Table 3.
Examples of porous spheres prepared by solid & emulsion templating approach.
| Polymer Matrix | Porogen | Preparation Method | Porogen Removal Process | Crosslinkers; Precipitants | APC | Pore Size | Sphere Size | Ref. |
|---|---|---|---|---|---|---|---|---|
| Silk fibroin | Ice crystals ~(−195 °C) |
Microinjection into liquid nitrogen and freeze-drying | Sublimation | - | Basic fibroblast growth factor (bFGF) | 1.5–7.0 µm | 95 µm to 260 µm | [39] |
| Ice crystals (−20 °C) |
w/o emulsion, rapid cooling, and freeze-drying | Sublimation | - | Strontium | (20 ± 5) to (34.8 ± 6.5) μm | - | [26] | |
| Microinjection into liquid nitrogen and freeze-drying | Sublimation | Ethanol-assisted precipitation | - | 0.3–10.7 μm | 208.4–727.3 μm | [102] | ||
| Chitosan | Ice crystals (−20 °C) |
w/o emulsion, low temperature, thermally-induced phase separation, and pH-assisted coacervation |
Drying under vacuum | - | - | 20–50 μm | ca. 150 μm | [74] |
| Ice crystals ~(−195 °C) |
Microinjection into liquid nitrogen and freeze-drying | Sublimation | Saturated sodium tripolyphosphate (STPP) crosslinker | - | <30 μm | <400 μm | [96] | |
| Chitosan/poly(L-glutamic acid) (PLGA) polyelectrolyte complex | Ice crystals (−20 °C) |
w/o emulsion, low temperature, thermally-induced phase separation |
Drying | - | - | (47.5 ± 5.4) μm | 250 μm | [75] |
| Collagen/cellulose | Solid polystyrene | w/o emulsion | Washing with acetone | n-butyl al-cohol as precipitant | BSA | ~198.5 nm | 8–12 μm | [62] |
| Alginate | NaCl | w/o emulsion, freeze drying |
- | Calcium chloride as crosslinker | - | 200–300 nm | ~158 μm | [73] |
| Soy protein | CaCO3 | Solid templating over porogen by incubation | Dissolution by EDTA | Transglutaminase as crosslinker | - | - | 3–12 μm | [61] |
| Silk sericin and hydroxylapatite | Silk sericin | Nucleation and growth of hydroxyapatite, induced by the sericin template in simulated body fluid | - | - | Doxorubicin | - | 1–3 μm | [103] |