Abstract: Stable sub 500 nm bovine serum albumin (BSA) microsphere suspensions were produced by controlled addition of acetone and ethanol to an aqueous solution of BSA, followed by stabilization process of the formed microspheres at an elevated temperature. Microspheres produced by this acetone-ethanol heat denaturation method were stabilized at relatively low temperatures (70~75 ºC) over a short period of time (20 min). The acetone-ethanol heat denaturation method, in comparison with the traditional oil/water technique for preparation of albumin microspheres, which requires high temperature (over 100 ºC) and longer heating time (more than 30 min) for stabilization, offers a number of advantages. This report describes the influence of process conditions, such as ratios of acetone to ethanol to BSA aqueous solution, heating time and heating temperature, on microsphere formation and their stability. A loading efficiency of 40% rose bengal was achieved. Rose bengal release rates from these microspheres in phosphate buffered saline medium at 37 ºC were dependent on microsphere stabilities and 25% to 60% of initial loading drug were released in 15 days.

Key words: Bovine serum albumin, Microsphere manufacture, Protein denaturation, Rose bengal, Release study, Microencapsulation