arms of the G-quartet may cause steric disruption to the stacking of G-quartets.
Reducing the molar ratio of 39 to 0.1 mol equiv. results in gelation. 39 shows
photocytotoxicity against cisplatin-resistant A2780C, human ovarian cancer cells,
with a photocytotoxic index <2, whereas 39 hydrogel exhibits more potent photocytotoxicity with a photocytotoxic index >5. Both Pt-DA and 39 hydrogels are
nontoxic towards normal cells. 39 hydrogel shows a great photocytotoxicity
selectivity factor (ratio of the activity between normal and cancer cells, >18). Such
high potency and selectivity provide a strong basis for development of gel materials
as photochemotherapeutic agents, with potential for localized immunogenic treatment of cancers.
N
N
N
N
O
N
H
H
H
N
N
N
N
O
N
H
H
H
N
N
N
N
O
N H
H
H
N
N
N
N
O
N
H
H
H
O
O
O
OH
B
O
O
O
O
O
HO
B
O
O
O
O
O
HO
B
O
O
O
O
O
HO
B
O
O
K +
O
OH
N
N
N
NH
O
H 2 N
O
HO
N
N
N
NH
O
NH 2
O
HO
N
N
N
HN
O
NH 2
N
H
O
O
Pt
O
N 3
N
N
HO
N 3
Self-assembly
O
O
O
HO
B
O
O
NH
O
O
Pt
O
N 3
N
N
OH
N 3
N
N
N
HN
O
NH 2
O
O
O
HO
B
N
N
N
HN
O
NH 2
O
O
O
OH
N
N
N
NH
O
H 2 N
+
40
HO
HO
NH
O
O
Pt
O
N 3
N
N
OH
N 3
39
KOH
B(OH) 3
Guanosine hydrate
H 2 O
K
+
K
+
Scheme 4.13 Synthesis of Pt-G 4 K
+ B 40 hydrogel
138
4 Dynamic Covalent Gels