Silica-coated Magnetic Nanoparticles Research Articles

Homo- and Heterogeneous Benzyl Alcohol Catalytic Oxidation Promoted by Mononuclear Copper(II) Complexes: The Influence of the Ligand upon Product Conversion.

The catalytic properties of three copper complexes, [Cu(en)2](ClO4)2 (1), [Cu(amp)2](ClO4)2, (2) and [Cu(bpy)2](ClO4)2 (3) (where en = ethylenediamine, amp = 2-aminomethylpyridine and bpy = 2,2'-bipyridine), were explored upon the oxidation of benzyl alcohol (BnOH). Maximized conversions of the substrates to their respective products were obtained using a multivariate analysis approach, a powerful tool that allowed multiple variables to be optimized simultaneously, thus creating a more economical, fast and effective technique. Considering the studies in a fluid solution (homogeneous), all complexes strongly depended on the amount of the oxidizing agent (H2O2), followed by the catalyst load. In contrast, time seemed to be statistically less relevant for complexes 1 and 3 and not relevant for 2. All complexes showed high selectivity in their optimized conditions, and only benzaldehyde (BA) was obtained as a viable product. Quantitatively, the catalytic activity observed was 3 > 2 > 1, which is related to the π-acceptor character of the ligands employed in the study. Density functional theory (DFT) studies could corroborate this feature by correlating the geometric index for square pyramid Cu(II)-OOH species, which should be generated in the solution during the catalytic process. Complex 3 was successfully immobilized in silica-coated magnetic nanoparticles (Fe3O4@SiO2), and its oxidative activity was evaluated through heterogenous catalysis assays. Substrate conversion promoted by 3-Fe3O4@SiO2 generated only BA as a viable product, and the supported catalyst's recyclability was proven. Reduced catalytic conversions in the presence of the radical scavenger (2,2,6,6-tetrametil-piperidi-1-nil)oxil (TEMPO) indicate that radical and non-radical mechanisms are involved.

Highly selective analysis of glipizide as an antidiabetic drug in urine samples using HPLC-DAD technique via magnetic nanocomposites (Fe3O4@SiO2@tryptophan)

The extraction of endogenous compounds and drugs from complex biological matrices such as bio fluids and solid tissues necessitates an appropriate analytical approach that allows for qualitative and quantitative analysis because of the very low concentrations of the target species. This present work surveys the universe to isolate, purify, and immobilize an antidiabetic drugs such as glipizide biomolecules in urine samples using a magnetic solid-phase extraction (MSPE) and high-performance liquid chromatography (HPLC-DAD). To accomplish this purpose, a synthesis strategy of silica-coated magnetic nanoparticles functionalized with Tryptophan which is known as an amino acid to be applied as sorbent for (MSPE) is elaborated and analyzed. The structural and optical properties of the new magnetic nanocomposite have been investigated using Scanning electron microscope (SEM), X-Ray diffraction (XRD), thermogravimetric analysis (TGA) and Fourier transformation infrared (FTIR) techniques. In addition, HPLC analysis was carried out for the detection and determination of glipizide concentration in urine samples after magnetic solid phase extraction. After MSPE, the linear range for glipizide molecules (R2 > 0.9942) was obtained in the range of 15.00–900.00 ng mL−1. The calculations yielded a limit of detection (LOD) of 4.38 ng mL−1 and a limit of quantification (LOQ) of 14.71 ng mL−1. Additionally, the relative standard deviation (RSDs %) was found to be below 3.8 %. Furthermore, the recovery values for synthetic urine were 96.5 %, 96.6 %, and 102.5 %, and for human urine were 104.5 %, 106.1 %, and 97.1 %. These findings indicate that the combined use of MSPE with HPLC-DAD is an effective and valuable approach for accurately determining the concentration of glipizide in human urine samples.

Hydroxyl-rich ferrofluid for efficient liquid phase microextraction of cinnamic acid derivatives in traditional Chinese medicine.

