**5. Case study**

Case study 1: Enantioselective release of ketoprofen enantiomers form alginate complexes with two ion metal type.

#### **5.1 Drug loading and beads preparation**

An ionotropic method was used to prepare alginate metal complex beads. Racemic ketoprofen was dissolved with sodium alginate in phosphate buffer solution (PBS, pH = 7.4). The final ratio was 1 to 3.75 (w/w) [62–64]. The congealing solution contained a metal chloride (3% w/v) at room temperature. Beads were commonly formed by dropping the alginate solution into the metal chloride. In this case, beads congealed with barium chloride for 3 hours. After that, the congealing continued with the other metal chloride (Ca, Zn, Al, Fe), and the total congealing time 24 hours. Beads were separated and dried at 40°C for 48 h, the method was described in detail in Refs. [62–64]. However, beads were released in PBS with pH = 7.4. 0.2 ml of aliquot was taken at different time intervals, and replenished to the release medium with fresh PBS to maintain the volume to 5 ml. the aliquot was extracted and analyzed by chiral HPLC.

Drug loading (KTP%) and loading efficiency (L%) were determined by the following equations:

$$\text{Drug loading} \left( \text{KTP@} \right) = \left( \text{W}\_{\text{l}} \, \middle| \, \text{W}\_{\text{db}} \right) \* \mathbf{100} \tag{1}$$

$$\text{Loading efficiency} \left(\text{L\%}\right) = \left(\text{W}\_{\text{l}} / \text{W}\_{\text{t}}\right) \* \text{100} \tag{2}$$

Where Wl: loaded KTP weight, Wt: Initial KTP weight, and Wdb: total dried beads weight. The shrinkage ratio was calculated using the formula:


#### **Table 2.**

*Drug loading and loading efficiency results for of the prepared beads.*

#### **Figure 7.**

*ESR for KTP from mixed alginate-metal complexes beads as R/S ratio (blue column), racemic release R/S = 1 (red line).*

$$\text{Shrinkage ratio} \left(\text{S\%}\right) = \left(\left(\text{D}\_{\text{b}} - \text{D}\_{\text{a}}\right) / \text{D}\_{\text{b}}\right) \* \mathbf{100} \tag{3}$$

Where, Db and Da are the diameters of the beads before and after drying respectively.

**Table 2** shows that KTP% values varied from 13.7 for ABaAlK to 15.3 for ABaCaK, while ABaAlK and ABaFeK have the highest shrinkage ratio due to the trivalent ion metal in the formed complex.
