QDs Using sulfo-SMCC

Prepare a 200 pi solution of amine-containing QDs at a concentration of 2.5 pM in 50mM sodium phosphate, pH 7.4 (reaction buffer). This represents 0.5nmole of QD in 200 pi buffer. 

Add 1 mg of sulfo-SMCC to the QD solution with mixing to dissolve the crosslinker. 

React for 60 minutes at room temperature with mixing. 

Remove excess crosslinker and reaction by-products by gel filtration on a desalting resin. The QD fraction is identified by its characteristic fluorescence. This operation should be 

React with mixing for 2 hours at room temperature. At the completion of the reaction, cysteine may be added at 50 mM to block excess maleimide-reactive sites. 

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