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Vacuum-Induced Surface Freezing for the Freeze-Drying of the Human Growth Hormone: How Does Nucleation Control Affect
Irene Oddone1, Andrea Arsiccio1, Chinwe Duru2
1Department of Applied Science and Technology, Politecnico di Torino, 24 corso Duca degli Abruzzi, Torino 10129, Italy.
Abstract:
In the present work, the effect of controlled nucleation on the stability of human growth hormone (hGH) during freeze-drying has been investigated. More specifically, the vacuum-induced surface freezing technique has been compared to conventional freezing, both with and without an annealing step. Size exclusion chromatography and cell-based potency assays have been used to characterize the formation of soluble aggregates and the biological activity of hGH, respectively. The results obtained indicate that controlled nucleation has a positive effect on both cycle performance and product homogeneity because of the formation of bigger ice crystals, and characterized by a narrower dimensional distribution. From the point of view of hGH stability, we observed that vacuum-induced surface freezing is not detrimental to the biological activity of the protein, or aggregate formation. In addition, the effect of 2 different formulations, including trehalose or cellobiose, on protein preservation was also considered for this study.
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