A quartz crystal microbalance study of polycation-supported single and double stranded DNA surfaces.
A quartz crystal microbalance with dissipation monitoring (QCM-D) was used to investigate the properties and formation of a genomic mammalian DNA surface on a polycationic poly(ethylenimine) (PEI) film. We show that both single- and double-stranded DNA films can be deposited on the PEI surface by modulating the DNA adsorption time. The two distinct DNA surfaces can be confirmed by their interactions with urea, a common DNA denaturant, and ethidium bromide, a common DNA intercalator, both of which lead to characteristic changes in the QCM-D frequency and dissipation. The hybridization process between surface-bound single-stranded DNA to complementary strands in solution can be resolved in real-time. Moreover, we have also investigated the effects of incorporating NaCl in the various PEI-DNA assemblies and have shown that higher ionic strengths lead to greater DNA adsorption to the PEI surface. An increase in the QCM-D resonant frequency and a decrease in dissipation occur when these assemblies are rinsed with salt-free water. We interpret these changes as a loss of counterions from the film and an increase in intrinsic ion-pair complexation, leading to a more rigid PEI-DNA assembly. Varying the salt content in the DNA film can be used to control the film thickness and morphology.
Yang
Amanda Y
AY
Department of Chemistry, Pomona College, 645 North College Avenue, Claremont, California 91711-6338, USA.
Rawle
Robert J
RJ
Selassie
Cynthia R D
CR
Johal
Malkiat S
MS
D000327:Adsorption; D003460:Crystallization; D004247:DNA / Q000737:chemistry*; D004277:DNA, Single-Stranded / Q000737:chemistry; D011073:Polyamines / Q000737:chemistry*; D000071228:Polyelectrolytes; D011094:Polyethyleneimine / Q000737:chemistry*; D011791:Quartz / Q000737:chemistry*; D013499:Surface Properties
D004247:DNA; D004277:DNA, Single-Stranded; D011073:Polyamines; D000071228:Polyelectrolytes; D011094:Polyethyleneimine; D011791:Quartz