IDT ships gBlocks Gene Fragments dry unless otherwise requested. While dry, they should be stable almost indefinitely.
After resuspending in a high-quality, molecular-grade water or buffer, pH 7.5–8.0, you should store the DNA at –20°C and if necessary, aliquot to avoid more than 2 or 3 freeze-thaw cycles.
For gBlocks Gene Fragments at concentrations lower than 1 ng/µL, we recommend resuspending in water or buffer containing 0.1–1.0 mg/mL tRNA (Sigma) or poly A (Sigma). Use this same buffer + carrier solution for subsequent dilutions. Without the carrier, we have observed a steady decrease in measured concentrations of these dilute solutions, even in low-bind tubes. This may be caused by the very high purity of the gBlocks fragment prep. Because gBlocks fragments are completely synthetic, they lack the normal cellular debris found in DNA isolated from natural sources.
Without these natural carriers, the gBlocks fragments bind irreversibly to the tube plastic over time, leading to the observed decrease in concentration. Adding a carrier to your resuspension and dilution buffers can help prevent this loss of product.