated at room temperature for 20.0 min. The supernatant was poured, and then, the isolated nanoparticles were eluted with methanol to desorb the adsorbed dyes. Different parameters were investigated and optimized to achieve effective extraction and preconcentration of the target dyes. Limits of detection and limits of quantification for malachite green and crystal violet under optimum conditions changed in the range of 2.82–3.27 ng mL−1 and 9.42–10.91 ng mL−1, respectively. Preconcentration factor and relative standard deviation for five repetitions of each dye were computed to be 188 and 4.77–4.17%, respectively. Finally, the mentioned dyes were extracted and determined using the proposed method from environmental aqueous samples. The recoveries range for malachite green and crystal violet were in 88–96%.

Highly selective uranium adsorption on 2-phosphonobutane-1,2,4-tricarboxylic acid-decorated chitosan-coated magnetic silica nanoparticles

The separation and recovery of uranium resources from nuclear waste solutions is important for achieving uranium reuse and environmental protection. In this study, a novel adsorbent, 2-phosphonobutane-1,2,4-tricarboxylic acid (PBTCA)-decorated chitosan-coated magnetic silica nanoparticles, was fabricated and applied to the highly selective adsorption of uranium from aqueous solution. Selective sorption in a multi-ion solution (pH 4.0) containing 14 coexisting cations resulted in CoFe2O4@SiO2@CS-PBTCA showing an excellent uranium adsorption capacity of up to 83.16 mg g−1, which was much higher than that of ungrafted CoFe2O4@SiO2@CS (29.99 mg g−1). The adsorbent also exhibited higher acid resistance than uncoated silica adsorbent under pH 1.0 conditions, with CoFe2O4@SiO2@CS-PBTCA showing barely any iron and cobalt leaching, while CoFe2O4@CS-PBTCA showed iron and cobalt leaching amounts of 2.97 and 0.93 mg L−1, respectively. The desorption experiment used 0.2 M PBTCA (pH 1.0) as eluent, with the results showing that uranium ions were readily and rapidly desorbed. Furthermore, CoFe2O4@SiO2@CS-PBTCA maintained outstanding stability and adsorption performance after five reuse cycles. The mechanism for U(VI) removal was investigated by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy, with the results suggesting that the adsorbent binds to uranium mainly though oxygen atoms of carboxyl groups and phosphonic groups in PBTCA. This strategy shows strong potential for developing a variety of novel, highly active, acid resistance, and reusable immobilized functional magnetic materials for effective separation of uranium from a multi-ion solution.

Biodistribution, biocompatibility and targeted accumulation of magnetic nanoporous silica nanoparticles as drug carrier in orthopedics

BackgroundIn orthopedics, the treatment of implant-associated infections represents a high challenge. Especially, potent antibacterial effects at implant surfaces can only be achieved by the use of high doses of antibiotics, and still often fail. Drug-loaded magnetic nanoparticles are very promising for local selective therapy, enabling lower systemic antibiotic doses and reducing adverse side effects. The idea of the following study was the local accumulation of such nanoparticles by an externally applied magnetic field combined with a magnetizable implant. The examination of the biodistribution of the nanoparticles, their effective accumulation at the implant and possible adverse side effects were the focus. In a BALB/c mouse model (n = 50) ferritic steel 1.4521 and Ti90Al6V4 (control) implants were inserted subcutaneously at the hindlimbs. Afterwards, magnetic nanoporous silica nanoparticles (MNPSNPs), modified with rhodamine B isothiocyanate and polyethylene glycol-silane (PEG), were administered intravenously. Directly/1/7/21/42 day(s) after subsequent application of a magnetic field gradient produced by an electromagnet, the nanoparticle biodistribution was evaluated by smear samples, histology and multiphoton microscopy of organs. Additionally, a pathohistological examination was performed. Accumulation on and around implants was evaluated by droplet samples and histology.ResultsClinical and histological examinations showed no MNPSNP-associated changes in mice at all investigated time points. Although PEGylated, MNPSNPs were mainly trapped in lung, liver, and spleen. Over time, they showed two distributional patterns: early significant drops in blood, lung, and kidney and slow decreases in liver and spleen. The accumulation of MNPSNPs on the magnetizable implant and in its area was very low with no significant differences towards the control.ConclusionDespite massive nanoparticle capture by the mononuclear phagocyte system, no significant pathomorphological alterations were found in affected organs. This shows good biocompatibility of MNPSNPs after intravenous administration. The organ uptake led to insufficient availability of MNPSNPs in the implant region. For that reason, among others, the nanoparticles did not achieve targeted accumulation in the desired way, manifesting future research need. However, with different conditions and dimensions in humans and further modifications of the nanoparticles, this principle should enable reaching magnetizable implant surfaces at any time in any body region for a therapeutic reason.

