Engineered silica nanocarriers as a high-payload delivery vehicle for antioxidant enzymes

Antioxidant enzymes for the treatment of oxidative stress-related diseases remain a highly promising therapeutic approach. As poor localization and stability have been the greatest challenges to their clinical translation, a variety of nanocarrier systems have been developed to directly address these limitations. In most cases, there has been a trade-off between the delivered mass of enzyme loaded and the carriers ability to protect the enzyme from proteolytic degradation. One potential method of overcoming this limitation is the use of ordered mesoporous silica materials as potential antioxidant enzyme nanocarriers. The present study compared the loading, activity and retention activity of an anti-oxidant enzyme, catalase, on four engineered mesoporous silica types: non-porous silica particles, spherical silica particles with radially oriented pores and hollow spherical silica particles with pores oriented either parallel to the hollow core or expanded, interconnected bimodal pores. All these silica types, except non-porous silica, displayed potential for effective catalase loading and protection against the proteolytic enzyme, pronase. Hollow particles with interconnected pores exhibit protein loading of up to 50 wt.% carrier mass, while still maintaining significant protection against proteolysis.