Sensitive, accurate and simple liquid chromatography-tandem mass spectrometric method for the quantitation of amphotericin B in human or minipig plasma

Amphotericin B (AMB) is still the standard care for systemic fungal infections. This paper describes a sensitive, accurate and simple liquid chromatography-tandem mass spectrometry method to quantify AMB in human or minipig plasma. Samples were prepared through protein precipitation by adding methanol-acetonitrile (1:3, v/v) to either human or minipig plasma. High-performance liquid chromatography separation was conducted on a 10-cm Gemini C18 column with a 7-min gradient of mobile phase comprised of buffer A (0.1% formic acid aqueous solution) and buffer B (methanol-acetonitrile, 2:3, v/v). AMB was detected through multiple reaction monitoring (MRM) with a mass transition of 924.60 → 743.30 and the internal standard paclitaxel was detected through MRM with a mass transition of 854.30 → 286.10. The method had a linear range between 5 and 2500 ng/mL with lower limit of quantitation of 3 ng/mL. The overall recovery was 113 ± 4.06% in human plasma and 94.8 ± 7.38% in minipig plasma. The method has been validated and applied for AMB pharmacokinetic study in both human and minipig plasma.     

Molecular-mediated crystal growth of PbTiO3 nanostructure on silicon substrate

A simple approach based on an organically modified sol-gel process has been developed to fabricate PbTiO₃ (PT) nanocrystals on Si (1 0 0) substrate, where the amorphous powder modified by acetylacetone (acac) was used as precursor. After dropping the amorphous powder precursor prepared by freeze-drying process, PT nanocrystals on Si (1 0 0) substrate were obtained after heat treatment at 720 °C for 30 min in air. PT nanocrystals have been detected by XRD to be tetragonal perovskite structure. With the increase of acac/Pb molar ratio, the relative (1 0 0)/(0 0 1) diffraction peak intensity gradually increases, which probably suggested an oriented growth of PT nanocrystal along [1 0 0] on Si (1 0 0) substrates. In addition, Atomic force microscopy (AFM) results indicated that the height and the average lateral size of PT nanocrystal increased and then decreased as the acac/Pb molar ratio increased. Piezoelectric force microscopy (PFM) results demonstrated that all the samples show obvious piezoelectric activity. These results implied that the acetylacetone molecular mediated the growth of PT nanocrystals on Si (1 0 0) substrates possibly by the acac/Pb molar ratio. This simple method has been suggested to be attractive for tailoring an oriented growth of the nanostructures of perovskite oxide systems on Si substrates.