Protocol for washing and modifying QCM - D sensors
Prepare solutions of 2 % SDS , 0.1 % SDS and 0.1 M HCl .
Clean the gold - coated QCM - D sensors by hand with 2 % SDS to mechanically remove contaminants .
Be sure that the glove is wet all the time so it doesn't scratch the sensor !
Place the sensors in a stand and put them in a 0.1 % SDS solution .
Heat for 10 min at 80°C , then rinse the sensors with water .
Place the sensors in a 0.1 M HCl solution .
Heat for 10 min at 80°C , then rinse the sensors with water several times to remove all HCl solution .
Then blow the sensors dry under a flow of nitrogen .
Make an ethanolic solution with total concentration 10 mM of mixed PEG thiols ( PEG and biotin - PEG thiols in a molar ratio of 99 : 1 ) .
( MW , dS - PEG = 386.5 Da and MW , dS - PEG - biotin = 788.0 Da ) Incubate the QCM - D sensors in the ethanolic PEG thiol solution for at least 16 hours at 4°C in darkness .
Rinse the sensors a couple of times with ethanol , then a couple of times with milli - Q water and lastly blow them dry with nitrogen .
They may now be used or stored .
