A G₄·K⁺ hydrogel that self-destructs

Abstract

A G4-quartet based hydrogel formed by self-assembly of borate esters of 5'-deoxy-5'-iodoguanosine (5'-IG 2) undergoes in situ cyclization to give 5'-deoxy-N3,5'-cycloguanosine (5'-cG 3). Formation of 5'-cG 3 causes self-destruction of the gel. This intramolecular cyclization can be used to release nucleoside analogs that have been pre-incorporated into the gel network.

Applications of guanine quartets in nanotechnology and chemical biology

“…c | Dynamic self-selection of aldehydes from (18) that provides the most stable gel 118 . d | Following gel formation, the cyclization of (21) to (22) triggers gel weakening and collapse, allowing the controlled release of acyclovir incorporated into the stacked guanosine (G)-quartet assemblies 124 . e | Biological application of a platinum-G-quartet-based hydrogel exhibiting photoactivatable anticancer properties 125 .…”

“…guanosine/bromoguanosine (20) (1/1) mixture 123 or 5′deoxy5′iodoguanosine (21) 124 . In the latter case, an intramolecular cyclization that forms 5′deoxyN3,5′cy cloguanosine (22) leads to gel breakdown, triggering the release of acyclovir (>80% release after 3 days) that had previously been incorporated into the stacked Gquartet assemblies through its guanine moiety (Fig.…”

Silver ions blocking crystallization of guanosine-based hydrogel for potential antimicrobial applications

“…The anti/syn conformation of the glycosyl bond was paramount to the canonical purine or pyrimidine nucleosides, which could be dened by the torsion angle c (O4 0 -C1 0 -N9-C4). The torsion angles c of F G d were measured to be À93.15 (33) , indicating that it adopted a normal anti conformation. Sugar puckering is another signicant conformational parameter dened by the pseudorotation phase angle (P) and maximum puckering amplitude (s m ).…”

“…Moreover, it was also a crucial structural parameter for the orientation of the 5 0 -hydroxyl group dened by the torsion angle g (O5 0 -C5 0 -C4 0 -O4 0 ) relative to the sugar ring. For F G d , it was in the ap (gauche, trans) range with the O5B 0 -OH at the axial position and pointing outside the sugar ring (g ¼ 61.98 (33) ). Secondly, as F G d has the same base moiety as guanosine, which has three faces with hydrogen bonding donors and acceptors, it can self-assemble into complex and unique supramolecular structures, such as dimers, ribbons, and tetramers.…”

“…[14][15][16][17][18][19] Although there has been a long history of guanosine-derivativebased hydrogels since Bang demonstrated the formation of gels with guanylic acid in 1910, [19][20][21][22][23][24] a major limitation of guanosinebased hydrogels was their poor lifetime stability owing to their crystallization within hours at room temperature, which hinders their latent applications in biological or pharmaceutical elds. 24 To overcome the above limitation, guanosine derivatives, [25][26][27][28][29][30][31][32][33][34] such as 5 0 -hydrazide-guanosine, 8-methoxy-2 0 ,3 0 ,5 0 -tri-O-acetylguanosine, and guanosine-borate esters, have been developed to improve the lifetime stability of hydrogels.…”