A facile two-step etching method to fabricate porous hollow silica particles

► Hollow silica particles are synthesized with Stöber silica particles. ► The process is facile than the conventional templates method. ► It does not need expensive organic silica precursors. ► Large pores with an average diameter of ∼12 nm can be generated on the shell. ► The hollow particles can effectively uptake protein-based biomolecules (hemoglobin).