Assessment of protein entrapment in hydroxyapatite scaffolds by size exclusion chromatography

Although it is well known that the textural properties of scaffolds play an important role in the process of tissue regeneration, the investigation of such effects remain difficult especially at the micro/nano level. Texture confers the material the additional ability to entrap/concentrate molecules circulating in the body fluid regardless of their binding affinity to the material. The goal of the present work is to isolate protein entrapment from protein adsorption phenomena in two macroporous hydroxyapatite scaffolds with identical chemical structure, similar macroporosity but different micro/nanoporosity using proteins of different sizes. This was achieved implementing size exclusion chromatography and using the scaffolds as chromatographic columns. The results showed that the larger the crystal size and the lower the packing density of the crystals composing the scaffold increased protein retention but decreased the protein dwelling time in the column. Differences in the amount of protein retained depended on the protein type.