Pyrene-Labeled and Quaternized Chitosan: Synthesis, Characterization, and Its Potential Application for Fluorescently Trackable Nucleic Acid Delivery into Cells.

A chitosan derivative (Pyr-CS-HTAP) having pyrene (Pyr) and N-[(2-hydroxyl-3-trimethylammonium)] propyl (HTAP) units conjugated at C6 and C2 positions, respectively, was synthesized and characterized. Dynamic light scattering and scanning electron microscopy revealed that Pyr-CS-HTAP self-assembled into spherical nanoparticles with a hydrodynamic diameter of 211 ± 5 nm and a ζ-potential of +49 mV. The successful binding of Pyr-CS-HTAP with nucleic acid was ascertained by fluorescence resonance energy-transfer analysis and gel electrophoresis. Pyr-CS-HTAP facilitated the cellular uptake of nucleic acid up to 99%. Co-localization analysis using fluorescence microscopy revealed the endosomal escape of the Pyr-CS-HTAP/nucleic acid complexes and the successful release of the nucleic acid cargoes from the polyplexes into the nucleus. It is strongly believed that Pyr-CS-HTAP can potentially be developed into a fluorescently trackable gene delivery system in the future.

Recyclability of Zinc Palmitate-Based Composites in Fatty Acid Methyl Ester Production from Oil Feedstocks at Varied Acidity.

Zinc hydroxide nitrate (Zn5) is one of the layered metal hydroxide materials, which has been extensively reported as an effective bifunctional catalyst for biodiesel production from acidic oils. This report gives a comprehensive summary of the reactivity of Zn5 in the methanolysis of various oil feedstocks, plant oils, free fatty acids, and other acidic oils. Notably, as evidenced by this work, Zn5 is highly effective in converting acidic oils [palmitic acid/palm oil (PO)] to fatty acid methyl ester (FAME or biodiesel) at high yields ranging from 80 to 95%, withstanding acid content up to 10% without soap formation. The high FAME yields result from complex methanolysis and hydrolysis processes, e.g., transesterification of triglycerides in the PO, esterification of palmitic acid, and hydrolysis of the triglycerides. Despite this, Zn5 is nonrecyclable because it is unstable in the reaction media and transforms into zinc hydroxide nitrate/zinc palmitate (Zn5/ZnP) composites. The Zn5/ZnP composites were suitable for use in FAME production from PO at 100 °C for 2 h by using a methanol-to-oil molar ratio of 30:1, yielding high FAME yields of 97 and 70.7% in the first and fourth cycles, respectively. This study added better insight into how to effectively produce FAME from oil feedstocks of varying acidity by using zinc layered hydroxide- or zinc carboxylate-based materials.

Molecular bowls for inclusion complexation of toxic anticancer drug methotrexate.

We describe the preparation and study of novel cavitands, molecular bowls 16+ and 26+, as good binders of the anticancer drug methotrexate (MTX). Molecular bowls are comprised of a curved tribenzotriquinacene (TBTQ) core conjugated to three macrocyclic pyridinium units at the top. The cavitands are easily accessible via two synthetic steps from hexabromo-tribenzotriquinacene in 25% yield. As amphiphilic molecules, bowls 16+ and 26+ self-associate in water by the nucleation-to-aggregation pathway (NMR). The bowls are preorganized, having a semi-rigid framework comprising a fixed bottom with a wobbling pyridinium rim (VT NMR and MD). Further studies, both experimental (NMR) and computational (DFT and MCMM), suggested that a folded MTX occupies the cavity of bowls wherein it forms π-π, C-H-π, and ion pairing intermolecular contacts but also undergoes desolvation to give stable binary complexes (µM) in water. Moreover, a computational protocol is introduced to identify docking pose(s) of MTX inside molecular bowls from NMR shielding data. Both molecular bowls have shown in vitro biocompatibility with liver and kidney cell lines (MTS assay). As bowl 26+ is the strongest binder of MTX reported to date, we envision it as an excellent candidate for further studies on the way toward developing an antidote capable of removing MTX from overdosed cancer patients.

