As the researchers discovered, the HMSC particles often have a large surface hole or a crack with dimensions in the range 25–50 nm. The combination of a hollow cavity and a large surface hole made it possible for the team to load and release large proteins – for example, glutathione S-transferase (GST, 52 kDa as a form of dimer), bovine serum albumin (BSA, 66 kDa), yeast alcohol dehydrogenase (yeast ADH, 150 kDa) and immunoglobulin G (IgG, 150 kDa).

According to analysis by confocal laser scanning microscopy (CLSM), the efficiencies of protein delivery using HMSC were about 3–22-fold higher than for mesoporous silica nanospheres.

The group's result may allow the cellular behaviour of various proteins to be studied with the molecules intact, because the delivery process does not require any modification to the proteins such as immobilization on the carrier surface. In addition, it seems that very large proteins can be transported without any difficulties.

Full details can be found in the journal Nanotechnology.