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Abstract Background Camptothecin (CPT) has recently attracted increasing attention as a promising anticancer agent for a variety of tumors. But the clinical application is largely hampered by its extreme water insolubility and unpredictable side effect. It is essential to establish an efficient and safe protocol for the administration of CPT versus melanoma. Methods Camptothecin was encapsulated with N-trimethyl chitosan (CPT-TMC) through microprecipitation and sonication. Its inhibition effect on B16-F10 cell proliferation and induction of apoptosis was evaluated by MTT assay and flow cytometric analysis in vitro. The anti-tumor activity of CPT-TMC was evaluated in C57BL/6 mice bearing B16-F10 melanoma. Tumor volume, tumor weight and survival time were recorded. Assessment of apoptotic cells within tumor tissue was performed by TUNEL assay. Antiangiogenesis and antiproliferation effects of CPT-TMC in vivo were conducted via CD31 and PCNA immunohistochemistry, respectively. Results CPT-TMC efficiently inhibited B16-F10 cells proliferation and increased apoptosis in vitro. Experiment group showed significant inhibition compared with free CPT-treated group (81.3% vs. 56.9%) in the growth of B16-F10 melanoma xenografts and prolonged the survival time of the treated mice (P < 0.05). Decreased cell proliferation, increased tumor apoptosis as well as a reduction in angiogenesis were observed. Conclusions Our data suggest that N-trimethyl chitosan-encapsulated camptothecin is superior to free CPT by overcoming its insolubility and finally raises the potential of its application in melanoma therapy.

In this work, the binding characteristics of methylene blue (MB) to human serum albumin (HSA) and the influence of Cu2+ and Fe3+ on the binding affinity ofMBto HSAwere investigated using fluorescence, absorption, circular dichroism(CD) spectroscopy andmolecular modelling. The results of competitive binding experiments using the site probes ketoprofen and ibuprofen as specific markers suggested that MB was located in site I within sub-domain IIA of HSA. The molecular modelling results agreed with the results of competitive site marker experiments and the results of CD spectra indicated that the interaction betweenMB and HSA caused the conformational changes in HSA. The binding affinity ofMB to HSAwas enhanced but to a different extent in the presence of Cu2+ and Fe3+, respectively, which indicated that the influence of different metal ions varied. Enhancement of the binding affinity of MB to HSA in the presence of Cu2+ is due to the formation of Cu2+-HSA complex leading to the conformational changes in HSA, whereas in the presence of Fe3+, enhancement of the binding affinity is due to the greater stability of the Fe3+-HSA-MB complex compared with the MB-HSA complex. [ABSTRACT FROM AUTHOR]

The pure γ-Ca 2SiO 4 (γ-C 2S) phase was prepared at 1623 K of calcining temperature, 10 h of holding time and furnace cooling. The β-C 2S phase was obtained through γ-C 2S conversion with the following calcination system which was adopted at 1473 K of calcining temperature, 1 h of holding time and then water-cooling. The conversion rate of γ-C 2S was studied by the Rietveld quantitative laboratory X-ray powder diffraction supported by synchrotron X-ray diffraction images. The refinement results show that the final conversion rate of γ-C 2S is higher than 92%. The absolute error of the γ-C 2S conversion rate between two Rietveld refinements (sample with or without α-Al 2O 3) is 3.6%, which shows that the Rietveld quantitative X-ray diffraction analysis is an appropriate and accurate method to quantify the γ-C 2S conversion rate. [ABSTRACT FROM AUTHOR]