Aqueous two-phase systems as a formulation concept for spray-dried protein.

Area of Science:

• Protein formulation and stabilization
• Biophysical characterization
• Spray drying technology

Background:

• Spray drying can lead to protein denaturation and loss of function.
• Aqueous two-phase systems (ATPS) offer potential for protein protection during drying.
• Polyvinyl alcohol (PVA) and dextran are common ATPS components.

Purpose of the Study:

• To evaluate the efficacy of ATPS in encapsulating and protecting protein secondary structure during spray drying.
• To investigate the role of PVA and dextran in protein partitioning and powder surface properties.
• To assess the impact of ATPS on protein stability and structural integrity post-drying.

Main Methods:

• Preparation of ATPS with varying PVA and dextran concentrations.
• Incorporation of bovine serum albumin (BSA) and trehalose into ATPS.
• Spray drying of ATPS-protein mixtures.
• Analysis using electron spectroscopy for chemical analysis (ESCA), differential scanning calorimetry (DSC), UV spectrophotometry, size exclusion high-performance liquid chromatography (SEC-HPLC), and Fourier transform infrared spectroscopy (FTIR).

Main Results:

• BSA preferentially partitioned to the dextran phase.
• In the absence of PVA, BSA dominated the powder surface, indicating poor encapsulation.
• PVA addition resulted in the polymer covering the powder surface, preventing protein-air interface interactions and improving encapsulation.
• Despite good encapsulation, PVA induced a partial loss of BSA's native secondary structure.

Conclusions:

• ATPS containing PVA can effectively encapsulate proteins during spray drying, preventing surface adsorption.
• PVA acts as a protective barrier on the powder surface, enhancing protein encapsulation.
• While encapsulation is improved, the secondary structure of the protein may be partially compromised by PVA during the process.