Synthesis, characterization and cytotoxicity evaluation of magnetic nanosilica in L929 cell line

Recently, the incorporation of magnetic nanoparticles in nanomaterials has been showning to be very efficient, which leads to several scientific studies being carried out. Magnetic silica nanoparticles have excellent properties, enabling application in different fields including nanoscience. In this context, this work aimed to synthesize and characterize nanosilica with magnetic properties, in order to evaluate of the cytotoxicity in L929 cell line. The methodology for incorporation of magnetic nanoparticles proved to be fast and effective for obtaining the magnetic nanosilica (Nano SiO2.Fe3O4). Through the characterization of FTIR, and exposure of the magnetic field it was possible to verify the incorporation of ferrite in the nanosilica, as well as the XRD technique, the reduction of the particle size and the degree of crystallinity was evidenced. It was possible to verify that the synthesized nano SiO2.Fe3O4 showed to be safe in the treatments with lower concentrations with less amount of incoporated ferrite. Nevertheless, more characterizations and studies will be developed to determine the safety and therapeutic efficacy of this magnetic nanoparticles.

Magnetic solid-phase extraction coupled with UHPLC-MS/MS for four antidepressants and one metabolite in clinical plasma and urine samples.

Aim: Routine therapeutic drug monitoring is highly recommended since common antidepressant combinations increase the risk of drug-drug interactions or overlapping toxicity. Materials& methods: A magnetic solid-phase extraction by using C18-functionalized magnetic silica nanoparticles (C18-Fe3O4@SiO2 NPs) as sorbent was proposed for rapid extraction of venlafaxine, paroxetine, fluoxetine, norfluoxetine and sertraline from clinical plasma and urine samples followed by ultra-HPLC-MS/MS assay. Results:The synthesized C18-Fe3O4@SiO2 NPs showed high magnetization and efficient extraction for the analytes. After cleanup by magnetic solid-phase extraction, no matrix effects were found in plasma and urine matrices. The analytes showed LODs among 0.15-0.75ng ml-1, appropriate linearity (R≥0.9990) from 2.5 to 1000ng ml-1, acceptable accuracies 89.1-110.9% with precisions≤11.0%.The protocol was successfully applied for the analysis of patients' plasma and urine samples. Conclusion: It shows high potential in routine therapeutic drug monitoring of clinical biological samples.

Comparison of some magnetic nanoparticles based on iron oxide for separation and determination of cadmium metal ion by atomic spectrometry in seawater, wastewater and urine samples

ABSTRACT Magnetic nanoparticles based on iron oxide can be synthesised easily and separated with a magnetic bar. To determine heavy and dangerous metal of cadmium, for the first time, five types of magnetic nanoparticles based on iron oxide were used for separation and measurement of heavy and dangerous metal ion of cadmium. To obtain the high specific surface area for nanocomposite, the silicate nanoparticles were used and TAR ligand was used for adsorption of the cadmium metal to the nanocomposite. The used complex ligand was 4-(2ʹ–thiazolylazo) – resorcinol which has a thiol group with a high tendency to silver and gold ion metals. To increase the specific surface, absorption and extraction of cadmium ion, the magnetic silica nanoparticles were used. To obtain more accuracy and precision for ion determination, the optimisation of the effective parameter is important. In this research, MINITAB software was used for the performance of response surface modelling (RSM) optimisation method. To determine the heavy metal ion of cadmium, the flame atomic absorption spectrometry was used. Under the optimum conditions (pH = 4.1, the concentration of ligand = 1.5 mM, temperature = 27ºC) and using the magnetic nanoparticle with high specific surface, a preconcentration factor of 180, the linear range 0.4–110 (µg L−1), recovery (98%), limit of quantification of 0.34 µg L−1 and a limit of detection of 0.11 µg L−1 for cadmium ion were obtained. To obtain the precision of the method, each measurement was repeated 5 times, and the relative standard deviation value for cadmium ion concentration of 8.0 µg L−1 was obtained to be 3.1%. Finally, to evaluate the suggested method, the detection and measurement of cadmium ion in seawater, wastewater and urine sample were performed.