Table 1.
Characterization of bioreducible poly(disulfide amine)s: apparent number average molecular weight (Mn), apparent weight average molecular weight (Mw), polydispersity index (PDI), buffering capacity in pH range 7.4 – 5.1, protonation degree (α) and apparent pKa.
| Polymers | Mn (kDa)a | Mw (kDa)a | PDIa | Buffering Capacity (pH 5.1-7.4) (%)b | Protonation Degree (α, %) | Apparent pKa | ||
|---|---|---|---|---|---|---|---|---|
| pH 5.1 | pH 7.4 | pKa1 (α=25%) | pKa2 (α=75%) | |||||
| Poly(CBA-SP) | 4.16 | 4.81 | 1.16 | 38.0 | 76.5 | 52.5 | 9.53 | 5.85 |
| Poly(CBA-APPD) | 3.36 | 4.23 | 1.26 | 36.0 | 76 | 54.5 | 9.57 | 5.76 |
| Poly(CBA-APED) | 4.62 | 6.12 | 1.33 | 26.0 | 73 | 55 | 9.63 | 4.75 |
| Poly(CBA-AEPD) | 3.64 | 4.19 | 1.15 | 28.0 | 71.5 | 53.5 | 9.51 | 4.89 |
| Poly(CBA-TETA) | 3.17 | 3.80 | 1.20 | 28.0 | 72 | 55 | 9.55 | 5.05 |
| bPEI (25 kDa) | – | – | – | 22.0 | 69 | 52 | – | – |
FPLC Conditions: poly(disulfide amine)s are dissolved in 0.5 mL Tris buffer (pH 7.4) at a concentration of 25 mg/mL. Superose 12 column is used to measure the apparent molecular weights, which are used to calculate polydispersity. Flow rate is 0.5 mL/min. Standard calibration is calculated by using poly[N-(2-hydroxypropyl)methacrylamide;] (pHPMA).
Acid-base titration conditions: poly(disulfide amine)s and bPEI (5 mmol amino nitrogen atoms) in 10 mL of 0.1 M NaCl was titrated by 0.01 M HCl solution from pH 11.0 to 3.0. The absolute weight average molecular weight of bPEI is 25kDa.