Process of conjugation between Au-NP and a 4-nm QD. (a, b) HS(CH2)15COOH is first self-assembled on the Au atoms at the AFM tip to expose the carboxylic acid functional group. (c, d) Reaction with EDC and sulfo-NHS to form amine-reactive ester. (e) Attachment of functionalized QDs by an amide bond.
Cheng et al. Nanoscale Research Letters 2013 8:482 doi:10.1186/1556-276X-8-482