aptamers, or single stranded oligonucleotides, are produced by systematic evolution of ligands by exponential enrichment, abbreviated as selex. in the amplification and regeneration step of selex technique, dsdna is conversed to ssdna. asymmetric pcr is one of the methods used for the generation of ssdna. the purpose of this study was to design a random dna library for selection of aptamers wit...

The interaction between the single-stranded DNA and the homologous duplex DNA is essential for DNA homologous repair. Here, we report that parallel triplex structure can form spontaneously between a mechanically extended ssDNA and a homologous dsDNA in protein-free condition. The triplex has a contour length close to that of a B-form DNA duplex and remains stable after force is released. The bi...

Fabricated solid-state nanopore chips are used to probe individual single stranded DNA (ssDNA) homopolymers. Based on the analysis of the current blockage caused by DNA translocation through a voltage-biased nanopore, we discovered that the hydrodynamic diameter of ssDNA homopolymer helix is comparable to that of double stranded DNA (dsDNA) helix. This proof-of-principle demonstration shows tha...

The sequence-length-dependent adsorption of single-stranded DNA (ssDNA) on unmodified gold nanoparticles is exploited as a new mechanism for colorimetric nuclease assay and measurement of oxidative DNA damage.

Voltage biased solid-state nanopores are used to detect and characterize individual single stranded DNA molecules of fixed micrometer length by operating a nanopore detector at pH values greater than approximately 11.6. The distribution of observed molecular event durations and blockade currents shows that a significant fraction of the events obey a rule of constant event charge deficit (ecd) i...

Helicases are molecular motors that separate DNA strands for efficient replication of genomes. We probed the kinetics of individual ring-shaped T7 helicase molecules as they unwound double-stranded DNA (dsDNA) or translocated on single-stranded DNA (ssDNA). A distinctive DNA sequence dependence was observed in the unwinding rate that correlated with the local DNA unzipping energy landscape. The...