Resuspending oligos IDT is a foundational skill for any molecular biologist or researcher working with synthetic nucleic acids. When you receive a dry oligo from Integrated DNA Technologies (IDT), it arrives as a lyophilized pellet that requires proper rehydration to achieve the precise concentration needed for your experiments. This initial step determines the accuracy of your subsequent pipetting and directly impacts the reliability of your PCR, sequencing, or hybridization results.
Understanding the Dry Oligo State
IDT ships oligonucleotides in a highly concentrated dry state to ensure stability during storage and shipment. At room temperature, the desiccated powder is less prone to degradation or bacterial growth compared to a liquid solution. However, this solid form is unusable for most applications until you calculate the correct volume of solvent to add. The goal of resuspension is to create a homogeneous stock solution that you can dilute accurately for your working assays.
Choosing the Right Solvent
The choice of resuspension buffer is critical and depends on the downstream application. For general use, IDT recommends resuspending their oligos in sterile, nuclease-free water (1x TE or pH 7.0–8.5). If your protocol requires a specific ionic strength or you need to inhibit exonuclease activity, you might opt for a buffer containing Tris-EDTA or specialized storage solutions. Always avoid using harsh solvents or liquids with extreme pH values, as they can denature the oligo and ruin its functionality.
Step-by-Step Resuspension Protocol
To resuspend your IDT oligo, first centrifuge the tube briefly to pellet all the material at the bottom. Remove the cap and add the appropriate volume of your chosen solvent directly into the tube. It is generally advised to add the solvent gently along the side of the tube rather than directly onto the dry pellet to prevent splashing. Cap the tube securely and vortex vigorously or incubate at room temperature with occasional mixing until the pellet fully dissolves and the solution appears clear.
Calculating Concentration
Once the oligo is fully dissolved, you must determine its concentration. You can use the provided extinction coefficient on the IDT order confirmation to calculate the optical density (OD) if you have a spectrophotometer. Alternatively, you can rely on mass calculations based on the oligo’s length and modified groups. For high accuracy, many labs utilize a plate reader or fluorometric quantification tools like Qubit, which are less susceptible to contaminants that might skew OD readings.
Storage and Long-Term Stability
After resuspending oligos IDT, storage conditions are vital to maintaining integrity. Aliquot the stock solution into smaller tubes to avoid repeated freeze-thaw cycles, which degrade nucleic acids. Store the working stocks at −20°C, and keep the original dry pellet at −80°C or in a desiccated container at room temperature. Proper storage ensures that your oligos remain stable for months or even years, depending on the specific modifications and storage temperature.
