Tuesday, 26 June 2012

How to Make Vaccines with a longer Shelf Life Faster for the Next Bird Flu Outbreak???

Like milk vaccines are a colloid.  What the hell is a colloid?  A colloidal system consists of two separate phases: a dispersed phase (or internal phase like fat in milk) and a continuous phase (or dispersion medium like water) in which the colloid is dispersed. WIth many colloids the surface tension is damn important.  When the phases seperate in milk as in non-homogenized natural milk, the fat droplets in the milk can be attacked easier by enzymes or be degraded by physical factors (heat).  However, when the homogenization takes place these fat droplets are dispersed within the milk and pasteurization can destroy the enzymes allowing a longer shelf life. A new technique called ultrahomogenization creates a colloid suspension of smaller more uniform droplets by increasing the amount of pressure in the homogenization process by seven times.

How does this relate to vaccines?  Like milk vaccines are also a colloid.  They are a suspension made from some microbe.  It is often made from weakened or killed forms of the microbe, its toxins or one of its surface proteins. These agents can stimulate some the immune response in the T-cells in the body after getting the vaccination.  By stimulating the memory T-cells you will be hopefully resistant to the actual active microbe when it is present.

One problem persists with vaccines as it does with milk.  Since vaccines discovery by Edward Jenner in 1770 there has been a difficult thing of making, storing and transporting the vaccines.  Since vaccines are a colloid an subject to physical and enzymatic degradation as other colloids they can expire (like milk).  Vaccine shortage is always a problem and a bigger problem in places other than North America.  The avian flu (see picture below) spread quickly but was not as widespread in places of people that got flu vaccines.  So how do make a vaccine last longer?  You change the surface tension of the vaccine emulsion.

One army researcher found that by changing the composition of an emulsion from a simple oil and water emulsion the imulsion is only good for a couple of months because it is not thermodynamically stable.  However, when you change the composition to an isotropic liquid of oil, water, glycerol, and surface tension lowering surfactants span 80 and tween 60 along with the proteins used in the vaccine can stay on the shelf for six months.  

U.S. Army Major Jean M. Muderhwa found this solution recently.  The higher amount of molecules found in most emulsion, heightened the surface tension results in components repelling each other until the composition degrades and fails.  The army helps to stockpile the vaccines in case of emergency.  If all goes well it will help them stockpile the vaccines for longer time for larger emergencies flu virus

So how can one make the process of measuring surface tension faster?  Nearly an infinite number of surfactants can be added to the emulsion to lower the surface tension.  Several different devices could be used for measuring surface tension but only one has high throughput capabilities.  Kibron's Delta-8 could be a reliable device to test the surface tension of different vaccine emulsions to help prolong their shelf life.  The best part is as the video shows.  It's damn fast!