A comparative study on thermoresponsive magnetic nanohydrogels: role of surface-engineered magnetic nanoparticles

A comparative study of thermoresponsive poly(N-isopropylacrylamide)(PNIPAAm)-chitosan (CS)-based magnetic nanohydrogels (MNHGs) encapsulating functionalized Fe₃O₄ nanoparticles (NPs) in terms of the parameters governing their suitability for real hyperthermia is reported. Iron oxide NPs functionalized with (a) citric acid (CA-Fe₃O₄), (b) ethylenediamine (Amine-Fe₃O₄) and (c) dimercaptosuccininc (DMSA-Fe₃O₄) have been synthesized and their encapsulation into MNHGs was obtained through physical encapsulation method. The structural characterizations of synthesized materials include X-ray diffraction, FT-IR, TGA, ICP-AES and X-ray photoelectron spectroscopy (XPS). Encapsulation of the functionalized NPs into MNHGs were observed in TEM micrographs, while SEM and AFM micrographs confirmed their spherical morphology (~250–300 nm). Lower critical solution temperature (LCST) variation was measured by UV–visible spectrophotometer and differential scanning calorimetry (DSC). MNHGs exhibited sufficient magnetization and heating ability for hyperthermia. Typically, hydrogels containing CA-Fe₃O₄ (50 mg/ml) raised the temperature of the medium to 43 °C, a suitable dose for in vivo application in tumor-bearing mice.     

A Rapid and Simple UPLC-MS–MS based Simultaneous Determination of the Medicinally Important E- and Z-Guggulsterone from Oleogum-Resins of Naturally Occurring Commiphora wightii Plants

A fast and simple method for simultaneous detection and quantification of the medicinally important E- and Z-guggulsterone from raw oleogum-resin of Commiphora wightii by UPLC was developed. Both E- and Z-guggulsterone were extracted from naturally occurring resin samples using ethyl acetate and methanol. Chromatographic separation of the analytes and their respective standards were performed on an Acquity UPLC BEH C₁₈ column followed by UV as well as a triple quadrupole detector in positive ionization mode. A linear gradient elution profile followed; mobile phase consisted of acetonitrile and 2 mM ammonium acetate in water. The method was validated over a range of 6.25 to 100 ng mL⁻¹ for both the guggulsterones. The calibration curves were linear with correlation coefficients of 0.9998 for E-guggulsterone and 0.9999 for Z-guggulsterone. The LOD and LOQ were 1.65 and 5.02 ng mL⁻¹ for E-guggulsterone and 2.57 and 7.79 ng mL⁻¹ for Z-guggulsterone respectively. The average recovery of E-guggulsterone (104.63%) and Z-guggulsterone (104.33%) achieved from spiked samples were consistent and reproducible. The intra- and inter-day assay precision of the analytes over the entire concentration range was less than 2%. The developed method required only 6 min to complete a run including 1 min to equilibrate the system and hence suitable for high throughput applications. Efficiency, reliability and accuracy of the developed method were evaluated by analyzing resin sample from different C. wightii populations. The result of this study offers improvement in terms of speed and sensitivity as compared to previously reported methods.

     

高效固体酸SBA-15-Zr(OTf)3催化胺或醇开环环氧化合物

通过简单的一锅两步法制备了三氟金属(铝,钛,锆)接枝介孔SBA-15 (AlTf/S,TiTf/S,ZrTf/S)固体酸材料,并通过XRD,N2吸附,TGA,FTIR,原位吡啶FTIR和元素分析对这些材料进行了详细的表征.其中,ZrTf/S能够高效催化环氧化物温和条件下被胺或醇开环生成对应β-氨基醇或β-烷氧基醇,并且催化剂能循环利用.ZrTf/S相较于AlTf/S和TiTf/S酸性最强,因而催化活性也最高.     

