Enzymatic synthesis of biphenyl-DNA oligonucleotides

The incorporation of nucleotides equipped with C-glycosidic aromatic nucleobases into DNA and RNA is an alluring strategy for a number of practical applications including fluorescent labelling of oligonucleotides, expansion of the genetic alphabet for the generation of aptamers and semi-synthetic organisms, or the modulation of excess electron transfer within DNA. However, the generation of C-nucleoside containing oligonucleotides relies mainly on solid-phase synthesis which is quite labor intensive and restricted to short sequences. Here, we explore the possibility of constructing biphenyl-modified DNA sequences using enzymatic synthesis. The presence of multiple biphenyl-units or biphenyl residues modified with electron donors and acceptors permits the incorporation of a single dBphMP nucleotide. Moreover, templates with multiple abasic sites enable the incorporation of up to two dBphMP nucleotides, while TdT-mediated tailing reactions produce single-stranded DNA oligonucleotides with four biphenyl residues appended at the 3'-end.

Preparation and characterization of DNA array slides via surface Michael addition

The reliability and stability of array slides are a big concern for array vendors and end users. Herein, we report on a new type of array slide with high reactivity toward DNA probes and low side reaction. A one-step surface reaction via the Michael addition involved in preparing array slides was developed and characterized by x-ray photoelectron spectroscopy, contact angle, and fluorescence labeling. The effects of array fabrication and storage conditions, i.e., spotting solution pH, high humidity, and long-term storage on the reactivity of the slides were examined. The fabricated DNA arrays could realize good hybridization efficiency (38.2% for slides with 0.88 pmol/cm²), low limit of detection (4 × 10^-14M), as well as high mismatch selectivity.