Aluminum oxide nanowires might be useful as safe and effective adjuvants for next-generation vaccines, according to research published in the journal Materials Today.

There are numerous materials used as adjuvants for vaccines. These substances act to accelerate, prolong, or otherwise enhance the immune responses to the specific antigens present in the vaccine against a given disease. The benefits of adjuvants were first noticed when variation in the efficacy of early manufactured vaccines was noticed. The manufacturers made efforts to cleanup their systems and discovered that the resulting purer formulations were actually less effective than those vaccines with contaminants from the manufacturing process. Since then, researchers have focused on finding safer adjuvants to deliberately boost vaccine efficacy in a controlled manner. The ultimate aim is to have so potent an adjuvant that it can induce an adequate immune response to a completely safe synthetic component of pathogen.

Today, commercial vaccines commonly use alum, salts of aluminum, such as aluminum oxyhydroxide and aluminum hydroxide as adjuvants, but these have only moderate benefits. Now, Gleb Yushin of the Georgia Institute of Technology, in Atlanta, Georgia, USA, and colleagues there Rostyslav Bilyy and at Danylo Halytsky Lviv National Medical University, in Lviv, Ukraine and Sabine Szunerits at the University of Lille, France, have found a way to make aluminum compounds much more effective. Aluminum oxide is not as effective as those "alums". However, it has the distinct advantage of much lower cytotoxicity. As such its use would be preferential if there were a way to make it more efficacious.

The team has formed aluminum oxide into nanowires with a high aspect ratio of approximately 1000. They are long and thin, in other words; 20 to 60 micrometers long and 20 to 40 nanometers in cross-sectional diameter. In tests, the nanowires showed a four times stronger humoral immune response by boosting dramatically the activation of white blood cells known as neutrophils - without any damaging effects on the blood capillaries and microvasculature. The team suggests that it is the shape of these particles, long and thin, that gives the aluminum renewed vigor as a vaccine adjuvant. Moreover, the manufacture of such nanowires would not add significant cost to any vaccine formulation.

"Our findings highlight the great promise of nanowires for a substantial breakthrough in the development of safer, more effective, and more affordable vaccines," the team says. "We also expect that modifying the surface chemistry of the nanowires and optimizing their dimensions and morphology may boost their performance further," the researchers conclude. [P Bilyy et al., Mater Today (2018); DOI: 10.1016/j.mattod.2018.10.034]

David Bradley blogs at Sciencebase Science Blog and tweets @sciencebase. His popular science book Deceived Wisdom is now available.