Two‐pronged attack: We describe the maturation of a bivalent aptamer by a chemically driven two‐step process. From an improved monovalent aptamer subdomain that had been modified by polycyclic aromatic hydrocarbons at individual positions, a mature bivalent variant with superior activities to its progenitor molecule was obtained through domain reassembly.

Twisted intercalating nucleic acid (TINA) has the ability to stabilize Hoogsteen triplex formation. New oligonucleotides containing 3‐(pyren‐1‐ylethynyl)indole as a DNA linked intercalator backbone have been added to the TINA family and their synthetic route has been devised. The indole ring, under acidic conditions, polarizes the triple bond in the intercalator and this makes hydration of the triple bond possible during the DNA synthesis and an oligonucleotide with 1‐(indol‐3‐yl)‐2‐(pyren‐1‐yl)ethanone as the intercalator is formed. Insertion of the unhydrated and hydrated linker systems gave characteristic UV spectra comparable to its monomeric diols due to π‐conjugated and isolated pyrene systems, respectively. Thermal denaturation profile at pH 6–7.2 showed excellent stabilization of the triplex upon insertion of 3‐(pyren‐1‐ylethynyl)indole when compared to wild‐type triplexes. The investigation includes fluorescence spectroscopic and molecular modeling studies.

Three or four aromatic rings interconnected by acetylene bridges form a stiff conjugated system with sufficient conformational freedom to make it useful to link together the two strands of a DNA clamp. Upon targeting a ssDNA, the conformational flexibility allows better stacking of the linker to the underlying non‐planar base triplet in the formed triplex. This type of triplexes has a substantially higher thermal melting temperature which can be further improved by inserting locked nucleic acids (LNAs) in the Hoogsteen part of the clamp. An extremely high sensitivity to mismatches is observed in an octamer triplex when placed in the middle of the sequence.