Improving the adsorption capacity for ovalbumin by functional modification of aminated mesoporous silica nanoparticles with tryptophan

Abstract

Tryptophan (Trp) modified aminated mesoporous silica nanoparticles (AMSNs), shortened to Trp-AMSNs, are prepared via covalent binding. The obtained Trp-AMSNs exhibit a uniform size of ca. 83 nm, a mesopore diameter of ca. 2.6 nm, along with a pore volume of 0.439 cm³ g⁻¹. It is demonstrated that Trp-AMSNs selectively adsorb ovalbumin (Ova) from complex biological matrices. At pH 5.0, 1.0 mg of Trp-AMSNs produces an adsorption efficiency of 96% for 100 mg L⁻¹ Ova in 1.0 mL of solution. An adsorption capacity of 1240.3 mg g⁻¹ is derived for Ova, which is much improved with respect to that of the native AMSNs. The retained Ova could be readily recovered by a sodium dodecyl sulfate (SDS) solution (0.5%, m/v), providing a recovery of 71.2%. Trp-AMSNs are further applied for the isolation of Ova from a protein mixture (with a molar ratio of ovalbumin/lysozyme of 1 : 10) and an egg-white sample. High-purity Ova is obtained, as demonstrated by SDS-PAGE assay results.