Table 1.
Evaluation of microencapsulation of aluminum hydroxide (Al(OH)3) in PLGA microspheres as a function of inner Al(OH)3/trehalose phase-to-1 mL oil phase ratio (ASM-2 and ASM-3), microspheres size (ASM-4 and ASM-5), PLGA concentration (ASM-6 and ASM-7), adjuvant type (ASM-8 to ASM-9), Al(OH)3 loading (ASM-10 to ASM-12), and trehalose loading (ASM-13 to ASM-16), and co-incorporation of hydrophobic plasticizers (ASM-1 and ASM-20 to ASM-26).
| Formulation | PLGA concentration (mg/mL) | Inner Al(OH)3/trehalose phase-to-1 mL oil phase ratio (mL) | Trehalose loading (wt%) | Hydrophobic plasticizer loading (wt%) | Microspheres size (μm) | Al(OH)3/CaHPO4 loading (wt%)
|
Al(OH)3 encapsulation efficiency (%)* | Tg (°C) | |
|---|---|---|---|---|---|---|---|---|---|
| Theoretical | Actual Al(OH)3 loading*a | ||||||||
| ASM-1 | 250 | 0.2 | 3.5 | 5 (DEP) | 20-63 | 3.20 | 3.10 ± 0.02 | 96.8 ± 0.7 | 37.4 |
| ASM-2 | 350 | 0.2 | 7.8 | - | 20-63 | 1.85 | 1.80 ± 0.03 | 97.3 ± 1.4 | - |
| ASM-3 | 350 | 0.3 | 7.8 | - | 20-63 | 2.80 | 2.69 ± 0.07 | 96.0 ± 2.6 | - |
| ASM-4 | 350 | 0.2 | 7.8 | - | 20-63 | 1.85 | 1.80 ± 0.03 | 97.3 ± 1.4 | - |
| ASM-5 | 350 | 0.2 | 7.8 | - | 63-90 | 1.90 | 1.79 ± 0.01 | 94.1 ± 0.7 | - |
| ASM-6 | 250 | 0.2 | 7.8 | - | 20-63 | 3.20 | 3.10 ± 0.07 | 96.8 ± 2.1 | - |
| ASM-7 | 350 | 0.2 | 7.8 | - | 20-63 | 3.10 | 2.97 ± 0.02 | 95.8 ± 0.6 | - |
| ASM-8 | 250 | 0.2 | 4.0 | - | 20-63 | 3.20 | - | - | - |
| ASM-9 | 250 | 0.2 | 4.0 | - | 20-63 | 3.20b | - | - | - |
| ASM-10 | 350 | 0.2 | 7.8 | - | 20-63 | 0.88 | 0.83 ± 0.02 | 93.9 ± 2.5 | 42.5 |
| ASM-11 | 350 | 0.2 | 7.8 | - | 20-63 | 1.85 | 1.80 ± 0.03 | 97.3 ± 1.4 | 42.6 |
| ASM-12 | 350 | 0.2 | 7.8 | - | 20-63 | 3.04 | 2.82 ± 0.03 | 92.7 ± 1.0 | 42.7 |
| ASM-13 | 250 | 0.2 | 0 | - | 20-63 | 3.20 | 3.10 ± 0.05 | 96.8 ± 1.5 | - |
| ASM-14 | 250 | 0.2 | 2.5 | - | 20-63 | 3.20 | 3.07 ± 0.09 | 95.8 ± 2.9 | - |
| ASM-15 | 250 | 0.2 | 4.0 | - | 20-63 | 3.10 | 3.02 ± 0.06 | 97.6 ± 2.0 | - |
| ASM-16 | 250 | 0.2 | 10.4 | - | 20-63 | 2.90 | 2.51 ± 0.04 | 86.6 ± 1.3 | - |
| ASM-17 | 350 | 0.2 | 4.0 | 20-63 | 3.20 | ||||
| B-1 | 350 | 0.2 | 4.0 | - | 20-63 | - | - | - | 42.7 |
| ASM-18 | 350 | 0.2 | 4.0 | 20-63 | 3.20 b | - | - | - | |
| ASM-19 | 250 | 0.2 | 3.5 | 0 | 20-63 | 3.20 | 3.04 ± 0.04 | 95.0 ± 1.3 | 42.7 |
| ASM-20 | 250 | 0.2 | 3.5 | 2.5 (DEP) | 20-63 | 3.20 | 3.11 ± 0.04 | 97.2 ± 1.2 | 39.0 |
| ASM-21 | 250 | 0.2 | 3.5 | 10 (DEP) | 20-63 | 3.20 | - | - | 29.1 |
| ASM-22 | 250 | 0.2 | 3.5 | 20 (DEP) | 20-63 | 3.20 | - | - | 20.3 |
| ASM-23 | 250 | 0.2 | 3.5 | 2.5 (TBAC) | 20-63 | 3.20 | - | - | 37.6 |
| ASM-24 | 250 | 0.2 | 3.5 | 5 (TBAC) | 20-63 | 3.20 | - | - | 32.7 |
| ASM-25 | 250 | 0.2 | 3.5 | 10 (TBAC) | 20-63 | 3.20 | - | - | 24.4 |
| ASM-26 | 250 | 0.2 | 3.5 | 20 (TBAC) | 20-63 | 3.20 | - | - | 13.2 |
| PLGA | - | - | - | - | - | - | - | - | 43.0 |