BACKGROUND: The adsorption of bovine serum albumin (BSA) onto mesoporous silica spheres (MPS) synthesized from silica colloids was studied employing real time in situ measurements. The stabilities of the BSA at different pH values, their isoelectric points and zeta potentials were determined in order to probe the interactions between the protein and the mesoporous silica. RESULTS: The pore size of MPS was designed for protein, and this, coupled with an in depth understanding of the physico-chemical characteristics of the protein and MPS has yielded a better binding capacity and delivery profile. The adsorption isotherm at pH 4.2 fitted the Langmuir model and displayed the highest adsorption capacity (71.43 mg mL(-1) MPS). Furthermore, the delivery rates of BSA from the MPS under physiological conditions were shown to be dependent on the ionic strength of the buffer and protein loading concentration. CONCLUSION: Economics and scale-up considerations of mesoporous material synthesized via destabilization of colloids by electrolyte indicate the scaleability and commercial viability of this technology as a delivery platform for biopharmaceutical applications. (C) 2007 Society of Chemical Industry.