Day 1: Monday, 15th May, 2017
I started out by watching youtube videos on how the Nano ITC machine works. ITC is a technique that deals with a wide variety of bimolecular interactions. It directly measures hear either released or absorbed during a biomolecular binding event and it is extremely sensitive to very small heat changes. The Nano ITC machine consists of two identical cells, made of gold due to its inertness and high thermal conductivity. These cells are surrounded by an adiabatic jacket. The instrument uses two very sensitive thermocouples, one in each cell to constantly monitor the temperatures of the cells. The temperatures of the cells are kept equal. The heat supplied to the sample cell will be lass than the heat supplied to the reference cell if the reaction is exothermic and vice versa.
Day 2: Wednesday, 17th May, 2017
Wednesday was all about synthesizing the chemicals required for measuring the heat of dilution using the ITC machine. We were to measure the heat evolving from the dilution of cobalt hexamine using 10 mM NaCl solution. I started by making a 0.2 M Cobalt Hexamine stock solution. I then used the 0.2 M stock solution to make 10 ml of 6mM Cobalt Hexamine solution. Subsequently, I made 10 ml of 10 mM NaCl solution from a 1 M stock by dilution with water. I split the 10 ml solution into two tubes, one with 2 ml of NaCl and the other with 8 ml of NaCl (for the DNA solution).
Day 3: Thursday, 18th May, 2017
On Thursday, I used the Nano ITC machine to measure the enthalpy of dilution of cobalt hexamine. I had to be extremely careful while loading the syringe with 50 microliters 6mM Cobalt Hexamine, to make sure that there were no air bubbles inside. Fontaine helped me with loading the reference cell with 300 microliters of water and the sample cell with 300 microliters of 10mM NaCl solution. I had to be extremely cautious so that there were no air bubbles inside the cells. The presence of air bubbles in cells or the syringe can give erroneous results. The injection interval for the cobalt hexamine injection was set to 175 s, 20 injections in total. The ITCRun software was used to operate the instrument. The spin rate was set at 250 rpm and the temperature was held constant at 25 C. The solutions were allowed to auto equilibrate for 1564 s. After that, the syringe automatically started injecting 2.5 microliters of Cobalt hexamine solution after every 175 s intervals. The NanoAnalyze software was used to measure enthalpy peaks after each injection: