Many cancer biomarkers in the bood get damaged during long term storage when kept at cryogenic temperatures due to stresses associated with ice formation and low temperatures. The aim of this research is to develop isothermal vitrification methods to ensure that the archival serum samples are stably stored at room temperature for a long time.
We have developed a lyoprotectant matrix that is used for stabilizing archival serum samples. Serum is pipetted into the wells filled with the lyoprotectant matrix, and dried overnight in a vacuum chamber, which vitrifes the sample making it stable during room temperature storage. The matrix is an electrospun non-woven fibrous material electrospun from a patent pending lyoprotectant solution. The capillary forces help adsorb the serum into the matrix, and dissolve to uniformly load the serum with the lyoprotectants, avoiding clumping.
The results of the initial validation studies we have conducted have recently been published [Scientific Reports, 6, 24186, 2016];
We are currently in the process of collecting longer term storage results after making some modifications to the existing matrix. Stay tuned!
Some questions we seek answers to:
What happens in a solution when it freezes?
Is the ice phase pure?
Where do the buffer salts, proteins, and cryo-/lyoprotectants go when ice freezes out?
Does it mean all the liquid water in the sample is frozen?
What is the difference of storing a solution at -4oC, -20oC or -120oC?
Does the thawing rate matter?
Does the pre-freeze cooling rate matter?
Does the ice nucleation temperature matter?
What happens when a solution vitrifies?
Role of Excipients on Freeze/Dried Protein Stability
In freeze-drying processes used to stabilize drugs and therapeutic formulations, it is desired that the structure-forming ingredients (e.g. mannitol) crystallize to avoid collapse of the cake while the lyoprotectants (e.g. trehalose) stay amorphous to protect the ingredients. This is a challenge as it is very difficult to come up with the formulation that would enable this under conditions of low temperatures, crowding etc. Our recent publications in this area, helps establish the guidelines while shedding light on the phenomena at work at the molecular level.
Effects of Excipient Interactions on the State of the Freeze-Concentrate and Protein Stability
Mutual Influence of Mannitol and Trehalose on Crystallization Behavior in Frozen Solutions