title: A DNA sieving matrix with thermally tunable mesh size.
abstract: We present a "proof-of-concept" study showing that a blend of thermo-responsive and nonthermo-responsive polymers can be used to create a DNA sieving matrix with a thermally tunable mesh size, or "dynamic porosity". Various blends of two well-studied sieving polymers for CE, including hydroxypropylcellulose (HPC), a thermo-responsive polymer, and hydroxyethylcellulose (HEC), a nonthermo-responsive polymer, were used to separate a double-stranded DNA restriction digest (Phi X174-HaeIII). HPC exhibits a volume-phase transition in aqueous solution which results in a collapse in polymer coil volume at approximately 39 degrees C. Utilizing a blend of HPC and HEC in a ratio of 1:5 by weight, we investigated the effects of changing mesh size on DNA separation, as controlled by temperature. High-resolution DNA separations were obtained with the blended matrix at temperatures ranging from 25 degrees C to 38 degrees C. We evaluated changes in the selectivity of DNA separation with increasing temperature for certain pairs of small and large fragments. A pure HEC (nonthermo-responsive) matrix was used over the same temperature range as a negative control. In the blended matrix, we observe a maximum in selectivity at approximately 31 degrees C for small DNA, while a significant increase in the selectivity of large-DNA separation occurs at approximately 36 degrees C as the polymer mesh "opens". We also demonstrate, through a temperature ramping experiment, that this matrix can be utilized to obtain high-resolution separation of both small and large DNA fragments simultaneously in a single CE run. Blended polymer matrices with "dynamic porosity" have the potential to provide enhanced genomic analysis by capillary array or microchip electrophoresis in microfluidic devices with advanced temperature control.
authors.affiliation: Department of Chemical Engineering, Northwestern University, Evanston, IL 60208, USA.
authors.forename: Cheuk Wai
authors.initials: CW
authors.lastname: Kan
authors.forename: Annelise E
authors.initials: AE
authors.lastname: Barron
mesh_terms: D010584:Bacteriophage phi X 174 / Q000737:chemistry; D002482:Cellulose / Q000031:analogs & derivatives*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004247:DNA / Q000302:isolation & purification*; D004279:DNA, Viral / Q000302:isolation & purification; D019075:Electrophoresis, Capillary / Q000379:methods*; D013053:Spectrophotometry; D013696:Temperature
chemical_list: D004279:DNA, Viral; D002482:Cellulose; C002283:hydroxyethylcellulose; D004247:DNA; C008079:hydroxypropylcellulose