The effect of pre-shear on the extensional rheology of wormlike micelle solutions

The effect of initial microstructural deformation, alignment, and morphology on the response of wormlike micelle solutions in transient uniaxial extensional flows is investigated using a pre-shear device attached to a filament stretching rheometer. In filament stretching experiments, increasing the strength and the duration of the pre-shear just before stretch is found to delay the onset of strain hardening. In these experiments, the wormlike micelle solution filaments fail through a rupture near the axial midplane. The value of the elastic tensile stress at rupture is found to decrease with increasing pre-shear rate and duration. The most dramatic effects are observed at shear rates for which shear banding has been independently observed. The reduction in the strain hardening suggests that pre-shear before filament stretching might break down the wormlike micelles reducing their size before stretch. Strain hardening is also observed in capillary breakup rheometry experiments; however, the pre-sheared wormlike micelle solutions strain harden faster, achieve larger steady-state extensional viscosities and an increase in the extensional relaxation time with increasing shear rate and duration. The difference between the response of the wormlike micelles in filament stretching and capillary breakup experiments demonstrates the sensitivity of these self-assembling micelle networks to pre-conditioning.     

Comparative Pharmacokinetics Profile of Vasa Swaras with Vasicine and Vasicinone

An RP-LC method was developed and validated for comparing the pharmacokinetics profile of Vasa Swaras (leaf juice of Adhatoda vasica Nees., Fam. Acanthaceae) with that of the pure vasicine and vasicinone (chief marker compounds of A. vasica) upon oral administration of Vasa Swaras in rats, and also in different animal groups. Significant difference with p < 0.05 was found in the oral bioavailability of vasicine and vasicinone when administered as Vasa Swaras and as single vasicine and/or vasicinone. Vasicine and vasicinone were found to be more bioavailable from Vasa Swaras than pure vasicine and/or vasicinone.     

Properties of Ionic Liquid Confined in Porous Silica Matrix

Porous silica matrices of different pore sizes with confined ionic liquid (1‐butyl‐3‐methylimidazolium hexafluorophosphate) [BMIM] [PF₆] were prepared by sol‐gel technique using a tetraethyl orthosilicate (TEOS) precursor with an aim to study the changes in physico‐chemical properties of ionic liquid on confinement. It is found that on confinement 1) melting point decreases, 2) fluorescence spectra shows a red shift and 3) the vibrational bands are affected particularly those of imadazolium ring, which interacts more with the walls of the silica matrix. Preliminary theoretical calculations suggest that SiO₂ matrix interact more with the heterocyclic group of [BMIM] cation than the tail alkyl chain end group resulting in significant changes in the aromatic vibrations.     

Validated ultra-performance liquid chromatography tandem mass spectrometry method for the determination of pramipexole in human plasma

A sensitive and high throughput ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS-MS) method has been developed for the determination of pramipexole, a dopamine agonist, in human plasma. Sample preparation involved liquid-liquid extraction of pramipexole and ranitidine as the internal standard (IS) in ethyl acetate from 100 μL human plasma. The chromatographic separation is achieved on a Waters Acquity UPLC BEH C18 (100 mm × 2.1 mm, 1.7 μm) analytical column using an isocratic mobile phase, consisting of 10 mM ammonium formate (pH 7.50)-acetonitrile (15:85, v/v), at a flow-rate of 0.5 mL/min. The precursor → product ion transition for pramipexole (m/z 212.1 → 153.0) and IS (m/z 315.0 → 176.1) were monitored on a triple quadrupole mass spectrometer, operating in the multiple reaction monitoring (MRM) and positive ion mode. The method was validated over a wide dynamic concentration range of 20-4020 pg/mL. Matrix effect is assessed by post-column infusion experiment and the process efficiency were 91.9% and 85.7% for pramipexole and IS, respectively. The method is rugged and rapid with a total run time of 1.5 min and is applied to a bioequivalence study of 0.25 mg PPX tablet formulation in 30 healthy Indian male subjects under fasting condition.     

Engineering of hydrophilic and plasmonic properties of Ag thin film by atom beam irradiation

Hydrophilic Ag nanostructures were synthesized by physical vapour deposition of 5 nm Ag thin films followed by irradiation with 1.5 keV Ar atoms. Optical absorbance measurements show a characteristic surface plasmon resonance absorption band in visible region. A blue-shift in absorbance from 532 to 450 nm is observed with increasing fluence from 1 × 10¹⁶ to 3 × 10¹⁶ atoms/cm². Atomic force microscopy was performed for the pristine and irradiated samples to study the surface morphology. The atom beam irradiation induced sputtering and surface diffusion lead to the formation of plasmonic surface. Rutherford backscattering spectroscopy of the pristine and irradiated film indicates that metal content in the film decreases with ion fluence, which is attributed to the sputtering of Ag by Ar atoms. The contact angle measurement demonstrates the possibility of engineering the hydrophilicity by atom beam irradiation.