Size Selective DNA Purification Using Swellable Organically Modified Silica

Brian Alexander Lupish, The College of Wooster


Abstract Swellable organically modified silica (SOMS) is a nanoporous material synthesized via the sol-gel method that swells to several times its original size in the presence of nonpolar organic solvents. It was proposed that, with various chemical modifications, SOMS could also absorb DNA fragments less than 10,000 kilo-bases in size. Novel materials were synthesized, systematically varying the bis(trimethoxysilyethyl)benzene (BTEB) to trimethoxysilylpropyl-N,N,N-trimethylammonium (TMAPS) ratio to create cationic exchange type sorbents. These cationic SOMS were characterized using infrared spectroscopy and nitrogen porimetry. Absorption was tested by mixing TMAPS SOMS with a DNA standard solution and a solution of oligonucleotides, and measuring the DNA concentrations by gel electrophoresis (for plasmid DNA fragments) and UV spectrometry (for PCR primers). The SOMS composed of 40% and 50% TMAPS removed nearly all the DNA and oligonucleotides from the standard solutions, while the SOMS composed of lower percentages of TMAPS did not. Additionally, 2.5%, 5%, and 25% TMAPS SOMS that was preswelled in ethanol removed some of the smaller plasmid DNA fragments from the standard solution. These results indicate that a SOMS with specific percentages of TMAPS may be useful to extract DNA molecules of smaller sizes from solutions containing both large and small DNA molecules.


© Copyright 2013 Brian Alexander Lupish