Preparation and in vitro targeting of sterically stabilized liposomes modified with chimeric TNT-3 monoclonal antibody / 药学学报

<p><b>AIM</b>To prepare sterically stabilized liposomes modified with chimeric TNT-3 monoclonal antibody (chTNT-3) and investigate their immunoreactivity and in vitro targeting.</p><p><b>METHODS</b>An end-group functionalized polyethylene glycol-lipid derivative (pyridylthiopropionoylamino-polyethylene glycol-hydrogenated soy phosphatidylethanolamine, PDP-PEG-HSPE) was synthesized and incorporated to sterically stabilized liposomes. After mild thiolysis of the PDP groups by dithiothreitol, liposomes were covalently linked with maleimide-derivatized chTNT-3 and formed sterically stabilized immunoliposomes. Coupling efficiency, antibody density, size distribution, immunoreactivity of chTNT-3-modified sterically stabilized liposomes (chTNT-3-SLs) and specific binding properties of the chTNT-3-SLs to fixed Raji cells were determined, separately.</p><p><b>RESULTS</b>Higher initial Ab/PDP-PEG-HSPE molar ratios resulted in higher antibody density on the surface of liposomes but lower coupling efficiency. The optimal coupling efficiency of 71% was obtained while antibody density in liposome was 106 microg antibody/micromol phospholipids (as initial antibody/PDP-PEG-HSPE = 1 : 10). The chTNT-3-SLs had a narrow size distribution after extrusion and the mean size of this immunoliposomes was (115 +/- 33) nm. The immunoreactivity of chTNT-3 can be preserved after efficient attachment of maleimide-derivatized chTNT-3 to the surface of liposomes. But calculated per antibody concentration, the immunoreactivity of chTNT-3-SLs would obviously decrease compared to that of chTNT-3 or chTNT-3 derivatives. Significantly higher binding of chTNT-3-SLs to fixed Raji cells directed by chTNT-3 was obtained compared to other preparations in serial dilutions (P < 0.01).</p><p><b>CONCLUSION</b>chTNT-3-SLs prepared by PDP-PEG-HSPE method remained most immunoreactivity of chTNT-3 and was able to bind nuclear antigens in vitro.</p>

Spectrophotometry on measuring the size of liposomes / 药学学报

<p><b>AIM</b>To establish a spectrophotometric method for measurement of the sizes of liposomes for evaluating physical stability of liposomes.</p><p><b>METHODS</b>The sterically stabilized liposomes (SLs) were prepared by ethanol injection method and extrusion method. The mean cumulant diameters (D) of the vesicles were determined by electron microscopy and dynamic light scattering. On the basis of Rayleigh-Gans-Debye theory, the absorbance at 436 nm per unit lipid concentration (A436 nm/Cp) was measured as a function of vesicle diameter.</p><p><b>RESULTS</b>log(A436 nm/Cp) was closely related to logD (r2 > or = 0.93, n = 5).</p><p><b>CONCLUSION</b>The absorbance of liposomes reflect their relative sizes and can be used to evaluate physical stability of liposomes.</p>