In this study, a hydroxyl-rich ferrofluid was prepared by dispersing silica-coated magnetic nanoparticles into a methyltrioctylammonium chloride-glycerol deep eutectic solvent and then employed in the preconcentration of trace-level of cinnamic acid derivatives (caffeic acid, p-hydroxycinnamic acid, ferulic acid, and cinnamic acid) in traditional Chinese medicine prior to high-performance liquid chromatography analysis. The structures of the synthesized materials were characterized by X-ray diffraction and infrared spectroscopy. The experimental parameters affecting the extraction performance, such as deep eutectic solvent composition, dosage of ferrofluid, pH of aqueous sample solution, salt concentration, extraction time, type, and volume of desorption solvent, were studied and optimized. Under the optimum conditions, the enrichment factors of four cinnamic acid derivatives were in the range of 107-114. Low detection limits (0.2-0.9ng/mL), good precisions (relative standard deviations 1.2%-9.5%), and satisfactory recoveries (96.0%-104.7%) were achieved. Subsequently, the possible microextraction mechanism of the proposed method was explored and elucidated. It showed that the prepared ferrofluid is easily dispersed in the aqueous sample and achieved recovery after the extraction. The developed approach is a simple, convenient, and efficient method for preconcentration and determination of cinnamic acid derivatives in complex matrices.

Nanofructosome encapsulated CalB enzyme immobilized silica-coated magnetic nanoparticles for rapid enzymatic hydrolysis and acylation

Nanofructosome encapsulated CalB enzyme immobilized silica-coated magnetic nanoparticles for rapid enzymatic hydrolysis and acylation

Contamination- and Perturbation-Free Fluorescent Monitoring of Zn2+ in Suspensions using Crown Ether-Functionalized Magnetic Nanoparticles

This study aims to introduce a fluorescence-based chemosensing method for Zn2+ in aqueous suspensions and untreated surface waters, conditions which generally hinder the application of conventional optochemical sensing platforms. A macrocyclic fluoroionophore was covalently bonded to a silica-coated magnetic nanoparticle and applied according to a predetermined protocol for analyzing trace amounts of Zn2+ under rarely investigated conditions. Utilizing the reversible complexation of the immobilized fluoroionophore, rapid regeneration was carried out via simple acidification after the magnetic-assisted solid-phase extraction of the particles. Forming inclusion complexes with Zn2+ with the receptor units of the particles leads to a significant enhancement in fluorescence intensity at 370 nm, above the detection limit of 5 ppb, with a dynamic linear range of quantification of 15–3000 ppb in a pH range of 5.5–7.5. Practical applicability was confirmed by analyzing untreated river water and an aqueous suspension of pumpkin seed flour as real and relevant heterogeneous multicomponent samples of predetermined sample composition and natural Zn2+ content. Our practical approach aims to broaden the applicability range of optochemical sensing platforms for Zn2+.

Glucosamine-Modified Mesoporous Silica-Coated Magnetic Nanoparticles: A "Raisin-Cake"-like Structure as an Efficient Theranostic Platform for Targeted Methotrexate Delivery.

This study presents the synthesis of glucosamine-modified mesoporous silica-coated magnetic nanoparticles (MNPs) as a therapeutic platform for the delivery of an anticancer drug, methotrexate (MTX). The MNPs were coated with mesoporous silica in a templated sol-gel process to form MNP@MSN, and then chloropropyl groups were added to the structure in a post-modification reaction. Glucosamine was then reacted with the chloro-modified structure, and methotrexate was conjugated to the hydroxyl group of the glucose. The prepared structure was characterized using techniques such as Fourier transform infrared (FT-IR) spectroscopy, elemental analysis (CHN), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), dynamic light scattering (DLS), a vibrating sample magnetometer (VSM), and X-ray diffraction (XRD). Good formation of nano-sized MNPs and MNP@MSN was observed via particle size monitoring. The modified glucosamine structure showed a controlled release profile of methotrexate in simulated tumor fluid. In vitro evaluation using the 4T1 breast cancer cell line showed the cytotoxicity, apoptosis, and cell cycle effects of methotrexate. The MTT assay showed comparable toxicity between MTX-loaded nanoparticles and free MTX. The structure could act as a glucose transporter-targeting agent and showed increased uptake in cancer cells. An in vivo breast cancer model was established in BALB/C mice, and the distribution of MTX-conjugated MNP@MSN particles was visualized using MRI. The MTX-conjugated particles showed significant anti-tumor potential together with MRI contrast enhancement.

