Near‐Quantitative Preparation of Short Single‐Stranded DNA Circles

Small, single-stranded DNA (ssDNA) circles have many applications, such as templating rolling circle amplification (RCA), capturing microRNAs, and scaffolding nanostructures. However, it is challenging to prepare ssDNA circles, particularly when the size becomes very small (e.g. a 20 nucleotide (nt) long circle). Often, short dominantly form concatemers (either linear or circular) due intermolecular ligation, instead of forming monomeric by intramolecular ligation. Herein, simple method overcome this problem designing complementary linker molecules reported. It demonstrated that ssDNA, 16 nts, can be enzymatically ligated (by commonly used T4 ligase) into at high concentration (100 μM) with yield (97 %). This does not require any special sequence, thus, expected generally applicable. The experimental protocol identical regular user friendly for general chemists biologists.