Fabrication of poly(ϵ-caprolactone)/paclitaxel (core)/chitosan/zein/multi-walled carbon nanotubes/doxorubicin (shell) nanofibers against MCF-7 breast cancer

In the present study, paclitaxel (PTX), multi-walled carbon nanotubes (MWCNTs), and doxorubicin (DOX) have been simultaneously doped into the poly(ϵ-caprolactone) (PCL)/chitosan/zein core-shell nanofibers to increase its cytotoxicity for MCF-7 breast cancers killing. The physico-chemical properties of synthesized nanofibers were determined by scanning electron microscope, Fourier-transform infrared spectroscopy, tensile strength, and degradation rate determinations. The in vitro release studies demonstrated the sustained release of drugs from core-shell nanofibrous scaffold. The cytotoxicity and compatibility of core-shell nanofibers were investigated by their treating with MCF-7 breast cancer cells and L929 normal cells, respectively. PCL/PTX/chitosan/zein/MWCNTs/DOX core-shell nanofibers containing 1 wt% MWCNTs, 100 μg ml⁻¹ DOX and 100 μg ml⁻¹ PTX had a high biocompatibility with a 84% MCF-7 cancer cells killing. The in vivo studies revealed the synergic effects of MWCNTs and anticancer drugs on the tumor inhibition. This method could be considered as a new way for developing of MWCNTs loaded-nanofibers for cancer treatment in future.     

Analysis of tamoxifen and its main metabolites in plasma samples of breast cancer survivor female athletes: Multivariate and chemometric optimization

A sensitive method based on liquid chromatography combined with a diode array detector was developed and validated to simultaneously determine tamoxifen, and its active metabolites N-desmethyltamoxifen, 4-hydroxytamoxifen, and endoxifen in human plasma samples. The green and sustainable vortex-assisted dispersive liquid-phase microextraction technique based on the natural hydrophobic deep eutectic solvent was used for the extraction and preconcentration of the analytes. Chemometrics and multivariate analysis were used to optimize the independent variables including the type and volume of deep eutectic solvent, extraction time, and ionic strength. Under optimal conditions, calibration curves were linear in a suitable range with the lower limits of quantification (0.8–10.0 μg/L), which covered the relevant concentrations of the analytes in plasma samples for a clinical study. Intra- and interday precision evaluated at three concentrations for the analytes were lower than 8.2 and 12.1%, respectively. Accuracy was in the range of 94.9–104.7%. The applicability of the developed method on human plasma samples illustrated the range 45.1–72.8, 98.4–128.3, 0.9–1.2, and 2.7–6.1 μg/L for tamoxifen, N-desmethyltamoxifen, 4-hydroxytamoxifen, and endoxifen, respectively. The validated method can be effective for the pharmacokinetics, pharmacodynamics, and therapeutic drug monitoring studies of tamoxifen and its main metabolites in biological fluids.     

Insights into Light‐driven DNA Repair by Photolyases: Challenges and Opportunities for Electronic Structure Theory

Ultraviolet radiation causes two of the most abundant mutagenic and cytotoxic DNA lesions: cyclobutane pyrimidine dimers and 6‐4 photoproducts. (6‐4) Photolyases are light‐activated enzymes that selectively bind to DNA and trigger repair of mutagenic 6‐4 photoproducts via photoinduced electron transfer from flavin adenine dinucleotide anion (FADH^?) to the lesion triggering repair. This review provides an overview of the sequential steps of the repair process, that is light absorption and resonance energy transfer, photoinduced electron transfer and electron‐induced splitting mechanisms, with an emphasis on the role of theory and computation. In addition, theoretical calculations and physical properties that can be used to classify specific mechanism are discussed in an effort to trace the fundamental aspects of each individual step and assist the interpretation of experimental data. The current challenges and suggested future directions are outlined for each step, concluding with a view on the future.     

Microwave Assisted Synthesis of Dibenzoxazepines

Dibenzo[b,f][1,4]oxazepine derivatives were synthesized in good yields and short reaction times by the reaction of 2‐chlorobenzaldehydes and 2‐aminophenoles in basic conditions under microwave irradiation.     

Modified dispersive liquid-liquid microextraction for pre-concentration of benzene, toluene, ethylbenzene and xylenes prior to their determination by GC

We have developed a modified method for the extraction and preconcentration of benzene, toluene, ethylbenzene and xylenes (BTEX) in aqueous samples. It based on dispersive liquid-liquid microextraction along with solidification of floating organic microdrops. The dispersion of microvolumes of an extracting solvent into the aqueous occurs without dispersive solvent. Various parameters have been optimized. BTEX were quantified via GC with FID detection. Under optimized conditions, the preconcentration factors range from 301 to 514, extraction efficiencies from 60 to 103 %, repeatabilities from 2.2 to 4.1 %, and intermediate precisions from 3.5 to 7.0 %. The relative recovery for each analyte in water samples at three spiking levels is >85.6 %, with a relative standard deviation of <7.4 %.

A new method for the synthesis of amides from imines

An efficient and straightforward method for the synthesis of amides by the reaction of imines and anhydrides in the presence of Et₃SiH/Zn is reported. Mild reaction conditions, good yields of products, short reaction times, and operational simplicity are advantages of this procedure.