Reduced lysosomal activity and increased amyloid beta accumulation in silica-coated magnetic nanoparticles-treated microglia.

Nanoparticles have been used in neurological research in recent years because of their blood-brain barrier penetration activity. However, their potential neuronanotoxicity remains a concern. In particular, microglia, which are resident phagocytic cells, are mainly exposed to nanoparticles in the brain. We investigated the changes in lysosomal function in silica-coated magnetic nanoparticles containing rhodamine B isothiocyanate dye [MNPs@SiO2(RITC)]-treated BV2 murine microglial cells. In addition, we analyzed amyloid beta (Aβ) accumulation and molecular changes through the integration of transcriptomics, proteomics, and metabolomics (triple-omics) analyses. Aβ accumulation significantly increased in the 0.1μg/μl MNPs@SiO2(RITC)-treated BV2 cells compared to the untreated control and 0.01μg/μl MNPs@SiO2(RITC)-treated BV2 cells. Moreover, the MNPs@SiO2(RITC)-treated BV2 cells showed lysosomal swelling, a dose-dependent reduction in proteolytic activity, and an increase in lysosomal swelling- and autophagy-related protein levels. Moreover, proteasome activity decreased in the MNPs@SiO2(RITC)-treated BV2 cells, followed by a concomitant reduction in intracellular adenosine triphosphate (ATP). By employing triple-omics and a machine learning algorithm, we generated an integrated single molecular network including reactive oxygen species (ROS), autophagy, lysosomal storage disease, and amyloidosis. In silico analysis of the single triple omics network predicted an increase in ROS, suppression of autophagy, and aggravation of lysosomal storage disease and amyloidosis in the MNPs@SiO2(RITC)-treated BV2 cells. Aβ accumulation and lysosomal swelling in the cells were alleviated by co-treatment with glutathione (GSH) and citrate. These findings suggest that MNPs@SiO2(RITC)-induced reduction in lysosomal activity and proteasomes can be recovered by GSH and citrate treatment. These results also highlight the relationship between nanotoxicity and Aβ accumulation.

Different Strategies for Bio-Conjugation of Anti-CD4 Monoclonal Antibodies to Silica-Coated Magnetic Nanoparticles and Their Application for the Positive Selection of CD4+ Lymphocytes

Different Strategies for Bio-Conjugation of Anti-CD4 Monoclonal Antibodies to Silica-Coated Magnetic Nanoparticles and Their Application for the Positive Selection of CD4+ Lymphocytes

The Use of Extraction on C18-Silica-Modified Magnetic Nanoparticles for the Determination of Ciprofloxacin and Ofloxacin in Meat Tissues.

A simple, fast, and low-cost method of extraction using magnetic nanoparticles was developed for sample preparation in the determination of ciprofloxacin and ofloxacin in meat tissues with the use of capillary electrophoresis. This study is the first utilization of silica-coated magnetic nanoparticles with attached C18 chains to extract fluoroquinolones from meat tissues. This method is therefore characterized by a very simple sample preparation procedure, but on the other hand, by satisfactory precision and accuracy. Magnetic nanoparticles with an appropriately modified surface were placed in an Eppendorf tube, then conditioned with methanol, next rinsed with water and, finally, a homogenized tissue sample was added. At the neutral pH of the sample solution, these compounds do not have a charge and are able to adsorb on the modified particles. After extraction, the nanoparticles were dried and, then, desorption of analytes was conducted with the use of a mixture of 0.1 mol/L HCl and acetonitrile (1:1). This approach made it possible to purify the sample matrix and to obtain satisfactory LOQ levels for the method using the CE technique with UV-Vis detection. In this method, the LOD and LOQ values for both analytes were 0.04 nmol/g tissue and 0.15 nmol/g tissue, respectively. The calibration curves were linear in the entire concentration range, and the accuracy and the recovery of the method were at the satisfactory levels. The square value of the linear correlation coefficients (R2) for Cpx and Ofx were 0.9995 and 0.9992, respectively. The precision value of the method was within the range of 3-11% and accuracy was in the range of 93-110%.

