DIRECT ESTIMATION OF INTERACTION POTENTIAL BETWEEN PHOSPHOLIPID LIPOSOME PARTICLE AND GLASS-SURFACE BY EVANESCENT-WAVE LIGHT-SCATTERING MICROSCOPE METHOD

The potential profile of interaction between a charged liposome partic le and glass surface was estimated directly by evanescent wave light s cattering microscopy (EVLSM), which can measure the distance between t he particle and surface as a function of time at intervals in the orde r of less than millisecond. The minimum of the potential profile, whic h is a result of electrostatic repulsion and attraction by gravity, wa s clearly observed. Liposome particles of different surface charge wer e prepared by using charged and apparently neutral lipid molecules at various mixing ratios. With the increase in the amount of negatively c harged liposomes, the potential minimum in interaction potential shift ed further away from the glass surface, reflecting an increase of elec trostatic repulsion between them. The potential profile clearly showed ionic strength dependence. We found that the electrostatic interactio n is an important factor for particle-surface interaction and that EVL SM is a powerful tool for quantitative estimation of particle-wall int eraction. (C) 1998 Elsevier Science B.V. All rights reserved.