Synthesis and evaluation of new magneto-fluorescent carbon dot based on manganese citrate for MRI imaging.

OBJECTIVE: Medical imaging techniques have widely revolutionized the diagnosis and treatment of various health conditions. Among these techniques, magnetic resonance imaging (MRI) has stood out as a noninvasive and versatile tool. Now, a breakthrough innovation called "manganese-carbon dots" is poised to enhance MRI imaging and provide physicians with even greater insight into the human body. MATERIALS AND METHODS: In this study, one-pot hydrothermal method was used to fabricate magneto-fluorescent carbon quantum dots using manganese citrate, urea, and Mn2+. Manganese citrateAQ3 acted as a carbon source and contrast agent. TEM,XPS, FTIR, UV-Vis, fluorescent analysis confirmed the successful synthesis of magneto-fluorescent carbon quantum dots. The MTT assay was used to study its biocompatiblity, Finallay application of itscompound for mri imaging was investigated. RESULTS: Characterization Techniques confirmed the succesful synthesis of product. MTT assay showed no toxicity of this product on HEK-293 cells. In addition, it exhibited high r1 relaxivity (7.4 mM-1 S-1) suggesting excellent potential of magneto-fluorescent carbon quantum dots as MRI T1 contrast agent and enabling specific imaging. CONCLUSION: Based on the results obtained, the synthesized carbon quantum dots could be used as fluorescence/MRI bimodal platform for in vivo imaging.

GNP/Al-MOF nanocomposite as an efficient fiber coating of headspace solid-phase micro-extraction for the determination of organophosphorus pesticides in food samples.

The synthesis and utilization of a high porous nanocomposite comprising MIL-53(Al) metal-organic framework (Al-MOF) and graphene nanopowder (GNP) is reported as a fiber coating for headspace solid-phase micro-extraction (HS-SPME) of selected organophosphorus pesticides (OPPs) from apple, potato, grape juice, tomato, and river water. The adsorbed OPPs on the coated fiber were subsequently determined using GC-MS. Several parameters affecting the efficiency of extraction including time and temperature of extraction, desorption condition of extracted analytes, pH and agitation of sample solution, and salt concentration were investigated. The optimum extraction condition was achieved at 70 °C with an extraction time of 40 min, pH = 4-8, and NaCl concentration of 6.0% (w/v). The best condition of desorption were observed at 280 °C for 2.0 min under a flow of helium gas in the GC inlet. Under optimal conditions, the detection limits ranged from 0.2 to 1.5 ng g-1 and the linear ranges between 0.8 and 600 ng g-1. The proposed method showed very good repeatability with RSD values ranging from 4.5 to 7.3% (n = 5). The relative recoveries were between 88% and 109% at the spiked level of 25.0 ng g-1 for the tomato sample. The fabricated fiber exhibited good enrichment factor (62-195) at optimum condition of HS-SPME. The applied HS-SPME technique is facile, fast, and inexpensive. The thermally stable GNP/Al-MOF exhibited a high sensitivity toward OPPs. So, this nanocomposite can be considered as a sorbent for the micro-extraction of other pesticides in food.

Synthesis of Fused Azo-linked Acridine Derivatives Using MCM-41/Ag2S-RHA Nanocomposite.

INTRODUCTION: In this study, the synthesis of azo-linked acridine by the reaction of dimedone and synthesized diazoaryl-(2-amino-5-(phenyl)methanone using Ag2S/RHA-MCM-41nanocomposite is reported. MATERIALS AND METHODS: The synthesized catalyst was characterized by FT-IR, XRD, and SEM. According to the obtained results, Ag2S/RHA-MCM-41 nanocomposite exhibited high activity in the synthesis of azo-acridine derivatives based on desirable yields and reaction time. Products were prepared in 1.5-2 h and with 88-93% yield. In all the reactions, the catalyst could be easily removed and reused, and its catalytic activity was maintained after five uses and did not decrease significantly. The structures of all newly synthesized products were characterized by spectroscopic spectra (FT-IR, 1H NMR, 13C NMR) and elemental analyses. RESULTS AND DISCUSSION: The results of the study showed that ionic liquid [DBU]OAc (entry 8) and MCM- 41/Ag2S-RHA nanocomposite (entry 8) possessed better efficiency and shorter time than other reaction conditions. CONCLUSION: In this study, new azo-linked acridine derivatives were synthesized by the reaction of different azo derivatives and dimedone using MCM-41/Ag2S-RHA nanocomposite, and the reaction products were obtained in 1.5-2 h with an efficiency of 88-93%. The short reaction time and high efficiency of the obtained products indicated the high efficiency of this method. In all the reactions, MCM-41/Ag2S-RHA nanocomposite could be easily removed and reused. Its catalytic activity was maintained in the sample reaction after five runs and did not decrease significantly.

