Gold nanoparticles grafted manganese doped Fe3O4 nanoparticles for determination of short-term release of silver and lead from dental amalgam in saliva

Ethylene glycol bisthioglycolate modified gold nanoparticles grafted Mn doped Fe3O4 nanoparticles (Au@Mn-Fe3O4 NPs) adsorbent was synthesized and applied for extraction and preconcentration of trace amounts of Ag+ and Pb2+ ions in artificial and natural saliva. The adsorbent was characterized by transmission electron microscopy (TEM), Brunauer–Emmett–Teller analysis (BET), X-ray diffraction spectroscopy (XRD) and vibrating-sample magnetometer  (VSM) [h1] techniques and Fusayama artificial saliva was prepared and used as a blank sample. Natural saliva samples were collected from nine volunteers who exposed to posterior decayed teeth amalgam filling, and short-term release of heavy metal ions was assessed in 24, 72 and 96 h after filling. The main factors affecting extraction and desorption efficiency of target ions have been investigated. In Optimum conditions, the detection limits of 0.23 and 0.11 ng mL-1 with preconcentration factors of 94 and 95 were obtained for Ag+ and Pb2+ ions, respectively. The results revealed that the adsorbent has high  capacity and good reusability for extraction and preconcentration of target metal ions in relatively high saline solution like biological fluids

CoFe2O4 nanoparticles grafted multi-walled carbon nanotubes coupled with surfactant-enhanced spectrofluorimetry for determination of ofloxacin in human plasma

An efficient and simple magnetic solid phase extraction based on the use of CoFe3O4 nanoparticles grafted multi-walled carbon nanotubes (MWCNTs) as adsorbent coupled with surfactant enhanced spectrofluorimetric detection was developed for determination of ofloxacin from biological samples. The adsorbent uses the advantages of both magnetic nanoparticles (i.e., magnetic separation) and MWCNTs (i.e., high adsorption capacity). The main factors affecting the quantitative recovery including SDS concentration, pH, extraction and desorption times, adsorbent amount, and desorption conditions were investigated in detail. Under the optimized conditions, the calibration curves were linear over a wide concentration range of 100-750 ng mL-1 with detection limit (LOD) of 23 ng mL-1. The relative standard deviation (RSD %) of 3.3% for concentration of 250 ng mL-1, n = 5 and the preconcentration factor of 93 were obtained. Finally, the proposed method was successfully applied to the extraction and preconcentration of ofloxacin in human plasma samples

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هدف مقاله حاضر بررسی رابطه بین آزادسازی اقتصادی و کارایی دولت در کشورهای خاورمیانه و شمال افریقا طی سالهای 1995 تا 2008 است. به این منظور از اطلاعات شاخص آزادسازی اقتصادی بنیاد هریتیج و از شاخص کارایی دولت بانک جهانی استفاده شده است. در این مقاله سعی شده است تا بر پایه مطالعات نظری و تجربی انجام گرفته و در قالب یک الگوی اقتصادسنجی، با استفاده از دادههای ترکیبی مقطعی- سری زمانی (پانل دیتا)، رابطه بین آزادسازی اقتصادی و کارایی دولت در کشورهای خاورمیانه و شمال افریقا طی دوره 1995 تا 2008 مورد برسی قرار گیرد. نتایج حاصل از تخمین نشان میدهد که رابطه مثبت و معنیداری بین آزادسازی اقتصادی و کارایی دولت در این کشورها وجود دارد. که نتایج حاصل از آزمون معنیدار بودن نیز، در سطح 5 درصد آن را تأیید نموده است. بر اساس نتایج تحقیق حاضر، تفاوت معناداری بین میانگین شاخص آزادسازی اقتصادی و کارایی دولت در ایران و متوسط کشورهای عضو MENA وجود ندارد

Magnetic nanoparticles grafted pH-responsive poly (methacrylic acid-co-acrylic acid)-grafted polyvinylpyrrolidone as a nano-carrier for oral controlled delivery of atorvastatin

Objective(s): Researchers have intended to reformulate drugs so that they may be more safely used in human body. Polymer science and nanotechnology have great roles in this field. The aim of this paper is to introduce an efficient drug delivery vehicle which can perform both targeted and controlled antibiotic release using magnetic nanoparticles grafted pH-responsive polymer.  Methods: Fe3O4 nanoparticles were prepared via a simple co-precipitation method and coated with APTS. Then, it was used as a core in synthesis of a core-shell pH-responsive polymer. After that, atorvastatin was loaded into the carrier and its release rate, kinetic and mechanism were investigated.   Results: The results revealed that cumulative release of the drug from nano carrier was 78% at pH 1.2 while in pH 5.5 and 7.2, the drug release was only about 5 and 31% respectively. Effect of different parameters on the atorvastatin release such as amounts of MAA monomer, EGDMA as cross-linker, AIBN as initiator, and MNPs were also studied. Furthermore, release kinetics and mechanism investigation along with the swelling behavior studies of plain polymer reveal Fickian pattern and diffusion controlled mechanism. Conclusions: The results indicate that the prepared nano-carrier can be serving as a suitable candidate for controlled delivery of the drugs

Gold nanoparticles grafted modified silica gel as a new stationary phase for separation and determination of steroid hormones by thin layer chromatography

