Table 1. Properties of PLDs with Different Intraliposomal Ammonium and Sulfate Concentrations.
| concn (mM) | size (nm) by DLS | PDI | ΔpH | loading efficiency (%) | [Dox] apparent (mM) | [Dox] inside liposome (mM)a | [SO42–] total (mM) | [NH4+] total (mM) | [NH4+] residual (mM)b | |
|---|---|---|---|---|---|---|---|---|---|---|
| gradient composition | ||||||||||
| ammonium sulfate (AS) | 100 | 82.1 | 0.06 | N.D. | 90.2 | 3.11 | 182.9 | 100 | 200 | 17.1 |
| 150 | 81.2 | 0.07 | 0.5 | 77.3 | 2.67 | 157.1 | 150 | 300 | 142.9 | |
| 200 | 76.9 | 0.05 | 1.2 | 91.7 | 3.16 | 185.9 | 200 | 400 | 214.1 | |
| 250 | 78.3 | 0.06 | 1.7 | 93.3 | 3.22 | 189.4 | 250 | 500 | 310.6 | |
| 300 | 78.4 | 0.05 | 1.8 | 92.5 | 3.19 | 187.6 | 300 | 600 | 412.4 | |
| mixture solutions | ||||||||||
| AS + ammonium chloride | 100 | 84.2 | 0.07 | N.D. | 63.3 | 2.18 | 128.2 | 100 | 350 | 221.8 |
| 150 | ||||||||||
| AS + sodium sulfate (SS) | 100 | 86.4 | 0.07 | N.D. | 90.1 | 3.11 | 182.9 | 250 | 200 | 17.1 |
| 150 |
a
Trapped aqueous volume of 16 mg/mL PLD total lipids measured based on intraliposomal sulfate amounts measured by ion chromatography (see Methods section) is 1.7% of total dispersion volume.
b
[NH4+]residual = [NH4+]total – [Dox]inside liposome, considering 1:1 mole exchange ratio of doxorubicin to ammonium during remote loading.