Table 1.
Particle size distribution (mean diameter and span) and surface charge (zeta potential) of microparticles on the preparation day.
| Formulation | ALG:CS Mass Ratio (w/w) | Chitosan MW | Particle Size, d0.5 (µm) | Span | Zeta Potential (mV) | Production Yield (%) |
|---|---|---|---|---|---|---|
| F0 | Low | 18.5 ± 0.7 | 1.4 ± 0.0 | −20.8 ± 7.9 | n.d. | |
| 4.23:1 | Medium | 260.5 ± 41.3 | 4.3 ± 0.6 | −26.7 ± 4.9 | n.d. | |
| High | 68.1 ± 10.6 | 5.2 ± 2.9 | −17.9 ± 6.8 | n.d. | ||
| F11 | Low | 37.1 ± 0.7 | 9.5 ± 0.5 | +34.0 ± 0.5 | n.d. | |
| 0.4:1 | Medium | 144.4 ± 5.1 | 3.0 ± 0.1 | +47.1 ± 1.7 | n.d. | |
| High | 107.5 ± 10.1 | 4.1 ± 0.9 | +30.4 ± 1.4 | n.d. | ||
| F12 | Low | 39.3 ± 2.0 | 2.6 ± 0.1 | +26.7 ± 1.1 | n.d. | |
| 0.6:1 | Medium | 94.7 ± 3.2 | 3.7 ± 0.2 | +30.9 ± 1.1 | n.d. | |
| High | 65.9 ± 4.4 | 4.1 ± 0.7 | +25.5 ± 0.5 | n.d. | ||
| F13 | Low | 33.8 ± 0.9 | 2.6 ± 0.1 | +22.7 ± 1.6 | 83.6 ± 0.0 | |
| 0.8:1 | Medium | 23.9 ± 0.6 | 2.7 ± 0.3 | +25.6 ± 1.8 | n.d. | |
| High | 51.3 ± 1.8 | 3.3 ± 0.1 | −0.2 ± 0.8 | n.d. | ||
| F14 | Low | 25.9 ± 0.7 | 1.7 ± 0.1 | +16.2 ± 0.6 | 36.8 ± 0.0 | |
| 1:1 | Medium | 139.0 ± 8.5 | 3.2 ± 0.1 | −10.9 ± 1.6 | n.d. | |
| High | 80.6 ± 3.8 | 4.9 ± 0.2 | −25.7 ± 3.3 | n.d. |
F0, microparticles obtained by Method (I) via alginate ionotropic pre-gelation with CaCl2 followed by chitosan addition; F11-F14, microparticles, obtained by Method (II) via chitosan pre-gelation with alginate, followed by TPP (pH 9.0) addition. The pH of alginate and chitosan solutions was initially set to 4.9 and 4.6, respectively. Microparticle size is characterized using the size distribution parameters d0.1, d0.5 and d0.9 (diameter for which 10%, 50% and 90% of the size distribution falls below, respectively) and span (width of particle size distribution, according to the formula (d0.1 − d0.9)/d0.5). Results are expressed as mean and standard deviation (n≥3). n.d., not determined.