Selective binding and controlled release of anticancer drugs by polyanionic cyclodextrins.

The binding stoichiometry, binding constants, and inclusion mode of some water-soluble negatively charged cyclodextrin derivatives, i.e. heptakis-[6-deoxy-6-(3-sulfanylpropanoic acid)]-ß-cyclodextrin(H1), heptakis-[6-deoxy-6-(2-sulfanylacetic acid)]-ß-cyclodextrin(H2), mono-[6-deoxy-6-(3-sulfanylpropanoic acid)]-ß-cyclodextrin (H3) and mono-[6-deoxy-6-(2-sulfanylacetic acid)]-ß-cyclodextrin (H4), with three anticancer drugs, i.e. irinotecan hydrochloride; topotecan hydrochloride; doxorubicin hydrochloride, were investigated by means of 1H NMR, UV-Vis spectroscopy, mass spectra and 2D NMR. Polyanionic cyclodextrins H1-H2 showed the significantly high binding abilities of up to 2.6 × 104-2.0 × 105 M-1 towards the selected anticancer drugs, which were nearly 50-1000 times higher than the corresponding Ks values of native ß-cyclodextrin. In addition, these polyanionic cyclodextrins also showed the pH-controlled release behaviors. That is, the anticancer drugs could be efficiently encapsulated in the cyclodextrin cavity at a pH value similar to that of serum but sufficiently released at an endosomal pH value of a cancer cell, which would make these cyclodextrin derivatives the potential carriers for anticancer drugs.

Metal-organic framework MIL-53(Al) as a solid-phase microextraction adsorbent for the determination of 16 polycyclic aromatic hydrocarbons in water samples by gas chromatography-tandem mass spectrometry.

In this paper, the potential applications of metal-organic framework (MOF) materials as fiber coatings for the solid-phase microextraction (SPME) of polycyclic aromatic hydrocarbons (PAHs) in water samples were explored. Fibers coated with MIL-53(Al, Cr, Fe) materials were fabricated by an adhesive method for SPME. The quantitation was performed by gas chromatography-tandem mass spectrometry (GC-MS/MS) using the multiple reaction monitoring mode. Among the three MIL-53(M) coatings, MIL-53(Al) showed the highest extraction efficiency towards PAHs under the current fabrication procedure. Under optimized conditions, the MIL-53(Al)-coated fiber showed good precision (relative standard deviation <12.5%), low detection limits (0.10 ng L(-1) to 0.73 ng L(-1), S/N = 3), and good linearity (R(2) > 0.98) for aqueous solutions containing 16 PAH . The fiber also offered high thermal and chemical stability. The method developed based on MIL-53(Al) SPME-GC-MS/MS was successfully applied in the analysis of real water samples. Based on the simulation results, the PAHs were adsorbed on MIL-53(Al) primarily through the hydrophobic and π-π interactions between PAHs and the organic linker of the material. The results presented in this paper indicate that water-stable MOF materials have great potential for the SPME of aromatic compounds in water samples.