Immobilization of α-transglucosidase on silica-coated magnetic nanoparticles and its application for production of isomaltooligosaccharide from the potato peel

In this study, the production of isomaltooligosaccharide from potato peel starch was carried out in three steps: liquefaction, saccharification, and transglucosylation. Further, cloning α-transglucosidase gene from Aspergillus niger (GH31 family), transforming into E. coli BL21 (DE3), overexpressing and purifying the resulting protein for the production of α-transglucosidase. The generated α-transglucosidase was then bound with magnetic nanoparticles, which improved reusability up to 5 cycles with more than 60% activity. All the modifications were characterized using the following methods: Fourier transform infra-red analysis, Transmission Electron Microscopy, Field Emission Scanning Electron Microscopy, Energy Dispersive X-ray spectroscopy, X-Ray Diffraction Spectroscopy, Thermogravimetric Analysis, and Dynamic Light Scattering (DLS) analysis. Further, the optimum conditions for transglucosylation were determined by RSM as follows: enzyme-to-substrate ratio 6.9 U g−1, reaction time 9 h, temperature 45 °C, and pH 5.5 with a yield of 70 g l−1 (± 2.1). MALDI-TOF–MS analysis showed DP of the IMOs in ranges of 2–10. The detailed structural characterization of isomaltooligosaccharide by GC–MS and NMR suggested the α-(1 → 4) and α-(1 → 6)-D-Glcp residues as major constituents along with minor α-(1 → 2) and α-(1 → 3) -D-Glcp residues.

Enhanced Versatility in Thorium Removal: Mesoporous Silica-Coated Magnetic Nanoparticles Functionalized by Phenanthroline Diamide as a Selective Adsorbent.

In order to promote the sustainable development of nuclear energy through thorium (Th(IV)) recycling, we synthesized SiO2-coated magnetic functional nanocomposites (SiO2@Fe3O4) that were modified with 2,9-diamide-1,10-phenanthroline (DAPhen) to serve as an adsorbent for Th(IV) removal. SiO2@Fe3O4-DAPhen showed effective Th(IV) adsorption in both weakly and strongly acidic solutions. Owing to its porous structure that facilitated rapid adsorption kinetics, equilibrium was achieved within 5 and 0.5 min at pH 3 and 1 mol L-1 HNO3, respectively. In weakly acidic solutions, Th(IV) primarily formed chemical coordination bonds with DAPhen groups, while in strongly acidic solutions, the dominant interaction was electrostatic attraction. Density functional theory (DFT) calculations indicated that electrostatic attraction was weaker compared to chemical coordination, resulting in reduced diffusion resistance and consequently faster adsorption rates in strongly acidic solutions. Furthermore, SiO2@Fe3O4-DAPhen exhibited a high adsorption capacity for Th(IV); it removed Th(IV) through chelation and electrostatic attraction at pH 3 and 1 mol L-1 HNO3, with maximum adsorption capacities of 833.3 and 1465.7 mg g-1, respectively. SiO2@Fe3O4-DAPhen also demonstrated excellent tolerance to salinity, adsorption selectivity, and radiation resistance, thereby highlighting its practical potential for Th(IV) removal in diverse contaminated water sources. Hence, SiO2@Fe3O4-DAPhen represents a promising choice for the rapid and efficient removal of Th(IV).

