Catalytically Controlled Ring-Opening Polymerization of 2-Oxo-15-crown-5 for Degradable and Recyclable PEG-Like Polyesters.

Poly(ethylene glycol) (PEG) has been extensively used in diverse applications. However, it is not biodegradable and shows abnormal immune responses. Herein, a fast, controlled, ring-opening polymerization (ROP) of 2-oxo-15-crown-5 (O-15C5) is reported to prepare well-defined PEG-like polyesters, poly(O-15C5). This approach relies on a coordination between the macrocyclic monomer and Na+ that increases the electrophilicity of the carbonyl group of O-15C5 and leads to a fast controlled ROP (dispersity, DM < 1.2). Both computational and mechanistic studies show that the selective Na+ binding to the monomer over poly(O-15C5) allows the ring-opening initiation and propagation to be more energetically favorable than side transesterifications. This is the key to control the challenging entropy-driven ROP of O-15C5. Moreover, with the aid of Na+ and organic base, poly(O-15C5) depolymerized readily into O-15C5 in 2 h. Also, it degraded in a buffer of pH 7.4 by hydrolysis.

Multi-functional liposomes showing radiofrequency-triggered release and magnetic resonance imaging for tumor multi-mechanism therapy.

Recently, nanoplatforms with multiple functions, such as tumor-targeting drug carriers, MRI, optical imaging, thermal therapy etc., have become popular in the field of cancer research. The present study reports a novel multi-functional liposome for cancer theranostics. A dual targeted drug delivery with radiofrequency-triggered drug release and imaging based on the magnetic field influence was used advantageously for tumor multi-mechanism therapy. In this system, the surface of fullerene (C60) was decorated with iron oxide nanoparticles, and PEGylation formed a hybrid nanosystem (C60-Fe3O4-PEG2000). Thermosensitive liposomes (dipalmitoylphosphatidylcholine, DPPC) with DSPE-PEG2000-folate wrapped up the hybrid nanosystem and docetaxel (DTX), which were designed to combine features of biological and physical (magnetic) drug targeting for fullerene radiofrequency-triggered drug release. The magnetic liposomes not only served as powerful tumor diagnostic magnetic resonance imaging (MRI) contrast agents, but also as powerful agents for photothermal ablation of tumors. Furthermore, a remarkable thermal therapy combined chemotherapy multi-functional liposome nanoplatform converted radiofrequency energy into thermal energy to release drugs from thermosensitive liposomes, which was also observed during both in vitro and in vivo treatment. The multi-functional liposomes also could selectively kill cancer cells in highly localized regions via their excellent active tumor targeting and magnetic targeted abilities.

A novel restricted access material combined to molecularly imprinted polymers for selective solid-phase extraction and high performance liquid chromatography determination of 2-methoxyestradiol in plasma samples.

A feasibility study was performed in order to ensure the possibilities in using a restricted access material combined to molecularly imprinted polymers (RAM-MIP) as sorbent material in solid phase extraction (SPE) for clean-up of 2-methoxyestradiol (2-ME) from plasma samples. The MIP with hydrophilic external layer was designed by precipitation polymerization. The polymer was characterized by thermogravimetric analysis (TGA) and scanning electron microscope (SEM). The use of analogs of 2-ME as templates, in combination with a chromatographic separation of the analytes in the sample, overcame the problem of the template bleeding. To demonstrate the property of the RAM-MIP obtained, a comparison of commercially available C18 SPE was performed. The results showed that the RAM-MISPE recoveries were significantly higher than that of C18 SPE for 2-ME in trace concentration. During the extraction process, 2-ME was sufficiently cleaned for further chromatographic analysis with no interferences from template leakage and matrix. Good linearity was obtained from 0.06 to 20 µg mL(-1) with the correlation coefficient r>0.9991. The coefficient of variation of the inter-assay precision was less than 11.9%. The recoveries of 2-ME in rat plasma at three spiked levels were in the range of 99.10-101.00%. Based on the analytical validation results, the proposed method (RAM-MIP off-line SPE/HPLC) can be a useful tool to determine 2-ME in rat plasma samples.