Nanocomposite prepared from ZnS nanoparticles and molecular sieves nanoparticles by ion exchange method: characterization and its photocatalytic activity.

In this article, we have reported synthesis of ZnS/MCM-41 nanocomposite and its photocatalytic activity. The photocatalytic activity was evaluated using basic blue 9 or methylene blue (MB) as model pollutant under UV light irradiation. The catalyst is characterized by transmission electron microscopy (TEM), UV-vis diffused reflectance spectra (UV-vis DRS), X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques. The effect of ZnS, MCM-41 support and different wt% of ZnS over the support on the photocatalytic degradation and influence of parameters such as ZnS loading, catalyst a mount, pH and initial concentration of dye on degradation are evaluated. The degradation reaction follows pseudo-first order kinetics. The effect of dosage of photocatalyst was studied in the range 0.02-5 g/L. It was seen that 0.4 g/L of photocatalyst is an optimum value for the dosage of photocatalyst. The degradation efficiency was decreased in dye concentration above 3.2 ppm for dye. In the best conditions, the degradation efficiency was obtained 0.32 ppm for methylene blue.

Photocatalytic activity of quantum dots incorporated in molecular sieves for generation of hydrogen.

MCM-41 molecular sieve coupled with lead sulfide quantum dots (PbS-MCM-41) was prepared by ion-exchange method. The photocatalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis spectroscopy, infrared spectroscopy (IR) and BET (Brunauer-Emmett-Teller) experiments. Exciton absorption peak at higher energy than the fundamental absorption edge of bulk lead sulfide indicates quantum confinement effects in quantum dots as a consequence of their small size. The hydrogen production rate from water photocatalytic decomposition under visible light irradiation (λ>400nm) over PbS nanoparticles formed in mesoporous material was much higher compared to the bulk PbS.

Studying effect of cell wall's carboxyl-carboxylate ratio change of Lemna minor to remove heavy metals from aqueous solution.

The pre-treated Lemna minor can remove Hg(II), Cr(III), Cr(VI) and Cu(II) from the aqueous solution. The concentration determination of carboxyl and carboxylate groups and its rule to change the metal ions uptake was done by the curves of the potentiometric titration. It was shown that the removal percent of the heavy metal ions (Co=1.00 mM) increased 25.1, 26.0, 17.2 and 24.1% for these ions, respectively, with increasing the carboxylate from 0.92 to 2.42 mmol/g L. minor and then activating by the activator chloride salts. The removal percent of these ions was decreased 33.1, 27.5, 20.7 and 15.01%, respectively, with increasing the carboxyl from 1.50 to 2.41 mmol/g L. minor, inspite of activating by the chloride salts. The enthalpy change (DeltaH) was -27.43, -25.94, -28.12 and -22.27 kJ/mol and the entropy change (DeltaS) was 81.3, 79.9, 86.1 and 67.7 J/mol K, by activated biomass, respectively. L. minor removed these heavy metals corresponding to pseudo-second-order kinetic model that the activation energy (E(a)) was obtained 18.59, 15.93, 20.36 and 21.12 kJ/mol by the activated and 23.02, 22.27, 23.98 and 24.46 kJ/mol by the reference biomass to uptake Hg(II), Cr(III), Cr(VI) and Cu(II), respectively.