A method of coating a peptide or protein useful for improving the cellular activity related to bone growth on an inorganic particle comprises the steps of freezing the residual liquid present on uncoated and or coated inorganic particles, and drying the uncoated or coated inorganic particles after freezing the residual liquid, the drying comprising causing the frozen residual liquid to sublime under vacuum. Further disclosed embodiments of the invention include further processes for forming inorganic particles coated with a peptide or protein useful for improving cellular activity related to bone growth and medical devices comprising the coated particles.