Oxidation of C–H bond of benzylic position in aromatic substrates by dehydroacetic acid based on an Iron (III) complex covalently anchored on Fe3O4 nanoparticles

In this study, the authors synthesize a novel mononuclear catalyst consisting of an iron (III) complex based on a dehydroacetic acid (DHA) ligand that is covalently anchored to silica-coated magnetic nanoparticles, and characterize it by using XPS, XRD, FT-IR, TGA, VSM, SEM, TEM, EDX, and ICP analyses. This heterogeneously homogenized catalyst was used for the effective and selective catalytic oxidation of a diverse range of C–H bonds of the benzylic position of aromatic substrates in water at room temperature. To the best of our knowledge, this is the first report of the DHA anchored on a nanomagnet. The DHA ligand tuned the Lewis acidity of the center of the metal, and this led to a greater dispersion of the catalyst in the aqueous solution. The magnetic catalyst was easily recovered by using a permanent magnet and reused for at least six cycles without a significant reduction in the conversion. The leaching test of the catalyst was also investigated during this process, and the results illustrated that the oxidation of the C–H bond occurred via a heterogeneous pathway.

Magnetic nanoadsorbent functionalized with aminophosphonic acid for NdIII ion extraction from aqueous media

The adsorption performance of a new magnetic nanoadsorbent of Nd3+ was investigated. First, the nanoadsorbent was synthesized by chemical coprecipitation, and covered with a silica layer by the sol–gel method to obtain the silica-coated magnetic nanoparticles (MNP@SiO2). Subsequently, it was functionalized with nitrilotris(methylene)triphosphonic acid(NTMP), obtaining the goal aminophosphonic-functionalized nanoadsorbent (MNP@SiO2-NTMP). The functionalized nanoadsorbent was characterized using TEM, XRD, VSM, TGA, ATR-FTIR, EDS, and zeta potential measurements, confirming its nanoscale size, superparamagnetic behavior, and the presence of surface amino-phosphonic groups. The influence of different operational parameters on neodymium adsorption was investigated. The highest adsorption capacity of neodymium(III) was approximately 18 mg·g−1 at pH 6.8, using an adsorbent dose of 1 g·L-1, a neodymium concentration of 100 mg·L-1, and a contact time of 15 min at room temperature. The neodymium(III) adsorption onto MNP@SiO2-NTMP followed a pseudosecond-order model, suggesting chemisorption mechanisms as the rate-limiting step. Batch experimental results showed that Nd3+ adsorption onto MNP@SiO2-NTMP was independent of the ionic strength, indicating the formation of inner-sphere surface complexes.Furthermore, the adsorption thermodynamic analyses suggested that neodymium adsorption was exothermic, entropy decreasing, and more favorable at low temperatures. The best adsorbent regeneration and neodymium desorption from the loaded adsorbent was achieved using acidic solutions of H2SO4, exhibiting excellent adsorbent reusability throughout the four adsorption–desorption cycles. The MNP@SiO2-NTMP was an effective adsorbent material for extracting neodymium(III) from dilute aqueous solutions. Therefore, it is expected that MNP@SiO2-NTMP can potentially be used in more sustainable recovery methods of neodymium from secondary sources, for example, from leaching solutions of NdFeB magnet scraps.

Silica-magnetite nanoparticles: Synthesis, characterization and nucleic acid separation potential

Silica-coated magnetic nanoparticles can be utilized for the magnetic separation of nucleic acids, which is an important step in many clinical procedures. A series of silica-functionalized superparamagnetic iron oxide nanoparticles (SiO2@MNPs) was synthesized to efficiently separate nucleic acids for the sensitive detection of viral infections. Magnetite nanoparticles (MNPs) coated with different thicknesses of silica layer resulting from different ratios of tetraethylorthosilicate (TEOS) precursor to magnetite (TEOS/MNPs = 0.4, 1.0, 2.0, 3.0, 4.0, 5.0 ml/g) have been selected for characterization of their physico-chemical properties and biological activities. The SiO2@MNPs' morphology, size, magnetic and surface properties, cytotoxicity and nucleic acid binding propensity were determined to select the ones with the highest RNA separation potential. Our results showed that RNA-binding properties and magnetic separation efficiency are nanoparticle size-dependent. The highest binding and separation efficiencies were detected for the smaller SiO2@MNPs with TEOS/MNPs (v/w) ratios equal to 1.0 and 2.0. These nanoparticles are promising candidates for clinical application relevant to RNA viruses.

