Why high Molar ratio (100) of PEI/QD NP's aggregate?

Hi I'm trying to make PEI/QD NP's with different molar ratio; 1,5,20,50,100. For the conjugation, I use QD-COO- and EDC first and then add different amount of PEI. PEI/QD 50 and higher aggregates...

18 April 2018 5,238 3 View