Polyhedral oligomeric silsesquioxane grafted silica-based core-shell microspheres for reversed-phase high-performance liquid chromatography.

Polyhedral oligomeric silsesquioxane (POSS) was used to modify spherical silica to fabricate core-shell POSS@SiO2 microspheres. The material was characterized by Fourier transform infrared experiments, scanning electron microscopy, thermogravimetric analysis and elemental analysis. The material was also used as a stationary phase for HPLC separation. The POSS@SiO2 column exhibits a reverse-phase liquid chromatography (RPLC) retention mechanism. The column efficiency of alkylbenzenes reaches 67,200 plates·m-1. The POSS@SiO2 column was also utilized for separation of basic anilines and polycyclic aromatic hydrocarbons. Compared with the commercial C8 column, the POSS@SiO2 column exhibits enhanced separation selectivity. The column was also used for the separation of synthetic cytokinins 6-benzylaminopurine and 6-furfurylaminopurine in bean sprout after extraction. In addition, the methacrylate groups on the surface of the POSS@SiO2 microsphere were further functionalized so as to facilitate the fabrication of versatile stationary phases with various separation mechanisms. Graphical abstract Schematic presentation of the two-step fabrication of polyhedral oligomeric silsesquioxane grafted silica-based (POSS@SiO2) core-shell microspheres for use in HPLC.

A small molecule screening strategy with validation on human leukemia stem cells uncovers the therapeutic efficacy of kinetin riboside.

Gene regulatory networks that govern hematopoietic stem cells (HSCs) and leukemia-initiating cells (L-ICs) are deeply entangled. Thus, the discovery of compounds that target L-ICs while sparing HSC is an attractive but difficult endeavor. Presently, most screening approaches fail to counter-screen compounds against normal hematopoietic stem/progenitor cells (HSPCs). Here, we present a multistep in vitro and in vivo approach to identify compounds that can target L-ICs in acute myeloid leukemia (AML). A high-throughput screen of 4000 compounds on novel leukemia cell lines derived from human experimental leukemogenesis models yielded 80 hits, of which 10 were less toxic to HSPC. We characterized a single compound, kinetin riboside (KR), on AML L-ICs and HSPCs. KR demonstrated comparable efficacy to standard therapies against blast cells in 63 primary leukemias. In vitro, KR targeted the L-IC-enriched CD34(+)CD38(-) AML fraction, while sparing HSPC-enriched fractions, although these effects were mitigated on HSC assayed in vivo. KR eliminated L-ICs in 2 of 4 primary AML samples when assayed in vivo and highlights the importance of in vivo L-IC and HSC assays to measure function. Overall, we provide a novel approach to screen large drug libraries for the discovery of anti-L-IC compounds for human leukemias.

Cauliflower-like resin microspheres with tuneable surface roughness as solid-phase extraction adsorbent for efficient extraction and determination of plant growth regulators in cucumbers.

New cauliflower-like phloroglucinol-glyoxylic acid resin microspheres (PGRMs) with controllable diameters and tuneable surface roughness were prepared using a one-step environmentally-friendly method without a catalyst. The PGRMs obtained exhibited a rough surface, narrow size distribution, and excellent adsorption capacity for polar compounds. The PGRMs were employed as an adsorbent for solid phase extraction (SPE) of kinetin (KT) and 6-benzyladenine (6-BA) in cucumbers and demonstrated better extraction recoveries and purification efficiency than phloroglucin-formaldehyde resin and common commercial adsorbents. Our PGRMs-SPE-HPLC method showed good linearity (r ≥ 0.9997) ranging from 0.04 to 4.00 µg/g for KT and 6-BA, and recoveries at three spiked concentration ranged from 77.8% to 104.4% with RSDs ≤ 6.8%. This PGRMs-SPE-HPLC method was applied successfully to determine of KT and 6-BA in cucumbers.

Simultaneous determination of different endogenetic plant growth regulators in common green seaweeds using dispersive liquid-liquid microextraction method.

A simple and rapid HPLC-based method was developed for simultaneous determination of major classes of plant growth regulators (PGRs) in Monostroma and different species of Ulva. The plant growth regulators determined included gibberellic acid (GA(3)), indole-3-acetic acid (IAA), abscisic acid (ABA), indole-3-butyric acid (IBA), salicylic acid and kinetin riboside (KR) and their respective elution time was 2.75, 3.3, 3.91, 4.95, 5.39 and 6.59 min. The parameters optimized for distinct separation of PGRs were mobile phase (60:40 methanol and 0.6% acetic acid in water), column temperature (35°C) and flow rate (1ml/min). This method presented an excellent linearity (0.2-100µg/ml) with limit of detection (LOD) as 0.2µg/ml for ABA, 0.5µg/ml for KR and salicylic acid, and 1µg/ml for IAA, IBA and GA(3). The precision and accuracy of the method was evaluated after inter and intra day analysis in triplicates. The effect of plant matrix was compensated after spiking and the resultant recoveries estimated were in the range of 80-120%. Each PGR thereby detected were further characterized by ESI-MS analysis. The method optimized in this study determined IBA along with IAA for the first time in the seaweed species investigated except Ulva linza where the former was not detected. In all the species studied, ABA level was detected to be the highest while kinetin riboside was the lowest. In comparison to earlier methods of PGR analysis, sample preparation and analysis time were substantially reduced while allowing determination of more classes of PGRs simultaneously.