A new thin layer chromatographic layer using gold nanoparticles grafted 3-triethoxysilyl propylamine modified silica gel (Au NPs-APTS modified silica gel) was developed as a stationary phase for separation and determination of two steroid hormones, namely progesterone and testosterone. Acetone–n-hexane 25:75 (v/v) was used as the mobile phase, and the results were compared with those obtained using plain (i.e., unmodified) silica gel plates. Some chromatographic parameters used for separation of the two steroids on an Au NPs-APTS modified silica gel plate as well as on a plain silica gel plate, including ΔRF, separation factor (α), and resolution (RS), were evaluated and compared. The reproducibility of RF values was also determined by analysis of the two steroids in 7 consecutive days on both plates. Validity of the method was investigated, and a wide linear range of 1–200 ng per spot, and low detection limits of 0.16 ng and 0.13 ng per spot, low quantification limits of 0.51 ng and 0.40 ng per spot, and good precision (expressed as percent relative standard deviation) lower than 3.1% and 2.7% were obtained for progesterone and testosterone, respectively. As the results revealed, the proposed method is rapid and sensitive, and it is applicable to separation and determination of progesterone and testosterone in biological matrices such as urine samples

Poly (methacrylic acid-co-acrylic acid)-grafted polyvinylpyrrolidone coated Magnetic nanoparticles as a pH-responsive magnetic Nano-carrier for controlled delivery of antibiotics

Objective(s): Pharmaceutical industries are leading to improved medications that can target diseases more effectively and precisely. Researchers have intended to reformulate drugs so that they may be more safely used in human body. The more targeted a drug is, the lower its chance of triggering drug resistance, a cautionary concern surrounding the use of broad-spectrum antibiotics. The aim of this paper is to introduce efficient drug delivery vehicles which can perform both targeted and controlled antibiotic release by synthesis of magnetic pH-responsive polymer.    Materials and Methods: Iron oxide nanoparticles were synthesized by chemical co-precipitation technique and primary coated with 3-trimethoxysilylpropylamine (APTS). APTS coated MNPs was used in the reaction medium for synthesis of a pH-responsive poly (MAA-co-AAc)-grafted PVP. The prepared vehicle was characterized by TEM, XRD, FT-IR, TGA, DSC and elemental analysis. Drug loading, release, kinetics and mechanism of the system were evaluated.Results: The results for drug release showed that the release of antibiotics in pH 5.5 and 7.2 could be effectively sustained, while about 92 % of the drugs were released at pH 1.2. Considerations demonstrate the tendency of drug release by Fickian mechanism and diffusion controlled release.Conclusion: The results indicate that the prepared magnetic nano-carrier could be suitable for site-specific antibiotic delivery through oral administration

FeMn2O4 nanoparticles coated dual responsive temperature and pH-responsive polymer as a magnetic nano-carrier for controlled delivery of letrozole anti-cancer

Objective(s): For cancer cells, an efficient and selective drug delivery vehicle can remarkably improve therapeutic approaches. This paper focuses on the synthesis and characterization of magnetic MnFe2O4 NPs and their incorporation in a dual temperature and pH-responsive polymer, which can serve as an efficient drug carrier. Materials and Methods: MnFe2O4 NPs were synthesized by chemical co-precipitation technique and coated with tetraethyl orthosilicate (TEOS) and modified with 3-mercaptopropionic acid (MPA). Then, it was used in the reaction medium during the synthesis of a temperature and pH-responsive poly (N-isopropylacrylamide-co-vinyl acetate-co-methacrylic acid). The prepared vehicle was characterized by FESEM, XRD, VSM, and FT-IR. Letrozole was used as a model drug and its loading and release and LCST of the vehicles were evaluated. Results: The results for LCST measurements reveal that the phase transition of polymer occurs at temperatures in the range of 37-40 ºC which is in the range of body conditions. Results for loading efficiency shows that maximum loading occur in about 10 h. The loading % for nano-carrier was lower than plain polymer which was due to lower polymer content in the nano-carrier with the same weight compare to the plain polymer. The results for drug release showed that the release of letrozole in pH 1.2, 5.5 and 7.2 was about 80, 45 and 35% for plain polymer and 81, 56 and 50% for the nano-carrier respectively. Conclusion: The results indicate that the prepared magnetic nano-carrier can be a suitable candidate for site-specific and controlled anti-cancer delivery through oral administration

Dispersive liquid-liquid microextraction coupled with magnetic nanoparticles for extraction of zearalenone in wheat samples

A new, sensitive and fast dispersive liquid-liquid microextraction (DLLME) coupled with micro-solid phase extraction (μ-SPE) was developed for determination of zearalenone (ZEN) in wheat samples. The DLLME was performed using acetonitrile/water (80:20 v/v) as the disperser solvent and 1-octanol as the extracting solvent.  The acetonitrile/water (80:20 v/v) solvent was also used to extract ZEN from solid wheat matrix, and was directly applied as the disperser solvent for DLLME process. Additionally, hydrophobic oleic-acid-modified magnetic nanoparticles were used in μ-SPE approach to retrieve the analyte from the DLLME step. So, the method uses high surface area and strong magnetism properties of these nanoparticles to avoid time-consuming column-passing processes in traditional SPE. Main parameters affecting the extraction efficiency and signal enhancement were investigated and optimized. Under the optimum conditions, the calibration curve showed a good linearity in the range of 0.1-500 μg kg−1 (R2=0.9996) with low detection limit of 83 ng g−1. The intra-day and inter-day precisions (as RSD %) in the range of 2.6-4.3 % and high recoveries ranging from 91.6 to 99.1 % were obtained. The pre-concentration factor was 3. The method is simple, inexpensive, accurate and remarkably free from interference effects