Glycidyl methacrylate–tert-butyl acrylate copolymers: Synthesis,characterization, and thermal studies

Glycidyl methacrylate was copolymerized with tert-butyl acrylate in bulk at 60°C using benzoyl peroxide as free radical initiator. The copolymer composition was determined by chemical analysis as well as from ¹³C-NMR data. The monomer reactivity ratios were calculated by using the YBR method. The number average sequence length of the copolymers was determined from ¹³C-NMR data and compared with those obtained from reactivity ratios. The intrinsic viscosity of the copolymers was determined in DMF, and thermal stability as well as mechanism of thermal degradation of the copolymers were evaluated.     

Validated LC–MS/MS method for quantitation of a selective JAK1 inhibitor,filgotinib in rat plasma,and its application to a pharmacokinetic study in rats

Filgotinib is a selective JAK1 (Janus kinase) inhibitor, filed in Japan for the treatment of rheumatoid arthritis. In this paper, we report a validated liquid chromatography coupled with tandem mass spectrometry for the quantification of filgotinib in rat plasma using tofacitinib as an internal standard (IS) as per the Food and Drug Administration regulatory guidelines. Filgotinib and the IS were extracted from rat plasma using ethyl acetate as an extraction solvent and chromatographed using an isocratic mobile phase (0.2% formic acid:acetonitrile; 20:80, v/v) at a flow rate of 0.9 mL/min on a Gemini C₁₈ column. Filgotinib and the IS were eluted at ~1.31 and 0.89 min, respectively. The MS/MS ion transitions monitored were m/z 426.3 → 291.3 and m/z 313.2 → 149.2 for filgotinib and the IS, respectively. The calibration range was 0.78–1924 ng/mL. No matrix effect and carryover were observed. Intra- and inter-day accuracies and precisions were within the acceptance range. Filgotinib was stable for three freeze–thaw cycles: on bench-top up to 6 h, in an autosampler up to 21 h, and at −80 ° C for 1 month. This novel method has been applied to a pharmacokinetic study in rats.     

Enantioselective LC–ESI–MS/MS method for quantitation of (−)-lumefantrine and (+)-lumefantrine in mice plasma and application to a pharmacokinetic study

We developed and validated a simple, sensitive, selective, and reliable LC–MS/MS–ESI method for the direct quantitation of lumefantrine (LFN) enantiomers [(−)-LFN and (+)-LFN] in mice plasma as per regulatory guideline. LFN enantiomers and carbamazepine (internal standard) were extracted from mice plasma using Strata X SPE (solid-phase extraction) cartridges. Good resolution between enantiomers was achieved on a Chiralpak IA-3 column using an isocratic mobile phase (0.1% of diethyl amine in methanol), which was delivered at a flow rate of 0.8 mL/min. Detection and quantitation were performed using multiple reaction monitoring mode following the transitions m/z 530.27 → 512.30 and 237.00 → 194.00 for LFN enantiomers and the internal standard, respectively, in the positive-ionization mode. The proposed method provided accurate and reproducible results over the linearity range of 2.39–895 ng/mL for each enantiomer. The intra- and inter-day precisions were in the range of 1.03–6.14 and 6.36–8.70 and 2.03–4.88 and 5.82–11.5 for (−)-LFN and (+)-LFN, respectively. Both (−)-LFN and (+)-LFN were found to be stable under different stability conditions. The method was successfully used to delineate stereoselective pharmacokinetics of LFN enantiomers in mice after an oral administration of rac-LFN (20 mg/kg). The pharmacokinetic results indicated that the disposition of LFN enantiomers was stereoselective in mice.     

Aromatic Foldamer Helices as α-Helix Extended Surface Mimetics

Helically folded aromatic oligoamide foldamers have a size and geometrical parameters very distinct from those of α-helices and are not obvious candidates for α-helix mimicry. Nevertheless, they offer multiple sites for attaching side chains. It was found that some arrays of side chains at the surface of an aromatic helix make it possible to mimic extended α-helical surfaces. Synthetic methods were developed to produce quinoline monomers suitably functionalized for solid phase synthesis. A dodecamer was prepared. Its crystal structure validated the initial design and showed helix bundling involving the α-helix-like interface. These results open up new uses of aromatic helices to recognize protein surfaces and to program helix bundling in water.     

Supportless PdFe nanorods as highly active electrocatalyst for proton exchange membrane fuel cell

The PdFe nanorods (PdFe-NRs) with tunable length were synthesized by an organic phase reaction of [Pd(acac)₂] and thermal decomposition of [Fe(CO)₅] in a mixture of oleyamine and octadecene at 160 °C. They show a better proton exchange membrane fuel cell (PEMFC) performance than commercial Pt/C in working voltage region of 0.80–0.65 V, due to their high intrinsic activity to oxygen reduction reaction (ORR), reduced cell inner resistance, and improved mass transport.     

