Reference

pH-sensitive liposomes mediate cytoplasmic delivery of encapsulated macromolecules

pH-sensitive liposomes mediate cytoplasmic delivery of encapsulated macromolecules. Straubinger, Robert M.; Duzgunes, Nejat; Papahadjopoulos, Demetrios (Cancer Res. Inst., Univ. California, San Francisco, CA 94143, USA). FEBS Lett., 179(1), 148-54 (English) 1985. CODEN: FEBLAL. ISSN: 0014-5793. DOCUMENT TYPE: Journal CA Section: 63 (Pharmaceuticals) Neg. charged liposomes are endocytosed by the coated vesicle system and accumulate in acidic intracellular vesicles. Liposomes that become unstable at acidic pH improve cytoplasmic delivery of membrane-impermeant macromols. such as calcein (CAL) [1461-15-0] and FITC dextran (18 or 40 kDa). Oleic acid [112-80-1] (OA): phosphatidylethanolamine (PE) (3:7 mol ratio) liposomes become permeable to CAL at pH <7.0. Control liposomes of phosphatidylserine:PE or OA:phosphatidylcholine are stable at pH 4-8. OA:PE liposomes promote cytoplasmic delivery of encapsulated CAL to CV-1 cells, as evidenced by the emergence of diffuse, cytoplasmic CAL fluoroscence. Delivery requires metabolic energy and is partially inhibited by chloroquine or monensin, which raise the pH of intracellular vesicles.

Spectrofluorometric determination of calcium(II) in fruits and vegetables using a calcium-calcein chelate

Spectrofluorometric determination of calcium(II) in fruits and vegetables using a calcium-calcein chelate. Correa, I.; Lopez-Martinez, Maria C.; Garcia-Villanova, R. (Fac. Farm., Univ. Granada, Granada, Spain). An. Bromatol., 29(3), 361-7 (Spanish) 1977. CODEN: ANBRAD. DOCUMENT TYPE: Journal CA Section: 17 (Foods) Ca in fruits and vegetables was detd. by spectrofluorometry using calcein [1461-15-0]. The sample was dried and digested with HNO3-HClO4 and an aliquot of the digested sample was mixed with 1.6 ′ 10-5 M calcein. After 3 min the fluorescence emission at 525 nm was detd., with excitation at 475 nm. Ca could be detd. at concns. of 8-150 mg %.