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Delivery of nitroxide spin label to cultured cells by liposomes.

Magnetic resonance in medicine (1988-10-01)
H C Chan, R L Magin, H M Swartz
ABSTRACT

The positively charged nitroxide spin label, 2,2,6,6-tetramethyl-piperidine-N-oxyl-4-trimethylammonium (Cat1), was encapsulated in two types of liposomes, phosphatidylserine/phosphatidylcholine (PS/PC) and phosphatidylserine/distearoylphosphatidylcholine/dipalmitoylphosphatidyl choline (PS/DSPC/DPPC). The liposomes were incubated with mouse thymus-bone marrow (TB) cells to study the uptake and metabolism of nitroxides entrapped in liposomes. The effects of temperature, metabolic inhibitors, and fixation of cells were investigated. The results indicate that different mechanisms are involved in the uptake of these two types of liposomes. PS/PC liposomes interact predominantely with the plasma membrane of TB cells and release Cat1 continuously, whereas the majority of PS/DSPC/DPPC liposomes are taken into the cells intact via endocytosis. These findings suggest that it may be possible to deliver nitroxides selectively, either to the membrane of cells or to their interior by manipulating the lipid composition of the liposomes. This study also found that the rate of reduction of Cat1 delivered using liposomes was increased under hypoxic conditions. Thus, the use of liposomes for in vivo delivery of nitroxides has the potential to provide NMR contrast that reflects different metabolic conditions.

MATERIALS
Product Number
Brand
Product Description

Avanti
16:0-5 Doxyl PC, Avanti Research - A Croda Brand 810601P, powder
Avanti
16:0-10 Doxyl PC, Avanti Research - A Croda Brand 810603P, powder
Avanti
16:0-12 Doxyl PC, Avanti Research - A Croda Brand 810600P, powder
Avanti
16:0-10 Doxyl PC, Avanti Research - A Croda Brand 810603C
Avanti
16:0-5 Doxyl PC, Avanti Research - A Croda Brand 810601C
Avanti
16:0-7 Doxyl PC, Avanti Research - A Croda Brand 810602P, powder
Avanti
16:0-16 Doxyl PC, Avanti Research - A Croda Brand 810604P, powder
Avanti
16:0-16 Doxyl PC, Avanti Research - A Croda Brand 810604C