Viscoelastic Characterisation of Calcium Alginate Gels Intended for Wound Healing

Abstract

Calcium alginate gels were prepared and characterised in terms of their viscoelastic properties. For all the gel samples, the storage or elastic modulus (G) increased with increase in frequency of oscillation of the samples whilst the dynamic viscosity (It') decreased with increase in frequency of oscillation. An increase in the concentration of Ca2+ caused an increase in the elastic modulus of the gels. The G' of gels prepared with different grades of alginate increased in the order of increasing viscosities of the alginate grades (SOBALG PH 160 <SOBALG PII 165< SOBALGPII 167). An increase in the concentration of sodium alginate resulted in the formation of gels with reduced G' values. There was no significant difference (p > 0.05) between the viscoelastic properties of gels prepared using Co2+ from two different sources (chloride and lactate). The G' of calcium alginate gels was significantly reduced (51 - 95%) when prepared with sodium alginate and calcium solutions autoclaved at 121 °C for 15 min. The longer the autoclaving time the greater the reduction in the G' of the gels. Ageing of calcium alginate gels resulted in a gradual increase in G' of the gels over a 24h period. The viscoelastic properties of calcium alginate gels were dependent on the concentration of Ca2+and sodium alginate, viscosity grade of sodium alginate, autoclaving and ageing of the gels formed.