Cobalt-Doped Mesoporous Silica Coated Magnetic Nanoparticles Promoting Accelerated Bone Healing in Distraction Osteogenesis.

Large bone abnormalities are commonly treated using distraction osteogenesis (DO), but it is not suitable for a long-term application; therefore, there is an urgent need for adjuvant therapy that can accelerate bone repair. We have synthesized mesoporous silica-coated magnetic nanoparticles doped with cobalt ions (Co-MMSNs) and assessed their capacity to quicken bone regrowth in a mouse model of DO. Furthermore, local injection of the Co-MMSNs significantly accelerated bone healing in DO, as demonstrated by X-ray imaging, micro-CT, mechanical tests, histological evaluation, and immunochemical analysis. In vitro, the Co-MMSNs exhibited good biocompatibility and induced angiogenic gene expression and osteogenic development in bone mesenchymal stem cells. And the Co-MMSNs can promote bone regeneration in a rat DO model. This study demonstrated the significant potential of Co-MMSNs to shorten the DO treatment duration and effectively reduce the incidence of complications.

Surface imprinted bio-nanocomposites for affinity separation of a cellular DNA repair protein.

Apurinic/apyrimidinic endonuclease 1 (APE1) is a multifunctional DNA repair protein localized in different subcellular compartments. The mechanisms responsible for the highly regulated subcellular localization and "interactomes" of this protein are not fully understood but have been closely correlated to the posttranslational modifications in different biological context. In this work, we attempted to develop a bio-nanocomposite with antibody-like properties that could capture APE1 from cellular matrices to enable the comprehensive study of this protein. By fixing the template APE1 on the avidin-modified surface of silica-coated magnetic nanoparticles, we first added 3-aminophenylboronic acid to react with the glycosyl residues of avidin, followed by addition of 2-acrylamido-2-methylpropane sulfonic acid as the second functional monomer to perform the first step imprinting reaction. To further enhance the affinity and selectivity of the binding sites, we carried out the second step imprinting reaction with dopamine as the functional monomer. After the polymerization, we modified the nonimprinted sites with methoxypoly (ethylene glycol) amine (mPEG-NH2 ). The resulting molecularly imprinted polymer-based bio-nanocomposite showed high affinity, specificity, and capacity for template APE1. It allowed for the extraction of APE1 from the cell lysates with high recovery and purity. Moreover, the bound protein could be effectively released from the bio-nanocomposite with high activity. The bio-nanocomposite offers a very useful tool for the separation of APE1 from various complex biological samples.

Cyano-2-oxopyridines: Green synthesis, cytotoxicity evaluation and molecular docking study

An efficient four-component and one-pot synthesis of 1,6-diamino-3,5-dicyano-2-oxopyridine compounds were investigated in the presence of three catalysts such as bulk and nanosheet graphitic carbon nitride and IS@SMNPs (piperazinium ionic salt attached on silica-coated magnetic nanoparticle) as recyclable heterogeneous catalysts. From the results, the magnetic nanocatalyst was the best among examined catalysts. The highest yield (85%) and the shortest reaction time (40 min) were obtained (for the four-component reaction between benzaldehyde, malononitrile, ethyl cyanoacetate and hydrazine hydrate) in the presence of 50 mg of‏ ‏IS@SMNPs at room temperature. Recycling of IS@SMNPs was tested, and after the fifth cycle, 80% yield was obtained. Good yields in a short time, simple recycling, and being environmentally friendly are advantages of the magnetic catalyst. MTT assay screened the cytotoxicity of 6a, 6b, 6e, and 6h derivatives against two carcinoma cell lines, such as HeLa and MCF-7 (estrogen receptor-dependent). 6h and 6b exhibited the most potent cytotoxicity, respectively, and 6b showed the lowest one against both cell lines. The interactions of selected derivatives and Genistein (an estrogen receptor inhibitor) in the active site of estrogen receptor-α were predicted using molecular docking. The docking results of synthetic compounds illustrated similar interactions to redocked Genistein in the active site, and compounds 6e and 6h had the highest binding affinity.

