Organo-Clay Nanomaterials Based on Halloysite and Cyclodextrin as Carriers for Polyphenolic Compounds

Antiradical and Antioxidant Activity of Compounds Containing 1,3-Dicarbonyl Moiety: An Overview

Free radicals and oxidants may cause various damages both to the lifeworld and different products. A typical solution for the prophylaxis of oxidation-caused conditions is the usage of various antioxidants. Among them, various classes are found-polyphenols, conjugated polyalkenes, and some sulfur and nitrogen derivatives. Regarding the active site in the molecules, a widely discussed group of compounds are 1,3-dicarbonyl compounds. Among them are natural (e.g., curcumin and pulvinic acids) and synthetic (e.g., 4-hydroxy coumarins, substituted Meldrum's acids) compounds. Herein, information about various compounds containing the 1,3-dicarbonyl moiety is covered, and their antiradical and antioxidant activity, depending on the structure, is discussed.

Fabrication of montmorillonite/ionic liquid composite coated solid-phase microextraction fibers for determination of phenolic compounds in fruit juices by gas chromatography and liquid chromatography

Novel montmorillonite composites including ionic liquid were prepared and utilized as coating materials for solid phase microextraction fibers. Ionic liquids containing amino terminated imidazolium cations with methyl and benzyl groups and hydrophobic anions (bis(trifluoromethylsulfonyl)imide) and hydrophilic anions (bromide and tetrafluoroborate) were intercalated to KSF-montmorillonite using stainless steel wire as support by using the layer-by-layer technique. After optimization of experimental conditions, solid phase microextraction (SPME) coupled to gas chromatography/mass spectrometry (SPME-GC/MS) after derivatization by silylation and high performance liquid chromatography/diode array detector (SPME-HPLC/DAD) were developed for the determination of 16 phenolic compounds. The developed SPME-GC/MS method had wider linearity and lower limit of detection than the developed SPME-HPLC/DAD method with similar repeatability (for 5 runs, less than 4.2 %) for a single fiber. The percentage of the variance between two different fibers was less than 6.0 % in both methods. The developed SPME methods were applied successfully to fresh fruit juices and the relative recoveries and the repeatabilities from spiked fruit juice samples were satisfactorily achieved. The results obtained with both chromatographic methods were in good agreement with each other.

Past, Present and Future Perspectives on Halloysite Clay Minerals

Halloysite nanotubes (HNTs), clay minerals belonging to the kaolin groups, are emerging nanomaterials which have attracted the attention of the scientific community due to their interesting features, such as low-cost, availability and biocompatibility. In addition, their large surface area and tubular structure have led to HNTs' application in different industrial purposes. This review reports a comprehensive overview of the historical background of HNT utilization in the last 20 years. In particular it will focus on the functionalization of the surfaces, both supramolecular and covalent, following applications in several fields, including biomedicine, environmental science and catalysis.

Enhanced superoxide sensitivity in organic field-effect transistor sensors by introducing nanoclay-polyphenol-polymer hybrid sensing channels

Here we report that nanoclay-polyphenol-polymer hybrid sensing channels can greatly enhance the sensitivity for hazardous reactive oxygen species (ROS) in organic field-effect transistor (OFET) sensors. The hybrid layers were prepared by introducing nanoclay into the binary mixtures of poly(3-hexylthiophene) (P3HT) and rutin (a polyphenol) at various weight ratios. The presence of nanoclay improved the P3HT crystallinity in the hybrid films, which contributed to the increased drain current and well-maintained hole mobility even at the reduced amount of charge-transporting P3HT part. At the best composition (P3HT:rutin:nanocaly = 10:1:2 by weight), the OFETs with the hybrid layers were able to sense even 1 nM superoxide (a ROS) and exhibited pronouncedly enhanced sensitivity compared to those without nanoclay. The morphology investigation disclosed that rutin-nanoclay complexes formed in the hybrid films might be responsible for the enhanced sensitivity, because they let more rutin molecules protrude on the surface of channel layers for reactions with superoxide.

Hierarchical bioresponsive nanocarriers for codelivery of curcumin and doxorubicin

Hierarchical responsive nanocarriers have received much attention for targeted delivery of chemotherapeutics. In this study, we designed pH and redox dual-stage responsive nanocarriers in the different delivery stages for co-delivery phosphorylated curcumin (p-Cur) with doxorubicin (Dox). The MSNs nanocarriers were functionalized via specific cleavable PEGylation and hydrogel coating crosslinked by disulfide bonds: MSNs as core load Dox; p-Cur encapsulated in hydrogel coating. In blood circulation, PEGylation endow the nanocarriers with long time during blood circulation; while in tumor tissue, PEG shells could be cleaved due to the pH-sensitive bond and expose the cationic hydrogel coating to improve cell uptake; while inside tumor cells, hydrogel coating could be cleaved due to the GSH and release the drugs. The results showed that the dual-responsive shells endowed the nanocarriers with tumor extracellular pH-triggered cell uptake and specific cancer cell target release. The synergistic effects of the p-Cur and Dox enhanced cellular apoptosis in Hela cells.