Amphiphilic Chitosan Bearing Double Palmitoyl Chains and Quaternary Ammonium Moieties as a Nanocarrier for Plasmid DNA.

Amphiphilic chitosan, bPalm-CS-HTAP, having N-(2-((2,3-bis(palmitoyloxy)propyl)amino)-2-oxoethyl) (bPalm) groups as double hydrophobic tails and O-[(2-hydroxyl-3-trimethylammonium)] propyl (HTAP) groups as hydrophilic heads was synthesized and evaluated for its self-assembly properties and potential as a gene carrier. The degree of bis-palmitoyl group substitution (DS bPalm) and the degree of quaternization (DQ) were approximately 2 and 56%, respectively. bPalm-CS-HTAP was found to assemble into nanosized spherical particles with a hydrodynamic diameter (D H) of 265.5 ± 7.40 nm (PDI = 0.5) and a surface charge potential of 40.1 ± 0.04 mV. bPalm-CS-HTAP condensed the plasmid pVAX1.CoV2RBDme completely at a bPalm-CS-HTAP:pDNA ratio of 2:1. The self-assembled bPalm-CS-HTAP/pDNA complexes could enter HEK 293A and CHO cells and enabled gene expression at negligible cytotoxicity compared to commercial PEI (20 kDa). These results suggested that bPalm-CS-HTAP can be used as a promising nonviral gene carrier.

Investigation of key chemical species from durian peduncles and their correlations with durian maturity.

The popularity and high price of durian make quality control in terms of ripeness very important, which in turn depends heavily on harvesting at an appropriate maturity stage. To date, reports on data-driven methods for maturity prediction are scarce, with many rather focusing on ripeness prediction. Herein, we report the first disclosure of key molecular markers in the liquid extract of durian peduncle that can be a predictive tool for maturity. Multiple chromatographic and spectroscopic techniques including TLC, HPLC, PS-MS, LC-MS/MS, and NMR, were used to characterize chemical profiles of the aqueous extracts from peduncles at different ages. Four compounds that show positive correlations with maturity were identified as sucrose, asparagine, arginine, and pipecolic acid, with asparagine as the most abundant species. This finding paves the way for more research of high impact such as the relationship between biochemical reactions in peduncle and pulp, and the development of accurate and non-destructive sensors for maturity prediction.

Electrospun cellulose acetate doped with astaxanthin derivatives from Haematococcus pluvialis for in vivo anti-aging activity.

This research aims to study the release, in vivo anti-aging activity against Caenorhabditis elegans and stability of astaxanthins in a crude acetone extract of Haematococcus pluvialis from electrospun cellulose acetate (CA) nanofibers. The content and 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical scavenging activity of astaxanthins in the crude extract were also determined. The content of astaxanthins was reported in terms of total carotenoid content (TCC) and found to be 10.75 ± 0.16 mg gcE-1. IC50 of DPPH radical scavenging activity for astaxanthins was 233.33 ± 4.18 µg mL-1. It has been well known that astaxanthins are very unstable under environmental conditions, so the electrospinning technique was used to enhance their stability. In order to fabricate CA nanofibers containing a crude acetone extract of H. pluvialis, various solvent systems and percent loading of the crude acetone extract were studied. The optimal solvent system for fabrication of CA nanofibers was the acetone/dimethylformamide (DMF) system (2 : 1 v/v) with incorporation of 0.25% v/v Tween80, resulting in good morphology of CA nanofibers with av. 420 nm diameter. The loading efficiency (%) of the crude astaxanthins extract was 5% w/w of CA. With regard to the results of the in vivo oxidative stress assay, C. elegans pre-treated with 200 µg mL-1 of the crude extract had a survival percent of 56 after administration of 250 mM of paraquat for 8 h. Under phosphate-buffered saline (pH 7.4) containing 10% v/v acetone, the release of astaxanthins from the CA nanofibers loaded with the crude extract exhibited a prolonged profile. The stability of astaxanthins in electrospun CA nanofibers was examined using the freeze-thaw cycle testing through a DPPH radical scavenging assay. It was found that their stability was significantly different (P < 0.05) after the 12th freeze-thaw cycle compared with the crude extract.