Green synthesis of silica-coated magnetic nanocarriers for simultaneous purification-immobilization of β-1,3-xylanase

Tailoring magnetic nanocarriers with tunable properties is of great significance for the development of multifunctional candidate materials in numerous fields. Herein, we report a one-pot biomimetic silicification-based method for the synthesis of silica-coated magnetic nanoparticles. The synthesis process was mild, low cost, and highly efficient, which took only about 21 min compared with 4.5–120 h in other literature. Then, the carriers had been characterized by VSM, SEM, TEM, XRD, FT-IR, and EDS to confirm their function. To evaluate the usefulness of the carriers, they were adopted to couple the purification and immobilization of β-1,3-xylanase from the cell lysate in a single step with high immobilization yield (92.8 %) and high activity recovery (82.4 %). The immobilized enzyme also retained 58.4 % of the initial activity after 10 cycles and displayed good storage properties, and improved thermal stability, which would be promising in algae biomass bioconversion as well as other diverse applications.

Rapid and sensitive detection of Pectobacterium carotovorum subsp. carotovorum in fresh produce using silica-coated magnetic nanoparticles combined with filtration-based real-time PCR

Pectobacterium carotovorum subsp. carotovorum (Pcc) possesses a powerful enzymatic mechanism that destroys plant-cell walls. Therefore, Pcc is the etiology of soft-rot disease in several crops and is recognized as one of the most important pathogens in agriculture. Soft-rot is difficult to control at the source when infection occurs. Thus, it is essential to develop sensitivity monitoring and diagnostic methods for timely control measures. Molecular detection methods, such as real-time polymerase chain reaction (PCR), are widely used for detecting Pcc. However, because Pcc is present at low levels in initial soft-rot infection, enrichment and efficient pathogen-separation methods are needed for sensitive monitoring. In this study, filtration was used as a pretreatment method for pathogen concentration, and silica-coated magnetic nanoparticles (SMN)- based real-time PCR was employed to detect low levels of Pcc in fresh produce. As a result, 102 CFU/10 mL was detected by various DNA-extraction methods in pure culture, whereas SMN detected up to 101 CFU/10 mL. In addition, when DNA was extracted using SMN after filtration using a cellulose acetate filter, the sensitivity of real-time PCR was improved to 10° CFU/10 mL. In conclusion, the pretreatment method including SMN, and concentration procedures increased the detection sensitivity by 100-fold; in potato and chicory, 101 CFU/g was detected at a frequency of 90% of the samples, and 10° CFU/g was detected at 70%; and in Kimchi Cabbage, 101 CFU/g was detected at 100% and 10° CFU/g was detected at 80%.

TEMPO and a co-reductant mediated aerobic epoxidation of olefins using a new magnetically recoverable iron(III) bis(phenol)diamine complex: experimental and computational studies.

A magnetically recoverable catalyst of an iron(III) bis(phenol) diamine complex immobilized onto amine functionalized silica-coated magnetic nanoparticles has been synthesized. The catalyst was characterized using FESEM, TEM and XRD which confirmed the nano structure of the catalyst. The physicochemical techniques of ICP, FT-IR, XPS, EDS and TGA proved the loading of the ligand and metal complex on silica-coated magnetic nanoparticles. Using the prepared heterogeneous catalyst, aerobic epoxidation reactions of different alkenes have been investigated in the presence of SO32- as a reducing agent. Moreover, using TEMPO (2,2,6,6-tetramethyl-1-piperidinyloxy) to discover the mechanism of the aerobic epoxidation of olefins, a new TEMPO-assisted route has been explored. Both of the reaction pathways led to a moderate to high percentage yield of epoxides in water at room temperature. For further understanding mechanistic aspects, density functional theory (DFT) computational studies have been performed. The DFT calculations confirm the suggested mechanism for the title reaction and show the electron density in the vicinity of Fe(II) in the presence of TEMPO as a co-catalyst was more than that in the presence of SO32-.