ADSORPTION STUDY OF CdSe/ZnS QUANTUM DOT ON SYNTHETIC TEMPLATE: INFLUENCE OF SUBSTRATE SURFACE CHEMISTRY AND pH

 

Jungjin Park, Silvia H. De Paoli Lacerda, Scott K. Stanley, Brandon Vogel,

Jack F. Douglas, Dharmaraj Raghavan and Alamgir Karim

 

The adsorption behavior of CdSe/ZnS core-shell quantum dot nanoparticles on synthetic templates has been investigated as a model system for developing methods for characterizing nanoparticle-substrate interactions.  The nanoparticles were functionalized with 11-mercaptoundecanoic acid and we considered self-assembled monolayers (SAM) with amine terminal groups (NH2) as the synthetic template.  SAM with different end-groups (CH2 and –COOH) were also considered to contrast with adsorption behavior on the SAM substrates with the amine terminal group.  We followed the kinetics of nanoparticles adsorption on the aminosilane layer by quartz crystal microgravimetry (QCM) over a range of particle concentrations so that isotherms can be deduced.  Analysis of the resulting Langmuir adsorption curves allows to determine the Langmuir adsorption constant quantifying the particle-substrate interaction and the maximum coverage concentration. (KL ≈ 2.25 mM-1 and qmax 224 ng/cm2)  The effect of varying solution pH on the adsorption was also investigated in order to gain insight into the role of electrostatic interactions on nanoparticle adsorption where a large effect was found.  These large changes of nanoparticle adsorption were performed by X-ray photoelectron spectroscopy (XPS) and confocal fluorescence microscopy.

Author information

Name: Jungjin Park,    Mentor: Alamgir Karim

Polymers Division,     Bldg 224      Room B 232,    Mail stop: 8542

Tel: 301-975-5391  Fax: 301-975-4924,        jungjin.park@nist.gov

not a member of Sigma Xi

Poster Category: Materials