Selective adsorption of acidic protein of bovine serum albumin onto sheet-like calcium hydroxyapatite particles produced by microreactor

•The sheet-like Hap particles were examined for the adsorption behavior of proteins.•The amounts of adsorbed proteins, especially for BSA, could be controlled optionally.•The BSA molecules could be completely separated from BSA–LSZ mixed solution.

The protein adsorption behavior onto sheet-like calcium hydroxyapatite Ca10(PO4)6(OH)2 (Hap) particles produced by microreactor was examined by using typical acidic bovine serum albumin (BSA) and basic lysozyme (LSZ). Since the sheet-like Hap particles were highly growth through b- (or a-) and c-axes, the particles had larger fraction of bc (or ac  ) crystal face. The saturated amounts of adsorbed BSA (nsBSA) for the sheet-like Hap nanoparticles were increased with increase in the particle size; i.e., nsBSA showed a good linear relationship with the total surface area of bc and ac faces of each particle. This result strongly suggested that the sheet-like Hap particles progressed in b- and c-axes with large fraction of C sites on bc and ac particle faces and exhibit a high selective adsorption of BSA. On the contrary, very few LSZ molecules adsorbed onto sheet-like Hap particles. Hence the present study developed that the amounts of adsorbed protein, especially for BSA, can be controlled optimally by altering the size of sheet-like Hap particles. It was also found that the sheet-like Hap particles can be applied to separate completely BSA molecules from BSA–LSZ mixed solution.

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