Influence of crosslinkerconcentration onthecharacteristics of erythropoietin-alginate microspheres

Context: Microspheres have several advantages including protecting proteins from degradation and clearance after administration and produce a long-term therapeutic effect. Erythropoietin as a neuroprotectant agent has protein-like properties, which are susceptible to degradation and have low in vivo bioavailability. Microspheres formulations is one of potential drug delivery system for erythropoietin. Aims: To evaluate the effect of CaCl₂ concentration on the characteristics (particle size, morphology, swelling index, and yield) of erythropoietin-alginate microspheres. Methods: Erythropoietin-alginate microspheres prepared by ionotropic gelation method with aerosolization technique using sodium alginate as polymer and CaCl₂ as crosslinker were dried using freeze drying method with maltodextrin as lyoprotectant. The concentrations of alginate used were 2%, and CaCl₂ concentrations were 0.5 M(F₁), 0.75 M(F₂) and 1 M(F₃). Results: Results showed smooth and spherical microspheres for all formula with average particle size were 3.23 ± 0.05 μm (F₁); 2.99 ± 0.07 μm (F₂); and 2.86 ± 0.03 μm (F₃). Mass swelling index at 24 h were 1.25 ± 0.10 (F₁), 1.18 ± 0.11 (F₂), and 1.11 ± 0.10 (F₃); at 30 h were 2.00 ± 1.25 (F₁), 1.85 ± 0.14 (F₂), and 1.72 ± 0.15 (F₃) while particle size swelling index at 24 h were 1.15 ± 0.10 (F₁), 1.11 ± 0.10 (F₂), and 0.97 ± 0.10 (F₃); at 30 h were 1.81 ± 0.09 (F₁), 1.73 ± 0.15 (F₂), and 1.54 ± 0.14 (F₃). Respectively yield percentages were 77.76 ± 6.49, 80.01 ± 3.53, and 82.97 ± 4.22. By using One Way ANOVA, it was found that there were significantly differences between three formulas. Conclusions: The particle size of formulas decreased by increasing concentration of CaCl₂, whereas no significant difference on swelling index and yield from microspheres with increasing CaCl₂ concentration simultaneously.