Preparation of antibody-loaded protein microbeads for pulmonary delivery via Shirasu porous glass membrane emulsification and freeze drying

Abstract

Reversible protein precipitates (protein microbeads) have been developed using Shirasu porous glass (SPG) membrane emulsification. Microbeads have a mean size of a few micrometers (2–5 μm), and their formation is reversible upon rehydration. Their feasibility was examined as dry powders for pulmonary delivery of intravenous immunoglobulin (IVIG). Protein stability was investigated using size-exclusion chromatography, dynamic light scattering, circular dichroism, and fluorescence spectroscopy. Particle size and size distribution were determined by scanning electron microscope and laser diffraction. A next-generation impactor was used to measure the microbeads aerodynamic performance. Effects of trehalose as a stabilizer revealed that absence or presence of low trehalose (50 mM), the reversibility of the IVIG was 72.52 % or 89.00 %, respectively. On the other hand, it increased more than 98 % when trehalose concentration was more than 100 mM. However, trehalose crystallization occurred more than 300 mM and it was associated with reduced IVIG stability. SPG method had a critical role in obtaining uniform microbeads. Moreover, the freeze drying suppressed interparticle agglomeration, which enhanced the aerodynamic performance of microbeads with a fine particle fraction (<5 μm) value of 87.59 %. These findings suggested that microbeads with an optimized formulation and manufacturing process can be applied for pulmonary applications. © 2024 Elsevier B.V.