ChargeSwitch® Nucleic Acid Purification Technology

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How ChargeSwitch® Technology Works Formats

Improve Your Downstream Performance Product Selection Guide

ChargeSwitch® nucleic acid purification technology (CST®) takes advantage of a unique ionizable (switchable) coating that can be covalently affixed to the surface of magnetic or nonmagnetic beads, membranes, or even plastic tubes and plates. ChargeSwitch®-based kits require just four simple steps (Figure 1) to extract nucleic acids from a wide variety of sources, including bacteria, tissues, cells, blood, forensic sample and buccal cells.

Figure 1. Typical ChargeSwitch® Technology protocol. The ChargeSwitch® Technology features a charged nucleic acid–binding surface that is “switchable” by changing the pH of the surrounding buffer. At low pH, the surface is positively charged and binds the negatively charged nucleic acid backbone, allowing easy removal of proteins and other contaminants using a simple wash step.

ChargeSwitch® technology can be used in a variety of formats—from magnetic beads to coated plates to spin columns. Initially ChargeSwitch® technology was available in the format of magnetic beads. All are water-based and do not employ the use of harsh reagents such as chaotropicsalts, ethanol, or organics and isopropanol precipitation.

Unlike classic ion exchange or silica-based nucleic acid purification technologies, ChargeSwitch®-based DNA and RNA purification is 100% water-based and does not require the use of ethanol, chaotropic salts, organic solvents or time consuming precipitation steps. Purified, the resulting nucleic acid lacks these potentially inhibitory compounds—improving DNA or RNA integrity for downstream performance in applications such as PCR (see Figure 2), qPCR, RT-PCR, Restriction Enzyme digestion, STR analysis, sequencing, whole genome amplification (WGA), and other similar applications. As a result, ChargeSwitch®-based protocols can offer significant performance benefits. Additionally, it excels at extracting DNA from forensic samples and buccal scrapes.

Figure 2. ChargeSwitch® technology for plasmid purification. The inhibitory reagents used in most plasmid purification techniques are difficult to detect when measuring DNA quality on gels or by UV spectophotometry. They can, however, inhibit enzymatic reactions. The actin gene was amplified by PCR from human placental DNA in a 50 µL reaction spiked with varying volumes of ethanol, isopropanal (IPA) and a competitor wash buffers, guanidinium isothiocyanate (GTC) and ChargeSwitch® wash buffer. Ten microliters of amplified product run on a 1% agarose gel and stained with ethidium bromide.