(75b) Project SAVE: Silica Adsorption Vaccine Encapsulation

It is estimated that 50% of vaccines produced annually are wasted because effectivity is dependent on protein structure and heat exposure disrupts the intermolecular interactions that maintain this structure. Since 90% of vaccines require a temperature-controlled supply chain, it is necessary to create a cold chain system to minimize vaccine waste. Influenza viruses cause seasonal flu epidemics that affect millions worldwide, and cause especially serious illness to children, elderly and those with compromised immune systems. Globally, influenza causes 390,000 to 650,000 deaths each year. We are developing a more sustainable technology via the adsorption of Quadrivalent Influenza Vaccine (QIV) onto mesoporous silica gels, improving the thermal stability of protein-based therapeutics. A solution depletion method in combination with UV-Vis is used to study the adsorption of QIV onto silica gels. The silica-QIV complex is heated above the denaturing temperature of the protein and then the QIV is removed using a detergent. Pore diameter, pore volume and surface area were characterized for different silica gels. In general, silicas with larger pore volumes and pore diameters tend to adsorb more QIV. Silica adsorption isotherms were created in order to calculate the maximum QIV monolayer coverage and the kinetic rates of adsorption and desorption. Circular Dichroism (CD) analyses confirmed that the adsorbed QIV after the heat treatment displayed a similar “W” shape CD signal as the native QIV, indicating the conservation of α-helices. In contrast, the unprotected QIV after being exposed to high temperature shows a flat CD signal, demonstrating the loss of secondary structure. In conclusion, we have successfully increased the thermo-tolerance for QIV using mesoporous silica and continue to further optimize mesoporous silica’s physiochemical properties to improve adsorption and desorption yields.