Estimation of trace elements in some anti-epileptic medicinal plants by PIXE

Trace elemental analysis was carried out in various parts of 10 anti-epileptic medicinal plants using PIXE technique. A 3?MeV proton beam was used to excite the samples and spectra were recorded using a Si(Li) detector. Data analysis was done using Gupix Software. The elements Cl, K, Ca, Ti, Mn, Fe, Ni, Cu, Zn, Br and Sr were identified and their concentrations estimated. The presence of some of these trace elements is correlated with the anti-epileptic curative property of these plants.     

Influence of hole mobility on the response characteristics of p-type nickel oxide thin film based glucose biosensor

RF sputtered p-type nickel oxide (NiO) thin film exhibiting tunable semiconductor character which in turns enhanced its functional properties. NiO thin film with high hole mobility is developed as a potential matrix for the realization of glucose biosensor. NiO thin film prepared under the optimized deposition conditions offer good electrical conductivity (1.5 × 10⁻³ Ω⁻¹-cm⁻¹) with high hole mobility (2.8 cm² V⁻¹ s⁻¹). The bioelectrode (GO_x/NiO/ITO/glass) exhibits a low value of Michaelis–Menten constant (K_m = 1.05 mM), indicating high affinity of the immobilized GO_x toward the analyte (glucose). Due to the high surface coverage (2.32 × 10⁻⁷ mol cm⁻²) of the immobilized enzyme on to the NiO matrix and its high electrocatalytic activity, the prepared biosensor exhibits a high sensitivity of 0.1 mA (mM⁻¹-cm⁻²) and a good linearity from 25 to 300 mg dL⁻¹ of glucose concentration with fast response time of 5 s. Various functional properties of the material (mobility, crystallinity and stress) are found to influence the charge communication feature of NiO thin film matrix to a great extent, resulting in enhanced sensing response characteristics.     

Efficient synthesis of [1,2,3]triazolo[5,1-c][1,4]benzoxazines through palladium-copper catalysis

A wide variety of [1,2,3]triazolo[5,1-c][1,4]benzoxazines were synthesized through palladium-copper catalyzed reactions of 1-azido-2-(prop-2-ynyloxy)benzene with aryl/vinyl iodides. A plausible reaction mechanism has also been proposed.     

Simple UV and visible spectrophotometric methods for the determination of doxycycline hyclate in pharmaceuticals

Doxycycline hyclate (DOX), a broad spectrum antibiotic with activity against a wide range of gram-positive and gram-negative bacteria, is widely used as a pharmacological agent and as an effector molecule in inducible gene expression system. Three simple, selective, rapid, accurate, precise and cost-effective spectrophotometric methods for the determination of DOX in bulk drug and in tablets have been developed and validated. First method (method A) is based on the measurement of absorbance of DOX in 0.1 M HCl at 240 nm. The second method (method B) is based on the measurement of yellow chromogen at 375 nm which is formed in 0.1 M NaOH. The third method is based on the measurement of 2: 1 complex formed between DOX and iron(III) in H₂SO₄ medium, the complex peaking at 420 nm (method C). The optimum conditions for all the three methods are optimized. Beer’s law was obeyed over the ranges 2.5–50.0, 1.50–30.0 and 10–100 g/mL for method A, method B and method C, respectively. The apparent molar absorptivity values are calculated to be 1.03 × 10⁴, 1.73 × 10⁴, and 5.21 × 10³ L mol⁻¹ cm⁻¹ for method A, method B, and method C, respectively. The Sandell sensitivity, limit of detection (LOD) and limit quantification (LOQ) values are also reported. All the methods were validated in accordance with current ICH guidelines. The developed methods were employed with high degree of precision and accuracy for the estimation of total drug content in commercial tablet formulations of DOX.     

Recent advances in ZnO nanostructures and thin films for biosensor applications: Review

Biosensors have shown great potential for health care and environmental monitoring. The performance of biosensors depends on their components, among which the matrix material, i.e., the layer between the recognition layer of biomolecule and transducer, plays a crucial role in defining the stability, sensitivity and shelf-life of a biosensor. Recently, zinc oxide (ZnO) nanostructures and thin films have attracted much interest as materials for biosensors due to their biocompatibility, chemical stability, high isoelectric point, electrochemical activity, high electron mobility, ease of synthesis by diverse methods and high surface-to-volume ratio. ZnO nanostructures have shown the binding of biomolecules in desired orientations with improved conformation and high biological activity, resulting in enhanced sensing characteristics. Furthermore, compatibility with complementary metal oxide semiconductor technology for constructing integrated circuits makes ZnO nanostructures suitable candidate for future small integrated biosensor devices. This review highlights recent advances in various approaches towards synthesis of ZnO nanostructures and thin films and their applications in biosensor technology.