Issue 12, 2020

Platinum(ii) non-covalent crosslinkers for supramolecular DNA hydrogels

Abstract

Manipulation of non-covalent metal–metal interactions allows the fabrication of functional metallosupramolecular structures with diverse supramolecular behaviors. The majority of reported studies are mostly designed and governed by thermodynamics, with very few examples of metallosupramolecular systems exhibiting intriguing kinetics. Here we report a serendipitous finding of platinum(II) complexes serving as non-covalent crosslinkers for the fabrication of supramolecular DNA hydrogels. Upon mixing the alkynylplatinum(II) terpyridine complex with double-stranded DNA in aqueous solution, the platinum(II) complex molecules are found to first stack into columnar phases by metal–metal and π–π interactions, and then the columnar phases that carry multiple positive charges crosslink the negatively charged DNA strands to form supramolecular hydrogels with luminescence properties and excellent processability. Subsequent platinum(II) intercalation into DNA competes with the metal–metal and π–π interactions at the crosslinking points, switching on the spontaneous gel-to-sol transition. In the case of a chloro (2,6-bis(benzimidazol-2′-yl)pyridine)platinum(II) complex, with [Pt(bzimpy)Cl]+ serving as a non-covalent crosslinker where the metal–metal and π–π interactions outcompete platinum(II) intercalation, the intercalation-driven gel-to-sol transition pathway is blocked since the gel state is energetically more favorable than the sol state. Interestingly, the ligand exchange reaction of the chloro ligand in [Pt(bzimpy)Cl]+ with glutathione (GSH) has endowed the complexes with enhanced hydrophilicity, decreasing the planarity of the complexes, and turning off the metal–metal and π–π interactions at the crosslinking points, leading to GSH-triggered hydrogel dissociation.

Graphical abstract: Platinum(ii) non-covalent crosslinkers for supramolecular DNA hydrogels

Supplementary files

Article information

Article type
Edge Article
Submitted
21 nov. 2019
Accepted
12 feb. 2020
First published
05 mar. 2020
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2020,11, 3241-3249

Platinum(II) non-covalent crosslinkers for supramolecular DNA hydrogels

K. Zhang and V. W. Yam, Chem. Sci., 2020, 11, 3241 DOI: 10.1039/C9SC05910E

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