Ionic liquid proteins: a route towards room temperature stable antibodies and vaccines

Vaccines are administered to more than 100 million infants a year, saving three million lives annually. The global health community has recognised the importance of vaccines in the prevention of diseases and are committed to making vaccines available globally. The Centres for Disease Control and Prevention (CDC) recommends that most vaccines should be stored between 2 and 8 Degrees Centigrade, except the oral polio vaccine, to maintain the vaccine efficacy. However, if the storage temperature is lower than the recommended temperature range, then accidental freezing of vaccines can lead to agglomeration, which can reduce the potency of vaccine. Cold chain practices tend to overlook accidental freezing of vaccines because of the associated heat damage at higher temperatures. Despite this, over 31 % of the US$ 439 million UNICEF spent on all vaccines in 2005 are spent on freeze-sensitive vaccines. Therefore, the distribution of vaccines to third-world countries, where electricity and cold storage are limited, puts additional stress on the already fragile 'cold chain'.
A proposed solution to the storage of therapeutic proteins is to increase the thermal stability of proteins and antibodies using ionic liquids (ILs), avoiding the need for refrigeration of vaccines during shipping and storage. The use of ionic liquids have become increasingly popular and have been used for various applications such as material science, catalysis and medicinal chemistry due to their unique and tuneable properties. Ionic liquids have high thermal, chemical and electrochemical stabilities. In addition, most of the interest in ionic liquids is due to their negligible vapour pressures and therefore the possibility of a 'green solvent' to replace volatile organic solvents. Despite these advantages, proteins tend to be highly unstable in anhydrous conditions and poorly soluble in ionic liquids. This study proposes using surface modification of antibodies and viruses to increase their solubility in ionic liquids increasing protein thermal stability whilst retaining their protein biological function.