DNA Adsorption to and Elution from Silica Surfaces:
Influence of Amino Acid Buffers
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Abstract
Solid
phase extraction and purification of DNA from complex samples
typically requires chaotropic salts that can inhibit downstream polymerase
amplification if carried into the elution buffer. Amino acid buffers
may serve as a more compatible alternative for modulating the interaction
between DNA and silica surfaces. We characterized DNA binding to silica
surfaces, facilitated by representative amino acid buffers, and the
subsequent elution of DNA from the silica surfaces. Through bulk depletion
experiments, we found that more DNA adsorbs to silica particles out
of positively compared to negatively charged amino acid buffers. Additionally,
the type of the silica surface greatly influences the amount of DNA
adsorbed and the final elution yield. Quartz crystal microbalance
experiments with dissipation monitoring (QCM-D) revealed multiphasic
DNA adsorption out of stronger adsorbing conditions such as arginine,
glycine, and glutamine, with DNA more rigidly bound during the early
stages of the adsorption process. The DNA film adsorbed out of glutamate
was more flexible and uniform throughout the adsorption process. QCM-D
characterization of DNA elution from the silica surface indicates
an uptake in water mass during the initial stage of DNA elution for
the stronger adsorbing conditions, which suggests that for these conditions
the DNA film is partly dehydrated during the prior adsorption process.
Overall, several positively charged and polar neutral amino acid buffers
show promise as an alternative to methods based on chaotropic salts
for solid phase DNA extraction