Separation of long DNA fragments by inversion field capillary electrophoresis

Capillary electrophoresis of DNA with high resolution based on copoly(pentaerythritoltetra succinimidylcarboxypentyl/aminopropyl polyoxyethylene) hydrogel

Capillary gel electrophoresis is widely applied for determination of sequence and size of DNA, in which the sieving gel plays an unignorable role. Herein, a pore-size controllable hydrogel was synthesized in the capillary with two symmetrical tetrahedron-like macromonomers consisting of pentaerythritoltetra (succinimidylcarboxypentyl) polyoxyethylene (PS) and pentaerythritoltetra (aminopropyl) polyoxyethylene) (PA). By capillary electrophoresis of the DNA fragments with this hydrogel, it is found that a homogenous structure of hydrogel which is more suitable for the DNA separation can be achieved when the molecular weight of PA is approximate to that of PS. DNA fragments smaller than 1500 bp can be well resolved in this hydrogel within 13 min. More than 100 consecutive runs can be carried out in such a dynamically coated capillary before performance begins to degrade. Notably, such hydrogel can realize separation of dsDNA up to single base pair resolution and same length of dsDNA with 1 bp difference.

The effect of electrophoretic parameters on separation performance of short DNA fragments

Effective separation of short DNA fragments is important for the identification of PCR or LAMP products. We investigated the effect of electric field strength, sample plug width, effective length of the capillary, concentration and molecular weight of polymer on the separation performance of small DNA. Results demonstrated that the sample plug played a non-negligible role in the peak broadening. The migration time of DNA was exponentially decreased with the increase of electric field strength. Increasing effective length of capillary, concentration or molecular weight of HEC may improve the separation performance, but it was at the cost of long migration time.

Three-dimensional Nanowire Structures for Ultra-Fast Separation of DNA, Protein and RNA Molecules

Separation and analysis of biomolecules represent crucial processes for biological and biomedical engineering development; however, separation resolution and speed for biomolecules analysis still require improvements. To achieve separation and analysis of biomolecules in a short time, the use of highly-ordered nanostructures fabricated by top-down or bottom-up approaches have been proposed. Here, we reported on the use of three-dimensional (3D) nanowire structures embedded in microchannels fabricated by a bottom-up approach for ultrafast separation of small biomolecules, such as DNA, protein, and RNA molecules. The 3D nanowire structures could analyze a mixture of DNA molecules (50-1000 bp) within 50 s, a mixture of protein molecules (20-340 kDa) within 5 s, and a mixture of RNA molecules (100-1000 bases) within 25 s. And, we could observe the electrophoretic mobility difference of biomolecules as a function of molecular size in the 3D nanowire structures. Since the present methodology allows users to control the pore size of sieving materials by varying the number of cycles for nanowire growth, the 3D nanowire structures have a good potential for use as alternatives for other sieving materials.

Polyethylene Oxide (PEO) and Polyethylene Glycol (PEG) Polymer Sieving Matrix for RNA Capillary Electrophoresis

The selection of sieving polymer for RNA fragments separation by capillary electrophoresis is imperative. We investigated the separation of RNA fragments ranged from 100 to 10,000 nt in polyethylene glycol (PEG) and polyethylene oxide (PEO) solutions with different molecular weight and different concentration. We found that the separation performance of the small RNA fragments (<1000 nt) was improved with the increase of polymer concentration, whereas the separation performance for the large ones (>4000 nt) deteriorated in PEG/PEO solutions when the concentration was above 1.0%/0.6%, respectively. By double logarithmic plot of mobility and RNA fragment size, we revealed three migration regimes for RNA in PEG (300-500k) and PEO (4,000k). Moreover, we calculated the smallest resolvable nucleotide length (N_min) from the resolution length analysis.