3.4.4. In vitro Drug Release from Hydrogels

UV-spectrophotometer (Agilent Technologies, 89090A, Santa Clara, CA, USA) was used to measure the in vitro DOX release from the hydrogels. Approximately, 30 mg of DOX-loaded hydrogel specimens were immersed in PBS (pH 4.5, 6.0, and 7.4) and gently incubated at 37 °C. At specified time intervals, 2 mL of DOX released buffer solution was withdrawn and replenished with 2 mL of fresh buffer to preserve the buffer volume constant. The drug release was measured. The release and concentration of DOX were determined by using UV spectrophotometer at 480 nm. The DOX release from specimens against release time was validated. Triplicate drug release experiments were carried. The following formula was used to calculate the drug release (%).