Biodegradable reduction and pH dual-sensitive polymer micelles based on poly(2-ethyl-2-oxazoline) for efficient delivery of curcumin.

A series of disulfide-linked amphiphilic polymers polyoxaline-SS-poly(lactide) (PEtOx-SS-PLA) were prepared and self-assembled into nano-micelles in water. The anticancer drug curcumin (Cur) was selected as a model drug, the entrapment of Cur in PEtOx-SS-PLA micelles was investigated and the intracellular transport and release of Cur-loaded micelles was studied in C6 cells. The preparation of Cur-loaded polymer micelles showed that micelle size decreased after drug loading, favoring cell phagocytosis. MTT experiments showed that PEtOx-SS-PLA 52 micelles have a small IC50 (2.05 µg mL-1). The release behavior of PEtOx-SS-PLA 52 drug-loaded micelles in C6 cells showed that polymer micelle enhanced the intracellular release of Cur, and increased the inhibition effect of cancer cells. In a word, these reduction and pH-dual sensitive, biodegradable, hydrophilic shell-discarding PEtOx-SS-PLA micelles have great potential for future tumour administration.

Facile Preparation of Reduction-Responsive Micelles Based on Biodegradable Amphiphilic Polyurethane with Disulfide Bonds in the Backbone.

In this paper, we synthesized a biodegradable amphiphilic polymer of polyurethane-polyethylene glycol with disulfide bonds in the main chain (PEG-PU(SS)-PEG). DLS and SEM showed that the polymer could self-assemble into micelles in aqueous solution and could be used to load the hydrophobic anticancer drug DOX. Intriguingly, drug release in vitro indicated that DOX-loaded PEG-PU(SS)-PEG micelles had good stability under the extracellular physiological environment, but the disulfide bonds broke rapidly and DOX was released quickly under the intracellular reducing conditions. CCK-8 assays showed that DOX-loaded PEG-PU(SS)-PEG micelles had a high in vitro antitumor activity in C6 cells, whereas blank PEG-PU(SS)-PEG micelles were nontoxic to C6 cells. It was also found that there was strong and persistent accumulation of DOX-loaded PEG-PU(SS)-PEG as compared with PEG-PU-PEG both by the cell internalization tests and the flow cytometry measurements. Hence, PEG-PU(SS)-PEG micelles will have a potential use for clinical treatment of cancer in the future.

Flow injection solid-phase extraction using multi-walled carbon nanotubes packed micro-column for the determination of polycyclic aromatic hydrocarbons in water by gas chromatography-mass spectrometry.

A flow injection solid-phase extraction preconcentration system using a multi-walled carbon nanotubes (MWCNTs) packed micro-column was developed for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in water by gas chromatography-mass spectrometry (GC-MS). The preconcentration of PAHs on the MWCNTs was carried out based on the adsorption retention of analytes by on-line introducing the sample into the micro-column system. Methanol was introduced to elute the retained analytes for GC-MS analysis using selected ion monitoring (SIM) mode. Important influence factors were studied in detail, such as sample acidity, sample flow rate, eluent flow rate and volume, dimensions of MWCNTs and amounts of packing material. Limits of detection of 16 PAHs for an extraction of 50 mL water sample were in the range of 0.001-0.15 microg L(-1), and the precisions (RSD) were in the range of 4-14%. The optimized method was successfully applied to the determination of 16 PAHs in surface waters, with recoveries in the range of 72-93% for real spiked sample.

[Study of the sensitizing effects of surfactants on the determination of aluminum by air-acetylene flame atomic absorption spectrometry].

The sensitizing effects of ten surfactants, such as cetyl trimethyl ammonium bromide (CTMAB) and cetyl pyridinium chloride (CPC), on the determination of aluminum were studied. The results showed that the cationic surfactants in the experiment were good sensitizers for the determination of aluminum, and the sensitization time was about 3.0. On the other hand, anionic surfactants had inhibition action, while particular surfactants had no action. With the sensitizing agent of CTMAB, the operating parameters of the spectrometer and the effects of CTMAB, solution medium and interfering elements in aluminum-nickel alloy sample were studied. The content of aluminum in aluminum-nickel alloy sample was determined by air-acetylene flame atomic absorption spectrometry, the linear range of aluminum of this method was 0.10-2.0 g x L(-1), the relative standard deviation was 2.6%, and the recoveries were in the range of 97%-103%.